Volume 58

Simulation on Two-stage heat pump/thermosyphon system for geothermal cascade utilization Yin Li, Hainan Zhang, Otabek Boltayev, Yanhui Feng

Abstract

In order to improve the energy efficiency and economy of geothermal cascade utilization system, this paper proposes a two-stage heat pump / thermosyphon system (THPTS), which optimizes the cascade utilization of geothermal energy by combining heat pump and thermosyphon technology. Based on TRNSYS software, the simulation models of traditional two-stage heat pump system (THPS) and THPTS are built, and their performances in geothermal heating are compared and analyzed. Taking an office building in Beijing as an example, the hourly load of the building is simulated, and the system operation strategy is designed: when the heat load is lower than the threshold, the thermosyphon mode is used for direct heat transfer; conversely, switch to heat pump mode. The results show that THPTS can maintain the heat extraction efficiency at 59.74 %, and the total power consumption in the heating season is 6.13 % lower than that of THPS, and the energy saving effect is obvious. This study provides an innovative solution for the efficient utilization of geothermal resources.

Keywords Geothermal cascade utilization, Two-stage heat pump/thermosyphon system, TRNSYS simulation, Heat extraction efficiency, Energy saving optimization