Abstract
The authors developed a ground heat exchanger (GHE) calculation model influenced by the ground surface by applying the superposition theorem. Furthermore, a simulation tool for ground source heat pump (GSHP) systems affected by ground surface was developed by combining the GHE calculation model with the simulation tool for GSHP systems that the authors previously developed. In this paper, the outlines of GHE calculation model is explained. Next, in order to validate the calculation precision of the tool, a thermal response test (TRT) was carried out using a borehole GHE with a length of 30 m and the outlet temperature of the GHE calculated using the tool was compared to the measured one. The relative error between the temperatures of the heat carrier fluid in the GHE obtained by measurement and calculation was 3.3% and this result indicated that the tool can reproduce the measurement with acceptable precision. In addition, the authors assumed that the GSHP system was installed in residential houses and predicted the performances of GSHP systems using the GHEs with different lengths and numbers, but the same total length. The result showed that the average surface temperature of GHE with a length of 10 m becomes approximately 2 °C higher than the average surface temperature of a GHE with a length of 100 m in August.
Highlights
In the recent years, global warming due to increase of CO2 emission has become a worldwide environmental issue
The operation of the ground source heat pump (GSHP) system was simulated by using the method for calculating the heat carrier fluid and underground temperature described in the previous section
When the borehole length of the ground heat exchanger (GHE) was set to 100 m, a difference in the temperature variation was hardly observed
Summary
Global warming due to increase of CO2 emission has become a worldwide environmental issue. Ground source heat pump (GSHP) systems, which use the underground thermal energy as a heat sink/source and supply cooling, heating, and/or hot water with high efficiency, have attracted widespread attention. Several million units have been installed in the world [1]. The number of GSHP system installed in Japan is still low it is gradually increasing. The main reason is that the installation cost of ground heat exchangers (GHEs) is expensive due to the complex underground formations. The utilization of shallow underground thermal energy such as short GHEs, energy piles and horizontal GHEs is effective to reduce the installation cost especially for the small building
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
