1. An Air Handling Unit (AHU) apparatus for conditioning environmental parameters in a premise, the AHU comprising: a cabinet provided with a first air cooling assembly (106) and a second air cooling assembly (108); a primary cooling coil (202) and a secondary cooling coil (204) operating as a heat sink, the primary cooling coil (202) disposed in the first air cooling assembly (106) and the secondary cooling coil (204) disposed in the second air cooling assembly (108); a Vapour Compression Refrigeration System (VCRS) assembly, wherein a refrigerant flows through the VCRS assembly and air surrounding the VCRS assembly is cooled by heat exchange between the refrigerant and the air; at least one supply air vent fabricated through the cabinet to supply air into the premise; a blower disposed within the cabinet to the supply air through the supply air vent, wherein said blower supplies cool air into the premise from one of: the primary coil and combination of the primary coil and the second coil (108); wherein the AHU apparatus conditions the premise by operating one of: VCRS assembly, a first air cooling assembly (106), a second air cooling assembly (108) and a combination of a first air cooling assembly (106) and a second air cooling assembly (108) based on environmental parameters in the premise.

2. The AHU apparatus as claimed in claim 1, further comprising a chilled water supply for the secondary cooling coil (204) through Vapour Compression Refrigeration System (VCRS), wherein the chilled water flows through the secondary cooling coil (204) and the air surrounding is cooled by the heat exchange between chilled water flowing in the secondary cooling coil (204).

3. The AHU apparatus as claimed in claim 1, wherein an air filter is arranged in close proximity parallel to the primary cooling coil (202), whereby the air intake is filtered before being further cooled and circulated into the premise.

4. The AHU apparatus as claimed in claim 1, wherein the water is pumped from a sump into the primary cooling coil (202) facilitating in cooling the air passing through it from the filter.

5. The AHU apparatus as claimed in claim 1, wherein the first air cooling assembly (106) comprises a plurality of cooling pads (206), the cooling pads are arranged parallel to the primary cooling coil (202).

6. The AHU apparatus as claimed in claim 4, the plurality of cooling pads (206) are wetted by the water in the water sump so as to cool temperature of air passing through it by direct evaporative cooling.

7. The AHU apparatus as claimed in claim 4, wherein the plurality of cooling pads (206) are cell deck pads.

8. The AHU apparatus as claimed in claim 1, wherein the secondary cooling coil (204) functions as a heat exchanger and cools the temperature of air flowing from the plurality of cooling pads (206) using evaporative cooling.

9. The AHU apparatus as claimed in one of claims 1 to 7, wherein the evaporator and the secondary cooling coil (204) are arranged parallel to each other and posterior to the air filter.

