TECHNICAL FIELD OF THE INVENTION

This invention relates generally to heating, ventilation air conditioning systems suitable for industrial or commercial applications. More particularly the present invention relates to air conditioning system using enthalpy of solar energy for its operation.

BACKGROUND AND THE PRIOR ART

The use of Solar Thermal Energy to save the electricity consumed in Heating, Ventilation and Air - Conditioning (HVAC) systems has been widely recommended. Of all the proposed technologies, solar-assisted HVAC systems using absorption chillers have become one of the most appealing. This directly impacts on fuel saving if steam based chiller is used in plant or any industrial premises. Additionally, it also replaces the use of hazardous gases (refrigerants used in vapor compression system) which damages to ozone layer and creates threat for entire flora-fauna on the earth. Furthermore, a Lithium Bromide – water based absorption system replaces the use of harmful ammonia based liquid refrigerant in absorption cooling systems.

In general, absorption is the process by which refrigerant vapor is absorbed to a concentrated solution. The heat of condensation of the water and the heat of mixing are released into the fluid by the absorption process. The fluid must be cooled to allow sufficient refrigerant to be continuously absorbed into solution while maintaining a low pressure condition. Water and lithium-bromide have been widely used in these systems. This working fluid utilizes water as the refrigerant and is therefore limited to refrigeration temperatures above 0° C. Solar thermal energy based HVAC system is demonstrated now a days in India and world –wide and their feasibility and performance evaluation is continuously monitoring for further improvement.
Absorption machines based on water and lithium-bromide are typically configured as water chillers for air-conditioning systems in large buildings.

Typical electrically operated ‘vapor compression machines’ are available in sizes ranging from 10 to 1500 tons. These machines have a reputation for consistent, dependable service. Nonetheless, they also require a large amount of electricity to operate. Although the aforesaid mentioned ‘Solar Powered Vapor Absorption Chiller’ has demonstrated the feasibility of reducing electricity usage, they have not become commercially available or widely used.

US5666818 titled ‘Solar driven ammonia-absorption cooling machine’ provides a cooling machine driven by solar energy, useful for air-conditioning, refrigeration, ice production, or the like. More particularly, the invention is directed to a device known as a generator forming part of the cooling machine which utilizes an aqueous solution of ammonia as the working fluid in an absorption type refrigeration thermodynamic cycle. The disclosed invention in this application is based on Lithium bromide – water based solution where LI-Br is solvent and water is refrigerant.

US6260370 titled ‘Solar Refrigeration And Heating System Usable With Alternative Heat Sources’ provides an apparatus for heating and cooling including a heat source for transferring incident heat energy to a liquid refrigerant material thereby changing the refrigerant material from the liquid state to a gaseous state. The heat source has an inlet for receiving the refrigerant material in the liquid state and an outlet tor discharging the refrigerant material in the gaseous state. An eductor-venturi is used to reduce a pressure of the gaseous refrigerant material and a condenser removes the heat energy thereby changing the refrigerant material back to the liquid state. A type of refrigerant and energy storage is not mentioned in the invention which has very well taken care in our disclosed invention.

US6539738 titled ‘Compact Solar-Powered Air Conditioning Systems’ which is specially designed for tropical climates includes an air-cooled single-effect absorption machine driven by an array of high performance flat-plate collectors along with a thermal storage tank. The absorption machine uses lithium-bromide as a refrigerant and a water-based absorption fluid. The disclosed invention here is specially meant for bulk air-conditioning usage. Secondly the solar block mentioned in the preferred disclosed invention usages solar concentrators. And further more aforesaid invention is for single effect vapour absorption cooling system. And disclosed invention is based in high efficiency double effect absorption cooling system.

