SPUT LEVEl SORPTION REFRIGERATION SYSTEM
The present invention relates to a novel split level sorption refrigeration system. In
particular, the present invention provides a split level sorption· based system as a novel
method of using the traditional sorption based refrigeration unit. The present invention
particularly provides a novel split level adsorption system. The present invention offers
orientation free configuration with efficient cooling power delivery to the various tooling load
locations which is achieved by splitting tlie evaporator of the adsorption chiller from the
sorption beds and the condenser. The essential fo'cus of the invention is on separating the
functions of condensation and thermal compression from evaporation in the device, and in
particular, in optimizing refrigerant flow in the device, to enable a more functionally friendly
mode of operation. The invention also provides a method for split level sorption refrigeration
as is described hereinafter.
BACKGROUND OF THE INVENTION
There is a call for rapid development of environmentally friendly technologies,
because of environmental issues such as global warming, air and water pollution as well as
primary energy consumption for heating and cooling. Among them, low temperature heat
source driven or thermally powered adsorption systems are considered as one of the key
technologies as these systems can recover and reuse low temperature waste heat sources
typically below 100"C [1-3], which otherwise will be purged to the ambient.
There is a recognized need to replace existing mechanically or electrically driven vapor
compression based systems used for chilling or refrigeration purposes. Such systems typically
use gases such as hydrofluorocarbons (HFCs); The 2ih Meeting of the Parties to the Montreal
Protocol (MOP27) was held at UAE in 2015 and discussed about the regulations HFCs) under
the Montreal Protocol. Accordingly, there is an urgent need to replace the use of such
material in view of the deleterious effect they have on the environment. [1-3]
Mechanical refrigeration units are well known. These units work on a vapor
compression refrigeration cycle wherein the condenser unit and an evaporator unit are
connected to each other through an electric compressor and a refrigerant line. Such systems
typically use synthetic refrigerants such as Freons, chlorofluorocarbons (CFCs) and
hydrofluorocarbons (HFCs) as the working fluid. While vapor compression systems are
efficient and compact, t~e substances being used as workin~ fluid are increasingly being found
responsible for .a range of environmental problems including ozone layer depletion and global
warming, and have also have been found to be carcinogenic.
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The vapor compression system has essentially four main components: the electrically
driven compressor, a condenser, and a throttling valve/expansion device, and an evaporator.
In a unitary product these are all housed on/in a single frame/casing. In a split unit, there are
two main sub sections into which the above referred unitary product is divided. One is
referred to as the outdoor unit, or the condensing unit, which houses mainly the electric
compressor and the condenser, and the other is referred to as the indoor unit, or the cooling ·
unit. It is i~ this indoor or cooling unit that the evaporator section is housed along with a
throttling device.
Vapor compression systems, whether used as a unitary model or as a split level model,
essentially comprise a condenser unit to cool the working fluid down and to re-circulate it to
an evaporator unit that is in direct contact with the atmosphere/space/fluid to be cooled. The
evaporated working fluid, also referred to as the refrigerant, is returned back to the
condenser unit through an electric compressor unit. The power consumption levels of such
vapor compression based systems are also.high leading to a high carbon footprint.
Over the last several decades, split units with a remote/indoor heating/cooling unit
have become very popular, particularly up to 35 kW as a single split, and generally over 3 to 5
kW as multiple splits from a common outdoor condensing unit or outdoor VRFs referred to as
variable refrigerant units.
Heat operated cooling systems are known in the art which use vapor absorption or
vapor adsorption as the working principle. However, such systems are known only for unitary
(non-split level) units where the condenser and the evaporator units necessarily have to be ·
provided in the same housing in close proximity to each other. While these systems overcome
some of the disadvantages of synthetic refrigerant based systems, they suffer from the
disadvantage that they are useful/economical mainly for larger capacity (>30 RT capacity)
systems. The adsorption or absorption refrigeration cycle utilized in such systems comprises
replacement of the electric compressor of the mechanical refrigeration cycle with an absorber
or adsorber based heat exchanger. The absorber or adsorbers are referred to as thermal
compressors, as akin to the electric compressor, and if taken together with condenser section,
the two would be akin to the condensing unit of the conventional vapor compression unit or
system. While adsorption based cooling technology was developed a few decades ago, both,
the prohibitive cost and difficulty of making units in small capacities/Sizes have not made this
technology very viable. In the recent 5 to 10 years, two things have happened that are noteworthy.
For one, there has been a strong push to develop green .technologies. Government
3
support across the globe, new regulations, and fiscal incentives have made this possible,
particularly in the background of urgent need for C02 reduction based on enhanced usage of
renewal energy options, waste heat etc. and less reliance on synthetics refrigerants that are
used extensively in current electric vapor compression cooling machines.
Recent technological advancements have made it possible to reduce cost and size of
unitary adsorption units, and hence increase usage, particularly in the range of< 20 kW. In the
last 5 to 10 years, increasing commercial viability of smaller capacity adsorption cooling units
has led to a need in the art to go a step further and develop a split type adsorption cooling
unit comprising essentially of two parts, namely the condensing unit, comprising the thermal
compressor and condenser, and the indoor/remote evaporator section/unit comprising the
evaporator heat exchanger as well as the means to ~hrottle the liquid refrigerant.
However, despite the recent advent of commercially available adsorption units,
particularly under 20 kW, mainly in the last 4 to 6 years, there has been no apparent attempt
made to develop any split type adsorption units, where the evaporator section is remote from
the remaining components of the adsorption unit.
The unitary design of the adsorption or absorption systems imposes significant losses
arisen from heat transfer from the additional air handling unit which conveys the cooling load
from different sources to the evaporator of the adsorption chiller using the chilled water
circuit. The present invention improves the efficiency and reduces the capital cost of the
adsorption chiller by introducing split type adsorption system that eliminates the chilled water
circuit as well as orientation free cooling system.
PRIOR ART
Several different split type units have been postulated in the art related to
conventional vapor compression systems. US Patent Publication 2015/0192309. discloses a
split air conditioner having an indoor unit, an outdoor unit. The indoor unit is connected to the
outdoor unit by a horizontal bar thereby allowing the use of the windowsill as a support to the
split air conditioner. There is no reference to guidance towards use of an adsorption based
thermal compression method in this disclosure. On the contrary it focuses on improving the
mobility and flexibility in use of regular prior art room type split air conditian·ers. EP 0789201
discloses a split type air conditioner with an indoor unit and an outdoor unit. This disclosure
focuses on the control through a mechanical temperature device detector provided in the
outdoor unit to detect the frosted condition of the outdoor heat exchanger, and activate the
current transformer in the indoor drive circuit of the outdoor fan motor. Again there is no
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disclosure or guidance towards the use splitting of the evaporator component as well as
towards use of thermal compression. US Patent publication 2006/0042290 disdoses a split
type room air conditioner. The focus in this disclosure is on ensuring access of split type room
air conditioning to apartment buildings and condominiums. However, not only is there no
disclosure as to how this purported objective is achieved, there 'is no disclosure at all of any
specific compression means or to splitting the evaporator section.
The above representative disclosures show that while research is on in the area of split
type air conditioners, attention has not been paid to ensuring separation of evaporator
component and use of thermal compression means.
Similarly, several different adsorbent based cooling systems have been postulated in
the art for the adsorption type heating/cooling units. US Patent 8,590,153 discloses an
adsorption heat exchanger where an adhesive layer is formed on the heat exchanger structure
and the exchanger is then dipped into sorbent material to ensure adhesion thereof. US Patent
Publication 2012/0216563 discloses a heat exchanger wherein a porous material is provided in
contact with the tubular portion of the exchanger in order to allow vapor to pass through. The
material is a fibrous material. US Patent Publication 2013/0014538 discloses a sub-assembly
for an adsorption chiller, comprising an adsorption component including a multiplicity of
plates which are arranged in a stack. The refrigerant sides of adjacent pairs of the plates in the
stack define refrigerant passages and an adsorbent material is provided within these passages.
JP Patent Publication No. 2005-291528 discloses a heat exchanger with enhanced adsorber
capacity. The heat exchanger comprises a plate. fin tube type heat exchanger with a specific fin
pitch, fin length and fin height. Activated charcoal is used as a filler adsorbent wherein the
charcoal has specific steam adsorbing capacity. The bed so formed is covered by a net like
material to prevent leakage of adsorbent material.
None of the above disclosures provide any information or guidance towards a split
adsorption refrigeration unit wherein the evaporator component is kept remote from the
condenser and compressor units and wherein at least one compressor unit is a thermal
compression unit. To the best knowledge of the applicants herein, no apparent attempt has
been made to invent the split type adsorption unit with a remote cooling section nor have the
technical challenges been addressed to overcome the same.
