CLIAMS:1. A system for improved heat exchange mechanism maintaining products at a desired storage temperature for prolonged time interval and/or in various environmental conditions during delivery and a method thereof,wherein includes;
providing a compact chamber with walls composed of heat conductive material for transfer of heat;
providing an inlet for phase change material that acts as a eutectic solution which is capable of being frozen and an inlet for freezing liquid capable of freezing the phase change material during charging process;
providing closed cycle air tubing system through the compact chamber for passing compressed air through freezing liquid during discharging process;
providing a coil in a specific configuration with spacing, extended surfaces etc. and refrigerant / secondary cooling fluid flowing through it to increase the heat transfer
providing equally spaced extended surfaces to said tubes and walls of saidconductive material for effective heat exchange between the eutectic solution and the chamber;
providing an air bubbling system or air tubing system also termed as air sparger at the bottom of said chamber, to circulate said compressed air from bottom to top of the chamber exclusively to create turbulence during discharge of heat from the product to the phase change material such that heat is distributed effectively through the phase change material during the discharging process.
2. A cold storage chamber in said heat exchange mechanism system according to claim 1 wherein said chamber has four walls made of conductive material has an outlet for air that has created during exchange of latent heat of fusion in between the product to the phase change material.

3. A cold storage chamber in said heat exchange mechanism system according to claim 1 wherein said space inside the chamber is filled with a tubing system with and inlet and outlet for passing the freezing solution through the tubes.

4. A cold storage chamber in said heat exchange mechanism system according to claim 1 wherein said tubing structure is surrounded by said phase change material that is in liquid state before said charging process filled into the chamber thorough an inlet present on the top of the left side of the chamber.

5. A cold storage chamber in said heat exchange mechanism system according to claim 1 has fins attached to the walls of the chamber internally to increase heat transfer rateduring a discharge process.

6. An air bubbling and or air tubing system attached at the bottom of said chamber in said heat exchange mechanism system according to claim 1 wherein said system comprises a tube with multiple holes/sparger through which the compressed air is jetted out for circulation of air bubble that creates turbulence due to buoyancy effect to increase heat transfer rate during discharging process.

7. A tubing system in a cold storage chamber in said heat exchange mechanism system according to claim 3 wherein said tubing system is attached with equally spaced extended surface of conductive material lies externally to the tubes, inside the chamber.

8. Extended surfaces attached to the walls of the chamber internally in a cold storage chamber in said heat exchange mechanism system according to claim 1 are of wavy structure to provide said turbulence effectively.

9. Extended surfaces attached to the tubes externally to the tubing system in a cold storage system according to claim 7 are attached longitudinally and/or spirally to the external surface of the tube.

10. Charging process in said heat exchange mechanism system according to the claim 1 invests passage of the liquid freezing material/refrigerant through the tubes surrounding with the phase change material in liquid phase which is capable to freeze at the freezing temperature with the passage of said freezing liquid/refrigerant, thus getting converted to solid phase.

11. Said discharge process in said heat exchange mechanism system according to claim 1 involves latent heat of fusion transferring heat from the products to the phase change material, thus cooling the products and maintaining the storage temperature.

12. Said discharge process in said heat exchange mechanism systemaccording to claim 11 is also accelerated using an additional fan attached to the ceiling of the vehicle beside the compact chamber. ,TagSPECI:FORM-2
THE PATENT ACT, 1970
(39 OF 1970)
&
THE PATENT RULES, 2003

COMPLETE SPECIFICATION

[SECTION 10; RULE 13]
“SYSTEM AND METHOD FOR TEMPERATURE MODULATION USING PHASE CHANGE MATERIAL IN A SPECIAL HEAT EXCHANGER”

THERMAL ENERGY SERVICE SOLUTIONS PVT. LTD
D 29/12, MIDC Turbhe, Navi Mumbai - 400705

FIELD OF INVENTION:
The present invention relates to the improved heat transfer based eutectic cold plate refrigeration system and the method and system related thereto.

