CLIAMS:
1. A system for cooling and storing milk, the system comprising:
a compressor for compressing refrigerant;
at least one thermal battery having heat transfer fluid stored therein;
a liquid chiller connected to the compressor and the thermal battery, the liquid chiller enables heat transfer between the refrigerant and the heat transfer fluid without mixing with each other;
a heat exchanger connected to the thermal battery for circulating heat transfer fluid therethough for cooling milk poured over the heat exchanger;
a storage container for storing chilled milk received from the heat exchanger, and
a control unit connected to the compressor, the thermal battery, the liquid chiller, the heat exchanger, storage unit, a grid power supply and at least one electric battery,
wherein the control unit regulates power supply from main supply to charge the thermal battery and the electric battery, the control unit regulates power supply from electrical battery to discharge thermal battery when main electrical supply is not available and the control unit monitors and analyses system operating parameters.

2. The system as claimed in claim 1, wherein the liquid chiller is heat exchanger enabling chilling of heat transfer fluid by the refrigerant without mixing.

3. The system as claimed in claim 1, comprises an expansion valve between the liquid chiller and the compressor, the expansion valve removes pressure from the liquid refrigerant to allow change of state from a liquid to a vapor in the liquid chiller.

4. The system as claimed in claim 1, wherein the milk heat exchanger is surface heat exchanger, the milk is poured on the outer surface and the inner surface is circulated with the chilled heat transfer liquid.

5. The system as claimed in claim 1, wherein the thermal battery and the electrical battery are charged during system standby and discharged during system operation for chilling milk.

6. The system as claimed in claim 1, wherein the storage container is an insulated container capable of storing chilled liquid.

7. The system as claimed in claim 1, further comprises a first pump for circulating heat transfer fluid from the liquid chiller to thermal battery in a close loop, and a second pump for circulating heat transfer fluid from the thermal batter to the heat exchanger in a close loop.

8. The system as claimed in claim 1, wherein the thermal battery is a thermal insulated container capable of storing heat transfer fluid.

9. The system as claimed in claim 1, further comprises a container with a opening for pouring milk on the heat exchanger at a predefined rate.

10. The system as claimed in claim 1, wherein the electric battery is a rechargeable battery.

11. The system as claimed in claim 1, further comprises sensors disposed on compressor, liquid chiller, thermal battery rapid milk chiller and the storage container for collecting readings at various stages and providing it to the control unit.
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FIELD OF THE INVENTION

The present invention relates to a milk cooling and storage system for use in rural areas with unreliable electricity supply. The same invention can also be used to shift the power load from peak times to off-peak times of the day.

BACKGROUND OF THE INVENTION

The world’s energy demand is expected to increase 60% by 2030 and a majority of this increase will originate in emerging economies where over two billion people still have no access to modern energy sources. In these markets, cold-storage for perishable food items such as milk, fruits and vegetables, poses a real challenge. In India alone nearly $10 billion worth of food spoils each year due to the lack of refrigeration systems in the supply chain. The lack of refrigeration is a direct result of the lack of reliable electricity supply in rural areas where fresh produce are harvested.

PRIOR ART

When it comes to milk cooling, the known art in the field falls into two broad categories:

1. Direct Expansion (DX) cooling tanks. These so-called Bulk Milk Coolers (BMCs) use a combination of AC-powered refrigeration compressors and a double-bottom tank where the refrigerant gas expands to cool the milk inside the tank. The DX systems cool milk using a batch or bulk process. Raw milk is poured into the tank and, after a minimum amount is collected in the tank, the DX system is started. It could take up to 4 hours for all milk to be bulk-cooled to target temperature. In addition, during the cooling process, milk must be constantly agitated to provide efficient heat transfer between milk and the double-bottom heat exchanger. The agitation process negatively affects the quality of milk. The main drawback of the DX system is that it needs a high surge of power to cool the milk. For Indian conditions this means that the DX system must be paired up with a sizable diesel generator in case electrical power is not available when the system needs to be used: during morning and evening collection period. Therefore, the DX systems are not designed to work with limited grid power and, therefore, are not suitable for the conditions found in rural India.