SUMMARY OF THE INVENTION
The present invention provides a split level air conditioning system which utilizes a
two-or multiple-bed, single or multi-stage adsorption cycle or a single or multi stage
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absorption cycle as its working norm. In the present invention, the evaporator serves as both
the air handling unit and the evaporation unit of the adsorption/absorption chiller hence
effectively eliminating the chilled water circuit.
In one embodiment, the entire evaporator section, also referred to as· the indoor
unit/section, is decoupled from the main unit, leaving the outdoor unit, also referred to as the
condensing unit, which comprises the thermal compressor and the condenser.
In this embodiment, the evaporator tubes may be placed horizontally or vertically with
airflow, or the fluid to be cooled, on the external surface of the tubes, with or without
extended fins or enhanced surface, with refrigerant passing through and evaporating in the
tubes. In this embodiment, the evaporator and the adsorber beds or the absorber are
connected via single or multiple vapor ducts with the liquid condensate returning from the
condenser to the evaporator. A small liquid pump may be required require on the condensate
line to make orientation free especially where the evaporator unit is located higher than the
pressure difference between the evaporator and the condenser. This split type evaporation is
also applicable to different adsorbent/absorbent cum refrigerant pairs in combination with
various throttling/expansion devices and substitutes thereof, like throttling valves, orifices,
capillaries, metering devices, and the like.
This type of split evaporator, in this embodiment, is also applicable to mobile transport
units using adsorption or hybrid vapor compression/adsorption units.
In another embodiment, the heat exchanger tubes, normally copper or metal, typically .
provided in the evaporator section, are taken out and housed in a remote/indoor unit. Here,
the evaporator and adsorber/absorber beds are connected only by liquid refrigerant lines. A
liquid refrigerant pump is used to convey refrigerant between the evaporator and the pseudo
evaporator or the spray chamber. This results in the evaporator section becoming a cooling
section or pseudo-evaporator section. The term 'pseudo-evaporation' hereinafter refers to
the specific embodiment where the evaporation means is separated from the cooling section
and the evaporation means is housed, either with the condenser section or independentiy.
This type of split evaporator, is also applicable to different adsorbent/absorbent cum
refrigerant pairs in combination with various throttling/expansion devices and substitutes
thereof, like throttling valves, orifices, capillaries, metering devices, and the like.
This type of split evaporator, in this embodiment is also applicable to mobile transport
units using adsorption or hybrid vapor compression/adsorption units.
Therefore, the invention provides a split type air conditioning unit comprising:
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a first component containing one or more compression means wherein at least one
compression means is a thermal compression means, and a condensation means; and
one or more second component{s) separate from the first component each provided in a
dedicated housing and comprising an evaporation means;
each evaporation means being connected to the condensation means through one or
more refrigerant inlet line(s) and one or more refrigerant outlet line(s);
the one or more of said refrigerant outlet line(s) providing used refrigerant fluid from
each evaporation means through the one or more compression means to· the
condensation means;
the one or more refrigerant inlet line(s) conveying condensed refrigerant fluid to each
evaporation means from the condensation means.
In one embodiment of this invention, the compression means is selected from the group
consisting of an adsorption unit, an absorption unit, a hybrid vapor compression/adsorption
unit, and a hybrid vapor compression/absorption unit.
In another embodiment of this invention the compression means is an adsorption unit
or a hybrid vapor compression/adsorption unit.
In yet another embodiment of this invention the adsorbent used in case of an
adsorption unit or hybrid vapor compression/adsorption unit is selected from the group
consisting of zeolites, mesoporous silicates, insoluble metal silicates, silica gel type A, silica gel
type RD, silica gel type S2, activated carbon fiber, granular activated carbon, activated alumin~,
highly porous activated carbon, Zr60 4(0H)4 bonded with linkers, MIL-101Cr, metal-organic
frameworks (MOFs), ·covalent organic frameworks (COFs), functional adsorbent materials, and
the like, alone or in any combination thereof.
In yet another embodiment of this invention, the compression means is an absorption
unit or a hybrid vapor compression/absorption unit.
In another .embodiment of this invention, the absorption unit or the hybrid vapor
compression/absorption unit is provided with a refrigerant-absorbent mixture selected from the
group consisting of water-lithium bromide, ammonia-water, and the like.
In another embodiment of this invention the refrigerant is selected from the group
consisting of water, methane, methanol, ethanol, ammonia, propane, CFCs, 134A, and the. like.
In another embodiment of the invention, each refrigerant inlet line(s) is provided with
one or more refrigerant flow control means selected from different types of throttling/
expansion devices, such as expansion valves, capillaries, P~traps, and metering devices.
7
In another embodiment of this invention, the evaporator(s) are selected from the group
consisting of falling film tubular (horizontal/vertical), rising/falling film tubular, forced circulation
(tubular/plate), plate-type, falling film plate, and forced circulation, and any combination
thereof, all with or without enhanced surface treatment for aiding surface evaporation.
In another embodiment of this invention, the split unit when containing an adsorption
unit or hybrid vapor compression/adsorption unit, is mountable on any vehicular device.
In another embodiment of this invention, the heat exchange tubes from the evaporator
are taken out and located in a separate split indoor/remote/cooling unit, and a pseudo
evaporation means is employed in the outdoor unit to cool the refrigerant to supply to the split
indoor/remote/cooling unit.
This invention also provides a split type air conditioning unit comprising:
a first component containing one or more compression means wherein at least one
compression means is a thermal compression means, and a condensation means, and a
pseudo-evaporation means; and
one or more second component(s) separate from the first component each provided in a
dedicated housing and comprising a cooling means;
each cooling means being connected to the pseudo evaporator means through one or
more liquid refrigerant supply and return line(s);
the one or more of said liquid refrigerant return line(s) providing discharged liquid
refrigerant from each cooling means to the pseudo ·evaporator means, wherein the
liquid portion of discharged refrigerant is returned to the pseudo evaporator means, and
vaporized refrigerant from the pseudo evaporator is directed to the condenser through
the compression means for condensation and recirculation.
In one embodiment of this invention, the compression means is selected from the group
consisting of an adsorption unit, an absorption unit, a hybrid vapor compression/adsorption
. unit, and a hybrid vapor compression/absorption unit.
In another embodiment of this invention the compression means is an adsorption unit
or a hybrid vapor compression/adsorption unit.
In yet another embodiment of this invention the adsorbent used in case of an
adsorption unit or hybrid vapor compression/adsorption unit is selected from the group
consisting of zeolites, mesoporous silicates, insoluble metal silicates, silica gel type A, silica gel
type RD, silica gel type 52, activated carbon fiber, granular activated carbon, activated alumina,
highly porous activated carbon, Zr60 4(0H}4 bonded with linkers, MIL-101Cr, metal-organic
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frameworks (MOFs}, covalent organic frameworks (COFs}, functional adsorbent materials, and.
the like, alone or in any combination thereof.
In yet another embodiment of this invention, the compression means is an absorption
unit or a hybrid vapor compression/absorption unit.
In another embodiment of this invention, the absorption unit or the hybrid vapor
compression/absorption unit is provided with a refrigerant-absorbent mixture selected from the
group consisting of water-lithium bromide, ammonia-water, and the like.
In another embodiment of this invention the refrigerant is selected from the group
consisting of water, methane, methanol, ethanol, ammonia, propane, CFCs, 134A, and the like.
In another embodiment of this invention, the pseudo evaporator unit has an
evaporation means selected from the group consisting of falling/sprayed film over a component
with considerably expanded surface area of the type cooling tower fill, wire mesh wool, metal or
inorganic fiber foam, and the like.
In another embodiment of the invention, the cooling unit has a heat exchanger selected
from a traditional tube fin heat exchanger and enhanced tube heat exchanger.
In another embodiment of this invention, the split unit when containing an adsorption
unit or hybrid vapor compression/adsorption unit, is mountable on any vehicular device.
BRIEF DESCRIPTION OF ACCOMPANYING DRAWINGS
The invention will be described in greater detail below inter alia, with reference to the
accompanying drawings, where:
unit.
Figure 1 is a depiction of prior art typical vapor compression unit or air conditioning
Figure 2 is a depiction of prior art typical adsorption cooling/air conditioning unit.
Figure 3 is a depiction of a prior art typical. absorption cooling/air conditioning unit.
Figures 4A and 4B are schematic depictions of a hybrid vapor compression/ adsorption
cooling/ air conditioning unit.
Figure 4C is a schematic depiction of a hybrid vapor compression/absorption
cooling/air conditioning unit.
Figure 5 is a schematic- depiction of a typical split vapor compression cooling/air
conditioning unit.
Figure 6 is a block diagram of the broad embodiment of the invention depicting the
isolation/remoteness of the cooling/indoor/remote unit from the' remaining components of
the device while retainin~ functional connectivity.
9
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Figure Ta is a schematic depiction of the split technology of the invention when
applied to an ·adsorption cooling/air conditioning unit with the evaporator and evaporator
tubes housed in a remote/indoor/cooling unit.
