Thermoeconomics Research Of A Large Reclaimed Water Source Heat Pump Central Heating System

At present, mankind is facing with energy and serious environmental problems, the environment is seriously threatened in greenhouse gases, the amount of greenhouse gas (GHG) emission have reached the concentration which can lead to climate change, if we don’t take some related actions to reduce greenhouse gas emission then the impact brought by climate change will be more serious. One of the most important actions to solve environmental problems is to make full use of energy, and using it more efficiently and rationally, and then achieving the unity of the quantity and quality between the supply and demand of energy, it includes reducing energy waste, recycling of waste heat utilization and the use of low-carbon fuels etc.. so, how to improve energy conversion efficiency and reasonably utilizing of renewable energy have become an important research direction.The reclaimed water coming from Municipal wastewater treatment plant is a new renewable energy, which has the advantages of the concentrated water flow, high temperature (compared to surface water) and relatively clean, etc.,so it is the ideal heat source for heat pump units. The effluent of larger sewage treatment plant can reach ⅠA emission standards, reclaimed water can be used not only in the green watering, artificial landscape water replenishment, but also for farmland irrigation and other large-scale water, it has huge potential for energy-saving.Firstly, taking the exergy analysis method and the thermoeconomic cost analysis method as the theoretical basis of this paper, using the method of theoretical analysis to qualitatively describe that it is reasonable for us to use heat pump systems for district heating, giving the calculation method of energy efficiency and exergy efficiency, and it is pointed out that the difference between the two, as well as their usage, Analysis pointed out that only taking into account these two methods can get a more comprehensive evaluation on energy conversion system. Established the thermal economics model for heat pump heating system and gas boiler heating system, list the cash balance equations of the two systems and exergy efficiency formula, laid the theoretical foundation for the actual run.Secondly, designing a reclaimed water source heat pump system which will match the heating of8million square meters, including distributed heat pump stations, distributed power systems, the main heat pump station. According to the characteristics of the reclaimed water and save the initial investment, we determined that the reclaimed water directly go into the Heat pump units, the first phase of the project uses distributed heat pump heating system, Phase Ⅱ project and Ⅲuses a combination of centralization and decentralization system.Finally, using the thermal economic theory to analysis the reclaimed water source heating pump system and gas boiler system, calculated their exergy efficiency and heating cost respectively; the average heating costs17.2yuan/(m2· a heating season), the average cost of gas-fired boiler system is26.3yuan/(m2· a heating season), although the distributed heat pump system at the beginning with the higher investment, but the energy costs are lower, about1/2of the latter, it provides a reference for future applications of the reclaimed water source heating pump system.