10. The AHU apparatus as claimed in claim 1, wherein the environmental parameters are temperature and relative humidity.

The present invention relates to Air Handling Unit (AHU), more particularly to an Air Handling Unit (AHU) apparatus for conditioning environmental parameters of a premise by a combination of vapour compression cooling and evaporative cooling.
BACKGROUND OF THE INVENTION
[0002] Generally, an Air Handling Unit (AHU) may employ two types of evaporative cooling, direct evaporative cooling and indirect evaporative cooling. Direct evaporative cooling is used to lower the temperature and increase the humidity of air by using latent heat of evaporation, changing liquid water to water vapour. Indirect evaporative cooling is a cooling process that uses direct evaporative cooling in addition to some type of heat exchanger to transfer the cool energy to the supply air. Some of the problems of conventional evaporative air coolers are that they accumulate dust leading to high dirt and salt concentration of water inside the tank, supply unstable air temperature due to fluctuations in the tank water temperature and are not effective at the time of high humidity.
[0003] An evaporative cooler also known as swamp cooler, desert cooler and wet air cooler is a device that cools air through the evaporation of water. Evaporative coolers are well suited for climates where air is hot and humidity is low. Said coolers cool the air by passing the air through pads wetted with water, whereby the evaporative absorption of the latent heat of evaporation via water directly cools the air.
[0004] Air conditioning apparatuses using vapour compression refrigeration are well known in the art and are widely used for controlling temperature in residential and commercial applications. There are air conditioning apparatuses that have been developed with an additional heat exchanger in the supply air flow path which furnishes conditioned air to the space being controlled. When humidity is high vapour compression air conditioning is required as evaporative coolers do not provide the necessary comfort.
[0005] The conventional hybrid air conditioners using a combination of vapour compression refrigeration and evaporative cooling works on two different modes, air conditioning mode and cooler mode. The air conditioners have certain drawbacks, firstly the cooler efficiency is limited only to the evaporation process, secondly there is inefficient cooling, thirdly the desert cooler mode has no provision for re-circulation of air.
[0006] Thus, there is a need for an improved Air Handling Unit (AHU) apparatus that facilitates multistage air cooling using a combination of vapour compression refrigeration and evaporative cooling so as to improve energy efficiency and reduce maintain a predetermined relative humidity.
SUMMARY OF THE INVENTION
[0007] In accordance with an embodiment of the present invention, an Air Handling Unit (AHU) apparatus for conditioning environmental parameters in a premise is disclosed. The AHU apparatus includes a cabinet provided with a first air cooling assembly and a second air cooling assembly. The AHU apparatus includes a primary cooling coil and a secondary cooling coil operating as a heat sink. The primary cooling coil is disposed in the first air cooling assembly and the secondary cooling coil is disposed in the second air cooling assembly. The AHU apparatus also includes a Vapour Compression Refrigeration System (VCRS) assembly. A refrigerant flow through the VCRS assembly and air surrounding the VCRS assembly is cooled by heat exchange between the refrigerant and the air. Further, the AHU apparatus also includes at least one supply air vent fabricated through the cabinet to supply air into the premise and a blower disposed within the cabinet to the supply air through the supply air vent. The blower supplies cool air into the premise from one of: the primary coil and combination of the primary coil and the second coil. The AHU apparatus conditions the premise by operating one of: VCRS assembly, a first air cooling assembly, a second air cooling assembly and a combination of a first air cooling assembly and a second air cooling assembly based on environmental parameters in the premise.
[0008] In an embodiment of the present invention, the AHU apparatus also includes chilled water supply for the secondary cooling coil (204) through Vapour Compression Refrigeration System (VCRS). The chilled water flows through the secondary cooling coil (204) and the air surrounding is cooled by the heat exchange between chilled water flowing in the secondary cooling coil (204).