Figures 7a(i), 7a(ii)and 7a(iii) are schematic depictions in detail of the split technology
· of the invention when applied to an adsorption cooling/air c~nditioning unit.
Figure 7b is a schematic depiction of the split technology of the invention when
applied to an adsorption cooling/air conditioning unit, wherein the cooling section is provided
remote from the evaporation means.
Figure 8a is a schematic depiction of the split technology of the invention when
applied to an absorption cooling/air conditioning unit with the evaporator and evaporator
tubes housed in a remote/indoor/cooling unit.
Figures 8a{i), 8a{ii) and 8a{iii) are schematic depictions in qetail of the split technology
of the invention when applied to an absorption cooling/air conditioning unit.
Figure 8b is a schematic· depiction of the split technology of the invention when
applied to an absorption cooling/air conditioning unit, wherein the cooling section is provided
remote from the evaporation means.
Figure 9a is a schematic depiction of the split technology of the invention when
applied to a hybrid vapor compression/adsorption cooling/air conditioning unit with the
evaporator and evaporator tubes housed in a remote/indoor/cooling unit.
Figures 9a(i), 9a{ii) and 9a(iii) are schematic depictions of split technology of the
invention when applied to hybrid vapor compression/adsorption cooling/air conditioning unit.
Figure 9b is a schematic depiction of the split technology of the invention when
applied to a hybrid vapor compression/adsorption cooling/air conditioning unit, wherein the
cooling section is provided remote from the evaporation means.
Figure lOa is a schematic depiction of the split technology of the invention applied to
another embodiment of hybrid vapor compression/adsorption cooling/air conditioning unit
with evaporator and evaporator tubes housed in a remote/indoor/cooling unit.
Figures lOa(i), 10aii} and 10a(iii} are schematic depictions in detail of the split
technology of the invention when applied to another embodiment of a hybrid vapor
compression/adsorption cooling/air conditioning unit.
Figure lOb is a schematic depiction of .the split technology of the invention when
applied to another embodiment of a hybrid vapor compression/adsorption cooling/air
conditioning unit, wherein the cooling section is provided remote from evaporatiol) means.
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Figure lla is a schematic depiction of the split technology of the invention when
applied to a hybrid vapor compression/absorption cooling/air conditioning unit with the
evaporator and evaporator tubes housed in a remote/indoor/cooling unit.
Figures 11a(i), lla(ii) and 11a(iii} are schematic depictions in detail of the split
technology of the invention when applied to a hybrid vapor compression/absorption
cooling/air conditioning unit.
Figure llb is a schematic depiction of the split technology of the invention when
applied to a hybrid vapor compression/absorption cooling/air conditioning unit, wherein the
cooling section is provided remote from the evaporation means.
DETAILED DESCRIPTION OF THE INVENTION
The present invention will now be described with reference to the accompanying
drawings.
In the present application, the term 'indoor unit' and cooling unit' when used with
reference to the present invention, are used interchangeably. Specifically, the term 'pseudoevaporation'
refers to the various embodiments wherein the indoor/cooling unit is provided
remote from the evaporation means, which can be combined with either with the condenser+
compressor section or provided separately.
The invention essentially resides in 'splitting' or separating the indoor/cooling
section/unit from the condensing unit, wherein at least one of the compression means used is
a thermal compression means.
If desired, the indoor/cooling section can be further 'split' such that the cooling
section is provided remote from the evaporator means. This specific embodiment is termed
the 'pseudo-evaporator' or 'pseudo-evaporation' means/mechanism in this document.
Figure 1, as stated above is a depiction of a prior art typical/traditional vapor
compression unit of an air conditioning unit which uses a typical vapor compression
refrigeration cycle. In this, several types of refrigerants can be used, most being CFCs or
synthetics refrigerants, all having a direct impact on C02 production as well as contributing to
global . warming. Also these use electrical energy directly, which also is the focus for
consumption reduction as the majority of electrical production is based in fossil fuels heavily
contributing to C02 production and global warming.
A typical/traditional vapor compression unit based air conditioning unit essentially
consists of an evaporator component 4, an electric compressor 1 and a condenser component
2. Both the evaporator unit 4 and the condenser unit 2 can be provided with respec:tive fans 7
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and 8 for ensuring input of air therein. In the case ofthe condenser unit 2, when provided as
an air-cooled condenser, the condenser fan 7 inputs ambient (outside) air 9 in and expels
warm air out 10. In the case where an air cooled evaporator is provided, the evaporator unit 4
has an evaporator fan 8 to draw in room warm return air 11 and ensure expulsion of
cool/chilled air 12 to the space to be cooled. A suction line 13 is provided connecting the
evaporator 4 to the condenser 2 through an electric compressor 1. The function of the suction
· line 13 is to transport the refrigerant back to the condenser unit 2. The condensed refrigerant
is recirculated to the evaporator unit 4 from the condenser unit 2 through a liquid flow line 15
provided with an expansion valve 6 or a device or a means that reduces the refrigerant
pressure and controls the amount of refrigerant flow into the evaporator 4, thereby
controlling the superheating at the outlet of the evaporator 4. The functioning of this prior art
system is explained below. The significant feature of this system is that it is unitary, in that
both the condenser component 2 and evaporator component 4 are provided in the same
housing 17.
In a typical vapor compression refrigeration cycle, the electrical compressor 1
compresses the refrigerants gas to an elevated pressure which moves on to the condenser
section 2. In the condenser 2, the compressed gas liquefies on cooling as the heat of
compression is extracted by cooling means dependent of ambient air 9 or cooling water. The
liquefied refrigerant gas than moves on to a throttling device, referred to as an expansion
valve6 or capillary, or orifice, where the pressure is reduced and temperature lowered. The
liquid to gas phase change takes place in the heat exchanger 5 referred to as the evaporator 4.
This latent heat of vaporization is given off as a cooling effect to a fluid which is cooled in
coming contact with the evaporator heat exchanger 5. This vapor in a gaseous form travels to
the compressor 1 and is again compressed, repeating the cycle.
Figure 2 is a schematic depiction of a prior art adsorption based cooling/air
conditioning unit. In the adsorption cooling system/unit, the electric compressor of a vapor
compression based unit is substituted by a thermal compressor comprising of two or more
alternating adsorber beds 1 and lA. These adsorber beds 1 and 1A are filled with various types
of adsorbents 27 coming from a family of silica gel, zeolites, molecular sieve, activated carbon,
MOFs, COFs, FAMs, and other new types of adsorbents under development.
As can be seen in Figure 2, thermal compression based air conditioning unit essentially
consists of an evaporator component 4, a compressor component consisting of two
alternating adsorbent reactors 1 and lA, and a condenser component 2. The condenser unit 2
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utilizes a cooling fluid such as water 9 circulating through a cooling means therein which is
introduced through an and ejected through an outlet 10. The evaporator unit 4 is connected
to the condenser unit 2 through two separate lines each running through an independent
adsorbent reactor. The two adsorbent reactors 1 and lA are each provided with respective
inlets for cool water 23 and outlets for warm water 24, and function alternatively at a
determined time cycle as described hereinbelow. Two way valves 18,19,20 and 21 are
provided on each line before and after the adsorbent reactors 1 and lA to ensure no return
flow of the used refrigerant to the evaporator unit 4. The condensed refrigerant is returned to
the evaporator unit 4 from the condenser unit 2 through a liquid flow line 15 provided
typically with a P-trap. ·
The significant feature of this system is that it is unitary, in that both the compression
component/adsorbers land lA, the condenser component 2, and evaporator component 4
are provided in the same housing 17.
As explained above, adsorption heat exchangers 1 and lA typically comprise a heat.
exchanger 22 and 22A structure which is used for supplying and discharging thermal energy and
is in a thermal contact with a sorbent material 27 which uses a phase change ofan adsorbate
working medium for binding and releasing latent heat. Heat is released through the adsorption
of a vaporous working medium. Conversely, the thermal energy supplied via the heat exchanger
structure 22 and 22A can be used for renewed vaporization of the adsorbate.
Various types of adsorbent reactor 1 and lA types are known, as are various
adsorbent/refrigerant pairs.
In the adsorption type refrigeration unit, the adsorbent and the refrigerant are
generally referred to as an adsorbent cum refrigerant pair. Whilst silica gel and water and
molecular sieve and water, are the most commonly used pairs as well as green and safe·
refrigerant pairs, several other refrigerant pairs like zeolite and water, activated carbon ·and
ethanol, activated carbon and propane [4-9] are under usage and investigation, and product
development.
In a typical adsorption cooling unit cycle, cooling energy is extracted from the
refrigerant evaporation via the mass transfer process from the evaporator 4 to the adsorber
bedlduring adsorption process. This process is normally termed as adsorption-assistedevaporation.