2. For areas with limited electricity, an improved alternative to the Direct Expansion systems are the so-called Ice Bank Tank (IBT) systems which use thermal storage to address the problem of irregular power supply. When electrical power is available, the refrigeration system creates ice which acts as a backup mechanism that releases its energy when needed. If electricity is not available, the system uses the stored energy in ice to cool the milk. The IBT systems still use the same batch cooling process as DX systems, the only difference being the ice backup in case of power failure. The IBT systems are not modular and therefore are difficult to expand for larger applications. The IBT systems are very expensive, not energy efficient and require a small diesel generator to operate during power outages. For this reasons, the use of IBT systems in India is very limited.

Industrial milk cooling systems are deployed only for large volumes (2000 liters and above) because smaller systems cannot be operated economically in rural areas. Furthermore, the above examples and all other prior art in this field are designed with components that require a stable AC power supply. As such, they cannot be modified to work effectively with unreliable AC power supply.

OBJECTS OF THE INVENTION

Object of the present invention is to provide a milk cooling and storing system that cools milk more efficiently without relying on a regular power supply or a back-up diesel generator.

Another object of the present invention is to provide a milk cooling and storing system, which is robust in construction.

Yet another object of the present invention is to provide a milk cooling and storing system, which minimizes maintenance cost by enabling each element of the system to be replaced independently of the other elements.

Further object of the present invention is to provide a milk cooling and storing system that seamlessly and automatically switches back and forth between main and backup power.

Further one object of the present invention is to provide a milk cooling and storing system, which eliminates need for a permanent diesel generator back-up.

One more object of the present invention is to provide a milk cooling and storing system, which can be used in rural areas where there is more fluctuation in power supply.

SUMMARY OF THE INVENTION

According to the present invention there is provided a system for cooling and storing milk. The system having a compressor, a thermal battery, a liquid chiller, a heat exchanger, a storage container and a control unit. The compressor is provided for compressing refrigerant. The thermal battery is having heat transfer fluid stored therein for cooling milk by transferring thermal energy from the battery to the milk. The liquid chiller is connected to the compressor and the thermal battery. The liquid chiller enables heat transfer between the refrigerant and the heat transfer fluid without mixing. The heat exchanger is connected to the thermal battery for circulating heat transfer fluid therethough for cooling milk poured on the heat exchanger. The storage container is detachably connected to the heat exchanger for storing chilled milk received from the heat exchanger. The control unit is connected to the compressor, the thermal battery, the liquid chiller, the heat exchanger, a grid power supply and electric battery. Further, the control unit regulates power supply from a main supply to an electric battery and to the system, power supply from the electric battery to the system, monitors and analyses the system for calculating various operating parameters such as operating cost, volume of chilled milk and the like.

BRIEF DESCRIPTION OF THE FIGURES

The advantages and features of the present invention will become better understood with reference to the following detailed description and claims taken in conjunction with the accompanying drawings, wherein like elements are identified with like symbols, and in which:

Figure 1 shows a diagram of the system, and

Figure 2 shows timeline of system use.

DESCRIPTION OF THE INVENTION

The foregoing objects of the present invention are accomplished and the problems and shortcomings associated with the prior art, techniques and approaches are overcome by the present invention as described below in the preferred embodiment.

The terms “first,” “second,” and the like, herein do not denote any order, quantity, or importance, but rather are used to distinguish one element from another, and the terms “a” and “an” herein do not denote a limitation of quantity, but rather denote the presence of at least one of the referenced item.

The disclosed embodiments are merely exemplary of the invention, which may be embodied in various forms.

