The Influence Exerted By The Imbalance Of Cooling And Heating Load On The Soil Temperature In GSHP

GSHP is powered in the way that heat exchangers with buried pipe absorb heat from underground soil. Though heat source and heat sink of heat pump system emit heat into the soil within its radius, the total sum of heat emitted in summer differs from that in winter due to the difference of climate. Long-term inconsistence of heat input and heat output of the heat exchangers leads to deviation of original soil temperature and the yearly decrease of efficiency of GSHP. This problem has provoked concerns over the long-term function of GSHP technology.To begin with, this dissertation analyzes the characteristics of cooling and heating load of architectures. Taken into consideration the service time, occupant density, turn-on time of cooling device, buildings with different functions exhibit different load totalities, load strengths and load durations. In GSHP, the buildings’load characteristics determine heat exchanger’s service duration, heat accumulation and heat-exchanging strength and directly influence its heat-exchanging performance.Secondly, this dissertation analyzes several models of common buried-pipe heat exchangers and systematically illustrates the simulation method of soil temperature field. DST model is employed to construct a heat transmission of buried-pipe heat exchanger and stimulant calculation is adopted to study the heat transmission between buried-pipe heat exchanger and soil so as to study the temperature changes of the soil within the area of buried pipes.Besides, the dissertation is based on the experimental platform that is designed in some of the laboratories equipped with GSHP, buried-pipe heat exchanger and data acquisition and processing system. This experiment aims to study the influence of load changes on soil temperature and testify the correctness of stimulant calculation based on models of buried-pipe heat-exchanger.Last but not least, this dissertation takes the example of office building featuring load characteristic and hotel featuring load characteristic, studies the temperature changes of the soil within the radius of buried-pipe heat exchanger and makes a stimulant calculation on the long-term performance of the GSHP of these two buildings under the same climate. The result is that with the premise of all-year-around balanced heat of the soil and taken into consideration of total sum of loads of buildings, the imbalance rate between cooling and heating load of GSHP for office building is26%and that of its counterpart is16%in Songjiang area.It can be concluded that when the imbalance between cooling and heating load of a building goes beyond the diffusivity capability of the soil proper, it may cause heat imbalance in soil. Since buildings with different functions bear difference load characteristics, the imbalance rate of heating and cooling load bore by the soil varies. Therefore, it is necessary to analyze the load characteristics of building when the building is designed so as to verify the imbalance of cooling and heating load bore by GSHP under local hydrogeology and weather. Otherwise, corresponding optimizing measures must be taken.