[0009] In an embodiment of the present invention, an air filter is arranged in close proximity parallel to the primary cooling coil, whereby the air intake is filtered before being further cooled and circulated into the premise. Further, the water is pumped from a sump into the primary cooling coil facilitating in cooling the air passing through it from the filter.
[0010] In an embodiment of the present invention, the first air cooling assembly comprises a plurality of cooling pads, the cooling pads are arranged parallel to the primary cooling coil. Further, the plurality of cooling pads are wetted by the water in the water sump so as to cool temperature of air passing through it by direct evaporative cooling.
[0011] In an embodiment of the present invention, the plurality of cooling pads are cell deck pads. Further, the secondary cooling coil functions as a heat exchanger and cools the temperature of air flowing from the plurality of cooling pads using evaporative cooling.
[0012] In an embodiment of the present invention, the evaporator and the secondary cooling coil are arranged parallel to each other and posterior to the air filter. Further, the environmental parameters are temperature and relative humidity.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] The following drawings are illustrative of particular embodiments for enabling the present invention, are descriptive of some methods, and are not intended to limit the scope of the invention. The drawings are not to scale (unless so stated) and are intended for use in conjunction with the explanations in the following detailed description.
[0014] The present invention is described by way of embodiments illustrated in the accompanying drawings wherein:
[0015] Figure 1 illustrates a plan view of Air Handling Unit (AHU) apparatus in accordance with an embodiment of the invention; and
[0016] Figure 2 illustrates a sectional view of Air Handling Unit (AHU) apparatus in accordance with an embodiment of the invention.
DETAILED DESCRIPTION OF THE INVENTION
[0017] The following disclosure is provided in order to enable a person having ordinary skill in the art to practice the invention. Exemplary embodiments are provided only for illustrative purposes and various modifications will be readily apparent to persons skilled in the art. The general principles defined herein may be applied to other embodiments and applications without departing from the spirit and scope of the invention. Also, the terminology and phraseology used is for the purpose of describing exemplary embodiments and should not be considered limiting. Thus, the present invention is to be accorded the widest scope encompassing numerous alternatives, modifications and equivalents consistent with the principles and features disclosed. For the purpose of clarity, details relating to technical material that is known in the technical fields related to the invention have not been described in detail so as not to unnecessarily obscure the present invention.
[0018] The present invention would now be discussed in the context of embodiments as illustrated in the accompanying drawings.
[0019] Figure 1 illustrates a plan view of Air Handling Unit (AHU) apparatus in accordance with an embodiment of the invention. The Air Handling Unit (AHU) apparatus is of window type and includes a cabinet, a vapour compression refrigeration assembly, a first air cooling assembly (106), a second air cooling assembly (108), a primary cooling coil (202), a secondary cooling coil (204) and a blower.
[0020] The cabinet is divided into two sections, a first section (102) and a second section (104). In an embodiment of the present invention, both the first section (102) and the second section (104) are cuboidal in shape. The second section (104) extends laterally from the middle to the distal end of the first section (102). It is to be understood that the cabinet can be of any suitable shape and size selected from a group of geometric and non-geometric shapes depending on the size of the premise where it is to be fitted and the amount of cooling capacity required. In an exemplary embodiment of the present invention, the first section (102) may comprise a first air cooling assembly (106) and a second air cooling assembly (108) and the second section (104) may comprise a machine premise configured to house controllers and power supply for the first section (102).
[0021] Further, a supply air vent is fabricated through the cabinet to supply air into the premise being conditioned. In the exemplary embodiment of the present invention the supply air vent is fabricated through the front side of the first section (102).
[0022] Further, the blower is positioned parallel to the supply air vent. In an embodiment of the present invention, the blower is a centrifugal blower, wherein an outlet of said blower is parallel to the supply air vent. The blower supplies cool air into the premise. A plurality of openings are fabricated at the rear side of the first section (102) of said cabinet to allow ambient air to enter said cabinet towards the second air cooling assembly (108).
[0023] The Vapour Compression Refrigeration System (VCRS) Assembly is disposed outside the cabinet. The VCRS assembly comprises an evaporator, a compressor and a condenser connected through a refrigerant circuit, such as a refrigerant flows through the compressor, the condenser and the evaporator via a refrigerant circuit and the air is cooled by the heat exchange between the cool evaporator and the surrounding air. The compressor and the condenser are disposed at the rear end of the second section (104) such that the compressor is arranged anterior to the condenser. A fan is arranged posterior to the condenser to blow air over the condenser.
[0024] The Air Handling Unit (AHU) apparatus further comprises a water sump and a water pump disposed within the cabinet. In an embodiment of the present invention, the water sump is fabricated within the first section (102) and the water pump is disposed within the first section (102). The water sump is connected to a water source, so as to refill the sump whenever the water level drops below a predefined limit. The sump is connected to the first air cooling assembly (106). The second air cooling assembly (108) and the secondary cooling coil (204) are connected to chilled water header through pipes The water pump pumps water to the first air cooling assembly (106), the second air cooling assembly (108) and the secondary cooling coil (204) from the water sump via the hose. A valve is connected to the hose to control the flow of water into the second air cooling assembly (108) and the secondary cooling coil (204). In an embodiment of the present invention, the valve is a solenoid valve. Thus, the AHU apparatus also includes chilled water supply for the secondary cooling coil (204) through Vapour Compression Refrigeration System (VCRS). The chilled water flows through the secondary cooling coil (204) and the air surrounding is cooled by the heat exchange between chilled water flowing in the secondary cooling coil (204) and the air.
[0025] Further, above the water sump in the second section (104) of the cabinet is disposed the first air cooling assembly (106). The first air cooling assembly (106) comprises a plurality of cooling pads (206). The plurality of cooling pads (206) are arranged parallel to the primary cooling coil (202). The atmospheric air flows via a filter and passes through the primary cooling coil (202) before passing via the plurality of cooling pads (206). The plurality of cooling pads (206) are wetted by the water in the water sump via the water pump. The wet cooling pads cools the temperature of air around the cooling pads and water inside the sump through direct evaporative cooling.
[0026] It is apparent to a person skilled in the art that the first air cooling assembly (106) the plurality of cooling pads (206) may be arranged in a suitable pattern such that water is collected in the water sump without deviating from the primary function of cooling the temperature of air. In an embodiment of the present invention, the plurality of cooling pads (206) are cell deck pads. The second air cooling assembly (108) is disposed within said cabinet, more particularly from the middle to the distal end of the first section (102) of said cabinet. The second air cooling assembly (108) comprises a secondary cooling coil (204). The secondary cooling coil (204) is arranged parallel to the front and rear side of the first section (102), such that the plurality of cooling pads (206) are anterior to the secondary cooling coil (204). The secondary cooling coil (204) receive water from the chilled water header connected to the cooling coil through pipe line. The primary cooling coil (202) and the secondary cooling coil (204) function as a heat exchanger.