US7451611 refers to a ‘Solar Air Conditioning System’, designed to operate with concentrated solar heat and using a circulating refrigerant in a cycle of compression and expansion. Solar concentrators raise the temperature and pressure of the refrigerant. The raised temperature is dissipated to the atmosphere and the refrigerant proceeds to the evaporator coil, which is located within a water tank containing of an anti-freeze water solution. As the water is the storage medium, heat can be added to or extracted from the storage medium by the evaporator coil. A radiator pickup coil is also located within the water tank and is part of a separate chilled water system which circulates its own water supply through other radiators located throughout a residence. Additionally, one or more bypass valves are also integrated in the system within the refrigerant system allows switching to solar heating. This invention requires more power as is it based on vapour compression system and additionally the system is quite bulky which is not in case of our disclosed invention here.

In contrast to the available technologies, the present invention uses advanced concentrating solar power technology (CSP) for producing solar thermal energy. This CSP technology is based on two axis tracking technology which is more productive than solar flat plate collector. The chilling effect is produced by ‘double effect vapour absorption machine’ which has higher than single effect machine. The energy storage technique is based on cold energy storage which is more efficient compared to hot energy storage due to lower temperature differential between the energy storage media temperature and ambient temperature. Additionally, present invention can work on three different modes depending on the solar radiation and air conditioning load as (i) Working Day Operation, (ii) Non-Working Day Operation, (iii) Lean / Non Solar period operation.

OBJECTS OF THE INVENTION

A basic object of the present invention is to overcome the disadvantages/drawbacks of the known art.

Another object of the present invention is to provide an air conditioning system using enthalpy of solar energy for its operation.

Another object of the present invention is to save the electricity consumed in Heating, Ventilation and Air - Conditioning (HVAC) by using Solar Thermal Energy.

Another object of the present invention is to replace the use of harmful ammonia based liquid refrigerant in absorption cooling systems by a Lithium Bromide – water based absorption system.

Another object of the present invention is to replace the use of hazardous gases (refrigerants used in vapour compression system) which damages to ozone layer and creates threat for entire flora-fauna on the earth.

Another object of the present invention is to store excess cold energy and use it to function during lean and non solar period.

Yet another object of the present invention is to produce ‘heating effect’ during winters.

These and other advantages of the present invention will become readily apparent from the following detailed description read in conjunction with the accompanying drawings.

SUMMARY OF THE INVENTION

There is provided an air conditioning system.

According to one embodiment of the present invention, there is provided an air conditioning system using enthalpy of solar energy for its operation, said system comprising one or more solar concentrator means, said concentrator means with one or more receiver means together defining a solar field configured to heat a fluid passing through said receiver means; an absorption chiller means taking enthalpy of steam from said solar field using a refrigerant means and further generating substantially chilled water; a fan coil unit operationally in communication with said absorption chiller means; a thermal energy storage means configured to store extra chilled water to be used during low solar radiation period; and a switching means for optionally selecting the heating or cooling effect.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS

The following drawings are illustrative of particular examples for enabling methods of the present invention, are descriptive of some of the 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.

Fig 1 illustrates the block diagram for sun radiation based climate control machine.

Fig 2 illustrates Scheme for Sun Radiation based Climate Control Machine in accordance with the present invention.

DETAILED DESCRIPTION OF THE ACCOMPANYING DRAWINGS

Accordingly the present invention provides radiation based climate control machine configured to function additionally for lean/non sun period.

Reference is first invited to Fig 1 where the block diagram for sun radiation based climate control machine for lean/non sun period is illustrated.

The schematic in fig 2 shows embodiment of the desired system used for air-conditioning cycle with the help of solar Thermal energy. Fig shows that it includes solar concentrator - paraboloid dish (101) designed aperture with Fresnel mirrors. At the focal point of the aperture there is heat capturing device called receiver (102) where all thermal energy fallen on aperture (101) gets concentrated. This solar dish assembly is point focus two, axis tracking Fresnel / flat mirror based dish.

Component (110) is vapor absorption machine comprising of four parts: Generator (103), Condenser (104), absorber (105) and Evaporator (106). Vapor absorption machine operates on different temperature level. First is 70 - to 900C called single effect vapor absorption machine where coefficient of performance is less than 1. Another temperature range is 165 to 170 0C which is called double effect vapor absorption machine with coefficient of performance is 1.3 or little more.