The uptake potential by the unsaturated adsorbent materials initiates the
evaporation of the refrigerant in the adsorption process. This is an exothermal process and
thus external cooling is required for the rejection of adsor.ption heat maintaining the
13
adsorption process. Once the adsorbent materials become saturated with the refrigerant or
the preset cycle time is reached, they are isolated from the evaporator 4 and are preheated
using external heat source increasing the pressure of the system. Once the pressure reaches
to the condenser pressure or the pre-set time, the adsorber bed is then commuted to the
condenser -2. The continuous heating of the adsorbent resulted in the regeneration process
and the ·desorbed vapor is condensed inside the condenser 2. At the completion of the
desorption process, the adsorber is cooled down using external cooling circuit whilst isolating
it from the condenser 2. The adsorbent materials undergo the adsorption-evaporation process
and the cycle completes. In practical adsorption system, multi-bed approach is adopted to get
continuous useful effect where one or a cluster of beds performs adsorption process whilst
the oth!=r undergo desorption process [10, 11L
Adsorption based systems are driven by the adsorption and desorption ·of an
adsorbate vapor by a porous solid adsorbent 27. In contrast to conventional vaporcompression
cooling systems which are driven by a mechani.cal compressor, no electrical
energy is needed to drive the adsorption cycle. The basic cycle involves an adsorption phase
and desorption phase. In the adsorption phase, the refrigerant vapor is adsorbed by the
adsorbent substance 27 resulting in the release of heat. In the desorption phase, heat is
applied to the adsorbent 27 causing desorption of the refrigerant. The heat transferred during
these processes is conveyed by a heat exchanger 22 and 22A between the adsorbent 27 and a
heat transfer fluid (e.g. water or methanol or a water-glycol mixture) or an external
environment. The adsorption and desorption processes occur in conjunction with evaporation
and condensation of refrigerant in an evaporator 4/condenser 2. The adsorption of the
gaseous refrigerant lowers the vapor pressure, promoting evaporation of the liquid refrigerant
in the evaporator 4. During this evaporation, heat is extracted from an environment to be
cooled, resulting in refrigeration. By supplying heat to the adsorbent 27 via the heat
exchanger 22 and 22A, the adsorbed refrigerant is released into the vapor phase, thus
regenerating the adsorbent material 27' for the next adsorption cycle. The resulting gaseous
adsorbate passes to a condenser 2 where heat rejection to the environment takes place. As in
conventional vapor-compression cooling, the liquid refrigerant is passed through a concentric
syphon, or a P trap or the like back into the evaporator 4, and the cycle can then be repeated.
Figure 3 is a schematic depiction of an absorption based cooling system. As is shown
therein, in the absorption cooling unit, the electric compressor is substituted by a thermal
compressor/section 1, but based on the principal of absorption. The adsorbent pairs used in a
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------------------------------------------------
typical absorption unit are water+lithium bromide 27 or ammonia+water, both considered
both highly toxic and corrosive.·
In the typical absorption chiller {cooling} unit, the evaporator 4 is provided proximate
to the absorber section 49. The evaporator unit 4 has an inlet 12 and an outlet 11 for chilled
water. The absorber unit comprises an absorber bed 37 with a line in 9 for flow of cooling
water which then leads to the condenser unit 2. The condenser unit 2 has an outlet 10 for
cooling water. A_ generator 36. is provided proximate to the condenser 2 and provided with
inlet means 25 and outlet means 26 for hot fluid. A heat exchange means is provided in
operative association with the evaporator 4 and the absorber section 49.
Figures 4A & 4B are schematic depictions of a hybrid vapor compression/adsorption
cooling/air conditioning unit, which are proprietary to the applicants herein, and are disclosed in
co-pending Indian Patent application 2154/DEL/2015, whose disclosure is deemed included
herein by reference, for the sake of brevity.
In particular, Figure 4A encompasses a device wherein heat from the adsorption bed of
the adsorption cycle is pumped to the desorption bed using the compression cycle.- In other
words, the evaporation process of the vapor compression cycle is utilized to maintain the
adsorption process which is an exothermic process. The condensation heat from the adsorption
cycle and the energy from the vapor compression cycle i.e., the compression energy can be
rejected to ambient through a water- or air-cooled heat exchanger.
In Figure 4B, heat from both the adsorber bed 39 and the condenser 2 is pumped to
desorber bed 39A. The excess energy i.e., the evaporation energy of the adsorption cycle and
compressor 1 power of the MVC cycle is rejected at the desorber 39A and to an external cooling
devices by further cooling down the refrigerant that comes out from the desorber bed 39A.
In both configurations, cooling energy is extracted from the evaporator 4 of the
adsorption cycle whilst the condensation heat of the adsorption cycle and the compressor 1
work is rejected at the heat rejection devices such as cooling tower
Figure 4Cis a schematic depiction of a hybrid vapor compression/absorbent system,
which are proprietary to the applicants herein, and are disclosed in co-pending Indian Patent
application 2154/DEL/2015, whose disclose is deemed include herein by reference for the
sake of brevity. The evaporator 4 is provided proximate to the absorber section 49. The
evaporator unit 4 has an inlet 12 and an outlet 11 for c_hilled water. The absorber unit
comprises an absorber bed 37 with a line in 9 for flow of cooling water which then leads to the
condenser unit 2. The condenser unit 2 has an outlet 10 for cooling water. A generator 36 is
... ""C! :: "']:' .. ~
...D::;-"- .. .=e:··o
15
provided proximate to the condenser 2 and provided with inlet means 25 and outlet means 26
for hot fluid. A heat exchange means 35 is provided in operative association with the
evaporator 4 and the absorber section 49. As can be seen the entire system is unitary, i.e. it is
provided in a single unitary housing. The evaporation process of the vapor compression cycle
is utilized to maintain the absorption process. The condensation heat from the absorption
cycle and the energy from the vapor compression cycle i.e., the compression energy can be
rejected to ambient through a water- or air-cooled heat exchanger.
Figure 5 is a schematic depiction of a typical split vapor compression cooling/air
conditioning unit. The fundamental distinction between the device of Figure 5 and the device
of. Figure 1 is that the evaporator unit 4 is kept remote. However, the compression unit
remains an electrically driven compressor unit 1 utilizing CFC's and/or synthetic refrigerants.
The parts of the device represented in Figure 5 bear the same reference as the corresponding
portions of the device of Figure 1. The housings for the evaporator unit and the
condenser/compressor unit are labeled as 20 and 21 respectively.
While the refrigeration cycle described in Figure 1 has been known for several years
since the invention of the first cooling unit, the usage of an electric compressor 1 based split
air-conditioning unit has taken place only over the past 30-40 years, particularly in capacities
below 30 kW. In this split type of unit, the evaporator section 4 is housed separately in an
indoor unit referenced in Figure 5.
The present invention essentially resides in isolating geographically the indoor/cooling
unit which supplies the cool supply air 12, either wholly br in part, from the condensing unit
32. For example, the scope of the invention includes both separation of the entire cooling unit
33 from the condensing unit 32, and connecting the two through a thermal compressor 1
provided in the same housing as the condenser 2.
Alternatively, it is within the scope of the invention to provide the cooling section as
)
two parts - a direct cooling/indoor/remote unit 33 which supplies cool supply air 12, and
which is fed with cooled liquid refrigerant from pseudo evaporator means in the main outdoor
unit. This pseudo evaporator can be included in the same housing as the condensing unit 32
comprising the thermal compressor 1 and the condenser 2, or as a separate unit altogether.
Figure 6 is a block diagram of the broad underlying inventive concept in the device
encompassed in this application. As can be seen, cooling /indoor/remote u·nit 33 is provided
as a remote/separate unit but connected functionally with the thermal compressor 1 and then
the condenser 2. The compressor unit 32 comprises at least one thermal compressor 1,
1! ~ ""'T. .., "'S:" .,("""'~ ..H: ;·- .. ..J·~~
16
. I
whether of adsorbent type or absorbent type. The dashed box lines 32 surrounding the
condenser2and compressor 1 units denote that both units are generally in one housing, but
can also be provided in separate housings. The cooling/indoor/remote unit 33 essentially
comprises the cooling portion which assists in the delivery of cool air 12 to the space to be
cooled. This unit may include evaporator 4 tubes in one of the embodiments. Alternatively,
the cooling portion can be provided remote from the pseudo evaporator unit 48. The pseudo
evaporator 48 is depicted through a dotted circle.
