Research On The Flow Control System Of Gas Engine-Driven Heat Pump

Gas Engine-driven Heat Pump (GEHP) is a high performance and energy saving heating and cooling equipment driven by the gas engine. This paper presents a controlling method for the refrigerant feed control using an electronic expansion valve(EEV) in the GEHP system due to the inapplicability of thermodynamic expansion valve(TEV). This paper mainly realizes hardware connecting, programming designing and control strategy analyzing of GEHP control system based on PLC. To be specific, the main contents that are included in this paper are as follows:To point that the EEV can be adapted to characteristics of the GEHP quickly and optimize the running performance of the whole system based on the theory analysis and experimental testing of the TEV, especially for the start-up and sudden large changes conditions. The working principals of control system for GEHP is analyzed, and the control strategy is put forward base on previously research.The dynamic characteristics of evaporator-EEV system are studied using test methods. The experimental results indicates that the speed of gas engine and the opening of EEV are the two primary factors which affect the GEHP system mostly. The step response method of the outlet superheat of evaporator is measured by conducting experiments, and dynamic model of EEV is established by LSE(least square estimation).This model provides theoretical reference for the simulation and experimentation.PID and Fuzzy controllers are using in the experimentation based on the simulation results of the PID, fuzzy and fuzzy self-tuning PID controllers and the driven method for EEV. The results indicate that the PID controller can feed the demands of the GEHP on steady condition, but the performance is bad in sudden large change conditions; while the Fuzzy controller can fit for the change conditions of GEHP easily.