An investigation of the performance of groundwater-based heat pipes in heating lawn systems.

• This study presents a new approach for the application of shallow geothermal energy. • Difference in temperatures of heat pipe systems with different diameter of vertical part is insignificant. • The heat resistance of the heat pipes only accounted for approximately 1% of the total thermal resistance. • The maximum heat transfer power of the heat pipe is 202 W. Owing to the depletion of global fossil energy and the increasing environmental awareness of environmental protection, the use of shallow geothermal energy has been receiving widespread attention. In this study, two sets of groundwater-based heat pipe (GBHP) systems were fabricated to explore the application of heat pipes in shallow geothermal energy and tested through lawn heating experiments during the winter. Results of the experiment showed that the vertical diameter of the heat pipe did not have any significant effect on its heat transfer performance, and the maximum difference in temperature between the horizontal section of the east and west heat pipes during the observation period was 1.6 °C. Furthermore, the heat pipe exhibited good isothermicity with a constant operation, with the average temperature difference between the condensation and evaporation sections were 2.1 °C. The heat pipe also exhibited good thermal conductivity, the thermal resistance accounting for only 1% of the total thermal resistance in the heat transfer process. The maximum heat transfer power of a single heat pipe was found to be 202 W. This study presents a new approach for the application of shallow geothermal energy. [ABSTRACT FROM AUTHOR]