Figure 7a is one schematic depiction of the device of the invention wherein the split
indoor/cooling/remote unit 33 is geographically isolated from the condensing unit 32 in a
separate housing. While the figure shows the condenser 2 and the adsorbent reactors 1 and
1A in the same housing, it must be understood that they can also be isolated/remote from
each other. Essentially, the liquid refrigerant is supplied to the split indoor/cooling/remote
unit 4 from the condenser unit 2 through an independent line 15. Generally, a P trap or a
concentric syphon or the like is included. The split remote/cooling/indoor unit 33 is supplied
with room return warm air 11 through a fan 8. The split cooling/remote/indoor unit 33
chills/cools the room return warm air 11 and converts it to supply air 12 for the space to be
cooled. The refrigerant is returned back to the condenser 2 through a thermal compression
unit having two or more adsorbers 1 and 1A working in pre-determined time cycles.
Each adsorber 1 and 1A is provided with an inlet for cooling water 23/26 and an outlet
for warm water 24/25. The two adsorbers work in tandem time cycles which are predetermined
as discussed below. Each adsorber/thermal adsorber/thermal compressor is
provided with dedicated non-return type valves 18, 19, 20 and 21 to transport the refrigerant
received from the evaporator 4 to the condenser unit 2.
As stated above, in the device of the invention, the compressor unit used in prior art
mechanical refrigerant systems is replaced by a dual pair of thermal compressor units 1 and
1A. Unlike a compressor which runs continuously, the two adsorbers work alternatively to a
given cycle time, say 3-15 minutes. Another advantage of the present split level system is that
the two adsorbent reactors 1 and 1A, the condenser 2 and the evaporator 4 unit are not
housed in a single casing - and are actually provided in separate housings alan~ with nonreturn
valves 18, 19, 20 and 21. The working pair can be silica gel/ zeolite/ MOF/ COF/ FAM
(adsorbent)+ water (refrigerant), both being very inert and environmentally friendly. With the
above working pair, the machine operates under a vacuum between 6,000 (6.0 TORR) micron
and 50,000 (50 TORR) micron, depending upon the operating design parameters.
;--::e.,~; ;;;~
~·:-;: ;;:_ n·- ~
17
In this adsorption based refrigerant cycle, the chilled water to be cooled provides the
heat to the refrigerant to boil off and vaporize driving it towards the adsorber through the
interconnecting valve V4/21 or Vl/21, depending on which adsorber is undergoing adsorption
process. The refrigerant on evaporation cools the incoming water to provide outgoing chilled
water. The vapor (adsorbate) continues to be adsorbed in the adsorbent in the adsorber .heat
exchanger 22. Nearing useful working capacity, the adsorber cycle is completed. During this
period cooling water is proviped into the adsorber heat exchanger 22 so as to extract and take
away the heat generated during adsorption. At the end of the cycle, the valve 20 between the
split indoor/cooling/remote unit 4 and adsorber 1 is closed and the valve 19 between adsorber ·
lA and condenser 2 is open, and hot water flows through the adsorber heat exchanger 22A to
provide the .heat for desorption of the adsorbate from the adsorbent 27, driving it to the
condenser 2.
Hot refrigerant, as vapor, under pressure enters the condenser 2 where external cooling
water extracts the heat thereby liquefying the refrigerant and having it flow by gravity to the
evaporator 4 on a continuous basis. At the end of the adsorption cycle, the next adsorber comes
into play becoming now the adsorber, just as explained earlier; after completion of the
adsorption cycle the adsorber switches its mode and become the desorber. The· cycle time,
between 3"'15 minutes, will depend upon the heat exchanger, the kinetics of the adsorbate onto
the adsorbent, the temperature of the regenerating hot water, and the type of adsorbent used,
and the cooling water temperature.
The devices depicted in Figure 7a(i),(ii) and (iii) differ mainly in the type, design, and
construction of the evaporator
The vacuum type evaporator houses a special falling film evaporator heat exchanger
providing an efficient means of evaporating the liquid refrigerant water, under vacuum, to gas
phase. The falling film evaporator 5, as shown is only one example, and other types of heat
exchangers for evaporation can also be applied. Typically, in the evaporator5under review,
water in vapor form is returned to the main unit at approximately 5-7°C.
Combined with the evaporator unit 5 is a P-trap which prevents the vaporized gas
from pushing back the liquid to the condenser 2 of the main unit. In the evaporator 5, the
evaporator tubes through which the refrigerant is flowing, falling, and getting vaporized are
shown as vertical. However,· this is not essential or mandatory, and horizontal or inclined
tubes can also be ·configured. In either case, usage is generally made of extended fins for
enhanced tube surface for more efficient heat exchange with air flow to be cooled. The
18
evaporator 5 as shown has a refrigerant sump and a small liquid pump 44 to circulate and
spray the refrigerant for flow into the tubes.
In another embodiment of the invention depicted in Figure 7b, the compression
means, along with the condenser means can be segregated, thereby isolating just the split
indoor/remote/cooling unit 33 into an indoor unit for supply of air 12 to the space to be
cooled. These embodiments/components are described in detail below and referred to as:
(a) split remote/indoor/cooling unit 33 fed with cooled liquio refrigerant from main
adsorption unit, and
(b) main adsorption unit 32 comprising thermal compressor 1 and 1A, condenser 2 and
pseudo evaporator 48.
The adsorber unit can utilize any known adsorbent-refrigerant pairs. The following
working principle is with reference to a silica gel-water pair since this is most commonly and
prominently used. In case of the .silica gel-water pair the pseudo evaporator has to operate
under negative pressure.
The split indoor/ cooling/ remote unit 33 depicted schematically in Figures 7a(i), 7a(ii),
7a(iii) and 7b describe the configuration for a one-ton remote unit, with the main unit also
having a cooling capacity of 1 RT (3.5 kW). Since water has a very high latent heat of
vaporization, the liquid line from the main unit to the split cooling/remote/indoor unit 33 is
designed to be small in diameter, at a temperature of approximately 30-35°C.
. /
In Figure 7b the fan coil unit 33, which is remote is fed with liquid {water) refrigerant,
from the main adsorption unit which is remote or outdoor. The indoor unit 32, as shown, is
complete with extended fin type heat exchanger, air filter arid blower along with motor and
condensate drain pan. For this type of indoor unit, cold refrigerant liquid water (chilled water),
say at 7°C and the liquid water after the heat exchanger, say at i2°C is returned to the main
unit into a pseudo evaporator 48 from which the heat exchanger tubes have been taken out
altogether. As shown in Figure 7b, the main unit traditional evaporation section from where
the tubes have been removed is replaced/substituted/occupied by i3 cooling tower fill type
arrangement, or any other equivalent suitable arrangement to continuously generate low
· temperature water liquid at approximately 7°C to the split remote/indoor/cooling unit 33. The
return water at approximately 12°C, along with the return condensate from the condenser 2,
is continuously supplied on to the pseudo evaporator 48. In the case of this cooling unit,
typically for 1 RT, the liquid line from the main unit sump will need to carry liquid water at 2.4
:t:"'=i.. :--. li It ii. ~
~~n::~ t:... ~~--- ~
19
USGPM at approximately 7°C and the typical return water temperature to the unit will be
approximately 12°C.
Figure 8a is a depiction of the application of the 'split' concept of the invention to an
absorption chiller system. Unlike the typical absorption chiller (cooling} unit. where the
evaporator 4 is provided proximate to the absorber section 49, in the present invention, the .
split indoor/remote/cooling section 33 is segregat~d and provided in an independent housing
33. The split cooling/indoor/remote unit 33 is functionally connected with the main housing
containing the absorber unit 49 and the heat exchanger 35. A separate line conveys the
refrigerant liquid from the condenser unit 2 to the split remote/indoor/cooling unit 33. The
warmed up vaporized refrigerant is conveyed out to the absorber unit. Cool supply air 12 is
provided to the room by means of an evaporator fan 8 provided in the evaporator housing 33.
The construction of the condenser 2, generator 36, absorber section 49 and heat
exchanger section 35 can remain the same as in the art. The absorber unit comprises an
absorber bed 37 with a line in for flow of used refrigerant from the indoor/remote/cooling
unit 33, which is then fed to the condenser unit 2. The condenser unit 2 has an outlet 10 for
cooling water. A generator 36 is provided proximate to the condenser 2 and provided with
means to inlet 25 and outlet 26 the hot fluid. A heat exchange means 35 is provided in
operative association with the evaporator 4 and the absorber section 49.
The devices depicted in Figure 8a(i}, (ii) and (iii) differ mainly in the type, design, and
construction of the evaporator.
Figure 8b is a depiction of an absorber based system wherein the pseudo evaporator
48 concept is utilized. As earlier, the evaporator means 5 and the split indoor/remote/cooling
section 4 are kept remote from each other. The evaporation and chilling function is carried out
at one level at the heat exchange tube unit 5. The chilled refrigerant liquid is introduced from
this unit to the evaporator/cooling section 4, utilized for chilling the room warm r~turn air 11
and dispelling cool supply air 12 to the space to be cooled. The used refrigerant fluid is then
recycled back to the pseudo evaporator unit 48. The liquid portion is returned to the sump of
the pseudo evaporator 48. The vaporized portion of the refrigerant is conveyed to the
condenser section 1 wherein it is condensed, and then recycled for use back to the pseudo
evaporator 48.