Solar thermal energy concentrated on receiver transfer its enthalpy to the fluid inside the receiver. As double effect vapor absorption machine operates on approx. 170 0C, once it’s achieved by receiver it generates hot fluid of 170 0C. This hot fluid enters into vapor absorption machine (110) specifically inside the generator (103). Inside the vapor absorption machine Absorber (105) and Evaporator (106) are maintained in vacuum. Two other fluids are used here for producing ‘chilled water’ and the same is used for ‘refrigerating effect’ as well. Fluids are Lithium-Bromide (Li-Br) and water. Here water is acts as a ‘refrigerant’ and Li-Br acts as ‘Absorbent’.

Boiling Point of water is function of ‘pressure’. At atmospheric pressure water boils at 100 0C. And at 6 mm of Hg (abs) pressure, water boils at 3.7 0C. Li-Br has high affinity towards water vapor. By using these principles vapor absorption machine (110) is designed to produce Chilled water.

Inside vapor absorption machine (110), evaporator (106) produces chilled water at 7 0C. It enters in Fan Coil Unit-FCU (109) which is inside the room (111) and cools the inside air. This chilled water comes out from FCU (109) at 12 0C carrying inside heat of room. This enters inside the absorber section (105) at 12 0C. Here water (refrigerant) is sprinkled on chilled water piping which takes heat from chilled water (at 12 0C) and turns into water vapor. This produces chilled water at 7 0C. As mentioned earlier Li-Br has high affinity towards water vapor. The turned water vapor gets absorbed by Li-Br and it becomes dilute solution of Li-Br due to mixing of water vapor. It thus needs to be re-concentrated by using heat source.

In this embodiment shown in fig 2, external heat source may be hot water, hot air, flue gas from the fossil power plant or direct steam etc. In this particular invention ‘hot fluid’ at 170 0C which is produced in Solar Dish assembly (101), (102) section. The selection of the temperature is for better COP. The result for producing hot fluid at different solar radiation is tabulated in next chapter. The lean solution is then pumped into generator (103) inside the vapor absorption machine (110). Inside the generator (103) steam of 170 0C cause the solution to release the absorbed refrigerant (water) in the form of vapor. This vapor is cooled in separate chamber to become liquid refrigerant (water). This chamber is in-built part of condenser (104). Here cooling water is used to convert the refrigerant vapor into liquid form which is then sprinkled over chilled water line inside the absorber section at vacuum. Then again it boils by taking heat from 12 0C chilled water and hence the same cycle repeats again and again to produce chilled water continuously.

Here VAM generates more chilled water than required for cooling the desired premises. The rest chilled water is continuously stored in thermal energy storage. This extra produced chilled water is then used during no solar / low solar radiation period. This design helps to improve the system reliability for continuous operation. On weekends or holidays the cooling load on VAM is zero hence all the chilled water generated on these days is transferred to thermal energy storage which will then capable to delivered the chilling effect for 10 to 12 hours.

The system is under operation and certain actual reading is indicated below:

Solar radiation
(W/m2) Saturated steam temp (0C) Pressure (bar) Chilling Effect (TR) Chilled water Flow rate (Kg/hr) Chilled water in room
(0C) Chilled water out room
(0C) Room Temp (0C) Ambient Temp (0C)
420.6756 173.305 7.188 19.26 21.08 20.796 23.561 30.53 41.57
403.8302 171.164 6.688 20.70 21.17 20.573 23.531 30.80 41.53
398.6335 160.031 4.904 33.86 21.96 18.671 23.338 30.61 41.28
380.6907 158.328 4.652 32.16 21.80 18.788 23.248 30.42 41.17
379.4509 154.734 4.070 30.23 22.01 18.878 23.027 29.61 41.10

Operation in non working days:

Solar radiation
(W/m2) Saturated steam temp (0C) Pressure (bar) Chilling Effect (TR) Chilled water Flow rate (Kg/hr) Tank temp (0C)
48.11452 144.891 2.916 24.23 21.72 21.131
59.85059 143.055 2.734 20.06 21.73 21.058
156.5415 138.883 2.305 17.68 21.79 20.940
169.5215 138.500 2.258 17.41 21.86 20.942
174.995 139.109 2.370 31.77 21.66 20.865

