基于TRNSYS的中深层地热供暖系统运行特性研究

Study on operation characteristics of the middle-deep geothermal heating system based on TRNSYS

文章依托实际工程,基于TRNSYS软件建立仿真系统,对地温梯度、岩土导热系数、延米取热功率及不同运行时间比等影响因素进行模拟分析,结果表明,地温梯度较小时,出口温度较低,系统无法长期正常运行,且系统能耗较大。进出口温度随着岩土导热系数的增大而缓慢增大,应对换热器采取保温措施,减小热量在浅层岩土层的散失。持续运行供暖系统延米取热功率不大于150 W/m,延米取热功率越大,进出口温度与土壤温度降低幅度越大,热开采与热恢复达到平衡所需时间越长。运行时间比越低,在同样的取热功率下,土壤的温度越高。间歇供暖可提高单井延米取热功率,考虑到间歇运行工况的热恢复,运行时间比为1/3,5/12,1/2时,延米取热功率应分别小于350,300,250 W/m。

The middle-deep borehole ground source heat pump heating system which can obtain heat without extracting groundwater to provide heating for the building. In this paper, a simulation system was established based on TRNSYS software which relied on the actual project. Using this simulation system to analyze different influencing factors, such as soil temperature gradient, soil thermal conductivity, the specific heat extraction rate and different running time ratios. The results showed that: when geothermal gradient is small, the outlet temperature will is low, the system cannot operate normally for a long time and the system energy consumption will be larger. The inlet and outlet temperature increase slowly with the increase of thermal conductivity of soil, so heat preservation measures should be taken to reduce heat loss in shallow soil layer. The continuous operation of the heating system should not exceed 150 W/m in the specific heat extraction rate. The larger of the specific heat extraction rate, the larger reduction range of inlet and outlet temperature and soil temperature is, and the longer time required for the heat mining and heat recovery to reach the balance. The lower running time ratio, the higher temperature of the soil under the same heat extraction power. Intermittent heating can increase the specific heat extraction rate of a single well, Considering the heat recovery in intermittent operating conditions,when the operating time ratio is 1/3,5/12,1/2 respectively, the specific heat extraction rate should not be greater than 350,300,250 W/m.