BACKGROUND OF THE INVENTION:
India is agriculture based economy having a production of 63.5 million tons of fruits and 125.89 million tons of vegetables, every year. India is also the largest producer of milk (105 million metric tons per year) and produces 6.5 million tons of meat and poultry and 6.1 million tons of fish. In addition to huge size of agro industry, the pharmaceuticals industry in India is the world’s third largest in terms of volume and stands 14th in terms of value. India has the potential to become one of the world’s major food suppliers.
India is the world’s largest producer of fresh fruits and vegetables, milk, spices, select fresh meat, dry fruits, agriculture-based textile raw materials, roots and tuber crops and eggs. India exported 600,000 metric tons of fish products to nearly half of all the world’s countries. This is a huge challenge in terms of costs for fresh produce especially vegetables, milk and fruits leading to high inflation as also spoilage / waste which is a threat to food security leading to hunger, malnutrition and premature deaths. There is an immediate need for investment & modernization of existing cold chain facilities. Efficient cold chain network will contribute in preventing spoilage.
Refrigerated Trucks, popularly called reefer trucks contain a refrigeration system on board that keeps the temperatures in the container constant and normally uses diesel for generating energy. Containers for refrigerated trucks at times are used to carry perishable products like dairy product, fruits, vegetables and fish from one location to another with travel time ranging from 6 hours to 24 hours.
Conventional methods that are used to cool the perishable items and transfer place to place includes method such as using the vehicle prime mover engine to operate a compressor and the separately powered refrigeration unit type systems that incorporates a small auxiliary diesel engine for autonomous operation as mentioned in the prior art application number EP19840901898, and an electric motor for use when at a loading and unloading location where electrical power is available.
Air cooling inside the container is accomplished by means of a refrigerant to air heat exchanger. The main drawback of such system is diesel consumption for engine to run refrigerant compressor. Such diesel powered refrigeration unit has undesirable failure mechanisms and maintenance requirements differing from the truck maintenance
An alternative to the diesel based systems is a latent energy storage based system. Current latent energy storage based systems for cold chain and air conditioning application use “Eutectic panels” which contain either a glycol water mixture or a eutectic salt. These pads are supplied with eutectic salt where they are frozen to store energy and melted to release energy. These Eutectic systems are designed to freeze over a 10-12 hour period which is too high for normal logistics operation.
The temperature pull down reduces drastically in all eutectic systems after a few openings. This is primarily due to uneven melting once the part closest to the outer plate melts. This was observed with the patent application no. EP19840901898 which uses spaced external fins to the surface of the walls.Furthermore same problem was recorded with an expired patent “Truck plates”, patent number US 2814186A and was issued to Dole Refrigerating Co. Dole remains the leading US manufacture of cold-plate Eutectic technology in the USA mentions about presence of fins in the body of the plate.
Furthermore the weight of eutectic plates is a barrier when it comes to larger vehicles. There is a problem using prior art eutectic panels for variable temperature applications.
These are typically used for local transport of perishable food and pharmacy supplies.
Thus what is needed is a method and system that provides improved heat transfer and regulate temperature inside the refrigeration system and also reduce the operational cost eliminating usage of diesel for its working.
Furthermore to solve the freezing requirements of different food items and variable products reducing the lapse time and providing constant temperature range till the end of the delivery, thus leading to huge savings in cost for storing and transporting fresh produce such as vegetable, milk, fruits, meat products etc.

SUMMARY/ OBJECT OF THE INVENTION:
The present invention provides a system for providing improved heat exchange between the product and the freezing material wherein system includes arrangement of inventive elements with improved method to achieve the required storage conditions of different food items and and maintain constant temperature range till the end of the delivery.
The main object of the invention is to provide a robust and operating cost efficient refrigeration solution for refrigerated truck/ reefer.
Further object of the invention is to provide a refrigerating system with enhanced freezing capability for fast charging. Thus providing an improvised Phase Change Material (PCM) heat exchanger with specific combination of tube spacing, tube configuration, extended surfaces (fins) and refrigeration circuit that enhances the heat transfer capability for freezing of PCM leading to freeze the material in time periods starting as low as 2 hours instead of the current 10-12 hours.
The object of the invention also includes providing maximum time for the exchange to take place thus introducing an air bubbler at the bottom of the chamber to create maximum mixing, also the presence of extended surface present on the outside of the tubing system provide maximum obstruction to the air passing from bottom to the top thus providing maximum heat exchange.
The object of the invention is to keep the perishable food and non-food products at desired temperature reducing the effect of changes in the external environment or frequent opening of the door of the vehicle etc. The combination of external and internal fins ensure that the melting of phase change material is uniform to reduce pull down temperature. In addition a fan based system is provided in some cases to increase external heat transfer and further reduce this pull down time.
Furthermore the invention aims to provide an improvised method to prolong this heat exchange time duration through better control and reduce the time gap between the sudden temperature drop and rise in the system.
BRIEF DESCRIPTION OF DRAWINGS:
Fig 1 illustrates an improved cold plate based outdoor stationary/vehicle mounted refrigeration system (100), cold plate assembly (101) and an insulated container body.
In the following description, for the purpose of understanding system details are set forth such as specifics components with internal, cold plate assembly/arrangement in order to provide a through explanation of the present invention. In other instance, well known compressor based refrigeration components like condenser, expansion valve, have not been given in details in order not to obscure the present invention unnecessarily.
Figure 2 illustrates cold plate assembly (101) placed inside the insulated casing (106). The cold plate assembly consists of proper insulated body with finned cold plate and axial fan (107) for air circulation inside the container. The cold plate assembly (101) is connected to the condensing unit that comprises compressor, expansion valves, refrigerant accumulator, refrigerant receiver, expansion valve and condenser.
Figure 3 below for individual cold plate to store cold energy comprises an air sparger/bubbler (105) situated at the plate bottom, direct refrigerant expansion coil (108) inside liquid/solid Phase change materials
Refrigerant expansion coil arranged to get maximum solid PCM thickness in short time. To reduce the charging period further refrigerant coil is finned longitudinally, spirally etc. Provided fins improves heat transfer rate and PCM solid formation rate enabling faster charging by up to 50% which enables faster turnaround time for the refrigeration vans .
Figure 4 illustrates closed air circulation circuit that includes a air compressor (104), an air return manifold (102) and an air supply manifold (103) or air bubbling system in this bottom tube with holes (105) (different sizes) is used to create turbulence during charging and discharging of cold plate (101). The air sparger also enables a change of conduction heat transfer to convection thereby increasing the heat transfer by several folds.

