Refrigeration system with flow control valve

1. A refrigeration system comprising:

a plurality of refrigerated display cases, each of the plurality of refrigerated display cases including a dedicated evaporator configured to cool return air from the respective refrigerated display case by at least partially evaporating a refrigerant;

a compressor assembly in fluid communication with the plurality of evaporators and configured to compress evaporated refrigerant from the plurality of evaporators;

a condenser located remotely from the plurality of refrigerated display cases and configured to reject heat from the refrigerant to an environment, the condenser including an inlet and an outlet;

a gas main in fluid communication with the inlet and configured to direct refrigerant from the compressor assembly to the condenser;

a liquid main in fluid communication with the outlet and configured to direct refrigerant from the condenser to the plurality of evaporators; and

a valve fluidly coupled between the gas main and the liquid main and including at least one sensor configured to measure the superheat of refrigerant in the gas main, the valve configured to regulate flow of the refrigerant from the gas main to the liquid main based on the superheat of refrigerant in the gas main.

2. The refrigeration system of claim 1 , wherein the valve is configured to regulate refrigerant flow from the gas main to the liquid main by bypassing the condenser.

3. The refrigeration system of claim 1 , wherein the valve is fluidly coupled between a portion of the gas main and a portion of the liquid main that is disposed vertically below the portion of the gas main, the valve configured to selectively drain refrigerant from the portion of the gas main to the portion of the liquid main.

4. The refrigeration system of claim 1 , wherein the at least one sensor includes a pressure sensor and a temperature sensor, wherein the pressure sensor is configured to sense the pressure of the refrigerant in the gas main, and wherein the temperature sensor is configured to sense the temperature of the refrigerant in the gas main.

5. The refrigeration system of claim 1 , wherein the valve is configured to open when the superheat of the refrigerant in the gas main is low and close when the superheat of the refrigerant in the gas main is high.

6. The refrigeration system of claim 1 , wherein the compressor assembly includes at least one dedicated compressor for each of the plurality of refrigerated display cases.

7. The refrigeration system of claim 6 , wherein the at least one dedicated compressor assembly is configured to compress evaporated refrigerant from the dedicated evaporator of a single refrigerated display case.

8. The refrigeration system of claim 6 , wherein the plurality of dedicated evaporators is connected to the liquid main in parallel, and wherein the plurality of dedicated compressor assemblies is connected to the gas main in parallel.

9. The refrigeration system of claim 1 , wherein the valve includes a reverse-acting thermostatic expansion valve.

10. A method of operating a refrigeration system including a plurality of refrigerated display cases each having a dedicated evaporator, the method comprising:

cooling return air from each of the plurality of refrigerated display cases by at least partially evaporating a refrigerant in each of the dedicated evaporators;

compressing the evaporated refrigerant;

directing the compressed refrigerant through a gas main in fluid communication with a condenser;

condensing the compressed refrigerant in the condenser; directing the condensed refrigerant through a liquid main in fluid communication with an inlet of each of the dedicated evaporators;

regulating a flow of refrigerant from the gas main to the liquid main;

sensing a superheat of refrigerant in the gas main; and

selectively draining refrigerant from the gas main to the liquid main.

11. The method of claim 10 , further comprising

at least partially filling the gas main with liquid refrigerant at startup of the refrigeration system, and

reducing an amount of refrigerant available in the liquid main at startup of the refrigeration system.

12. The method of claim 11 , wherein at least partially filling the gas main includes at least partially condensing refrigerant in the gas main at startup of the refrigeration system.

13. The method of claim 10 , wherein sensing the superheat of the refrigerant in the gas main includes sensing a refrigerant pressure and sensing a refrigerant temperature.

14. The method of claim 10 , wherein selectively draining refrigerant from the gas main to the liquid main includes

draining condensed refrigerant from the gas main, and

bypassing the condenser.

15. The method of claim 14 , wherein draining the condensed refrigerant from the gas main includes draining condensed refrigerant at more than one sensed superheat.

16. The method of claim 10 , wherein selectively draining refrigerant from the gas main to the liquid main includes opening a valve when the superheat of the refrigerant in the gas main is low, and closing the valve when the superheat of the refrigerant in the gas main is high.

17. The method of claim 10 , further comprising

connecting the plurality of dedicated evaporators in parallel with the liquid main, and

connecting a plurality of dedicated compressor assemblies in parallel with the gas main,

wherein providing the dedicated compressor assembly includes compressing evaporated refrigerant from the dedicated evaporator of a single refrigerated display case.

18. The method of claim 10 , wherein regulating the flow of refrigerant from the gas main to the liquid main includes inhibiting flow of superheated refrigerant in the gas main to the liquid main.