The present invention generally relates to thermal energy storage systems. In particular, the present invention relates to a thermal energy storage based air conditioning system and method for improving overall heat transfer rate and ensuring maximum energy conservation without compromising the comfort level of the occupants.

BACKGROUND OF THE INVENTION

[0002] The continuous depletion of fossil fuels and increase in energy demand has led to energy insecurity. Both energy conservation and efficiency are energy consumption reduction techniques, yet the advantages of energy conservation are fairly straight forward.

[0003] In India, more than 30% of total energy demand comes from the building sector, wherein heating, ventilation and air conditioning (HVAC) systems consume nearly 50% of total building energy consumption. In several parts of India the air conditioner (AC) in commercial buildings run for almost eight months in a year. On the other hand, in places where diurnal temperature (max temp deviation in a given day) is high, the night time atmospheric temperature drops below the daytime AC set point temperature. For such places there is a great potential available in the night time cool atmospheric air’s thermal energy to be used for maintaining comfortable temperature in the living space in subsequent daytime. For this purpose, the thermal energy need to be stored in the night time and be used in daytime with or without the main building AC system.

[0004] Thermal Energy Storage (TES) is defined as the change in internal energy of a material by sensible heating, latent heating, and thermo-chemical heating, or combination of these. In case of Sensible heat storage (SHS) the temperature of liquid or solid is changed by heating or cooling to store thermal energy and releasing it for increasing/decreasing the temperature when it is required.

[0005] In the most widely used TES based Air Conditioning systems a standard chiller runs during the night to produce an ice pile. Water then circulates through the pile during the day to produce chilled water that is used as the chiller during daytime. Such a system usually runs in ice-making mode more than half a day and in ice-melting mode for 6 hours a day. Capital expenditures are minimized because the chillers can be just 40 - 50% of the size needed for a conventional air conditioning design.

[0006] Another method for TES is performed by chilled water, wherein water is stored inside a tank at 4 to 6 ºC in stratified layers in the night time, which is then used for daytime cooling.

[0007] However, the application of SHS based Air Conditioning system is restricted to large building structures owing to the huge volume requirement for storing thermal energy, which is also the main hindrance for widespread use of this technology.

[0008] In case of Latent Heat Storage (LHS), the material undergoes change in phase with heating or cooling. The material that absorbs or release thermal energy during phase change is termed as Phase Change Material (PCM). Several research works are being done in the field of LHS due to its advantages over SHS, like (a) LHS has higher energy density and it stores heat at constant temperature corresponding to the phase transition, and (b) LHS requires 5 to 10 times smaller sized system than SHS system etc. In LHS system the Solid-Liquid phase transition system is preferred, because of little change in volume (< 10%). Some of the important works with LHS are listed as under.

[0009] Incorporating PCM with chilled water based AC systems using spherical or cylindrical encapsulations is being used in the HVAC systems for large-scale buildings, which enhances the energy conservation.

[0010] The research paper titled “The Evaluation of Peak Shaving by a Thermal Storage System Using Phase-Change Materials in Air Distribution Systems” (Yamaha and Misaki; HVAC&R RESEARCH 12(3):861-869; September 2006) describes a mixture of paraffin wax and fatty acid as PCM in an air distribution duct for an office building and maintain the room temperature at around 19ºC without cold operation sources.

[0011] The research paper titled” Efficiency of free cooling using latent heat storage integrated into the ventilation system of a low energy building” (Arkar et al.; International Journal of Refrigeration 30(1):134-143, January 2007) mentions two LHSs, wherein one works for cooling the fresh air temperature and the second removes the room cooling load by re-circulating the internal air to get the chosen temperature limit.

[0012] The research paper titled “Study of a floor supply air conditioning system using granular phase change material to augment building mass thermal storage—Heat response in small scale experiments” (Nagano et al.; Energy and Buildings 38(5):436-446, May 2006) describes an embedded PCM in the form of granules which is several millimetres in diameter directly below floorboard. During the night-time the cold air circulates through the packed bed and floor board to charge the concrete slab, this energy is released during daytime to reduce the cooling load of the room.