DESCRIPTION:
The state-of-the-art reveals latent energy storage based systems for cold chain and air conditioning application use “Eutectic panels” which contain either a glycol water mixture or a eutectic salt. These pads are supplied with refrigerant or cold liquid where they are frozen to store energy and melted to release energy. These Eutectic systems are designed to freeze over a 10-12 hour period which is too high for normal logistics operation.
Furthermore the weight of eutectic plates is a barrier when it comes to larger vehicles. There is a problem using prior art eutectic panels for variable temperature applications. The explained invention resolves the problem of existing technology by making modifications in the design of the eutectic plate (called the Advanced PCM heat exchanger) and by adjusting the configuration of the unit. One of the largest issues with PCM is the low conductivity of the material. In this invention, PCM heat exchanger uses specific combination of tube spacing, types of extended surfaces (fins) which is also referred as fins in some places in the specification and refrigeration circuit that enhances the heat transfer capability for freezing of PCM. Thus such heat exchangers freeze the material in time periods starting from as low as 2 hours
Each plate or heat exchanger unit has four connections like refrigerant liquid supply, refrigerant vapor exit, Air bubble pipe inlet and PCM filling and air exit port. Individual finned cold plate is filled with a eutectic material exhibiting a phase change either liquid to solid or solid to liquid at required Phase change temperature for particular application like air conditioning, process cooling, and refrigeration.
The internal fins on the heat exchanger surface provide an even melting profile of the PCM. These fins are added on the inside surface of the panel using a metal joining process and embossing. These fins differ from size space range of 2-10 fins per inch of the space of the tube or the external surface attached depending on the requirement and is variable.
In order to reduce the weight of the eutectic system, 100% Aluminum (specific grades) heat exchanger are used as conductive material thereby reducing the weight by 50%. This will enhance the usability of these systems across larger vehicles and longer travel times. Also the used of conductive material is not limited to aluminum but can be replaced by any metal including stainless steel, Mild Steel, copper etc. according to the requirement of the product to be carried and the temperature that needs to be maintained in the system.
Both air supply and exit manifolds are installed above the cold plate level to avoid liquid carry over. Air holes at the bottom of air tube are arranged in such way that air can pass through plate surface & finned coil.
The higher heat transfer capability by using internal fins and also adding external fins (like radiators), lead to a much higher rate of melting the PCM. Therefore a fan based system can be employed to vary the air flow and therefore control the internal temperature of the container. The fan in such case is placed beside the eutectic plate on the roof such that opening of the doors of the vehicle and closing that would cause the temperature drop and recovery will be quick using such fans.
There is an air sparger also mentioned as air bubbling or air tubing system in the claims is the same, added to the plate which enables a change of conduction heat transfer to convection thereby increasing the heat transfer by several folds. This is especially critical if we are trying to extract the last bit of energy in the heat exchanger.This system includes bottom tube with holes (different sizes) is used to create turbulence during charging and discharging of cold plate.
Closed air circulation circuit mainly consist air tubing, non return valve, service valves, air distributor/manifold, compressor. Once compressed air passed through the tube holes as a bubbles, creates mixing inside the PCM when bubble travels from bottom to top of the plate due to buoyancy force. This improves heat transfer rate especially during melting of PCM (i.e. during the discharge process). Air releases through Upper port and passed to compressor for compression. Same compressed air being circulated through cold plate assembly. The charging system includes attaching the charging plug into the eutectic plate also mentioned as compact chamber in the specification ahead in the claims and thus passing the freezing liquid through the inlet into the compact chamber comprising tubes with extended surface surrounded by the phase change material, thus freezing the phase change material into solid phase. This charging process takes place for 3-6 hours.
During delivery of products when the food or non-food products are loaded in the truck in front of compact chambers also called as eutectic plates assembly during delivery the temperature is maintained through latent heat of melting wherein the frozen PCM absorbs the heat from the product and keeps the product freeze for longer period.
Present invention is to develop improved cold plate based refrigeration system. The heat transfer characteristic of cold plate during charging and discharging have improved with provision of extended outer fins and closed air circulation inside the PCM. Thus heat exchanger battery (stacked finned cold plates) is charged using an external stationery refrigeration unit. The desired temperature maintained for a period ranging from six hours to a day depending on the product storage volume and insulation provision & heat loss rate.