Wind Speed And Direction On The Wall Surface Heat Transfer Coefficient Experimental Study

Heat transfer coefficient of wall surface is an important parameter that characterizes the heat transfer process of wall surface. It is widely used in air conditioning load calculation and building energy consumption analysis. Moreover, it is also the key parameter to analyze and solve the problem of wall condensation. Because the heat transfer process of wall surface is influenced by many factors such as airflow velocity and direction, radiation, etc, the heat transfer coefficient of wall surface becomes very difficult to be derived or measured with high accuracy. In order to solve this problem, the effects of airflow velocity and airflow direction on heat transfer coefficient of wall surface are studied in this paper.A new simple experimental method of measuring heat transfer coefficient of wall surface is presented and the identification methods of heat transfer coefficient of wall surface are also studied profoundly. Not only Least Square (LS) method and Genetic Algorithm (GA) are introduced, but also Least Square-Genetic Algorithm (LS-GA), a kind of new approach of mixing these two methods, is created in this paper. The temperature difference and heat flux for 30 sets of different air velocities and airflow directions are measured, then the dynamic model of wall surface heat transfer system including the heat flux meter is identified by LS-GA to get the heat transfer coefficients of wall surface, and the expressions of the effects of air velocity and airflow direction on heat transfer coefficient of wall surface are procured after all. The results show that the heat transfer coefficient of wall surface is proportional to air velocity under normal airflow velocity, but it is not affected significantly by airflow direction.