[0013] The research paper titled “Heat transfer and pressure drop studies on a PCM-heat exchanger module for free cooling applications” (Antony Aroul Raj and Velraj; International Journal of Thermal Sciences 50(8):1573-1582, August 2011) recites a regenerative PCM heat exchanger (shell and tube) module incorporated into the ventilation system. By selectively opening/closing the dampers, cold air passes through the PCM heat exchanger and stores the cool energy in night time; and in daytime, the energy is retrieved by the circulation of air by the fan to cool the room.

[0014] The research paper titled “Cooling of Room with Ceiling Fan Using Phase Change Materials” (Stalin et al., Proceedings of the World Congress on Engineering 2013 Vol III, WCE 2013, July 3 - 5, 2013, London, U.K) recites a mounted PCM on ceiling fan to impart air conditioning effect. The PCM harnesses the room’s hot air and in process of passing it over PCM cools the room.

[0015] The research paper titled “Experimental investigation of free cooling using phase change material-filled air heat exchanger for energy efficiency in buildings” (Muthuvelana et al., Journal of Advances in Building Energy Research, November 11, 2016) evaluates the ability of storing useful energy available in the night time ambient air in a flat modular type PCM-based storage type heat exchanger and retrieving the same for daytime cooling requirements. From the results obtained it is inferred that an average reduction of 2.5°C in the room temperature is possible.

[0016] The research paper titled “ Application of model-based control strategy to hybrid free cooling system with latent heat thermal energy storage for TBSs” (Wang et al.; Energy and Buildings 167; February 2018) explores the application of model predictive control technology to the telecommunication base stations hybrid free cooling system with LHS unit for minimizing the building operational cost without sacrificing temperature requirements. In comparison to a defined baseline case, the model predictive control method could achieve energy saving of up to 18%.

[0017] The research paper titled “System performance and economic assessment of a thermal energy storage based air-conditioning unit for transport applications” (Nie et.al.; Applied Energy, Volume 251, 1 October 2019, 113254) addresses the low energy efficiency and thermal comfort challenges of the traditional AC system, wherein integration of TES containing a PCM with a conventional AC unit (PCM-AC) is done. The comparison between AC and PCM-AC showed that, temperature fluctuation of the PCM-AC is reduced up to 2.56?°C and also the ON-OFF frequency of the compressor. The overall COP of PCM-AC is increased by 19%.

[0018] Several studies have been conducted towards LHS in the form of PCM in the ventilation system either in the form of capsules or by using dual ventilation system to recycle the in-house cold air. The PCM are also used to store cooling energy below the floor level. Storing of the PCM in the shell & tube heat exchanger is also tried and by selective opening of the damper LHS process is performed. PCM are also coupled with ceiling fan to avail AC feeling. Convectional AC system coupled with PCM was developed, which established better temperature stability & efficiency.

[0019] The existing methods of LHS system are applicable only for large scale buildings and till date no study has been conducted in the LHS based system to make the system compact by improving the heat transfer in the heat exchanger device, so the application level can range from household level to a large building.

[0020] Therefore, there exists a need to develop a thermal energy storage based air conditioning system and method for improving overall heat transfer rate and ensuring maximum energy conservation without compromising the comfort level of the premises thereby saving in energy charges.

OBJECTIVE OF THE INVENTION

[0021] The objective of the present invention is to overcome the shortcomings associated with the existing systems and methods.

[0022] Another objective of the present invention is to provide a thermal energy storage based air conditioning system and a method for improving overall heat transfer rate and ensuring maximum energy conservation without compromising the comfort level of the premises.

[0023] Another objective of the present invention is to provide a thermal energy storage based air conditioning system that controls the heat exchanger as per the atmospheric temperature which can be used even in the daytime, if the atmospheric temperature is desirable.

[0024] Another objective of the present invention is to provide a system that can be used for night time room heating with usage of day time heat in a cold climate area.

[0025] Another objective of the present invention is to provide a system comprising a Micro-Controller Based Control Unit (MCCU) that monitors the thermocouple, control valve, switching mechanism of fan and fan speed embodied in the system.

