경계 조건에 따른 지열 응답 함수의 차이가 수직형 지열 교환기 길이 산정에 미치는 영향

Abstract

Eskilson's g-function, a well-known geothermal heat response factor, is widely used for sizing of the ground heat exchangers. Unlike the Eskilson's original model that uses common temperature boundaries for all boreholes and along the borehole height, an analytical-solution-based g-function uses a uniform heat transfer rate over the height with variable heat transfer rates for respective boreholes. To evaluate the impact of such a boundary difference on g-function and the design length, a simple case study was carried out on the cooling-dominant commercial buildings. The results show that the design lengths given by the boundary of uniform heat transfer rates are longer than those given by Eskilson's boundary for all cases tested. The difference in length is more important when the bore field is composed of more boreholes with shorter length of each borehole.