Expansion valve control system

1 . A vapor compression system, comprising:

a heat exchanger configured to facilitate heat transfer between a refrigerant and a conditioning fluid;

an expansion valve disposed along a conduit coupled to the heat exchanger, wherein the conduit is configured to direct a flow of the refrigerant into the heat exchanger;

a sensor configured to provide feedback indicative of a temperature of the conditioning fluid exiting the heat exchanger; and

a controller comprising a memory and processing circuitry, wherein the processing circuitry is configured to:

receive a signal indicative of the temperature of the conditioning fluid exiting the heat exchanger from the sensor;

determine a temperature difference between the temperature of the conditioning fluid exiting the heat exchanger and a saturated temperature of the refrigerant in the heat exchanger;

adjust operation of the expansion valve based on a comparison of the temperature difference and a temperature difference set point, wherein the temperature difference set point is a variable temperature difference set point; and

adjust a value of the variable temperature difference set point based on data indicative of a capacity of the heat exchanger.

2 . The vapor compression system of claim 1 , wherein the processing circuitry is configured to:

output a signal indicative of instructions to adjust the expansion valve toward a closed position based on a determination that the temperature difference is less than the variable temperature difference set point; and

output a signal indicative of instructions to adjust the expansion valve toward an open position based a determination that the temperature difference is greater than the variable temperature difference set point.

3 . The vapor compression system of claim 1 , wherein the processing circuitry is configured to:

receive a signal indicative of a pressure of the refrigerant within the heat exchanger; and

determine the saturated temperature of the refrigerant based on the pressure of the refrigerant within the heat exchanger.

4 . The vapor compression system of claim 3 , wherein the sensor comprises a first sensor, and the vapor compression system comprises a second sensor configured to provide feedback indicative of the pressure of the refrigerant within the heat exchanger.

5 . The vapor compression system of claim 1 , wherein a value of the variable temperature difference set point is between zero degrees Celsius and five degrees Celsius.

6 . The vapor compression system of claim 1 , wherein the processing circuitry is configured to estimate the capacity of the heat exchanger based on a parameter of the conditioning fluid exiting the heat exchanger.

7 . The vapor compression system of claim 1 , wherein the heat exchanger comprises an evaporator configured to transfer heat from the conditioning fluid to the refrigerant.

8 . The vapor compression system of claim 1 , comprising a cooling load, wherein the vapor compression system is configured to circulate the conditioning fluid through tubing of the heat exchanger and through the cooling load.

9 . A vapor compression system, comprising:

a condenser configured to transfer heat from a refrigerant to a cooling fluid;

an evaporator configured to transfer heat from the refrigerant to a conditioning fluid;

an expansion valve configured to direct the refrigerant from the condenser to the evaporator;

a sensor configured to provide feedback indicative of a temperature of the conditioning fluid exiting the evaporator; and

a controller comprising a memory and processing circuitry, wherein the processing circuitry is configured to:

receive a signal from the sensor indicative of the temperature of the conditioning fluid exiting the evaporator;

determine a temperature difference between the temperature of the conditioning fluid exiting the evaporator and a saturated temperature of the refrigerant within the evaporator;

adjust operation of the expansion valve based on a comparison of the temperature difference and a temperature difference set point, wherein the temperature difference set point is a variable temperature difference set point; and

adjust a value of the variable temperature difference set point based on data indicative of a capacity of the evaporator.

10 . The vapor compression system of claim 9 , wherein the processing circuitry is configured to:

output a signal indicative of instructions to adjust the expansion valve towards an open position based on a determination that the temperature difference is greater than the variable temperature difference set point; and

output a signal indicative of instructions to adjust the expansion valve towards a closed position based on a determination that the temperature difference is less than the variable temperature difference set point.

11 . The vapor compression system of claim 9 , wherein the sensor is a first sensor, and the vapor compression system comprises a second sensor configured to provide feedback indicative of a pressure of the refrigerant within the evaporator, and wherein the processing circuitry is configured to determine the saturated temperature of the refrigerant based on the pressure of the refrigerant.

12 . The vapor compression system of claim 9 , wherein the value of the variable temperature difference set point is between zero degrees Celsius and two degrees Celsius.

13 . The vapor compression system of claim 9 , wherein the processing circuitry is configured to determine the value of the variable temperature difference set point based on a type of the refrigerant, a type of the conditioning fluid, a size of the evaporator, a type of the evaporator, or a combination thereof.

14 . The vapor compression system of claim 9 , comprising a heating load, wherein the vapor compression system is configured to direct the cooling fluid through the heating load and the condenser.

15 . The vapor compression system of claim 14 , comprising a cooling load, wherein the vapor compression system is configured to direct the conditioning fluid through the cooling load and the evaporator.

16 . A method of controlling an expansion valve of a vapor compression system, the method comprising:

detecting a temperature of a conditioning fluid exiting a heat exchanger;

determining a temperature difference between the temperature of the conditioning fluid and a saturated temperature of a refrigerant within the heat exchanger;

adjusting the expansion valve toward a closed position based on a determination that the temperature difference is less than a temperature difference set point, wherein the temperature difference set point is a variable temperature difference set point;

adjusting a value of the variable temperature difference set point based on data indicative of a capacity of the heat exchanger; and

adjusting the expansion valve toward an open position based on a determination that the temperature difference is greater than the variable temperature difference set point.

17 . The method of claim 16 , comprising:

detecting a pressure of the refrigerant within the heat exchanger; and

determining the saturated temperature of the refrigerant based on the pressure of the refrigerant within the heat exchanger and based on a type of the refrigerant.

18 . The method of claim 16 , comprising estimating the capacity of the heat exchanger based on a pressure of the refrigerant at a first inlet of the heat exchanger, a pressure of the refrigerant at a first outlet of the heat exchanger, a pressure of the refrigerant within the heat exchanger, a nominal pressure of the refrigerant within the heat exchanger, a temperature of the conditioning fluid at a second inlet of the heat exchanger, a temperature of the conditioning fluid at a second outlet of the heat exchanger, a temperature of the conditioning fluid within the heat exchanger, a pressure differential of the conditioning fluid across the heat exchanger, a volume flow rate of the conditioning fluid within the heat exchanger, a nominal temperature of the conditioning fluid, or a combination thereof.