The Applications Of Hybrid Ground Source Heat Pump System And Study On Operation Control Strategies In Chongqing

Along with the acceleration of urbanization in our country, the requirement of heating ventilation and air condition (HVAC) of public and residential buildings has become popular demand with the increasing development of economy and the improvement of people's living standard. However, the traditional heating and cooling system is insufficient for reducing energy consumption. Therefore, renewable technology such as Ground Source Heat Pump (GSHP) with imponderable potential accelerate the building energy saving. While GSHP system is applied in building that is cooling-dominated, especially located in hot-climate areas. The annual accumulated air-conditioning system cooling load is much greater than heating load. Ground temperature will be changed due to imbalance heating and cooling load after long-term circulation. On the other hand, ground heat exchangers operating energy consumption increase as well as system performance reduction will be effected as a result. Towards this background, composite ground source heat pump system with auxiliary cooling function can play an important role in improving existing HVAC system efficiency and reducing the initial cost of the system considerably.In this paper, heat transfer mathematical model has been established to identify the relationship inside heat pump model. Secondly, in order to evaluate the accuracy and feasibility, this analytic model has been validated by field measurement data.Based on a composite ground source heat pump demonstration project in the city of Chongqing, traditional GSHP system and Composite ground source heat pump system are adopted for contrastive research. The entire year cooling and heating load is calculated via DeST (Designer's Simulation Toolkit) software. Compare traditional GSHP system with Composite GSHP system, analog computation is conducted for 7 years simulative time, analyzing the impact of initial operating time on system performance, ground heat exchangers and water temperature. The initial investment and maintain cost saving by using Composite GSHP system is effective, especially in cooling load dominant area. Two kinds of control strategies are implementing in Composite GSHP system, the result indicate that underground soil temperature has been well maintained and the system energy-saving goal has been achieved. Under different control set point value, this paper analyzes two important parameters, system performance and drilling wall temperature, of the composite system. The best set point value of control strategy was proposed as the result of comparison, and gave rise to operational control method and guidance for practical engineering application.