The present invention provides a system for cooling milk. The system cools milk more efficiently without relying on a regular power supply or a back-up diesel generator. The system is most suitable for the areas having fluctuating supply of electricity. In India the system is more useful in villages, where supply of electricity is fluctuating. The system is robust in construction and minimizes maintenance cost by enabling each element of the system to be replaced independently of the other elements. The system eliminates need for a permanent diesel back-up. The system can be used in rural areas where there is more fluctuation in power supply.

This present invention is illustrated with reference to the accompanying drawings, throughout which reference numbers indicate corresponding parts in the various figures. These reference numbers are shown in bracket in the following description.

Referring now to figure 1, a system 100 for cooling and storing milk in accordance with the present invention is shown. The system 100 includes a compressor 10, a liquid chiller 12, at least one thermal battery, for the purpose of explanation the present invention is shown to include one thermal battery 14, a milk heat exchanger 16, a storage container 18, a control unit 20 and an electrical battery, for the purpose of explanation the present invention is shown to include one electrical battery 22. The compressor 10 along with liquid chiller 12 configures a refrigeration cycle. The compressor 10 compresses a liquid refrigerant to gaseous form by increasing pressure and heat. This compressed refrigerant is then condensed to liquid form. In an embodiment, the system 100 may include a condenser to condense the compressed refrigerant therein.

The system 100 may include an expansion valve (not shown) to expand the refrigerant by immediate reduction in pressure. The expanded refrigerant is then passed though the liquid chiller 12, where the refrigerant boils and evaporates thereby reducing the temperature. This reduced temperature of the refrigerant is used to cool heat transfer fluid in the liquid chiller 12. Further, the evaporated refrigerant is again passed through the compressor 10 for next cycle. The heat transfer fluid is pumped from the thermal battery 14 to the liquid chiller 12. After cooling, the heat transfer fluid is stored back to the thermal battery 14 for further use. The heat transfer fluid is circulated from the thermal battery 14 and the liquid chiller 12 in a close loop 14a. In an embodiment, a pump 26 is used for circulating the heat transfer fluid from the thermal battery 14 to the liquid chiller 12 and back to the thermal battery 14.

In the present invention, the heat transfer fluid, such as water and propylene glycol (PPG) and the likes may be used, which is obvious to a person skilled in the art.

The liquid chiller 12 is a heat exchanger which enables heat transfer from the heat transfer fluid to the refrigerant without getting in contact with the each other. The liquid chiller 12 may be shell in tube type heat exchanger or tube in tube type of heat exchanger or any other similar heat exchanger which may be obvious to a person skilled in the art. The heat transfer fluid is circulated through tubes 14b and 14c between the thermal battery 14 and the liquid chiller 12. In an embodiment, the tube 14c is connecting to the thermal battery from the liquid chiller 12 is insulated for preventing heat loss to the surrounding.

The thermal battery 14 is an insulated container capable of storing chilled heat transfer fluid therein. The thermal battery 14 may also contain phase-change material (PCM) for storing more energy. The chilled heat transfer fluid received from the liquid chiller 12 is stored in the thermal battery 14 for longer duration. Due to the insulation, temperature of the heat transfer fluid is maintained for a longer duration. Further, it may be obvious to a person skilled in the art to use any other type of thermal battery capable of storing chilled heat transfer fluid.

Referring again to figure 1, the milk heat exchanger 16 is connected to the thermal battery 14 through tubes 16b and 16c. The milk heat exchanger 16 is a rapid surface heat exchanger. The heat transfer fluid is circulated on the inner surface of the heat rapid surface heat exchanger and the milk is allowed to flow on the outer surface of the heat exchanger under the force of gravity forming a thin film of the milk thereover. The heat transfer fluid is circulated from the thermal battery 14 to the heat exchanger and back to the thermal battery 14 in a close loop 16a. In an embodiment, the milk heat exchanger is inverted dome shaped heat exchanger, wherein the milk is allowed to flow over the outer surface and the heat transfer fluid from the inner surface of the heat exchanger. Further, the heat exchanger may have any other configures and vise-versa arrangement, which may be obvious to a person skilled in the art. Also, the pipe 16b used for pumping the heat transfer fluid from the thermal batter 14 to the milk heat exchanger 16 may be insulated to avoid any loss in the heat transfer from the heat transfer fluid to the surrounding, thereby enhancing the efficiency.

