Study On The Light And Thermal Environment Of The NJ-6 Type Energy-saving Multi-span Greenhouse

The multi-span greenhouse is playing an important role in accelerating the development of equipped agriculture in China and the environment of greenhouse will decide the production of plants. Among the factors that affect the greenhouse抯 environment, the light and thermal factors are the most important aspects. They will affect the production of plants directly. So, what we concern about is that if we can provide good light and thermal environment when we design greenhouse. At present, the main problems in the process of greenhouse抯 production are that too much energy is used to raise the temperature in wintertime or reduce the temperature in summer time. Also, the light transmission in the multi-span greenhouse is low. So, the cost in constructing greenhouse and maintaining the production is very high and the benefit from the greenhouse is very low. In order to solve these problems better, in 1998, the Research Center in Equipped Agricultural Engineering of China Agricultural University designed one new type multi-span greenhouse (named NJ-6 type). Some NJ-6 type greenhouses have been constructed and used in Henan and Shandong Province. The author did some research in the light and thermal environment of NJ-6 type greenhouse for the first time in China. According to one year抯 experimental research in this kind of greenhouse in Yantai city, proved that: The NJ-6 type multi-span greenhouse has more advantage in solar light transmission and energy-saving effect than other kinds of multi-span greenhouse used in China. It抯 suitable to use in most areas in North China. From the end of 1999 to the beginning of 2000, in one month抯 time, the author did some research on the light and thermal environment of the greenhouse. Improved that NJ-6 type greenhouse has a good thermal and light environment, the light diffusion rate is higher than other kinds of multi-span greenhouses. It抯 suitable to plan most kind~s of flowers or plants the whole year. In the spring and autumn time, the author did some research on the effect of ventilation system, improved that this system has quite good result. The author also, at the first time in china, improved that it抯 successful to use quit to keep the inside temperature of multi-span greenhouse. The author improved that it抯 feasible to design this kind of greenhouse with the idea of applying the theory of solar greenhouse. According to meteorology, geometrical optics and radiology, a mathematical model of solar radiation environment was developed for NJ-6 which can be used to calculate and analyze the relations among structural parameters of the greenhouse抯 roof and the width and place of feeble light area on the ground inside the greenhouse. This will give useful reference to engineers who may optimize and design this kind of greenhouse in different kinds of areas in china.