The Effect On Heat Dissipation Of The Outdoor Unit Of Split Air-conditioner Due To Its Installation

In residential building design, outdoor units of air-conditioners are often installed in the grooves in order to ensure the overall appearance of the facade, which causes a serious impact on the normal operation of outdoor units. If the groove is too small, hot air is difficult to discharge from the narrow and enclosed space and then will be drawn back to the outdoor unit, which results in lower efficiency and refrigeration effect, higher power consumption and seriously short longevity of the air-conditioner. Large groove is often unrealistic and also not encouraged because of waste of building space and materials. Thus, the rational layout of outdoor units and optimization of the surrounding thermal environment is worthy of further exploration.This paper mainly studies heat emission of outdoor units in the grooves in residential buildings. Firstly, through literature reviewing, the paper systematically combines the research process of heat dissipation of outdoor units at home and abroad and concludes several installation methods. Secondly, by on-site measurement it is observed that the return air temperature is similar basically with ambient temperature when the outdoor unit installed directly, while the return air temperature is 12℃over the ambient temperature when the outdoor unit is installed in the groove. Thirdly, it provides a detailed description of numerical simulation theory and the reasons to set the parameters, and then builds the model for numerical simulation. After that a laboratory model is established according to the numerical model in order to verify the accuracy of the simulation. The simulation is proved to workable and correct by comparing experimental results with numerical simulation part. Then the work focuses on groove height, width and depth, and the orthogonal analysis is used to design simulation programs. By the methods of range and variance analysis, the significant factors of affecting the average return air temperature of the outdoor units in order are groove depth, width and height. The ambient temperature is set as 35℃. There is a difference of 2.7℃between return air average temperature of the outdoor unit and ambient temperature when the groove depth is 90cm, the width is 180cm and the height is 80cm. With the depth climbing up, the return air average temperature changes little. When the depth is 90cm, the height is 80cm and the width exceeds 220cm the return air average temperature of the outdoor unit remains around 2℃over the ambient temperature. When the width continues to increase, return air average temperature has no obvious change. When the depth is 90cm, the width is 220cm and the height exceeds 220cm, the return air average temperature of the outdoor unit remains around 2℃over the ambient temperature. When the width further increases, the return air average temperature has no obvious change. The suggested values are proposed that the depth recommended is more than 90cm and the distance between the outdoor unit and the back wall should more than 40cm; the width should be not less than 220cm and the height> 70cm.