Sensitivity Analysis of the Design Factor for Vertical Closed-loop Geothermal System using Numerical Analysis : Focused on Heating Operation

Purpose: Recently, in order to realize eco-friendly buildings, studies on renewable energy technologies have conducted in field of building energy. Among these technologies, a ground source heat pump (GSHP) system can achieve higher performance than conventional air source system. However, the GSHP system has been delayed due to high initial cost and lack of guidelines for performance analysis of various design factor. Therefore, this paper aims to proposed design and operation method to improve the performance of the GSHP system and to minimize the additional cost. Method: In this study, numerical simulation was conducted to accurately predict the heat exchanger rate (HER) and entering water temperature (EWT) of the GSHP system. The numerical simulation was coupled with soil model, ground heat exchanger (GHX) model and ground surface heat flux model. Furthermore, the performance of GSHP system was analyzed according to the operation method of the system such as flow rate, operation time, and limit temperature. Result: As a result, the HER and the EWT of base case were 34.3W/m, 10.26℃ respectively in the condition of 9.3lpm flow rate, 9 hours per day operation, and 5℃ limit temperature.