| At present,China’s economic development has entered a high-quality development stage,traditional coal,oil and other non-renewable energy cause great pollution to the environment because of its use,so how to use clean energy such as wind and solar energy to replace non-renewable energy has become the research focus of many scholars.The use of coal-fired heating in some areas of our country has promoted the production of haze,in order to "green water and green mountains".The state advocates "coal-to-electricity" and "peak-valley power" to reduce environmental pollution and ease the pressure of electricity consumption.Solar heating collects scattered solar energy and then converts it into heat energy,but the solar thermal energy COPs is low and the heat is discontinuous.The heating mode of air source heat pump has the advantages of comfort,energy saving and good safety,but the heating capacity will decrease with the decrease of ambient temperature,and it is easy to frost.The heating mode of phase change heat storage technology has the advantages of clean,non-pollution and rational use of "peak and valley electricity",but the COPs of phase change heat storage box is very low and is affected by outdoor ambient temperature.Therefore,based on solar energy,air source heat pump and phase change heat storage technology,this paper combines the three heating technologies and uses them reasonably.This paper studies the application of heating operation in cold areas.Taking Beijing as an example,Shunyi District is selected to build the experimental platform.In order to make rational use of "peak and valley electricity",Beijing area puts forward the policy of "cutting peak and filling valley",and Beijing area is rich in solar energy resources.therefore,on the basis of air source heat pump,phase change heat storage box and solar energy auxiliary system are introduced to achieve the purpose of "peak cutting and valley filling",energy saving and emission reduction.According to the climatic conditions of Beijing area,combined with the practical use of experimental buildings and the rational use of "peak and valley electricity",a set of solar energy-phase change heat storage-air source heat pump multi-energy complementary heating system is designed.The experimental heating platform and system were built and designed in July 2020.After a series of installation and debugging,the stability of the experimental platform was determined.The heating period in Beijing area is from November 15 to March 15.The variation law of outdoor average temperature during the whole heating period is analyzed as follows:first,the temperature decreases rapidly to the lowest point,then rises slowly,and then rises steadily in a temperature range.Finally,it shows an upward trend.According to the law of outdoor temperature change during heating period and practical engineering experience,the whole heating period is divided into initial cooling period(-5 ℃ ～ 5 ℃),intermediate cooling period(-15 ℃ ～-5 ℃)and final cooling period(-5 ℃ ～ 5 ℃).On the basis of the completion of the experimental platform and the normal operation of the system,according to the outdoor temperature changes in the initial,middle and last cold periods,four operation modes are designed,namely: air source heat pump single heating mode,heat pump-phase change heat storage intermittent heating mode,solar-assisted heat pump-phase change heat storage intermittent heating mode,heat pump-phase change heat storage coupling heating mode.In the initial and final cooling period,the four heating modes can meet the heat users,and the indoor temperature is maintained at 20 ℃ ～ 23 ℃,but in the intermediate cooling period,when the outdoor temperature is lower than-10 ℃,the intermittent heating mode of heat pump-phase change accumulator can not meet the heat users.By testing the system energy efficiency ratio(COPs,)of the four modes,it is found that in the initial,middle and last cooling periods,the system energy efficiency ratio of the coupled heat pump-phase change heat storage mode is the highest,which is about1.7 times higher than that of the intermittent heating mode COPs and 1.25 times higher than that of the heat pump alone.In order to accurately calculate,analyze and evaluate the expected annual economic benefit of the technical experiment scheme,this experiment uses the annual cost method of dynamic analysis to analyze the economy of the system.The solar assisted heat pump-phase change heat accumulator intermittent heating mode has the largest annual cost due to the large initial investment,but it has the lowest cost in terms of energy consumption.compared with the air source heat pump heating alone,it can make effective use of "peak and valley electricity".Achieve energy saving and emission reduction.In terms of technology,two phase change heat storage boxes are connected in parallel in this mode.after the phase change heat storage box is added,valley electricity heat storage and peak electricity heat release are realized.This model is suitable for heat users who have large energy consumption and need to save energy and reduce emissions during the heating period. |
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