Study On The Influence Of Heating By Household Air Conditioner On Indoor Thermal Environment

In recent years,with the promotion of clean heating policy and the growth of heating demand in the south of China,the proportion of using household air-conditioner for heating has gradually increased.Although this heating method is energy-saving,environmental friendly,economical and safe,the poor indoor thermal environment is a major factor restricting its further promotion.The purpose of this paper is to study the influence of different air-conditioning parameters and air-conditioning installation location on the indoor thermal environment,and to analyze the primary and secondary relationship and the degree of influence of different factors on the indoor thermal environment through orthogonal test,so as to point out the direction for improving the thermal environment of household air conditioner heating.In this paper,an experimental platform for indoor thermal environment research of household air conditioner heating was built,and the influence of air supply angle and air supply speed on indoor thermal environment is studied.Based on the experimental data,the effects of air supply angle and speed on the indoor vertical temperature field,horizontal temperature field,local thermal environment,indoor inner wall temperature and average radiation temperature,as well as the heating speed of air conditioning are analyzed.Then,a model was built according to the experimental room,and the influence of air supply temperature,air conditioning installation height and horizontal position on indoor velocity field and temperature field was numerically simulated through CFD.Finally,the orthogonal test was used to optimize the indoor thermal environment for heating by household air-conditioner.The vertical temperature difference of 0.1m horizontal plane and 1.1m horizontal plane and the air diffusion performance index(ADPI)of the working area are adopted as the evaluation index of indoor thermal environment.Extremum difference analysis is used to explore the major and minor relationship between the air supply angle,air supply speed,air supply temperature,installation height and horizontal position of the air conditioner,and to seek the best combination of factors and levels to improve the indoor thermal environment.And the variance analysis method is used to obtain quantitative estimate of the degree of influence of five factors on the test index.The results of this paper show that: under the heating mode of household air conditioner,the upper and lower cold and heat stratification in the room is serious,and the average indoor radiation temperature is obviously lower than the indoor air temperature,and the double effects of large vertical temperature difference and cold radiation results in the poor indoor thermal environment.Reducing the air supply Angle,increasing the air supply speed,reducing the air supply temperature or reducing the air conditioning installation height can all effectively improve the phenomenon of large vertical temperature difference.However,it is difficult for the horizontal surface at the height of 0.1m to reach the standard requirement of 18?.Moreover,while reducing the vertical temperature difference,the difference between the average radiation temperature and the indoor average temperature is increasing.Therefore,it is necessary to raise the temperature of 0.1m horizontal plane and indoor average radiant temperature through auxiliary measures to meet the thermal comfort requirements.The primary and secondary order of the influence of the five factors on the vertical temperature difference is as follows: air supply speed > air supply Angle > air supply temperature > air conditioning installation height > air conditioning horizontal position,and the primary and secondary order of the influence on the air distribution characteristic index is as follows: air supply speed > air conditioning installation height > air supply temperature > air supply angle > air conditioning horizontal position.The air supply parameters of the air-conditioner and the installation height of the air-conditioner have a great influence on the indoor thermal environment,while the horizontal position of the air conditioner only has a certain influence on the distribution of air distribution in the room,and has almost no effect on the indoor thermal environment.The research work in this paper can provide a useful reference for improving the thermal environment of household air-conditioner.