[0027] The water from cooling tower sump is pumped to the heat exchanger via the primary cooling water pump via the pipe connected to coil (202), thereby the temperature of air around the heat exchanger is reduced via indirect evaporative cooling. The secondary cooling pad is wetted by the sump water, whereby temperature of air already cooled by the primary heat exchanger is further reduced via direct evaporative cooling. The secondary cooling coil (204) is disposed within the cabinet and is arranged anterior to the second air cooling assembly (108) in the first section (102).
[0028] The Air Handling Unit (AHU) apparatus receives power through a standard Mains voltage supply cord connected to a mains voltage supply. The Air Handling Unit (AHU) apparatus further comprises a plurality of sensing means, wherein at least one of the sensing means detects the ambient environmental parameters such as relative humidity by a RH sensor. A control unit facilitates the operation of said Air Handling Unit (AHU) apparatus and enables the Vapour Compression Refrigeration System (VCRS) or the evaporative cooling based on the predetermined configuration. The control unit can be selected from a group consisting of microprocessors, microcontrollers, multiprocessors or other devices capable of processing data.
[0029] The control unit is configured to operate said Air Handling Unit (AHU) apparatus in a at least two modes, wherein one of the modes uses vapour compression refrigeration and is referred to as an air conditioning mode and the second mode uses evaporative cooling and is referred to as a cooler mode, the Air Handling Unit (AHU) apparatus switches between the air conditioning mode and the cooler mode based on environmental parameters. The environmental parameters may be predefined values of relative humidity and temperature. The control unit has its inputs connected to the plurality of sensing means such as the RH sensor and temperature sensor. In response to the input from said sensor the control unit controls and provides outputs to the vapour compression assembly, the first air cooling assembly (106), the second air cooling assembly (108),
[0030] In an embodiment of the present invention, the microcontroller enables automatic switching ON/OFF of the compressor, the blower, the condenser fan, water pump, the air controllers and the valve based on the signals received from various sensors or user inputs. The control unit further supplies predetermined frequency of operation for the compressor, the RPM’s for the blower based on the selected mode, and illuminates light emitting diodes (LED's) on the control panel to alert the user with the details of the selected mode.
[0031] The Air Handling Unit (AHU) apparatus is operated in the air conditioning mode based on the user input or if the ambient relative humidity is more than a predefined value, such as 65% as sensed by the RH sensor. When the air conditioning mode is initiated by a user input or automatically based on the relative humidity, the control unit closes the valve to prevent the supply of water to the second air cooling assembly (108) and the secondary cooling coil (204), thereafter the control unit operates the water pump to pump water from the water sump to the plurality of cooling pads (206) of the first air cooling assembly (106). Wetting of said cooling pads reduces the temperature of surrounding air using evaporative cooling. This colder ambient air reduces the condensing temperature of the condenser, thereby improving overall efficiency of the condenser. The colder ambient air also cools the compressor shell to improve overall performance.
[0032] The vapour compression refrigeration assembly is operated by the control unit. After cool air around the evaporator is sucked by the centrifugal blower, the centrifugal blower supplies the cooled air into the premise through the supply air vent.
[0033] The Air Handling Unit (AHU) apparatus is operated in the cooler mode based on the user input or if the ambient relative humidity is less than a predefined value, such as 65% as sensed by the ambient humidity sensor. When the control unit receives relative humidity value less than a predetermined value which is 65% in the particular embodiment from the RH sensor, the cooler mode is initiated. The control unit switches OFF the compressor to shut down the vapour compression assembly operates the water pump to pump water from the water sump to the plurality of cooling pads (206) of the first air cooling assembly (106).
[0034] The control unit opens the valve and operates the water pump to supply water cooled by the first air cooling assembly (106) from the water sump to the second air cooling assembly (108) and the secondary cooling coil (204). The heat exchanger of the second air cooling assembly (108) further reduces the temperature of air. During said process air enters the cabinet from the air return inlet and the plurality of openings. This precooled air passes through the secondary cooling pad, whereby the temperature of air further drops. The centrifugal blower sucks the air cooled by the second air cooling assembly (108) and supplies it into the premise being conditioned through the supply air vent.
[0035] In operation, the conditioning of environmental parameters of a premise by an Air Handling Unit (AHU) apparatus may be initiated by a user input or automatically based on the environmental parameters. Further, upon initiating the air conditioning mode, the Vapour Compression Refrigeration System (VCRS) assembly is switched ON by the controller. Upon initiating the VCRS assembly, air in ambience of the VCRS assembly is cooled by the VCRS assembly to a predetermined temperature and humidity by convectional heat transfer. Next, the blower supplies the air cooled by the VCRS assembly to the premise.
[0036] In accordance with an embodiment of the present invention, the conditioning of environmental parameters of the premise by an Air Handling Unit (AHU) apparatus in cooler mode may be initiated by a user input or automatically based on the environmental parameters. Further, upon initiating the cooler mode, a control unit operates a water pump to pump water from a water sump to the plurality of cooling pads (206) in the first air cooling assembly (106). The wetting of the plurality of cooling pads (206) facilitates in reducing the temperature of air flowing through it.
[0037] Further, the pump is initiated to supply water from the water sump to the second air cooling assembly (108) and the secondary cooling coil (204). Upon, initiating the cooler mode, a blower is operated to facilitate the passage of atmospheric ambient air via the first air cooling assembly (108). Furthermore, upon supplying the water to the second air cooling assembly (108), the ambient atmospheric air is configured to flow from the first air cooling assembly (106) to the second air cooling assembly (108) via an air inlet. The passage of air through the first air cooling assembly (106) to the second air cooling assembly (108) reduces the temperature of the ambient air by direct evaporative cooling.
[0038] Upon cooling the ambient air and the first air cooling assembly (106) and the second air cooling assembly (108), the cooled air is blown into the premise by the blower via at least one supply air vent to condition the environmental parameters of the premise.
[0039] Accordingly, the present invention provides the following effects or advantages. The invention provides an Air Handling Unit (AHU) with multistage air cooling combining Vapour Compression Evaporation System (VCRS) and direct evaporative cooling. The invention allows to maintain a predetermined humidity level in the area to be cooled. Further, the AHU provides for different modes as per the user needs so as to fluctuate between VCRS and direct cooling. The different modes enable the AHU to improve energy efficiency and reduce the cost in maintaining the temperature. Also, the present invention provides the user flexibility of option to select between the modes depending on the cooling needs.
[0040] While the exemplary embodiments of the present invention are described and illustrated herein, it will be appreciated that they are merely illustrative. It will be understood by those skilled in the art that various modifications in form and detail may be made therein without departing from or offending the scope of the invention as defined by the appended claims.