[0026] Still another objective of the present invention is to provide a system that uses PCM material with no harmful effects.

[0027] Yet another objective of the present invention is to provide a system that is self-operative, simple in design , compact, economical and possess quick recharging capability.

[0028] These and other objectives of the present invention will be apparent from the drawings and descriptions herein. Every objective of the invention is attained by at least one embodiment of the invention.
SUMMARY OF THE INVENTION
[0029] The present invention is to create a thermal energy storage based air conditioning system and a method for improving overall heat transfer rate and ensuring maximum energy conservation by exploiting atmospheric cooling energy for air conditioning and without compromising the comfort level of the occupants.

[0030] According to an embodiment of the present invention, the thermal energy storage based air conditioning system, comprises of the following :

[0031] resistance temperature detectors (RTD) for measuring temperature,

[0032] a Micro-Controller Based Control Unit (MCCU) for monitoring and controlling various parts of the thermal energy storage based air conditioning system, like thermocouple, control valve, switching mechanism of fan, fan speed;

[0033] a data logger for recording temperature data;

[0034] a control valve operational by the stepper motor;

[0035] an inlet duct for allowing cool atmospheric air to enter into the system;

[0036] a suction type fan for drawing air from atmosphere;

[0037] a nozzle to increase the velocity of incoming flow;

[0038] a heat exchanger interlinked to MCCU that comprises of 9 nos. of perforated plate for emanating impingement jets, which are arranged in 3 rows and each row has 3 such perforated plates

[0039] 9 nos. of stainless tubes containing PCM (PCM tubes) arranged in 3 rows and each row has 3 such PCM tubes.

[0040] PCM tubes are kept immediate downstream of each perforated plate and the said jets impinges on the surface of the PCM tube surface.

[0041] RTD-Sensors for measuring temperature and in-turn notifying about the solidification of PCMs. RTD sensor wires extended from heat exchanger to the MCCU for sending temperature reading to MCCU;

[0042] convergent or nozzle shaped flow paths in the heat exchanger that allows cool air to pass through it and increase the velocity in the downstream;

[0043] a bypass duct through which exhaust air from heat exchanger is sent back to atmosphere during the charging process and remains closed during the discharging process;

[0044] a diffuser shaped duct that allows conditioned air to enter to the space during the discharging step and

[0045] a return air flow duct for returning air from the room to the heat exchanger during the discharging process.

[0046] According to another embodiment of the present invention, the method of operation of the thermal energy storage based air conditioning system, comprises the steps of:
a) initiating the charging mechanism once the atmospheric temperature drops below freezing point temperature of the PCM;
b) receiving input for the MCCU from RTD sensor that measures atmospheric air temperature;
c) sending signals by MCCU to open the control valve to allow air into the system;
d) passing cool air through a perforated plate and emanate jets to impinge on the stainless steel tube containing PCM to enhance the heat transfer process;
e) solidifying the PCM-Tube when cool air impinges on the PCM tube surface;
f) shutting the heat exchanger’s inlet and outlet once all PCM in the tube are solidified with signal from RTD sensor and direction from MCCU;
g) initiating the discharging mechanism, wherein MCCU switches ON the fan and keeps the inlet valve in the shut OFF position;
h) drawing of air from the space by the fan and passing it through the heat exchanger, which cools the air and in turn melts the PCM; and
i) allowing conditioned air to enter the space by the diffuser shaped duct.

[0047] The invention provides a number of novel features and benefits. while practising the invention, an embodiment can be constructed to include one or more features or benefits of embodiments disclosed herein but not others. Accordingly, the preferred embodiments discussed herein are not to be construed as limiting.

