Research On Performance Of Ground Source Heat Pump Under Dynamic Load

The rapid development of urbanization and industrialization in China as well as the high requirements for living standard, which lead directly to an increase in building energy consumption accounted for the total commercial energy consumption ratio, and a short supply of energy; therefore, building energy conservation has become the focus of attention of all trades. Building energy conservation mainly emphasizes on the adjustment for building energy consumption and the enhancement of utility efficiency of HVAC.As a new technology in HVAC, ground source heat pump system (GSHP), with renewable energy as heat and cold source, is considered to be one of the most promising energy saving technology. Underground heat exchanger distinguishes the GSHP from the traditional air conditioning system. Through exchange heat between the underground heat exchanger and soil, GSHP can achieve the end of adjusting the indoor thermal and humidity environment. Dynamic changes of indoor cooling and heating load cause dynamic changes in heat transfer performance of ground heat exchanger, which in turn influence the operation of ground source heat pump unit. Normal operation of the whole system will depend on whether the indoor terminal, ground source heat pump unit and ground heat exchanger can match correctly and reasonably.The GSHP in a toll station is used as research subjects in this paper, through input hourly dynamic load to analyze the dynamic characteristics of the system. First of all, the construction thermal environment simulation software package DeST is used to establish model and simulate the annual hourly dynamic load; then, with considering different heat transfer condition of inlet and outlet pipes, a theory about three areas heat transfer along the depth direction is proposed, which used to analyze the influence of dynamic load on the heat transfer performance of ground heat exchanger; finally, coupling formula is verified through analyzing the coupling relationship among the parameters of buried side and load side with multiple linear regression method.In order to better understand the heat transfer performance, the three-dimensional soil temperature field of single U-tube is simulated numerically based on the experiment. Then the reliability of the model is verified using measured temperature data. The verified model is applied to simulate heat transfer performance of single U-tube. Meanwhile, the influence of water inlet temperature and flow on heat transfer performance is analyzed.