HVAC System with Electronically Controlled Expansion Valve

摘要

A two temperature electronic expansion valve control for variable speed compressors that utilizes a correlation between airflow percentage and heat exchanger pressure drop to control the operation of an expansion valve. An indoor airflow percentage request may be communicated from an outdoor controller to an air handler controller. Using a correlation between airflow percentage and pressure drop across the heat exchanger, the airflow percentage may be used in predicting an outlet pressure of refrigerant exhausted from the heat exchanger. The predicted pressure drop may be used in determining a saturated temperature for the exhausted refrigerant. The determined saturated temperature may be compared to a sensed temperature of the refrigerant at the outlet of the heat exchanger to determine a superheat value, which is compared to a reference superheat value in determining the degree to open or close the expansion valve.

主权项

1. An HVAC system comprising:
a heat exchanger; a fan adapted to flow air toward the heat exchanger, the fan controlled in response to an airflow percentage request; an expansion valve in fluid communication with the heat exchanger, the expansion valve configured to control a flow of a refrigerant; and a controller adapted to control the operation of the expansion valve based at least in part on a correlation between a drop in a pressure in the heat exchanger and the airflow percentage request.