BRIEF DESCRIPTION OF THE DRAWINGS

[0048] The present invention and its advantages will be better understood by referring to the following detailed description and the attached drawing in which
Figure 1 illustrates a schematic diagram of the components of the present system;
Figure 2a to 2e illustrates schematic diagram of the heat exchanger, wherein Figure 2(a) depicts working principle, Figure 2(b) is regarding dimension details {in Figure 2 (a) & (b) all the dimensions are in millimetre} and Figures 2(c), 2(d) and 2 (e) depict dimension detail of the holes in the 70 mm diameter stainless steel tube filled with PCM (5.1); 55 mm diameter stainless steel tube filled with PCM (5.2) and 40 mm diameter stainless steel tube filled with PCM (5.3) respectively; {in Figure 2 (c), (d) & (e) if not explicitly mentioned all the dimensions are in inches}
Figure 3a and Figure 3b illustrate the surface impingement of a single jet and surface impingement of an array of jets.
Figures 4 illustrates the stainless steel tube filled with PCM and temperature measuring arrangement;
Figure 5 illustrates a photographic view of the present system;
Figure 6 illustrates a circuit diagram of the MCCU and its communication process; and
DETAILED DESCRIPTION OF THE INVENTION

[0049] The following description includes the preferred embodiment of the present invention. It will be clear from this description that the invention is not limited to these illustrated embodiments but that the invention includes a variety of modifications and embodiments thereto. Therefore, the present description should be seen as illustrative and not limiting. There is no intention to limit the invention to the specific form disclosed and the invention will cover all modifications, alternative constructions, and equivalents falling within the spirit and scope of the invention as defined in the claims.

[0050] In any embodiment described herein, the open-ended terms "comprising," "comprises,” and the like (which are synonymous with "including," "having,” and "characterized by") may be replaced by the respective partially closed phrases "consisting essentially of," “consists essentially of," and the like or the respective closed phrases "consisting of," "consists of,” and the like.

[0051] As used herein, the singular forms “a,” “an,” and “the” designate both the singular and the plural, unless expressly stated to designate the singular only.

[0052] The present invention is directed to a thermal energy storage based air conditioning system and a method for improving overall heat transfer rate and ensuring maximum energy conservation by exploiting atmospheric cooling energy for air conditioning and without compromising the comfort level of the occupants.

[0053] The thermal energy storage based air conditioning system as illustrated in Figures 1, comprises of resistance temperature detectors (RTD) 1 sensor for measuring atmospheric temperature, a micro-controller based Control unit (MCCU) ) 2 for monitoring the thermocouple, control valve, switching mechanism of fan and fan speed; a data logger 3 for recording temperature data; a control valve 4 which is operated by stepper motor; an inlet duct 5 for allowing cool atmospheric air to enter into the system; a suction type fan 6 for drawing air from atmosphere; a nozzle 7 to increase the velocity of incoming flow; a heat exchanger interlinked to MCCU 2 that comprises of nine perforated plates 8 for emanating impingement jets, stainless tubes 9 containing PCM, RTD-Sensors 11 for notifying about the solidification of PCM’s and corresponding sensor wires 12 arranged between the heat exchanger and MCCU, convergent or nozzle shaped flow path that allows cool air to pass through it and increases the velocity in the downstream; bypass duct through which exhaust air 13 from heat exchanger is sent back to atmosphere in charging mechanism; a diffuser shaped duct 14 that allows conditioned air to enter to the space 15 in the discharging mechanism; and a return air flow duct for returning air 16 from the room to the heat exchanger, enclosure of the heat exchanger 17 where glass wool insulation is sandwiched between GI sheet and plywood, where the plywood is on the outer side and an independent exhaust fan 18 installed in the space.

[0054] The method of operation of the thermal energy storage based air conditioning system, comprises the steps of: initiating the charging mechanism once the atmospheric temperature drops below freezing point temperature of the PCM; receiving input for the MCCU 2 from a RTD sensor 1; sending signals by MCCU 2 to open the control valve 4 to allow air into the system by switching on the fan 6; passing cool air through nine nos. of perforated plate 8 to convert normal crossover flow of air into jets to enhance the heat transfer process; solidifying the PCMs in the nine nos. of PCM Tube 9 located downstream of each perforated plate when cool air impinges on the PCM tube surface; the air passes through zig-zag channels 10 which are formed by baffles making nozzle shaped path in each row, and the air comes out via exit duct 13; initiating the discharging mechanism, wherein MCCU 2 switches ON the fan 6 and keeps the inlet valve 4 in the shut OFF position; drawing of air by the fan 6 and passing it through the heat exchanger, which cools the air and simultaneously melts the PCM; and allowing conditioned air to enter the space 15 by the diffuser shaped duct 14.

