Experimental And Theoretical Study On The Spiral Coil Heat Exchanger Of Surface Water Source Heat Pump

Based on the global energy and environmental issues, heat pump technology has been rapidly developed and applied. China is vast territory and abundant with water resources, and the closed surface water source heat pump system has been widely used in recent years. For the closed surface water source heat pump system, the method of the design and calculation is very important when using the spiral coil as the heat exchanger of the low heat source. However, the lack of basic theoretical and experimental data for the design of the low side heat exchanger, what is a huge block on the development of the closed surface water source heat pump. Therefore, it is of great significance to carry out experimental research on the heat transfer and flow resistance characteristics of the low side heat exchanger of the closed surface water source heat pump.In order to study the heat transfer and flow resistance characteristics of the coil heat exchanger, the experimental principle and mathematical model are established. After the analyzing of the existing experimental platform’s shortcomings, the design and improvement of the original experimental platform are carried out, which is used to simulate the actual operation of the low side heat exchanger of the closed surface water source heat pump in the flowing water.With the transformed experimental platform, this paper carried out the experiments of the heat transfer and flow resistance characteristic under the summer and winter condition. There are many influence variables have been carried on the theoretical analysis and discussion. Such as the tube-inside water flow rate, the tube-outside surface water flow rate, the approximate temperature difference, the horizontal spacing of the spiral coil ratio, helical coil vertical spacing ratio, coil row number on the heat transfer heat transfer characteristics and the tube-inside Reynolds number, the spiral coil horizontal spacing ratio, vertical spacing than on the flow resistance characteristics. Experimental results show that the tube-inside water flowing with the strong turbulent state and field surface water under the low Reynolds number flow, the forced convection heat transfer of the tube-outside is the main factor on controlling the coil heat exchanger’s thermal performance; spiral coil pipe for thermal performance is worse with the increasing of horizontal spacing. With the increasing of vertical spacing and row number, but did not change significantly. The increasing of the horizontal spacing ratio and the vertical spacing ratio will increase the pressure loss of the coil.Finally, the experimental data of the spiral coil heat transfer and flow resistance characteristics were compared with the non-dimensional correlation calculated values of the straight tube, the spiral coil experimental correlations of heat transfer and flow resistance characteristics were also given in a certain range applicable. And heat transfer and flow resistance characteristics were analyzed under the given non-dimensional correlation. Experimental correlation error is within 5%, meeting the requirement of engineering precision.