BACKGROUND

The present disclosure relates generally to heating, ventilating, and air conditioning systems. Specifically, the present disclosure relates to systems and methods for controlling an electronic expansion valve (EEV) in a vapor compression system.

A wide range of applications exists for heating, ventilating, and air conditioning (HVAC) systems. For example, residential, commercial, and industrial systems are used to control temperatures and air in residences and buildings using a fluid, such as a refrigerant. The HVAC systems may circulate the refrigerant through a closed loop between an evaporator where the refrigerant absorbs heat and a condenser where the refrigerant releases heat. As an example, the refrigerant may absorb heat from a first fluid and transfer the heat to a second fluid to ultimately cool the first fluid and/or heat the second fluid. The refrigerant evaporates into a vapor when flowing through the evaporator by absorbing the heat from the first fluid. The compressor then compresses the vapor to cause the pressure and/or temperature of the vapor to rise for subsequent cooling by the second fluid in the condenser, thereby transferring heat from the first fluid to the second fluid.

In some cases, the vapor is superheated at the inlet of the compressor to ensure that the refrigerant is in a vapor state before entering the compressor. To control an amount of superheat of the refrigerant entering the compressor, existing systems include a liquid injection device that cools the vapor within the compressor. For example, the liquid injection device injects liquid refrigerant droplets into the compressor, or at an inlet of the compressor, to adjust an amount of superheat of the vapor entering the compressor and/or a temperature of the vapor exiting the compressor. Unfortunately, liquid injection devices include additional components (e.g., tubing, pumps, nozzles, among others) to inject the liquid refrigerant into the compressor. Additionally, injecting liquid refrigerant into the compressor may reduce a performance of the compressor, and thus, reduce a performance of the HVAC system.

SUMMARY

In one embodiment, a heating, ventilating, and air conditioning (HVAC) system includes a vapor compression system having a refrigerant, a compressor of the vapor compression system configured to circulate the refrigerant through the vapor compression system, an expansion device of the vapor compression system configured to adjust a flow of the refrigerant through the vapor compression system, and a controller configured to adjust a position of the expansion device based on a measured amount of superheat of the refrigerant entering the compressor, a measured discharge temperature of the refrigerant leaving the compressor, or a combination thereof, such that the measured amount of superheat of the refrigerant entering the compressor reaches a target amount of superheat, the measured discharge temperature of the refrigerant leaving the compressor reaches a target discharge temperature, or a combination thereof.

In another embodiment, one or more tangible, non-transitory machine-readable media includes processor-executable instructions to receive first feedback indicative of a temperature and a pressure of refrigerant entering a compressor of a vapor compression system, determine a measured amount of superheat of the refrigerant entering the compressor of the vapor compression system using the temperature and the pressure of the refrigerant entering the compressor of the vapor compression system, receive second feedback indicative of a discharge temperature of the refrigerant leaving the compressor of the vapor compression system, and adjust a position of an expansion device of the vapor compression system based on the measured amount of superheat of the refrigerant entering the compressor, the discharge temperature of the refrigerant leaving the compressor, or a combination thereof, such that the refrigerant entering the compressor reaches a target amount of superheat, the refrigerant leaving the compressor reaches a target discharge temperature, or a combination thereof.

In an another embodiment, a method includes receiving first feedback indicative of a temperature and a pressure of refrigerant entering a compressor of a vapor compression system, determining a measured amount of superheat of the refrigerant entering the compressor of the vapor compression system using the temperature and the pressure of the refrigerant entering the compressor of the vapor compression system, receiving second feedback indicative of a discharge temperature of the refrigerant leaving the compressor of the vapor compression system, and adjusting a position of an expansion device of the vapor compression system based on the measured amount of superheat of the refrigerant entering the compressor, the discharge temperature of the refrigerant leaving the compressor, or a combination thereof, such that the refrigerant entering the compressor reaches a target amount of superheat, the refrigerant leaving the compressor reaches a target discharge temperature, or a combination thereof.