[0055] The present system has two phases, (i) charging and, (ii) discharging. In the charging phase, cooling energy is stored in the PCM from cool atmospheric air, whereas in discharging phase, the cooling energy is withdrawn from the PCM to cool the room. In discharging process, air from the room that is at relatively lower temperature is circulated over the PCM to absorb cooling energy stored during charging process. Discharging process is longer with room air in comparison to outside air. The room air then recirculates till all the PCM melts.

[0056] Figure 2a to 2e illustrates schematic diagram of the heat exchanger, wherein Figure 2a depicts the operating principle of the heat exchanger along with the components. The heat exchanger of Figure 2a comprises of control valve 1; plywood 2; glass wool insulation 3; G.I sheet 4, nine perforated plate emanating impingement jets 5.1,5.2,5.3 in each of the three rows; impingement jets 6, guided plates 7, 8, 9, 10 that zig-zag but nozzle shaped convergent path; 70 mm diameter stainless steel tube filled with PCM 11; 55 mm diameter stainless steel tube filled with PCM 12; and 40 mm diameter stainless steel tube filled with PCM 13, the 70/55/40 mm diameter tubes are available in each of the three rows.

[0057] Heat transfer rate generally increases with increase in Reynolds number (Inertia Force/Viscous Force) of the flow. Therefore, in the present invention, the simple cross over flow is converted into impingement flow which has a higher Reynolds number. The impingement jet (high individual jet Reynolds number) has significantly high level of heat transfer coefficient than the normal convective flow. Physics of the same is discussed as under with help of Figure 3 (a) and (b).

[0058] Figure 3a illustrates the surface impingement of a single jet, whereas Figure 3b illustrates the surface impingement of an array of jets. In Figure 3(a), when a jet (characterized by a uniform velocity profile) is discharged into a quiescent ambient from a hole/nozzle (in present arrangement it is the holes of the perforated plate) with increasing distance from the exit momentum exchange between the jet and the ambient causes the free boundary of the jet to broaden and the potential core to contract. The region of the flow over which conditions are unaffected by the impingement (target) surface is termed the free jet, in the zone at which jet 1st touches the target (solid) surface is called as stagnant or impingement zone. In the stagnation or impingement zone, flow is influenced by the target surface and is decelerated/accelerated in the normal/transverse directions. However, since the flow continues to entrain zero momentum fluid from the ambient, accelerating flow from the stagnation zone in transverse direction transforms to a decelerating wall jet. Accordingly, the heat transfer rate is characterized by a bell-shaped curve for which it monotonically decays from a maximum value at the stagnation point to zero in transverse direction. With multiple jets impinging on a surface as shown in Figure 3 (b), in addition to flow from each jet’s stagnation and wall jet regions, secondary stagnation zones result on the surface from the interaction of adjoining wall jets. Therefore, several stagnation zones with high heat transfer coefficient is formed across surface. Similar situation happens in present perforated plate and PCM tube arrangement, where the array of jets from perforated plate impinges on the PCM tube and improves the overall rate of heat transfer on the tube surface by forming several stagnation/impingement zones all across the interacting surface of the PCM tube; i.e. on the perforated plate side.

[0059] Impingement reduces flow velocity so that the air flow path is made convergent to regain the velocity in downstream. Thus in a row the 1st PCM-tube 11 has highest diameter (i.e. 70 mm) and the last PCM-tube 13 diameter is least (i.e. 40 mm). The heat exchanger enclosure has a multilayer structure, where glass wool insulation (3) is sandwiched between GI sheet (4) and Plywood (2) to ensure insulation and strength. Plywood is considered because it is easy to fabricate, robust and bad conductor of heat. On the outer side, thick glass wool is used to avoid heat loss from the stored (cooling) energy. Further, the PCM tubes on either sides are fixed with the said enclosure, in other words the enclosure is holding the PCM tubes steadily. Based on the pressure loss calculation and net path to travel by the air, commercially available suction type 45 Watt fan is used in the prototype developed for present purpose.

