Control system and operational characteristics of gas engine-driven heat pump

Abstract

The control system is an important component of a gas engine-driven heat pump (GHP). Recent studies conducted on GHPs focus on the model construction and optimization, while neglecting the control system. This study proposes an embedded control system to monitor GHP cold–hot water equipment (GHPW). The accuracy of the control system and strategy was verified. Additionally, the operational characteristics of GHPW system based on the control system were discussed through cooling and heating experiments. The experimental results demonstrated that double closed-loop control of the engine speed and evaporator superheat via the main controller ensured stable and accurate outlet water temperature control in the GHPW system. The heating capacity of the heat pump was increased from 42.37 to 75.2 kW in the heating mode with a gradual increase in the engine speed from 1200 to 2400 rpm, while the heating capacity of the experimental system was increased from 56.18 to 105.87 kW. The waste heat recovery of the engine significantly improved the system heating capacity and primary energy ratio (ratio of GEHP heating capacity to natural gas consumption power). Additionally, the GHPW system improved energy saving. The circuits and control strategy proposed in this study are simple and easy to implement. The control system improved the performance of GHPs and reduced the peak power load during summer.