For pouring milk over the milk heat exchanger 16 at a predefined rate to achieve maximum and uniform cooling of the milk, a container 24 with an opening (not shown) is provided. In an embodiment, the container 24 having funnel shape. The milk collected from various locations in a village is poured in the container 24. The milk from the container 24 is passed through the opening having predefined circumference depending upon the size of the milk heat exchanger 16 and allowed to fall over the milk heat exchanger. This opening allows flow of milk in such a manner that the milk flows uniformly over the heat exchanger thereby cooled the milk to 04oC temperature by the time it reaches end of the milk heat exchanger 16 in a single pass. The milk is allowed to flow under gravity thereby eliminating need of pump. The chilled milk after flowing over the heat exchanger is collected in the storage container 18 for further use. In an embodiment, the storage container 18 may be insulated for avoiding heating of the milk due to surrounding temperature. In another embodiment, the storage container 18 may be chilled by using refrigeration cycle or by any other means, which are obvious to a person skilled in the art. Further, the storage container 18 is detachably secured to the milk heat exchanger 16, which enables to replaced the container with the other when it is filled with the chilled milk.

For operating all these elements electricity is required. The electricity is supplied to the compressor 10, , pumps 26 and 28, and the electrical battery 22 through control unit 20. The control unit 20 receives electricity from the main supply 40, which is used to charge thermal battery by operating the compressor 10, and pump 26. The thermal battery 14 is considered charged when heat transfer fluid inside thermal battery 14 reaches a pre-defined temperature. The control unit 20 also charges the electrical battery 22. Furthermore, the control unit 20 provides power to the pump 28 for the purpose of chilling milk. When milk is added to the storage container 24 and the pump 28 is running, the milk will be chilled. The pump 28 can be operated directly from main power supply or from the electrical battery 22. In case of power failure, the pump 28 continues to run using electrical energy stored in the electrical battery 22. In this manner, thermal energy from the thermal battery 14 is extracted to continue chilling milk in the milk heat exchanger 16.

In case there is power failure, the stored thermal energy in thermal battery 14 and electrical energy in electrical battery 22 are used for operating the system 100 seamlessly and again on receiving power supply, the system 100 is operated by the main supply and the thermal battery 14 and electrical battery 22 are placed again on charging mode. This enables automated continuous operation without loss of working time and eliminates human intervention for the purpose of switching to backup power.

Figure 2 further illustrate the operation of the system 100 in a day. Milk chilling is typically done at two fixed period of the day: in the morning 06:00am to 08:00am and in the evening 06:00pm to 08:00pm. If the thermal battery 14 and the electrical battery 22 are charged during period (1) that is from 0:00, then milk chilling can proceed period during 06:00am to 08:00am even if electrical power is not available at period (2). The system 100 will use stored thermal energy in thermal battery 14 and electrical energy in the electrical battery 22. Later, when electrical power comes back, thermal and electrical batteries (14 and 22) are re-charged. If electrical power is available during milk chilling period as shown in period (3), then energy extracted from the batteries is immediately replenished using available electrical power. Operation of the system 100 is seamless and an operator is not needed to switch between main and backup power.

The control unit 20 is placed in line with the system 100 and include a processor and data storage. The data storage enables to store the reading from all the sensors of the system and the processor enables to calculate the efficiency. In the present embodiment, the element of the system operate in single phase electricity supply.

