Feasibility Study Of Hybrid Ground Source Heat Pump System Based On Cooling Tower Cool-storage In Transition Season

In order to solve the heat accumulation problem of ground-source heat pump(GSHP) system in cooling load dominated area with high humidity in summer, this paper presents a novel hybrid ground-source heat pump(HGSHP)system based on cooling tower(CT) cool-storage in transition season. Then the suitable operation time of CT under this system is given on the base of performance evaluation model of CT. And the performance evaluation model for ground heat exchanger(GHE) system is built on the base of GHE multiple borehole finite line heat source theory and TRNSYS software. Using this evaluation model, an actual project in Nanjing is chosen to compare the thermal performance of novel HGSHP system,conventional HGSHP system and GSHP system. And some results are given:1) Under the thermal imbalance situation, using novel HGSHP system in this project, the outlet water temperature of GHE in cooling season can maintain from 28℃ to 30℃,and the outlet water temperature of GHE in heating season can maintain from 10℃ to 12℃.,which is better than GSHP system and conventional HGSHP system.2) The temperature field of novel HGSHP system under long term operation is better than both conventional HGSHP system and GSHP system.3) Using novel HGSHP system, the average exiting water temperature of CT in cooling season is 25℃,and the average relative efficiency of CT is 0.78, the total cooling capacity produced by CT in cooling season is 548.74MWh; and the average exiting water temperature of CT in transition season is 14.7℃, the according average relative efficiency of CT is 0.57, with the total cooling capacity produced by CT in transition season can reach 781.47 MWh. Above all, the total heat rejection mass is 2684.13 MWh, and the total heat extraction mass reaches 2417.52 MWh. These results can provide reference on high efficiency operation and system optimization of GSHP system in cooling load dominated area.