We claim:

1. An Air Handling Unit (AHU) apparatus for conditioning environmental parameters in a premise, the AHU comprising:
a cabinet provided with a first air cooling assembly (106) and a second air cooling assembly (108);
a primary cooling coil (202) and a secondary cooling coil (204) operating as a heat sink, the primary cooling coil (202) disposed in the first air cooling assembly (106) and the secondary cooling coil (204) disposed in the second air cooling assembly (108);
a Vapour Compression Refrigeration System (VCRS) assembly, wherein a refrigerant flows through the VCRS assembly and air surrounding the VCRS assembly is cooled by heat exchange between the refrigerant and the air;
at least one supply air vent fabricated through the cabinet to supply air into the premise;
a blower disposed within the cabinet to the supply air through the supply air vent, wherein said blower supplies cool air into the premise from one of: the primary coil and combination of the primary coil and the second coil (108);
wherein the AHU apparatus conditions the premise by operating one of: VCRS assembly, a first air cooling assembly (106), a second air cooling assembly (108) and a combination of a first air cooling assembly (106) and a second air cooling assembly (108) based on environmental parameters in the premise.
2. The AHU apparatus as claimed in claim 1, further comprising a chilled water supply for the secondary cooling coil (204) through Vapour Compression Refrigeration System (VCRS), wherein the chilled water flows through the secondary cooling coil (204) and the air surrounding is cooled by the heat exchange between chilled water flowing in the secondary cooling coil (204).
3. The AHU apparatus as claimed in claim 1, wherein an air filter is arranged in close proximity parallel to the primary cooling coil (202), whereby the air intake is filtered before being further cooled and circulated into the premise.
4. The AHU apparatus as claimed in claim 1, wherein the water is pumped from a sump into the primary cooling coil (202) facilitating in cooling the air passing through it from the filter.
5. The AHU apparatus as claimed in claim 1, wherein the first air cooling assembly (106) comprises a plurality of cooling pads (206), the cooling pads are arranged parallel to the primary cooling coil (202).
6. The AHU apparatus as claimed in claim 4, the plurality of cooling pads (206) are wetted by the water in the water sump so as to cool temperature of air passing through it by direct evaporative cooling.
7. The AHU apparatus as claimed in claim 4, wherein the plurality of cooling pads (206) are cell deck pads.
8. The AHU apparatus as claimed in claim 1, wherein the secondary cooling coil (204) functions as a heat exchanger and cools the temperature of air flowing from the plurality of cooling pads (206) using evaporative cooling.
9. The AHU apparatus as claimed in one of claims 1 to 7, wherein the evaporator and the secondary cooling coil (204) are arranged parallel to each other and posterior to the air filter.
10. The AHU apparatus as claimed in claim 1, wherein the environmental parameters are temperature and relative humidity.