| With the continuous improvement of people's living standards,the south heating has become an urgent social problem to be solved in our country.At the same time,in the northern towns,the existing coal-heating and gas-heating lead to serious environmental pollution problem,which is also one of the most serious problems in our country at this stage.In the dual pressure of heating demand and environmental pollution,the air-source heat pump heating system is favored with its highly efficient,environmentally friendly features.The existing research on air-source heat pump heating system is mainly focused on heat pump performance and heat supply of multiple heating source.Breakthroughs and progress have been made in the unit load rate,outdoor temperature and energy efficiency of multi-energy complementary systems.However,the climatic characteristics of different regions vary widely,which results in very different load characteristics.There is very limited literature on air source heat pump heating system energy efficiency and operating characteristics combined with the end of the building system and climate characteristics.Based on the climatic characteristics of the heating season in Chongqing,this paper analyzed the characteristics of various heat sources,end forms and the building load in this area,and put forward a new kind of heating system for residential building in Chongqing,namely the sensible heat storage air source heat pump for floor radiant heating system.Two heating modes of the sensible heat storage air source heat pump for floor radiant heating system were analyzed in detail combined with the study of the operating characteristics of floor radiant heating system(FRHS).At the same time,an experimental test platform was established in Jiangbei District,Chongqing to verify the simulation results.Firstly,the natural room temperature and hourly load model of the experimental test platform was established by DeST software.The results show that the average heat load per unit area is between 5 W/m2 to 20W/m2 and the duration is about 40 days at the beginning and the end of the heating season.During the middle of the heating season,the average heat load per unit area is between 15 W/m2 to 30W/m2 and the duration is about 50 days.This indicates that the building heat load fluctuates greatly for different periods of the heating season.Besides,the daily building heat load distribution is also very uneven.Secondly,this paper established a mathematical model of two-dimensional heat transfer for floor radiant heating room,and its physical model was established by Gambit software.The law of room temperature fluctuation and natural decay in heating process were calculated by Fluent software.From the numerical results,it can be seen that in the case of water supply flow of 0.15m3/h,when the water supply temperature are 35?C,40?C and 45?C,the time required for the room temperature to rise to 20?C are 5h,3.75 h,3.5h,respectively.In the case of the water supply temperature is 45?C,when the water supply flow are 0.125m3/h and 0.15m3/h,the time required for the room temperature to rise to 20?C are 4h and 3.5h,respectively.Therefore,the rise rate of indoor temperature is affected by the water supply temperature and the water supply flow.At the same time,the water supply temperature is also the main factor to determine the maximum indoor temperature.Analysis of the room temperature natural attenuation law shows that at the beginning and end of the heating season,the input heat of a single heating cycle is basically able to ensure that the building room temperature is maintained above 16?C throughout the day.By comparing the numerical solution and the experimental results,it can be seen that for the indoor temperature in different height in the heating process,the difference between the two values is between 5.5% and 7.5%,and for the temperature rise,the difference between the two values is between 11.5% and 15.4%.In this paper,two operation modes were established using TRNSYS software,namely air source heat pump direct supply floor radiant heating end system and the air source heat pump floor radiant heating with the water tank as the heat storage device system.According to the law of heating season load,intermittent heating strategy was adopted in the middle heating season and certain-time heating strategy at the beginning and end of the heating season.The system operation rules and energy efficiency characteristics of the two strategies were calculated.The results show that the daily average energy efficiency ratio of the air source heat pump direct supply floor radiant heating end system in the whole heating period is 2.93,and the daily average energy efficiency ratio are 2.97 and 2.90 for certain-time heating period and intermittent heating period,respectively.The daily average energy efficiency ratio of the air source heat pump floor radiant heating with the water tank as the heat storage device system in the whole heating period is 3.04,and for certain-time heating period and intermittent heating period,the daily average energy efficiency ratio are 3.21 and 2.91,respectively.In order to verify the accuracy of the numerical results of the air source heat pump heating system performance,the system performance was tested by using the experimental platform of the air source heat pump floor radiant heating system in Jiangbei District,Chongqing.The results show that the energy efficiency ratio of the heat pump heating period and the start-stop period are 3.27,2.67 on December 5,respectively,and 2.97,2.53 on January 1,respectively,and 3.13,2.90 in the whole heating period,respectively.Compared with the numerical results that the heating energy efficiency ratio in the whole heating period are 3.06 and 2.85 on December 5 and January 1,respectively,the experimental values are increased by 0.07 and 0.05,respectively.The differences between the numerical solution and the experimental results are relatively small.It can be found that the decrease of the length of the start-stop period during the actual operation is the main reason for the discrepancies. |
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