[0060] The charging process initiates when the atmospheric temperature drops below freezing point temperature of the PCM, which is otherwise the desired comfort level temperature of the occupant (typically 24 degree C to 28 degre C). The atmospheric temperature is measured by the resistance temperature detectors (RTD) sensor 1 and the same intimates the micro-controller based Control unit (MCCU) 2. Simultaneously, the temperature data is recorded in the data logger 3 for later analysis. The MCCU 2 sends signal to open the control valve 4 operated by the stepper motor. Through the control valve 4 and then the inlet duct 5 cool atmospheric air enters into the system. The inlet duct 5 has a wider inlet diameter to avoid fluctuation, and a filter to remove dust particles. Suction type fan 6 is used to draw air from atmosphere and the operation of this fan 6 is governed by the MCCU 2. Downstream, the air passes to the heat exchanger through a nozzle 7 to increase the velocity of incoming flow.

[0061] The heat exchanger is designed in such a manner that it enhances the heat transfer rate and minimize the pressure drop in air flow. The cool air passes through perforated plate 8 from which on the opposite side jets ejects out. The PCMs are kept inside stainless steel tube or PCM-Tube 9 immediately after each perforated plate 8. So, when cool air impinges on the tube surface the cooling energy gets conducted through the tube wall to cool down the PCM to freezing point when it solidifies. To notify about the solidification of PCMs, RTD-Sensors 10 are prefabricated into the tube. The cool air passes through convergent or nozzle shaped flow path to increase the velocity in the downstream. The fan 6 keeps on running till all the PCM solidifies. The MCCU 2 shuts OFF the fan and inlet valve 5 as soon as the temperature sensor connected to last PCM-tube confirms solidification. For this purpose, RTD sensor 10 is continuously monitored by MCCU 2. In the process of charging, exhaust air 14 from heat exchanger is sent back to atmosphere through the bypass duct.

[0062] In the discharging process, MCCU 2 switches on the fan 6 while keeping the inlet valve 4 in shut OFF position. The fan 6 draws air from the space and pass it through the heat exchanger. Counter to charging process, air gets cooled and PCM starts melting due to comparatively high temperature air flowing pass it. The conditioned air enters to the space 15 through the diffuser shaped duct 13 and the shape is chosen to avoid jet like entry and to achieve uniform air distribution inside the room, while the bypass duct is kept shut-off position.

[0063] Figure 4 illustrates a stainless steel tube filled with PCM and temperature measuring arrangement, comprising of screw fitting for thermocouple fitting 1, thermocouple wire up to 2 meters in length 2, measuring end of thermocouple (Length 10mm, Diameter approx. 3mm) 3; and a SS Tube (Length=40 inch, Diameter= 70/55/40mm) 4.

[0064] Figure 5 illustrates the pictorial view of the prototype developed for the Thermal Energy Storage based Air Conditioning system. As can be seen the temperature data logger 1 is used to record temperature via RTD sensor 6. The control valve 2 placed at the entrance of the system. The arrangement of perforated plate 3 and PCM-tube 4 can be understood from the pictorial view. Arrangement of the baffles 5 to make favourable flow path is also can be seen. The connection link between the heat exchanger 9 and space to be considered 8 is the diffuser shaped path, which also has a control valve. Cut portion of the heat exchanger enclosure 10 is also can be seen where glass wool is between GI sheet and Plywood (makes outer enclosure).

[0065] Figure 6 illustrates the circuit diagram of Micro Controller based Control Unit 3 and its communication process. The Micro Controller based Control Unit 3 comprises of four ports A, B, C and D 4.1, 4.2, 4.3, 4.4 respectively; LCD (16*2) 2; temperature sensors 1 for measuring both fluid and solid temperature. The data is sent to the Peripheral Interface Controller (PIC) microcontroller 3 and recorded in the temperature data logger. The MCCU 3 further sends signal to other device to take further action. In the prototype the communication is of wire type and later RF type communication is also attempted. Based on the temperature condition and charging/discharging process the control valve 4 is made operational. For precise control of the valve, stepper motor 7 is used. As in present case only fully open and fully close condition is required a two-step stepper motor is used. For prototype development two valves are controlled simultaneously. Optimum utilization of the fan is very important as it consumes most of the energy in present system. To bring energy efficiency the fan speed is controlled, mainly during charging process.

