| In 2013,"smog" became the key word of the year.The severe smog in northern my country in winter has aroused people’s attention to clean heating.In 2014,winter heating in rural areas in northern China mainly relied on coal combustion.Coal for heating in winter accounts for more than 90% of domestic coal.In this regard,the state has deeply promoted clean energy alternative policies in key cities.Strive to eliminate coal burning for heating in these cities by 2021.Beijing’s "coal to electricity" policy is one of them.However,the efficiency of using air source heat pumps as a single heat source for heating in this policy is not high.The huge electricity subsidy affected the later implementation of this policy.Reducing heating costs has become the key to the implementation of this policy.With the goal of using clean energy to reduce heating operating costs,this paper analyzes the disadvantages of existing heating systems,and specifically designs a combined heating system with flexible and adjustable system processes.According to outdoor weather conditions in the heating season in Beijing,three system operation modes have been designed.Through experiments,the performance of the combined heating system under different system composition,operating strategies,and solar load rates is explored,and the system’s scalability and impact on the environment are evaluated.The results show that the heating performance of the combined heating system during the experiment is significantly better than that of the existing air source system.The total energy efficiency ratio of the combined heating system under the time operation strategy of the air source heat pump heating system is 2.50,which is 62.34% higher than the existing air source system.The heating performance of the combined heating system under the time operation strategy that is conducive to the solar heat collection system is better than the time operation strategy that is conducive to the air source,and the energy efficiency ratio is increased by22.00%.The increase in the solar load rates can effectively improve the performance of the solar heat collection system’s heat collection time,the average temperature of the heat supply to the end of the heat dissipation,and the energy efficiency ratio.In the time control mode that is conducive to the solar heat collection system,the performance of the combined heating system with a solar load rate of 30% is significantly better than that of the solar system with a solar load rate of 20% and 10%.Compared with the latter,the total energy efficiency of the system is increased by 13.38% and 50.99% respectively.Through the performance analysis of the combined heating system in the time-optimized control mode,it is obtained that the increase in solar energy guarantee rate and the reasonable arrangement of the heating period of the solar heating system can improve the performance of the combined heating system.Comprehensive combined heating system performance analysis and engineering application evaluation,the best operating strategy and system composition form are: a combined heating system with a solar load rate of 30% under a time control mode that is conducive to the solar heat collection system.The total energy efficiency of the system is 3.05,and the proportion of solar energy system providing heat is 58.00%.Assuming that the heating performance of the combined heating system during its service life does not decay,and under the same operating strategy of the same system form,the daily power consumption of the combined heating system does not change over time,the static investment payback period of the system is about 9 years.The replacement amount of traditional energy in each heating season is 2687.24 MJ,which can reduce carbon dioxide emissions by 4,851.91 kg during the service life.The annual daily reduction of emissions of sulfur dioxide,nitrogen oxides,smoke and dust,and comprehensive PM2.5 can reach 89.22,176.37,35.27,and 97.52 g. |
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