Turning now to Figures 9a and lOa, they depict alternative mechanisms for a split hybrid
vapor compression/adsorption system. Figure 9a depicts a system. wherein heat from the
adsorption bed 39 of the adsorption cycle is pumped to the desorber bed 39A using the
20
compression cycle. In other words, the evaporation process of vapor compression cycle is
utilized to maintain the adsorption process which is an exothermic process. Condensation heat
from adsorption cycle and energy from the vapor compression cycle i.e., the compression
energy can be rejected to ambient through a water- or air-cooled heat exchanger 38.
In Figure lOa, heat from both the adsorber bed 39 and the condenser 2 is pumped to
desorber bed 39A. The excess energy i.e., the evaporation energy of the adsorption cycle and
compressor power of the MVC cycle is rejected at the desorber 39A and to an external cooling
device by further cooling down the refrigerant that comes out from the desorber bed 39A.
In both configurations, cooling energy is extracted from the evaporator 4 of the
adsorption cycle whilst the condensation heat of the adsorption cycle and the compressor 1
work is rejected at the heat rejection devices such as cooling tower.
The condensation process of the vapor compression cycle provides the heat source for
the regeneration process of the adsorption cycle working in desorption mode. Thus, the
combined cycle essentially eliminates th.e cooling and heating circuits to the adsorber beds 39
and 39A of a conventional adsorption cycle and the system becomes significantly compact,
portable and operational by electrically-driven compressor l.The method of cooling and heating
for adsorption, condensation and regeneration of adsorption cycle is applicable to any kind of
adsorbent+adsorbate pairs.
The combined cycle discussed hereinabove provides superior coefficient of performance
{COP) as compared to either conventional vapor compression cycle or adsorption cycle. The
switching between the adsorber beds 39 and 39A for the 'evaporation and the condensation of
the vapor compression cycle is achieved using a 4-way valve 50 whilst a 3-way valve 51 is used
for the rejection of the condensation energy from the adsorption cycle as depicted in Figure 2.
The split hybrid vapor compression/adsorption system adsorption cycles can range from
two adsorber beds 39 and 39A to multi-bed systems such as 3-bed or 4-bed. For multi-bed
scenarios, the refrigerant for the cooling and heating can be distributed to the adsorber beds 39
and 39A accordingly, thus realizing adsorption and desorption processes.
Various material pairs (water-silica gel, water-zeolite etc.) can be used in the adsorption
cycle, which typically operates in vacuum and is independent from the vapor compression cycle.
This adsorption cycle system solely uses the heat from the condenser which otherwise is
rejected to the ambient. Refrigerant fluids never mix to each other. The vapor compression
system is utilized for cooling the adsorber bed and heating the desorber bed completely,
thereby eliminating external cooling and heating for the adsorbers. Cooling load is extracted
21
from the evaporator 4 of the adsorption cycle. The evaporation temperature of the MVC cycle is
raised to adsorption temperature whilst condenser 2 of the refrigeration occurs at desorption
temperature. The system has two separate refrigerant circuits namely one for adsorption cycle
and the other the MVC cycle.
As can be seen the embodiments of figures 9a and lOa differ essentially iti that in the
latter heat from both the adsorption bed and the condenser 2 are pumped to the desorption
bed 39A, whereas in the fanner, only the heat from the adsorption bed 39 is pumped. In both
sub-embodiments, the split indoor/remote/cooling section 4 is remote and housed separately
from the other components of the system. The split indoor/cooiing/remote unit 4 is
operatively connected to the heat exchangers 38 and 38A for return of refrigerant gas and to
the condenser 2 for inlet of refrigerant fluid 15.
Figure 9a(i}, 9a(ii} and 9a(iii) are further depictions of the device of Figure 9a wherein
different types of evaporators 4 are utilized. Figure 9b is a depiction of a 'split' hybrid vapor
compression/adsorbent system wherein the split remote/indoor/cooling unit 4 is remote from
the pseudo evaporator means. The pseudo evaporator tubes are provided distant from the
split remote/indoor/cooling unit and can be integral or separate from the main/outdoor unit
containing the condenser unit 2 and the compression systems. The refrigerant gas is outlet
from the split indoor/ remote/ cooling unit into pseudo-evaporator 48 component unit, and
therefrom into compression system. This is then sent on to the condenser 2, and then
returned back to the pseudo evaporator means for chilling and onward transmission into the
split indoor/cooling/remote unit in the form of cooled refrigerant liquid 15. Figure 10a{i),
lOa(ii) and lOa(iii) are further depictions of the device of Figure lOa w~erein different types of
evaporators are utilized.
Figure lOb is a depiction of a 'split'· hybrid vapor compression/adsorbent system
wherein the split remote/indoor/cooling unit 4 is remote from the pseudo evaporator means.
The pseudo evaporator tubes are provided distant from the split remote/indoor/cooling unit
and can be integral or separate from the main/outdoor unit containing the condenser unit 2
and the compression systems. The refrigerant gas is outlet from the split indoor/ remote/
cooling unit into the pseudo-evaporator 48 component unit, and therefrom into the
compression system. This is then sent on to the condenser 2, and then returned back to the
pseudo evaporator means for chilling and onward transmission into the split indoor/ cooling/
remote unit in the form of cooled refrigerant liquid 15. .
22
Figure 11a is a depiction of the application of the 'split' ·concept of the invention to a
hybrid vapor compression/absorption chiller system. Unlike the typical absorption chiller
(cooling) unit where the evaporator 4 is provided proximate to the absorber section 49, in the
present invention, the split indoor/remote/cooling section 33 is segregated and provided in an
independent housing 33. The split cooling/in.door/remote unit 33 is functionally connected
with the main housing containing the absorber unit 49 and the heat exchanger 35. A separate
line conveys the refrigerant liquid from the condenser unit 2 to · the split
remote/indoor/cooling unit 33. The warmed up and partially vaporized refrigerant is conveyed
out to the absorber unit 33. Cool supply air 12 is provided to the room by means of an
evaporator fan 8 provide<;i in the evaporator housing 33. The evaporation process of the vapor
compression cycle is utilized to maintain the absorption process. Condensation heat from the
absorption cycle and energy from the vapor compression cycle i.e., the compression energy
can be rejected to ambient through a water- or air-cooled heat exchanger.
The construction of the condenser 2, generator 36, absorber section 49and heat
exchanger section 35 can remain the same as in the art. The absorber unit comprises an
absorber bed 37 with a line in for flow of used refrigerant from the indoor/remote/cooling
unit 33, which is then fed to the condenser unit 2. The condenser unit 2 has an outlet 10 for
cooling water. A generator 36 is provided proximate to the condenser 2 and provided with
means to inlet 25 and outlet 26 hot fluid. A heat exchange means 35 is provided in operative
association with the evaporator 4 and the absorber section 49.
Figure 11a(i), 11a(ii) and 11a(iii) are further depictions of the device of. Figure 11a
wherein different types of evaporators are utilized. Figure 11b is a depiction of a 'split' hybrid
vapor compression/absorbent system wherein the split remote/indoor/cooling unit 4 is
remote from the pseudo evaporator means. The pseudo evaporator tubes are provided
distant from the split remote/indoor/cooling unit and can be integral or separate from the
main/outdoor unit containing condenser unit 2 and compression systems. The refrigerant fluid
is outlet from the split indoor/ remote/ cooling unit into pseudo-evaporator 48 component
unit, and therefrom into the compression system: This is then sent on to the condenser 2, and
then returned back to pseudo evaporator means for chilling and onward transmission into the
split indoor/cooling/remote unit in the form of cooled refrigerant liquid 15.
Extensive work is globally under way to shrink the size of the thermal compressor i.e.
the adsorber combining advanced "materials" with special heat exchanger providing improved
kinetics, shorter cycle time, and highly improved cooling capacity per unit volume of heat
,._ ~'" ~~ ...;,; .r- •. .:J·~·
23
exchanger. All this has made possible to use adsorption cooling units for mobile
transportation. The remote cooling methods described in the in-vention can easily -be used for
such mobile transport equipment.
Several advancements for improved COP (coefficient of performance) are under way
using hybrid vapor electric compression units along with adsorption/absorption units. Since in
all such cases there is a common type of evaporator section, this evaporator section can also be
converted into a remote, split, indoor cooling unit as already described above, in both and
additional ways.
The adsorption heat exchanger forms a critical part of the device. This component and
its specific cooling output is signifiCantly influenced by the adsorbent, referred to as "material"
and the way it is joined in relationship to the heat exchanger, the combination influencing the
kinetics, the cyi::le time, and the overall specific cooling power per volume of the adsorber.
