Investigation into the influence of multiple factors on the buried pipes clusters system based on similarity theory

In rural areas, the building volume is small and geothermal energy is abundant. As a crucial medium of the development of shallow geothermal energy, identifying the factors influencing buried pipes can provide a reliable reference for the operation of rural ground source heat pump systems. To explore this question, a sand box test bench was constructed based on similarity theory and nine tests were designed using orthogonal theory. The orthogonal results showed that the F values of inlet temperature, operation mode, circulating flow rate and the quantities of buried pipes were 8.30, 1.71, 0.10, 0.01 in order for heat transfer capacity; the F values of these factors were 19.24, 0.32, 0.38, 0.05 in order for total heat transfer amount. The temperature difference between the inlet temperature and the soil temperature was positively related to heat transfer amount, moreover, the thermal performance was significantly higher during intermittent operation compared to partial intermittent operation. The temperature difference between the inlet and outlet of buried pipes reached 0.6 °C under intermittent operation, which was greater than the 0.15 °C observed under partial intermittent operation. This study provides valuable insights for the development of shallow geothermal energy systems.