Research on the natural circulation characteristic of deep borehole heat exchanger and the influences on the water circulation resistance  

作　　者：Jiewen Deng Yanhui Wang Yangyang Su Yuanguo Wang Yin Chen Minghui Ma Chenwei Peng Wanlong Cai Ji Li Qingpeng Wei 

机构地区：[1]Hubei Key Laboratory of Multi-media Pollution Cooperative Control in Yangtze Basin,School of Environmental Science&Engineering,Huazhong University of Science and Technology,Wuhan,Hubei 430074,China [2]Department of Building Science,Tsinghua University,Beijing 100084,China [3]School of Human Settlements and Civil engineering,Xi'an Jiaotong University,Xi'an,Shaanxi 710049,China [4]China Academy of Building Research,Bejing 100101,China

出　　处：《Building Simulation》2024年第12期2213-2232,共20页建筑模拟(英文)

基　　金：support from the National Natural Science Foundation of China(Grant No.52308095);the National Key Research and Development Program of China(Grant No.2022YFE0197400);the Natural Science Foundation of Hubei Province of China(Grant No.2024AFB586).

摘　　要：As deep borehole heat exchangers(DBHEs)extract heat from geothermal energy with depth of 2–3 kilometers,the circulation water pressure drop is larger than that of shallow-depth borehole heat exchangers,influenced by the water flow rates.This paper conducted field tests and simulation analysis to study the heat transfer performance and water circulation resistance of DBHE in coupled,where the natural circulation characteristic has been discovered and analyzed quantitatively.Results show that the water temperature and density variation along DBHE forms the driving force of natural circulation.For mechanical flow rate of 6.0 kg/s and inlet water temperature of 20.0℃,the natural circulation flow rate reaches about 2.2 kg/s with transient heat extraction power of 78.5 kW,without energy consumption of water pumps.And the larger inlet water temperature,smaller mechanical water flow rate,higher inner tube thermal conductivity coefficient and larger depth of DBHE all contribute to the larger natural circulation water flow rate.In addition,the natural circulation could effectively decrease the comprehensive water pressure drops of DBHE,which is about 47.3%smaller than the calculated value of traditional models.Thus the natural circulation characteristic has significant influence on the heat transfer performance of DBHE,and also on the energy performance of whole heat pump systems.

关 键 词：deep borehole heat exchangers water circulation resistance natural circulation field tests simulation analysis 

分 类 号：O62[理学—有机化学]