Experimental Study On Heat Transfer Of Prestressed Concrete Pile

With the continuous development of world economy, global demand for energy is increasingly augmented. Energy shortage has become a restrict factor of economic development in different countries and humans are exploring all ways to develop clean and efficient energy to reduce their reliance on conventional energy. The ground source heat pump technology has been accepted world-wildly as one of the application of renewable energy in architecture. Among all ground heat pump technologies, ground-coupled heat pump technology is most widely used. Using prestressed concrete pipe pile technology is the only way to realize the industrial modernization of ground-coupled heat pump system. Although prospect is extensive, there is need for theoretical In the heat transfer performance and engineering application researches.In consideration of the special geometric and structure condition of the pile spiral pipe heat exchanger, green function and line-heat-resource method were used to analyze the temperature distribution of the finite surface heat source model, meanwhile, integrated average temperature of this heat source was also calculated and discussed. In addition, finite coil model was proposed and result shows that its vertical distribution periodically oscillates, and when the temperature rise by the thermal resistance of the tube and wall was considered, temperature response of the fluid in tube was obtained.According to the model analysis, a ground thermal response experimental platform of pile spiral pipe heat exchanger and drilling double U tubes exchanger was established. Experiments shows that finite coil model basically corresponds to the actual heat transfer situation of pile spiral pipe heat exchanger. The average temperature and thermal properties of the ground were tested, and results show the influence of different inlet temperature and inlet velocity on heat exchange performance of the pile spiral pipe heat exchanger.Finally, inlet temperature and inlet velocity of pile spiral pipe heat exchanger and drilling double U tubes exchanger under the same condition were analyzed and compared, and reference data was proposed for the design and calculation of pile spiral pipe heat exchanger.