The material used can be either silica gel/molecular sieves, MOF, FAMs, COFs, etc. The
adsorber heat exchanger essentially comprises of two main items: the basic tube fin or
enhanced surface heat exchanger + the adsorbent ("material"). The combination of these two
improves the specific cooling power per liter of the adsorber heat exchanger. Several
advancements are underway using new materials, new adsorbent (material) adhering methods
to improve the thermal conductivity and kinetics, etc.
Adsorbents used can be either physical adsorbents, chemical adsorbents, or composite
adsorbents. Physical adsorbents that are usable include materials with differing pore sizes such
mesoporous silicates; zeolites, metalloalumino phosphates, porous carbons and meta·l organic
frameworks. Mesoporous silicates include materials such as synthetic amorphous silica gel that
have a rigid and continuous net of colloidal silica connected to small grains of hydrated Si04•
Porous carbons include activated carbons obtained by gasifying char with an oxidizing agent.
Zeolites include crystalline microporous alumina silicate materials and include several ranges
such as HZSM-5, ZSMS, zeolite HY etc. The advantages of zeolite or zeolite based materials are
their diversity of uses, and their susceptibility to modification dependent on the purpose of use.
Metal organic frameworks are a new generation of materials which are microporous, have high
porosity, uniform pore size and have well defined adsorption sites and large surface area. These
frameworks typically comprise of organic linkers which connect metal ce.ntres.
Chemical adsorbents include metal chlorides such as calcium chloride, bari~m chloride,
strontium chloride etc., salt and metal hydrides such as lithium hydride, calcium hydride, high
polymerized hydrides of covalent nature, and non-metal molecular hydrides, and metal oxides.
24
Composite adsorbents include combinations of chemical and physical adsorbents such
as combinations of metal chloride and activated carbon fibres, expanded graphite, silica gel, or
zeolite. Composite adsorbents provide an advantage in enhancement of performance of
physical adsorbents without incurring the effect of chemical adsorbents such as swelling, poor
conductivity, or agglomeration.
The heat exchangers used can be two-bedtype or three-bed type and can utilize either
coated fins or a granular bed approach or a combination thereof. For purpose of brevity, the .
description of co-pending patent application 81/DEL/2014 filed on January 10, 2014 is
incorporated herein by reference. This co-pending application relates to a novel hybrid
adsorption heat exchanger device with enhanced specific cooling capacity. This device with all
its modifications can be utilized in the split adsorption air conditioning unit of the invention.
The device of the invention is reasonably believed to provide several distinct advantages
over prior art systems. These are summarized below:
1. Regeneration temperature as low as 50oC (typically below 100°C}.
2. Operational over a wide range of temperature for hot, cooling and chilled.
3. Waste process heat energy/solar energy drives its operation.
4. Low operational costs and maintenance.
5. Extended machine life.
6. Use of water as refrigerant thereby avoiding environmental issues such as global warming
potential and ozone layer depletion, additionally avoiding a high carbon emission footprint.
7. No crystalli~ation, corrosion, hazardous leaks, or chemical disposal issues.
8. No vibration or noise and simple and continuous operations.
9. Improved efficiency of the overall cycle by eliminating additional air handling un.it (AHU).
10. Lower capital and operational cost by eliminating additional AHU and chilled water circuit.
11. Orientation free sorption system with split-type evaporator.
It is to be understood that modifications and developments to the disclosure provided
herein are within the scope of the invention.
REFERENCES
[1] B. B .. Saha, A. Chakraborty, 1.1. · EI-Sharkawy, S. Koyama, K.C. Ng, K. Srinivasan, On
thermodynamics of advanced adsorption cooling devices, in: 2008 ASME International
Mechanical Engineering Congress and Exposition, IMECE 2008, Boston, MA, 2009, pp. 555-561.
[2] B.B. Saha, 1.1. EI-Sharkawy, S. Koyama, J.B. Lee, K. Kuwahara, Waste heat driven multi-bed
adsorption chiller: Heat exchangers overall thermal conductance on chiller performance, Heat
Transfer Eng, 27(5) (2006) 80-87.
[3] K. Thu, K.C. Ng, B.B. Saha, A. Chakraborty, S. Koyama, Operational strategy of adsorption
desalination systems, Int. J. Heat Mass Transf., 52(7-8) (2009) 1811-1816.
[4] A. Chakraborty, B.B. Saha, S. Koyama, K.C. Ng, K. Srinivasan, Adsorption thermodynamics of
silica gel-water systems, J Chem Eng Data, 54(2) (2009) 448-452.
[5] P. Dutta, P. Kumar, K.C. Ng, S. Srinivasa Murthy, K. Srinivasan, Orgc:mic Brayton Cycles with
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[6] W.S. Loh, 1.1. EI-Sharkawy, K.C. Ng, B.B. Saha, Adsorption cooling cycles for alternative
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[7] A.B. Ismail, W.S. Loh, K. Thu, K.C. Ng, A study on the kinetics of propane-activated carbon:
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[8] 1.1. EI-Sharkawy, B.B. Saha, S. Koyama, J. He, K.C. Ng, C. Yap, Experimental investigation on
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CLAIMS
1: A split type air conditioning unit, essentially comprising:
a first component co·mprising essentially of one or more compression means wherein at
least one compression-means is a thermal compression means, and a condensation means; and
one or more second component(s) separate from said first component each provided in
a dedicated housing and comprising an evaporation means;
each evaporation means being connected to the condensation means through one or
more suction line(s) and one or more liquid line(s);
said one or more of said suction line(s) providing discharged refrigerant fluid from each
said evaporation means through said one or more compression means to said condensation
means;
said one or more liquid line(s) conveying refrigerant fluid to each said evaporation
means from said condensation means.
2: A device as claimed in claim 1 wherein the compression means is selected from the
group consisting of an adsorption unit, an absorption unit, a hybrid vapor compression/
adsorption unit, and a hybrid vapor compression/absorption unit.
3: A device as claimed in claim 1 or 2 wherein the compression means is an adsorption unit
or a hybrid vapor compression/adsorption unit.
4: A device as claimed in claim 3 wherein the adsorbent used in case of an adsorption unit
or hybrid vapor compression/adsorption unit is selected from the group consisting of zeolites,
mesoporous silicates, insoluble metal silicates, silica gel type A, silica gel type RD, silica gel type
52, activated carbon fiber, granular activated carbon, activated alumina, highly porous activated
carbon, Zr60 4(0H)4 bonded with linkers, MIL-101Cr, metal-organic frameworks, covalent organic
frameworks, functional adsorbent materfals, and the like, alone or in any combination thereof.
5: A device as claimed in claim 1 or 2 wherein the compression means is an absorption unit
or a hybrid vapor compression/absorption unit.
6: A device as claimed in claim 5 wherein the absorption unit or the hybrid vapor
compression/absorption unit is provided with a refrigerant-absorbent mixture selected from the
group consisting of water-lithium bromide, ammonia-water, ammonia-lithium nitrate,
ammonia-sodium thiocyanate, or in combination thereof.
7: A device as claimed in claim 1 to 5 wherein the refrigerant is selected from the group
consisting of water, methane, methanol, ethanol, ammonia, CFCs, HCFCs, HFCs, and the like.
8: A device as claimed in claim 1 to 6 wherein the liquid line is provided with one or more
refrigerant flow control means selected from the group consisting of different types of throttling
valves, expansion valves, capillaries, P-traps, and metering devices.
9: A device a·s claimed in claim 1 to 8 wherein the one or more evaporator(s} are selected
from the group consisting of falling film tubular (horizontal/vertical), rising/falling film tubular,
forced circulation (tubular/plate}, plate-type, falling film plate, and forced circulation, and any
combination thereof, all with or without enhanced surface treatment for aiding surface
evaporation.
10: A device as claimed in claim 1 to 8 wherein the split unit when containing an adsorption
unit or hybrid vapor compression/adsorption unit, is mountable on any vehicular device.
11: A device as claimed in claim 1 wherein the evaporator unit is a cooling unit and the
evaporator heat exchange tubes are taken out and perform the heat exchange/cooling function
in the remote cooling unit.
· 12: A split type air conditioning unit, essentially comprising:
a first component containing one or more compression means wherein at least one
compression means is a thermal compression means, and a condensation means, and a pseudoevaporation
means; and
one or more second component(s) separate from said first component each provided in
a dedicated housing and comprising a cooling means;
each cooling means being connected to the pseudo evaporator means through one or
more liquid refrigerant supply and return line(s);
said one or more of said liquid refrigerant return line(s) providing discharged liquid
refrigerant f~om each said cooling means to said pseudo evaporator means, wherein the liquid
portion of said discharged refrigerant is returned ·to the pseudo evaporator means, ·and
vaporized refrigerant from the pseudo evaporator is directed to said condenser through said
compression means for condensation and recirculation.
