Refrigerant-based thermal energy storage and cooling system with enhanced heat exchange capability
Disclosed is a method and device to increase the cooling load that can be provided by a refrigerant-based thermal energy storage and cooling system with an improved arrangement of heat exchangers. This load increase is accomplished by circulating cold water surrounding a block of ice, used as the thermal energy storage medium, through a secondary heat exchanger where it condenses refrigerant vapor returning from a load. The refrigerant is then circulated through a primary heat exchanger within the block of ice where it is further cooled and condensed. This system is known as an internal/external melt system because the thermal energy, stored in the form of ice, is melted internally by a primary heat exchanger and externally by circulating cold water from the periphery of the block through a secondary heat exchanger.
1. A refrigerant-based thermal energy storage and cooling system comprising:
a primary cooling loop comprising:
a condensing unit, said condensing unit comprising a compressor and a condenser;
a thermal energy storage unit comprising a tank filled with a fluid capable of a phase change between liquid and solid and containing a primary heat exchanger therein; and,
a refrigerant management unit connected to said condensing unit and to said primary heat exchanger that regulates, accumulates and transfers refrigerant between said condensing unit and said primary heat exchanger to cool said fluid and to freeze at least a portion of said fluid within said tank in a first time period; a load cooling loop comprising:
said primary heat exchanger; and,
said refrigerant management unit that in a second time period transfers refrigerant that has been cooled within said primary heat exchanger by said frozen fluid in said tank, to a load heat exchanger, said load heat exchanger that provides cooling to a cooling load by increasing the enthalpy of said refrigerant and returns said higher enthalpy refrigerant to said primary heat exchanger;
a secondary cooling loop comprising:
a secondary heat exchanger that facilitates thermal contact between said cooled fluid and said higher enthalpy refrigerant to decrease the enthalpy of said refrigerant downstream of said load heat exchanger and transfer cooling from said fluid in said tank to said higher enthalpy refrigerant.
2. The system of claim 1 wherein said secondary heat exchanger is connected to said refrigerant management unit and said secondary heat exchanger that receives said refrigerant from said refrigerant management unit and lowers the enthalpy of said refrigerant and transfers lower enthalpy refrigerant to said load heat exchanger.
3. The system of claim 1 wherein said primary heat exchanger and said secondary heat exchanger both receive high enthalpy refrigerant from said load heat exchanger and transfer lower enthalpy refrigerant to said refrigerant management unit.
4. The system of claim 1 wherein said refrigerant management unit further comprises a refrigerant accumulator and a liquid refrigerant pump.
5. The system of claim 4 wherein said refrigerant management unit further comprises a mixed-phase regulator.
6. The system of claim 4 wherein said refrigerant management unit further comprises an oil still/surge vessel.
7. The system of claim 1 wherein said fluid is water.
8. The system of claim 1 wherein said thermal energy storage and cooling system is used to boost the capacity of an air conditioning system.
9. The system of claim 1 wherein said thermal energy storage and cooling system is used to shift at least a portion of the power consumption time period of an air conditioning system.
10. The system of claim 1 further comprising at least one valve that allows said secondary heat exchanger to be excluded from said connection to said load heat exchanger.
11. The system of claim 1 wherein said secondary heat exchanger utilizes a secondary cooling source that is placed in thermal contact with said refrigerant to reduce the enthalpy said refrigerant.
12. The system of claim 1 wherein said secondary heat exchanger is placed within said tank and in thermal communication with said fluid.
13. The system of claim 1 further comprising:
a tertiary heat exchanger that receives said fluid from said secondary heat exchanger and facilitates additional thermal contact with said refrigerant further reducing the enthalpy of a portion of said refrigerant, and transfer cooling from said fluid in said tank to said higher enthalpy refrigerant.
14. The system of claim 1 further comprising:
a tertiary heat exchanger connected in parallel with said secondary heat exchanger that additionally facilitates thermal contact between cooled said fluid and said refrigerant, thereby reducing the enthalpy of said refrigerant, and transfer cooling from said fluid in said tank to said higher enthalpy refrigerant.
15. A refrigerant-based thermal energy storage and cooling system comprising:
means for condensing a refrigerant with a condensing unit to produce a condensed refrigerant;
means for supplying said condensed refrigerant to an evaporating unit constrained within a tank filled with a fluid capable of a phase change between liquid and solid;
means for expanding said condensed refrigerant during a first time period, within said evaporating unit, to freeze a portion of said fluid within said tank and produce a cooled fluid, a frozen fluid and an expanded refrigerant;
means for circulating said expanded refrigerant back to said condensing unit;
means for circulating said expanded refrigerant during a second time period through said evaporating unit within said frozen fluid to condense said expanded refrigerant and produce said condensed refrigerant;
means for expanding said condensed refrigerant within a load heat exchanger to provide load cooling and produce said expanded refrigerant;
means for circulating said expanded refrigerant from said load heat exchanger to said evaporating unit;
means for circulating at least a portion of said cooled fluid through a secondary heat exchanger in thermal contact with said expanded refrigerant from said load heat exchanger to reduce the enthalpy of said expanded refrigerant.