Study On Optimizing The Heating Scheme Of Air Source Heat Pump In Coal-to-electricity Conversion

For a long time,winter heating in rural areas of northern China has been the focus of attention.Traditional coal-fired boilers not only have low combustion efficiency,but also emit flue gas,which has caused great pollution to the environment.In order to further promote the process of energy cleanliness and realize coal-free in Beijing,the Work Programme for Winter Clean Heating in Villages of Rural Areas of Beijing in 2018 was issued to encourage urban land.Air source heat pumps with high COP are used in the district,including hot water heat pumps and hot air heat pumps.Air source heat pump uses air as heat source and consumes a small amount of electricity to extract heat energy from air which can not be directly used by people and flow to the end device of indoor side for people to use.Generally speaking,the outlet temperature of air source heat pump is lower than that of traditional coal-fired boiler.Whether the indoor thermal comfort performance of air source heat pump can meet people’s needs needs needs needs further research.Research.Firstly,this chapter introduces the design and calculation of air source heat pump-radiator heating system,puts forward two common calculation methods of heat load,and calculates the measured building heat load.According to the heating characteristics of the low temperature heating system,the changes of the number of radiators before and after the renovation are analyzed,the selection of fan coil units and the heat dissipation under the low temperature hot water are checked,and the influence of the heat dissipation terminal equipment on the indoor space before and after the renovation is compared.The results show that,compared with the traditional supply and return water temperature of 75℃/50℃,it is necessary to increase the number of radiators by about one time on the basis of the original number of radiators to meet the indoor heat load demand.The fan coil unit suitable for low temperature heating system can meet the demand of room heat load through correct selection.Although the number of radiators has doubled,the increased radiators are divided into two groups on both sides of the wall.Similarly,the indoor area occupied by four fan coil units is smaller than that of the radiator,and the utilization rate of the room will not be greatly affected.Secondly,through the establishment of physical model and mathematical model of the room,the indoor temperature field and velocity field of different heat dissipation ends are compared and analyzed with Airpak software.The results show that the room temperature heated by fan-coil unit is higher than that heated by radiator.The room temperature heated by fan-coil unit is generally between 14 and 16 degrees Celsius,and the room heated by fan-coil unit is heated by fan-coil unit.The room temperature can reach 17℃.The uniformity of temperature distribution and airflow speed in the radiator room load the thermal comfort requirement of human body.Through the comfort equation of human thermal balance and the calculation of PMV-PPD index with the help of MATLAB software,the effects of environmental factors and individual factors on human thermal comfort are analyzed concretely.Finally,the economic evaluation of air source heat pump systems with different heat sinks is carried out by using the annual cost method of dynamic economic evaluation index,and the economic and energy-saving comparison of several heating modes commonly used in rural areas is made.The results show that the initial investment of air source heat pump-fan coil unit is 1.32 yuan/m² higher than that of air source heat pump-radiator system,and the annual operating cost of air source heat pump-wind source heat pump is 1.32 yuan/m²higher than that of air source heat pump-radiator system.The unit-coil system is 3.28 yuan/m² lower than the air-source heat pump-radiator system.The total air-source heat pump-fan-coil system saves247.1 yuan per year compared with the air-source heat pump-radiator system.By comparing the economy of five heating modes,the results are as follows:bulk coal heating furnace>gas wall hanging furnace>briquette heating furnace>air source heat pump+radiator>air source heat pump+fan coil unit according to annual cost.From the point of view of energy saving,compared with bulk coal heating furnace,the highest energy saving rate of air source heat pump heating system can reach58.9%,the highest CO₂ emission reduction can reach 4.06t/a,the highest SO₂emission reduction can reach 32.88 kg/a,and the highest smoke and dust emission reduction can reach 16.44 kg/a.