Research On The Long Term Operation Of Ground Source Heat Pump And The Heat Transfer Characteristics On The Upper Surface

In order to analyze the long-term operation of ground source heat pump system and investigate its effects on the underground temperature distribution and surface flux,this paper did a two years'monitor on a ground source heat pump project and did some experiments and simulations to investigate the surface flux.Firstly,the monitoring shows that the system operating is stable and normal,meeting the design requirements.However,the electricity consumption of water pump account for about 39.7%of total electricity consumption which is too high.Besides,it is obvious that the rejected heat is 390 GJ and 1,423 GJ more than the absorbed heat in this system during the first year and the second year,respectively.Thus the imbalance of underground energy is about 24%and 53%in the first year and the second year,respectively.Secondly,the underground temperature variation shows that the average soil temperature has increased by about 0.4?and there is a obvious“Heat accumulation”phenomenon after one year's operation.Moreover,the extra heat rejected by the ground heat exchanger has accumulated in the deeper soil layers.Besides,this paper presents a simple model to verify underground heat unbalance measured from the system side and calculated from the underground side,the results are agreed well and the underground heat unbalance are verified.Thirdly,the result of measurement shows that the surface heat flux is multiply influenced by ambient temperature,ambient humidity and solar radiation.The daily soil heat fluxs of 5mm,45mm and 300mm underground variy from-21~99W/m~2,-12~36W/m~2 and-1~0.1W/m~2.Besides,the daily surface heat flux is varies from-22~99W/m~2,which is very similar to the soil heat flux 5mm underground.Finally,the results show that the proposed model in this paper has a good performance in modelling surface heat flux.Due to the existence of ground heat exchanger,the surface cooling heat flux decreased 2.4 W/m~2and the surface heating heat flux increased 3.3 W/m~2 in a typical day's simulation in heating season.It can be observed that the range of surface heat flux didn't has an obvious change.But there are lots of buried pipes and the system keeps running year by year.Consequently the total heat flux is considerable.In a word,the application of ground source pump has a significant impact on the underground temperature distribution and the surface heat flux.It is hoped that this paper could make some contributions to relevant researches of interaction between ground source heat pump and environment,then make the ground source pump more efficient and eco-friendly.