| Title |
Dynamic Simulation of Ground Source Heat Pump with a Vertical U-tube Ground Heat Exchanger |
| Authors |
이명택(Myung Taek Lee) ; 김영일(Youngil Kim) ; 강병하(Byung Ha Kang) |
| Keywords |
지열열교환기 ; 지열원 열펌프 ; 보어홀 ; 동적 시뮬레이션 Geothermal heat exchanger ; Ground source heat pump ; Borehole ; Dynamic simulation |
| Abstract |
GHX (Geothermal Heat Exchanger) design which determines the performance and initial cost is the most important factor in ground source heat pump system. Performance of GHX is strongly dependent on the thermal resistance of soil, grout and pipe. In general, GHX design is based on the static simulation program. In this study, dynamic simulation has been performed to analyze the variation of system performance for various GHX parameters. Line-source theory has been applied to calculate the variation of ground temperature. The averaged weather data measured during a 10-year period (1991～2000) in Seoul is used to calculate cooling and heating loads of a building with a floor area of 100m2. The simulation results indicate that thermal properties of borehole play significant effect on the overall performance. Change of grout thermal conductivity from 0.4 to 3.0W/(m℃) increases COP of heating by 9.4% and cooling by 17%. Change of soil thermal conductivity from 1.5 to 4.0W/(m℃) increases COP of heating by 13.3% and cooling by 4.4%. Change of GHX length from 100 to 200m increases COP of heating by 10.6% and cooling by 10.2%. To study long term performance, dynamic simulation has been conducted for a 20-year period and the result showed that soil temperature decreases by 1℃, heating COP decreases by 2.7% and cooling COP decreases by 1.4%. |