取/释热平衡状态下负荷分布对地埋管换热的影响

Impact of Load Distribution on Ground Heat Exchanger Under Thermal Equilibrium Between Heat Extraction and Heat Release

采用情景模式研究方法,设置了8种典型连续运行和间歇运行的负荷分布情景,研究了在取/释热平衡状态下的地埋管换热性能。研究发现,在相同的最大取热和释热负荷情况下,地埋管负荷时间频数分布对换热性能影响较大,最大时间频数所在的负荷区间越高,释热期地埋管平均水温越高,取热期地埋管平均水温越低;在相同的地埋管负荷时间频数分布情况下,运行模式对地埋管的换热性能影响较大,释热期间歇运行的地埋管平均水温低于连续运行,取热期间歇运行的平均水温高于连续运行,且随着最大时间频数所在负荷区间的上移,两种模式的水温差异越大;确定地埋管换热器钻孔长度时应综合考虑地埋管负荷的时间频数及运行模式等情况。

Based on scenario analysis methods, eight typical load distribution scenarios including continuous operation and intermittent operation are organized to study heat transfer performance of ground heat exchanger under the condition of thermal equilibrium between heat extraction and heat release. It＇ s indicated that the load time frequency is greatly influential to the heat transfer performance. The average water temperature at heat release period is higher and that at heat extraction period is lower when the load range with maximum time frequency moves up. Operation modes are also significantly influential to heat transfer performance of ground heat exchanger when load time frequency distributions are the same. The average water temperature of intermittent operation is lower than continuous operation in heat release period and reverse result is obtained in heat extraction period. The water differences between the two operation modes are bigger when the load range with maximum time frequency moves up. Load time frequency and operation modes should be considered to determine bore length of ground heat exchanger.