Low solar / no solar period:

Chilled water Flow rate (Kg/hr) Chilled water in room
(0C) Chilled water out of room
(0C) Tank Temp (0C) Room Temp (0C) Ambient Temp (0C)
21.44 20.252 20.848 19.939 24.71 42.45
22.05 21.339 21.928 19.972 24.27 42.41
19.97 21.857 22.453 19.974 23.96 41.13
21.41 22.170 22.766 20.046 23.62 41.10
24.31 20.381 21.167 20.094 24.07 41.35

Experimental data for the heat retention capability of the said storage means:

Chilling Effect (TR) Chilled water Flow rate to Tank (Kg/hr) VAM Temp in (0C) VAM Temp out (0C) Tank temp (0C)
24.23 21.72 22.230 18.847 21.131
20.06 21.73 22.166 19.372 21.058
17.68 21.79 22.044 19.586 20.940
17.41 21.86 22.020 19.614 20.942
31.77 21.66 21.983 17.537 20.865

Storage tank to Room (no-solar /low solar period operation):

Chilling Effect (TR) Chilled water Flow rate to Tank (Kg/hr) Tank Temp (0C)
4.23 21.44 19.939
4.31 22.05 19.972
3.94 19.97 19.974
4.22 21.41 20.046
6.33 24.31 20.094

The invented machine has a provision to produce ‘heating effect’ during winter days. This can be done without any alteration in piping and valve fittings. This is basically software selected mode of operation where the machine can produce heating or cooling whichever is required. The system comprises a switching means that incorporates software selected mode of operation configured to produce heating or cooling optionally.
Although the embodiments herein are described with various specific embodiments, it will be obvious for a person skilled in the art to practice the embodiments herein with modifications. However, all such modifications are deemed to be within the scope of the claims.
It is also to be understood that the following claims are intended to cover all of the generic and specific features of the embodiments described herein and all the statements of the scope of the embodiments which as a matter of language might be said to fall there between.

WE CLAIM:

1. An air conditioning system using enthalpy of solar energy for its operation, said system comprising:
one or more solar concentrator means, said concentrator means with one or more receiver means together defining a solar field configured to heat a fluid passing through said receiver means;
an absorption chiller means taking enthalpy of steam from said solar field using a refrigerant means and further generating substantially chilled water;
a fan coil unit operationally in communication with said absorption chiller means;
wherein a thermal energy storage means operatively connected with said absorption chiller means and configured to store extra chilled water produced at said absorption chiller means to be used during low solar radiation period; and a switching means for optionally selecting the heating or cooling effect.
2. System as claimed in claim 1 wherein said absorption chiller means comprising lithium bromide solution as an absorbent means.
3. System as claimed in claim 1 wherein said refrigerant means is water.
4. System as claimed in claim 1 wherein said solar concentrator means comprising substantially paraboloid dish with Fresnel mirrors and said receiver is substantially a cavity receiver.
5. System as claimed in claim 1 wherein said solar concentrator means optionally configured to an axis tracking Fresnel or a flat mirror based dish.
6. System as claimed in claim 1 wherein said absorption chiller means comprising:
a generator means configured to allow said operating fluid to release the absorbed refrigerant in the form of vapour; said vapour cooled in a condenser means thereby providing a liquid refrigerant that is further sprinkled over the chilled water line in said absorber means; an evaporator means operatively configured to produce substantially chilled water.
7. System as claimed in claim 1 and 6 wherein said vapour absorption chiller means in communication with a cooling tower configured to operate at substantially varying temperature range.
8. System as claimed in claim 1 and 6 wherein said evaporator means configured to produce chilled water and further transfer said chilled water to said fan coil unit thereby cooling the room.
9. System as claimed in claim 1 wherein said fan coil unit operatively configured with refrigerant means taking room inside heat to said absorbent means.
10. An air conditioning system using enthalpy of solar energy for operation as herein described and illustrated with reference to accompanying drawings read in conjunction with the detailed description.