Development Of In-situ Wall Thermal Resistance Test Instrument And Application Of Double-heat Flow Meter

With the sustained and steady growth of China’s economy,the impact of energy supply and demand on economic development has become increasingly prominent,energy has become an important issue that restricts the sustained and healthy development of China’s economy.Building energy consumption accounts for a large proportion in the total energy consumption,actively carry out building energy efficiency is the key to control China’s energy consumption in the future.The thermal resistance of the building envelope is one of the important thermal properties of the building,which is greatly affects the building energy consumption.Accurate detection of building envelope thermal resistance to reduce the work of building energy consumption is of great significance.In this paper,several common wall thermal resistance test methods are introduced,the advantages and limitations of different methods in-situ test are compared in detail.Based on the principle of the widely-used heat flow meter,a new method of on-site thermal resistance measurement is proposed.The improvement of the test equipment design makes the new test method equipment greatly improve the portability and operability during the in-situ test,which greatly facilitates the on-site testing of wall thermal resistance.The main equipment of the new test system and their working principle are introduced in detail.The installation method of each equipment and the precautions of the installation process are described.At the same time,the process of data acquisition and the processing method are introduced.The paper also analyzes the heat transfer process between the interior wall and the wall surface,According to the wall of the heat transfer process speculation the factors that may have an impact on the test.The paper also analyzes the heat transfer process inside the wall and the wall surface,according to the wall heat transfer process speculation may have an impact on the test factors.In the testing process to choose an effective way to avoid these unfavorable factors on the test results,and to choose an effective way to avoid these unfavorable factors on the test results.With powerful numerical simulation tool ANSYS simulating the heat transfer process of the wall during the testing of a new type of test system.The real test system is simplified,the physical model of the numerical simulation is established,the grid is divided and the boundary condition of the model is set up according to the actual test condition,the steady and unsteady processes are analyzed respectively.The distribution of temperature and heat flux on each wall was observed,and the three-dimensional heat transfer in envelope was analyzed and the change of the heat transfer direction along the heating center was also discussed,which provides a theoretical support for the new thermal resistance detection method of envelope structure.A new type of test method was used to measure different wall types.Double-heat flow meter was used in the data processing,the heat flow was calculated by averaging the heat flow on the hot side wall and the cold side wall instead of the one side wall.The thermal resistance of the test wall is calculated and compared with the calculated results.It is found that the double-heat flow meter method can improve the test accuracy remarkably.As a result,analysis of the performance characteristics of the average heat flow reflected that,the stability of the average heat flow can exit longer than the stability of a single side of the heat flow,for the environmental changeable field test,achieving a stable state test time as soon as possible can be helpful to reduce test time.It is of great importance for testing with fewer adverse impacts.