Research status of factors affecting heat transfer in energy piles
With the increasing demand for heating,researcher are exploring better ways to utilize geothermal energy.Compared with medium and deep ground source heat pumps,energy piles in shallow ground source heat pumps ignore the drilling process based on good heat transfer efficiency,do not need to occupy additional underground space,and can work with underground engineering structures,which solve two major problems of ground source heat pump systems covering a wide area and high cost in cities.The research progress on the factors influencing heat transfer in energy piles(tube type,circulating medium flow rate,pile spacing,groundwater seepage,intermittent operation mode,and soil type)are reviewd.It is found that the spiral tube type has the largest heat transfer area and the best heat transfer efficiency,the flow rate of the circulating medium generally only needs to ensure that its flow state is turbulent,the larger the pile spacing the better the heat transfer effect.The soil with small specific heat capacity has obvious thermal interference and reduced heat transfer efficiency,the intermittent cycle has relatively larger heat transfer efficiency values than the continuous operation mode.On this basis,the next research suggestions and outlook of energy piles are proposed.
ground source heat pumpburied pipeenergy pileheat transfer performance
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