The Static Characteristic of the Evaporator Superheat Control Loop

Abstract

One of two primary control loops of the vapour compression cycle-based system is the evaporator superheat control loop. Its function is to protect the components from damage and increase the energy efficiency of the system. The process part of the loop consists of the electronic expansion valve and the evaporator. The paper presents the static characteristic of the process part. The characteristic is determined experimentally on the water-to-water domestic heat pump installation. The input is the control signal of the valve, and the output is the evaporator superheat temperature. The static characteristic is static, multivalued nonlinearity with hysteresis and saturation on one side. Using the approximation of nonlinearity by means of linear segments, the simulation results in obtaining the describing function of the static characteristic.