[0066] The Phase Change Material used in the present invention possess the following properties; non corrosive, nontoxic, no phase segregation, least reacting with container, high chemical & thermal stability, least volume change, high enthalpy of fusion, high thermal conductivity, low cost, availability etc.

[0067] Although the foregoing description contains many specifics, these should not be construed as limiting the scope of the present invention, but merely as providing illustrations of some of the presently preferred embodiments. Similarly, other embodiments of the invention may be devised which do not depart from the spirit or scope of the present invention. Features from different embodiments may be employed in combination.

[0068] The scope of the invention is, therefore, indicated and limited by the claims and their legal equivalents. All additions, deletions and modifications to the invention as disclosed herein which fall within the meaning and scope of the claims are to be embraced thereby.

We Claim:

1. A thermal energy storage based air conditioning system, comprising;
a) plurality of resistance temperature detectors (RTD) 1 sensor associated to a micro-controller based Control unit (MCCU) 2 for measuring atmospheric temperature;
a data logger 3 interlinked to said MCCU for recording temperature data received from said MCCU;
a control valve 4 operational by a stepper motor;
an inlet duct 5 coupled to said control valve 4, wherein said duct allows cool atmospheric air to enter into said system;
a suction type fan 6 for drawing air from atmosphere;
a nozzle 7 associated to said fan 6, wherein said nozzle 7 increases the velocity of incoming flow;
b) a heat exchanger interlinked to MCCU 2, wherein said exchanger consists of multiple perforated plate 8 for emanating impingement jets each followed by a stainless tubes 9 containing PCM, RTD-Sensors 10 for notifying about the solidification of said PCM’s, convergent or nozzle shaped flow path that allows cool air to pass through and increase the velocity in the downstream;
bypass duct 13 through which exhaust air from said heat exchanger is sent back to atmosphere in the charging mechanism;
a diffuser shaped duct 13 that allows conditioned air to enter to the space 15 in the discharging mechanism.
2. The system as claimed in Claim 1, wherein said system comprises of two phases, charging and discharging phase.
3. The system as claimed in Claim 1, wherein in said charging phase, cooling energy is stored in said PCM from cool atmospheric air, whereas in said discharging phase the cooling energy is withdrawn from said PCM to cool the room.
4. The system as claimed in Claim 1, wherein said system improves overall heat transfer rate and ensuring maximum energy conservation without compromising the comfort level of the occupants.
5. The system as claimed in Claim 1, wherein said heat exchanger comprises of control valve 1; plywood 2; insulation 3; G.I sheets 4; perforated plate emanating impingement jets 5.1,5.2,5.3; impingement jets 6, guided plates 7,8,9, 10; 70 mm diameter stainless steel tube filled with PCM 11; 55 mm diameter stainless steel tube filled with PCM 12; and 40 mm diameter stainless steel tube filled with PCM 13.

6. A method of operation of the thermal energy storage based air conditioning system as claimed in Claim 1, comprising the steps of:
a. initiating the charging mechanism once said atmospheric temperature drops below the freezing point temperature of said PCM;
b. receiving input for said micro-controller based Control unit (MCCU) 2 from said resistance temperature detector (RTD) sensor 1 ;
c. sending signals by said MCCU 2 to open said control valve 4 to allow air into said system;
d. passing cool air through said perforated plate 8 to enhance the heat transfer process;
e. solidifying said PCM-Tube 9 when cool air impinges on the PCM tube surface;
f. initiating the discharging mechanism, wherein said MCCU 2 switches ON the fan 6 and keeps inlet valve 5 in the shut OFF position;
g. drawing of air from the space 15 by said fan 6 and passing it through said heat exchanger, which cools the air and further melts the PCM; and
h. allowing conditioned air to enter the space 15 by the diffuser shaped duct 14.