Open The Thermal Diffusion Of Cooling Water, Lake Water Source Heat Pump Application Simulation And Experimental Research

Lake water source heat pump is a special category of the surface water source heat pumps. As an important kind of clean renewable energy, it is developing rapidly. At the same time, the thermal discharge and cold discharge will cause unfavorable influence on the water environment and ecological system, especially on the weak lake ecosystem. The change of the water environment ecological system will cause greater crisis as lakes, reservoirs and other waters with weak liquidity. In addition, the operating efficiency of the heat pump system is decreased and the cooling capacity is reduced because of the inlet water temperature rise, but meanwhile the operation cost is rising. The problems of thermal discharge diffusion should be taken into depth study in order to maintain the resource utilization being sustainable and efficiency. Accurate simulation of the lake temperature field in the drainage condition becomes more and more important in the system design.In this paper, a three-dimensional mathematical model of the temperature field of the thermal discharge into the lake is developed based on the Nanjing lake water source heat pump engineering. According to the meteorological data of Nanjing and lake water temperature data, the calculation procedure is programmed. And the surface heat transfer coefficient average value Ks and surface heat flux average diameter of φn, both in the refrigeration and heating period are computed. The suitable surface boundary condition for this engineering is confirmed through the calculation results analysis and comparison which not only reduces the calculated amount of the three-dimensional mathematical model, but also ensures the accuracy of the simulation results.In this study, the heat capacity of using the lake around the architectural complex as heat source-sink is investigated combining the experience of the lake water heat pump system and an optimization plan is put forward. The temperature field is also calculated using the three-dimensional mathematical model. So, the feasibility of the open-loop lake water heat pump (LWIIP) system has been verified, and some references for the water intake and drainage system are provided.The effect of the thermal diffusion caused by the different locations of the outfall was mainly researched when the lake-depth is uneven. By comparison and analysis of the simulation results, there is a greater influence as to the horizontal distribution than to the vertical direction, and the temperature rise area is not changed in some extent along the vertical direction. In conclusion, the outfall should be located as close as possible to the water surface, and closer to the deeper position in a certain range so as to improve the system efficiency and to provide a better environment for the system.The high temperature zone concentrates on a small area near the outfall. The flow velocity around the outfall should be speeded up so that the thermal area can be increased, thereby the inner lake water quality can be improved, and accordingly, energy conservation and environmental protection will be realized.The experiment platform of the open-loop lake water heat pump system is established under the condition of refrigeration, including heating temperature control system, temperature data acquisition system, cooling water system, and flow control system. Comparing the refrigeration experimental results with the simulation results, it is found that the trend of their temperature rise curve of the outfall is same. And the experimental results are in good agreement with the simulation results. Thus, it can be concluded, the model and simulation solution is reliable.