Optimization Study On The Operation Of The Hybrid Ground-source Heat Pump System For Residential Buildings In Hot-summer And Cold-winter Region

In hot-summer and cold-winter region, there are many residential communities use the ground-source heat pump(GSHP) system. The problem of soil heat accumulation, high energy consumption happened in residential GSHP system because of unreasonable system design flows in the initial stage and improper management in the later. Additionally, in recent years, due to the residential occupancy rate is not high, there are many new challenges for GSHP system operation control and metering method. To solve the problems above, this paper disigns a hybrid ground-source heat pump(HGSHP)system for the residential community, and studies the operation strategy and the metering method.Firstly, the HGSHP system for the residential district has been designed according to the residential building dynamic load, the rock soil thermal properties and other parameters. The simulation model of HGSHP system has been built in the TRNSYS platform. This model is divided into heat pump system, terminal system, ground source pipe system, cooling tower system and control system.The sub-system models have been established according to the function of each module,calculation of parameters and the coupling relationship between modules.The 5 sub-systems are basd on coupling relationship between the systemic circulation loop to make up the whole system model.Secondly, what’s the impact on the heat transfer performance of the ground heat exchanger when the single ground-source heat pump system is turned on in the cooling season or in the heating season has been researched. And what’s the difference between a single and a hybrid ground-source heat pump systems in maintaining the heat balance of soil has been researched too.The results show that a single ground-souce heat pump system is turned on in the cooling season better than in the heating season, and hybrid ground source heat pump system is more conducive to maintaining the heat balance.Thirdly, aimed at the problem of what operation strategies of new residential HGSHP system should be used to run based on differnet occupancy rate.This paper analyzes annual energy consumption and operation strategies of HGSHP system for 100%,70%,50% and 30% occupancy rate respectively.The results show that for high occupancy rate, the underground pipe water temperature control with the set point of 22℃ is the optimal operation strategy for the HGSHP system.For low occupancy rate, the system using ground heat exchanger + cooling tower in summer and ground source alone in winter is the best operation strategy.When occupancy rate less than 30%, the single ground-source heat pump sytem should be used.Finally, aimed at the problem of what metering method for residential district’s GSHP system should be used. This paper analyses the composition of two-part price,developes a method for calculating, counts the corporate annual profit and user annual expenditure under the different metering method. Considering the corporate profit, the user interest and accurate measurement, the optimal metering method is the on-off time and area method.