ABSTRACT
The major thermal properties of a covering material are heat-transfer coefficient, thermal-conductivity coefficient, surface heat-exchange coefficient, transmissibility of the cover to infrared radiation, reflectivity of the cover to infrared radiation, absorptivity of the cover to infrared radiation and thermal store coefficient. The K -value (the overall heat transfer coefficient) is an important factor to reflect thermal performance of the covering material in a green house, which reflects the interactions between the physical characters of the material itself and the environment, so it can reflect the heat conservation performance of the covering material and estimate its performance. In general we test the K -value in the nature environment condition or simulated real environment in lab. Mihara and Hayashi (1970) kept the constant temperature inside of the room using the control instrument, and calculated the electricity quantity to get the K-value. P.Feuilloley and G.Issanchou (1996) compared thermal performance between the glass and the plastic covering materials. Xinqun Zhou (1998) tested the thermal insulation of honeycomb covering materials with plastic sheets, and he got the K -value using multi-conversion switch and the direct current potentiometer. The measuring process of K -value was burdensome in labors, low accuracy, complicated in dealing with data that is difficult to meet the development of modern agriculture. New testing methods need to be developed, and specially designed for greenhouse covering materials.
