| Bath wastewater is one of the main sources of sewage with the characteristics of larger amount of water and higher temperature. The impacts on water conservation, energy conservation and environmental protection are important by rationally reusing the heat from bathing waste water. In this paper, a system composed of sewage-source heat pumps and solar hot water system was proposed with transforming the heat source of the hot water system to a public bath in Dalian In order to explore the mode of the hot water system after reforming as well as the design, requirements, and advantages compared with the original fuel boiler, following works had been done in this paper:Firstly, the sewage-source heat pump recycling heat from bath wastewater was designed. The system use valley electricity at night to provide part of the hot water load and the other energy was provided by solar collectors during daytime.The gas-fired boiler worked when the solar is insufficient.Meanwhile, a selection of various components of the system has been done and the pattern in practical operation in summer has been provided.Secondly, the mathematical models of the heat pump units, solar collector, water tankand auxiliary heat source were respectively established. The structure parameters of all parts in the unit was obtained through an optimization design and simulation of the heat pump unitand the parameters affecting the performance of the unit were analyzed. According to the climate conditions in Dalian, the simulation programming of the sewage-source heat pump hot water system and solar hot water system simulation was programed with MATLAB.Finally, the mode of the system in practical operation was designed and the temperature and water level values affecting the control of system were determined. According to the simulation programming of the hot water system, the changes of temperature and water volume of water tank respectively in the conditions of sunny day in summer, cloudy day in summer, sunny day in winter and cloudy day in winter were analyzed, the results provide reference for scientific operation of the system compared with cases under design. The annual operating cost and energy consumption of the system were compared with these of coal-fired boiler heating system. The results indicate that the system offers significant reductions in energy consumption and operating cost. Therefore, the system has a promising application prospect. |
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