3.2 Analysis of experimental results Based on the existing operating experience, in a stable heating season, the heat pump unit usually runs for 3-4 hours at the first power-on to reach a steady state [4]. Therefore, combined with the actual heating needs and heat pump operating conditions, the use of intermittent operation technology to make up for the slow underground heat exchangers, heat exchanger temperature recovery and improve overall efficiency. In this experiment, a cycle of 24 hours was used, and man-made control of on-off time was 1: 1 and 2: 5 [3,4]. The following experimental data are all measured results. 3.2.1 underground heat exchanger wall temperature change analysis 24 hours intermittent operation test from March 16, 2005 test to March 19. It can be seen from Fig. 2 that the condition of ground temperature recovery is very favorable. After 5 hours of operation and shutdown, the temperature of the pipe wall is restored to about 0.2ºC , The unit continued to run for 4 hours to meet the user's heating needs, and then stop running, the wall temperature after 10 hours to restore the initial temperature. For the next cycle boot to provide better heat transfer conditions. 3.2.2 Temperature change of inlet and outlet water temperature of heat pump In the normal operation of heat pump unit used in this experiment, the outlet temperature can not be lower than 4 ºC. When it is lower than this The heat pump will stop operating at temperature. Therefore, we must ensure that the load to meet user needs, based on the import and export as stable as possible to ensure that the heat pump in the ideal operating conditions. As can be seen from Figures 3 and 4, under intermittent operating conditions, the water temperature at the inlet and outlet of the heat pump is stabilized at a higher temperature, which is conducive to the operation of the unit under ideal operating conditions. 3.2.3 heat pump heat removal from the soil heat exchanger due to the heat of the heat exchanger buried, soil temperature field changes. Just when the unit is running, the temperature of the water in the pipe is quite different from the temperature of the soil, the amount of heat is rapidly increased, and as the endothermic process progresses, the temperature of the soil is reduced. Therefore, for a period of time, the heat exchange of the underground pipe heat exchanger Reached a steady state. Figure 5 shows the intermittent operation and continuous operation of the heat exchanger heat exchange curve. It can be seen from the figure that the heat exchange capacity of intermittent operation is obviously larger than that of the continuous operation under the same experimental conditions. Continuous operation of up to 3-4 hours, the heat exchange capacity of about 27.9W / m, with the increase of running time, the soil temperature decreases, the heat exchange between soil and heat exchanger will be affected, when running continuously for 24 hours , Heat transfer down to 26.5W / m. Intermittent ground temperature was restored (Figure 2), more conducive to the soil and heat exchanger full heat transfer; heat transfer can be guaranteed at 27.9W / m, compared with continuous operation heat transfer increased by 5%. Fig.3 The temperature of heat pump Fig.4 The temperature of heat pump Fig.4 The heat flux of underground heat exchanger Fig.5 The heat-flux of underground heat exchangerFig.5 The heat flux Conclusions (1) The controllable intermittent process can change the trend of the temperature change around the underground heat exchangers. Under winter operating conditions, it is possible to increase the equilibrium temperature and stabilize the temperature of the unit under ideal conditions Run under. (2) Through reasonable human intermittent control, to achieve a good trend of ground temperature changes, to maximize the heat exchange capacity of underground heat exchangers. (3) In the same conditions, intermittent operation and continuous operation compared to achieve full heat transfer, minimize the number of drilling, reduce initial investment. (4) The technology of intermittent operation of ground-source heat pump proposed in this paper is of great significance and practical value to make full use of ground in air-conditioning system. It is necessary to further study the energy-saving characteristics of ground-source heat pump after applying intermittent operation technology.