13: A device as claimed in claim 12 wherein the compression means is selected from the
group consisting of an adsorption unit, an absorption unit, a hybrid vapor
compression/adsorption unit, and a hybrid vapor compression/absorption unit.
14: A device as claimed in claim 12 or 13 wherein the compression means is an adsorption
unit or a hybrid vapor compression/adsorption unit.
15: A device as claimed in claim 14 wherein the adsorbent used in case of an adsorption unit
or hybrid vapor compression/adsorption unit is selected from the group consisting of zeolites,
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mesoporous silicates, insoluble metal silicates, silica gel type A, silica gel type RD, silica gel type
52, activated carbon fiber, granular activated carbon, activated alumina, highly porous activated
carbon, Zr60 4{0H)4 bonded with linkers, Mll-101Cr, metal-organic frameworks, covalent organic
frameworks, functional adsorbent materials, and the like, alone or in any combination thereof.
16: A device as Claimed in claim 12 or 13 wherein the compression means is an absorption
unit or a hybrid vapor compression/absorption unit.
17: A device as claimed in claim 16 wherein the absorption unit or the hybrid vapor
compression/absorption unit is provided with a refrigerant-absorbent mixture selected from the
group consisting of water-lithium bromide, ammonia-water, ammonia-lithium nitrate,
ammonia-sodium thiocyanate, or in any combination thereof.
18: A device as claimed in any preceding claim wherein the refrigerant is selected from the
group consisting of water, methane, methanol, ethanol, ammonia, CFCs, HCFCs, HFCs, and the
like.
19: A device as claimed in claim 12 to 18 wherein one or more refrigerant flow control
means selected from the group consisting of different types of throttling valves, expansion
valves, capillaries, P-traps, and metering devices is provided on the liquid refrigerant line
between said condenser means and said pseudo evaporator means.
20: A device as claimed in claim 12 to 19 wherein the pseudo evaporator unit has a heat
exchanger selected from the group consisting of falling/sprayed film over a component with
considerably expanded surface area of the type comprising cooling tower fill, wire mesh wool,
metal or inorganic fiber foam.
21: A device as claimed in claim 12 to 20 wherein the cooling unit has a heat exchanger
selected from the group consisting of a traditional tube fin heat exchanger and enhanced tube
heat exchanger
22: A device as claimed in claims 12-19 wherein the split unit when containing an adsorption
unit or hybrid vapor compression/adsorption unit, is mountable on a vehicular device.
23: A method for split level adsorption refrigeration with a device as claimed in any
preceding claim 1 to 11 wherein the method comprises:
providing a first component comprising of one or more compression means wherein at
least one compression means is a thermal compression means, and a condensation means;
providing one or more second component{s) separate from said first component, in a
dedicated housing, wherein the one or more second component comprises an evaporation
means;
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29
connecting each evaporation means to the condensation means through one or more
suction line(s) and one or more liquid line(s) for inlet and outlet of refrigerant medium;
discharging refrigerant fluid from each said evaporation means through said one or
more of said suction line(s) into said one or more compression means and therethrough to said
condensation means;
conveying refrigerant fluid through said one or more liquid line(s) to each said
evaporation means from said condensation means.
24: A method as claimed in claim 23 wherein the compression means is selected from the
group consisting of an adsorption unit, an absorption unit, a. hybrid vapor compression/
· adsorption unit, and a hybrid vapor compression/absorption unit.
25: ·A method as claimed in claim 23 or 24 wherein the compression means is an adsorption
unit or a hybrid vapor compression/adsorption unit.
26:. A method as claimed in claim 25 wherein the adsorbent used in case of an adsorption
unit or hybrid vapor compression/adsorption unit is selected from the group consisting of
zeolites, mesoporous silicates, insoluble metal silicates, silica gel type A, silica gel type RD, silica
gel type 52, activated carbon fiber, granular activated carbon, activated alumina, highly porous
activated carbon, Zr60 4(0H}4 bonded with linkers, MIL-101Cr, metal-organic frameworks,
covalent organic frameworks, functional adsorbent materials, and the like, alone or in any
combination thereof.
27: A method as claimed in claim 23 or 24wherein the compression means is an absorption
unit or a hybrid vapor compression/absorption unit.
28: A method as claimed in claim 27 wherein the absorption unit or the hybrid vapor
compression/absorption unit is provided with a refrigerant-absorbent mixture selected from the
group consisting of water-lithium bromide, ammonia-water, ammonia-lithium nitrate,
ammonia-sodium thiocyanate, or in combination thereof.
29: A method as claimed in any preceding claim wherein the refrigerant is selected from the
group consisting of water, methane, methanol, ethanol, ammonia, CFCs, HCFCs, HFCs, and the
like.
30: A method as claimed in claim 23 to 29 wherein the liquid line is provided with one or
more refrigerant flow control means selected fi-om the group consisting of different types of
throttling valves, expansion valves, capillaries, P-traps, and metering devices.
31: A method as claimed in claim 23 to 29 wherein the one or more evaporator(s) are
selected from the group consisting of falling film tubular (horizontal/vertical), rising/falling film
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,L;. !~~ ~- n;;--~ n:,;_, 8 ~ ~
"it."':"" ?.r"' . i:: j'?:• .-> ::J: ·~"H
30
tubular, forced circulation (tubular/plate), plate-type, falling film plate, and forced circulation,
and any combination thereof, all with or without enhanced surface treatment for aiding surface
evaporation.
32: · A method as claimed in claim 23 to 31 wherein the split unit when containing an
. adsorption unit or hybrid vapor compression/adsorption unit, is mounted on any vehicular
device.
33: A method as claimed in claim 23 wherein the heat exchange/cooling function is carried
out in a remote cooling unit where the evaporator heat exchange tubes are taken. out from the
base evaporator unit.
34: A method for split level adsorption refrigeration with a device as claimed in any
preceding claim 12 to 22, said method comprising:
providing a first component containing one or more compression means wherein at
least one compression means is a thermal compression means, and a condensation means, and
a pseudo-evaporation means; and
providing one or more second component(s) separate from said first component, each in
a dedicated housing and comprising a cooling means;
connecting each cooling means to the pseudo evaporation means through one or more
liquid refrigerant supply and return line(s);
providing discharged liquid refrigerant through said one or more of said liquid
refrigerant return line(s) to said pseudo evaporator means, wherein the liquid portion of said
discharged refrigerant is returned to the pseudo evaporator means, and vaporized refrigerant
from the pseudo evaporator is directed to said condenser through said compression means for
condensation and recirculation.
35: A method as claimed in claim 34 wherein the compression means is selected from the
group consisting of an adsorption unit, an absorption unit, a hybrid vapor
compression/adsorption unit, and a hybrid vapor compression/absorption unit.
36: A method as claimed in claim 34 or 35 wherein the compression means is an adsorption
unit or a hybrid vapor compression/adsorption unit.
37: A method as Claimed in claim 36 wherein the adsorbent used in case of an adsorption
unit or hybrid vapor compression/adsorption unit is selected from the group consisting of
zeolites, mesoporous silicates, insoluble metal silicates, silica gel type A, silica gel type RD, silica
gel type 52, activated carbon fiber, granular activated carbon, activated alumina, highly porous
activated carbon, Zr60 4(0H)4 bonded with linkers, MIL-101Cr, metal-organic· frameworks,.
31
covalent organic frameworks, functional adsorbent materials, and the like, alone or in any
combination thereof.
38: A method as claimed in claim 34 or 35 wherein the compression means is an absorption
unit or a hybrid vapor compression/absorption unit.
39: A method as claimed in claim 38 wherein the absorption unit or the hybrid vapor
compression/absorption unit is provided with a refrigerant-absorbent mixture selected from the
group consisting of water-lithium bromide, ammonia-water, ammonia-lithium nitrate,
ammonia-sodium thiocyanate, or in any combination thereof.
40: A method as claimed in any preceding claim wherein the refrigerant is selected tram the
group consisting of water, methane, methanol, ethanol, ammonia, CFCs, HCFCs, HFCs, and the
like.
41: A method as claimed in claim 40 wherein one or more refrigerant flow control means
selected from the group consisting of different types of throttling valves, expansion valves,
capillaries, P-traps, and metering devices is provided on the liquid refrigerant line between said
condenser means and said pseudo evaporator means.
42: A method as claimed in claim 34 to 41 wherein the pseudo evaporator unit has a heat
exchanger selected from the group consisting of falling/sprayed film over a component with
considerably expanded surface area of the type comprising cooling tower fill, wire mesh wool,
metal or inorganic fiber foam.
43: A method as claimed in claim 34 to 42 wherein the cooling unit has a heat exchanger
selected from the group consisting of a traditional tube fin heat exchanger and enhanced tube
heat exchat:Jger.
44: A method as claimed in claim 34 to 42 wherein the split unit when containing an
adsorption unit or hybrid vapor compression/adsorption unit, is mountable on any vehicular
device.