Active refrigerant charge compensation for refrigeration and air conditioning systems
A variable refrigerant charge refrigeration/air conditioner system is described that allows the refrigerant charge for the system to be altered based on operating or environmental factors. The system includes a main refrigerant loop holding a volume of refrigerant corresponding to a first level of refrigerant charge, a compressor in the main refrigerant loop, a condenser in the main refrigerant loop, and an evaporator in the main refrigerant loop. A branch refrigerant loop allows the alteration of the refrigerant charge using a control valve in the branch refrigerant loop and a receiver in the branch refrigerant loop. The receiver acts to hold a volume of refrigerant when the control valve is open, thereby removing the volume of refrigerant from the main refrigerant loop. A return path from the receiver to the main refrigerant loop allows refrigerant to flow back into the main loop from the receiver.
1. A variable refrigerant charge refrigeration/air conditioner system comprising:
a main refrigerant loop holding a volume of refrigerant corresponding to a first level of refrigerant charge;
a compressor in the main refrigerant loop;
a condenser in the main refrigerant loop, the condenser operable to remove heat from the refrigerant;
an evaporator in the main refrigerant loop, the evaporator receiving refrigerant from the condenser and operable to cause the refrigerant to absorb heat;
a branch refrigerant loop in fluid communication with the main refrigerant loop;
a control valve in the branch refrigerant loop;
a receiver in the branch refrigerant loop, the receiver operable to hold a volume of refrigerant drawn from the main refrigerant loop when the control valve is open; and
a return path from the receiver to the main refrigerant loop;
wherein the first level of refrigerant charge is reduced to a second level of refrigerant charge by storing the volume of refrigerant in the receiver when the control valve is open.
2. The system of claim 1 wherein the return path from the receiver to the main refrigerant loop is a capillary tube through which refrigerant in the receiver flows back into the main refrigerant loop.
3. The system of claim 1 wherein the branch loop is connected to a high pressure side of the main refrigerant loop.
4. The system of claim 1 wherein the return path connects to a low pressure side of the main refrigerant loop.
5. The system of claim 1 wherein the control valve is operated based on an operating mode of the system.
6. The system of claim 1 wherein the control valve is operated based on environmental conditions for the system.
7. The system of claim 1 further comprising a thermal expansion valve in the main refrigerant loop between the condenser and the evaporator.
8. The system of claim 1 further comprising a reheater, wherein the system operates at the first level of refrigerant charge when the reheater is off and at the second level of refrigerant change with the reheater is on.
9. A variable refrigerant charge refrigeration/air conditioner system comprising:
a main refrigerant loop holding a volume of refrigerant corresponding to a maximum level of refrigerant charge;
a compressor in the main refrigerant loop;
a condenser in the main refrigerant loop, the condenser operable to remove heat from the refrigerant;
an evaporator in the main refrigerant loop, the evaporator receiving refrigerant and operable to cause the refrigerant to absorb heat;
a branch refrigerant loop in fluid communication with the main refrigerant loop;
a control valve in the branch refrigerant loop;
a receiver in the branch refrigerant loop, the receiver operable to hold a volume of refrigerant when the control valve is open, wherein the maximum level of refrigerant charge minus the volume of the receiver corresponds to a minimum level of refrigerant charge;
a return path from the receiver to the main refrigerant loop;
a level sensor in the receiver producing a signal indicative of a level of refrigerant in the receiver; and
a controller receiving the signal indicative of the level of refrigerant in the receiver and operable to open and close the control valve to maintain a desired level of refrigerant in the receiver.
10. The system of claim 9 wherein the return path from the receiver to the main refrigerant loop is a capillary tube through which refrigerant in the receiver flows back into the main refrigerant loop.
11. The system of claim 9 wherein the branch loop is connected to a high pressure side of the main refrigerant loop.
12. The system of claim 9 wherein the return path connects to a low pressure side of the main refrigerant loop.
13. The system of claim 9 wherein the desired level of refrigerant in the receiver is determined based on an operating mode for the system.
14. The system of claim 9 wherein the desired level of refrigerant in the receiver is determined based on environmental conditions for the system.