The control unit 20 also monitors and keeps the record at what time milk was poured in the heat exchanger 16, when electricity was not available and when the system was operated using thermal energy stored in thermal battery 14 and electricity stored in the electrical battery 22 as shown in figure. This helps in calculating various operating parameters such as operating costs and volume of milk chilled and the like. Further, as the control unit 20 is connected to all the elements with sensors therebewteen. For example, a thermal sensor may be disposed on the liquid chiller, the thermal batter 12, the heat exchanger 16 and the storage container 18. The thermal sensor senses the temperature. The readings are stored in the control unit 20, which can be used for calculating efficiency of the system.

The system 100 of the present invention has following advantages:

1. The system 100 cools milk using an in-line process rather than a bulk or batch process. Milk can be cooled immediately as it is delivered by farmers. In our current embodiment, farmers directly pour the milk on the milk heat exchanger.

2. The system 100 cools milk using a single pass over the heat exchanger, thereby rapidly chilling milk to target temperature. Once the milk is chilled by the heat exchanger, it can simply be stored in an insulated tank where it can be kept below a critical temperature for up to 24-48 hours. No additional chilling is needed.

3. The system 100 uses gravity to pass the milk through the heat exchanger, thereby eliminating the need to pump the milk through a heat exchanger. Pumping affects milk quality negatively and increases chance of contamination.

4. The system 100 cools milk using a thin-film heat exchanger, thereby cooling every particle of milk immediately without the need for constant agitation. Constant agitation affects milk quality negatively and increases chance of contamination.

5. The system 100 uses thermal and electrical battery backup which allows the cooling process to continue even when electrical power is cut off.

6. The system 100 seamlessly switches between battery operation and electrical supply operation. If electrical power cuts off during chilling, the system continues to cool milk to target temperature until the power is restored or the battery is exhausted. Likewise, when the power is restored, the system resumes normal operation and charges the batteries for future use. A human operator need not intervene at all when power switches on/off.

7. The system 100 can use a smaller compressor than normally would be needed because it uses the thermal battery to provide the additional power. For example, a single-phase compressor, which may provide only 5 kW of cooling power, can be used to chill milk at a rate of 8 kW. The additional power is provided by the thermal battery.

8. The systems 100 is modular so it can be configured for different operating conditions or milk collection processes. For example:
a. If the system 100 operates in an area with unreliable electricity, the thermal battery and electrical battery sub-systems provide all necessary backup to continue chilling milk until power is restored. If the system operates in an area that has stable, reliable electricity supply, the system can shift cooling load to night time when electrical grid load is less. In this case, the system 100 charges the thermal battery at night and makes the energy available in the morning or evening when milk needs to be chilled.
b. The system 100 can be operated with traditional milkman collection system or with tanker collection system. Because the cooling is done in-line, the cold milk can be deposited

9. The system 100 eliminates the need for a permanent diesel back-up generator because of the thermal and electrical backup.

10. The system 100 can be installed in rural locations which may have limited space available. Sub-systems can be arranged such that the systems fits available space.

11. The system 100 enables large amounts of milk to be cooled using only a single-phase power connection which may be the only option available in rural area. This is because the system can use a smaller compressor than it would normally be needed for bulk milk chilling systems.

12. The system 100 minimizes maintenance cost by enabling element of the system 100 to be replaced independently of the other elements.

The foregoing objects of the invention are accomplished and the problems and shortcomings associated with prior art techniques and approaches are overcome by the present invention described in the present embodiment.

Detailed descriptions of the preferred embodiment are provided herein; however, it is to be understood that the present invention may be embodied in various forms. Therefore, specific details disclosed herein are not to be interpreted as limiting, but rather as a basis for the claims and as a representative basis for teaching one skilled in the art to employ the present invention in virtually any appropriately detailed system, structure, or matter

The embodiments of the invention as described above and the methods disclosed herein will suggest further modification and alterations to those skilled in the art. Such further modifications and alterations may be made without departing from the spirit and scope of the invention.