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 method of varying a refrigerant charge in a refrigeration/air conditioning system comprising:
monitoring at least one condition associated with the system;
determining a desired refrigerant charge for the system based on the at least one condition;
determining if a current refrigerant charge for the system equals the desired refrigerant charge; and
in response to a determination that the current refrigerant charge does not equal the desired refrigerant charge, operating a control valve in the system to change the current refrigerant charge to the desired refrigerant charge, the control valve controlling the amount of refrigerant held in a receiver;
wherein the refrigeration/air conditioning system comprises an unvalved return path from the receiver directly to an evaporator.
2. The method of claim 1 wherein the at least one condition is an operating mode for the system.
3. The method of claim 1 wherein the at least one condition is one or more environmental factors.
4. The method of claim 1 wherein the at least one condition is a combination of operating modes and environmental conditions.
5. The method of claim 1 wherein the refrigerant charge is changeable from a first charge level and a second charge level and back.
6. The method of claim 1 wherein the refrigerant charge is variable between a maximum charge level and a minimum charge level.
7. The method of claim 1 wherein the refrigeration/air conditioning system comprises:
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;
the control valve in the branch refrigerant loop; and
the 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.