Research On Solar Greenhouse Heating System Based On The Use Of Burning-cave

A unique characteristic of Chinese traditional solar greenhouse is that the existence of the north wall which has certain heat storage capacity. Theoretically speaking, during the day, the north wall absorbs the solar energy, transforms and storages it, which is released into the greenhouse to increase the indoor air temperature at night. But the influence of the limited heat storage capacity of the wall, sometimes the indoor air temperature cannot meet the demands of the plants'growth. To solve this problem, and based on long-term research on the foundation of burning-cave smolder cascade utilization of energy on the purpose of maximizing the collection and storage of solar energy, this research designed multi energy complementary heating system in solar greenhouse. This paper will focus on the design of solar greenhouse heating system based on the use of burning-cave and system experiments to carry out the following research.Firstly, to accurately understand the problems of the indoor sun-light greenhouse thermal environment, this research took the thermal environment of solar greenhouse as the research object, and discussed the research object from two aspects of the actual measurement and theoretical analysis. A survey was conducted with the solar greenhouse in three different cities, and through the analysis of the measured data. Based on the REPS concept of solar greenhouse, the author establishes the heat balance equation of the heat exchange between the solar greenhouse and the outside world, and analyses ways of heat gain and heat loss of solar greenhouse. On principle of building design energy saving, this research puts forward ways to improve the optimization of the thermal environment of solar greenhouse. A one dimensional unsteady heat transfer model of the north wall which was based on the solar greenhouse in Dalian city was established; this research makes finite difference on the heat transfer model and compiles MATLAB solution procedure. The results show that the simulation results agree well with the measured data. Based on the data of numerical simulation, it is concluded that the energy flow path of the wall and the effective of heat storage capacity are obtained, and the importance of the thermal insulation board to the thermal properties of the wall is verified.Secondly, according to the previous study of the problems lie in the solar greenhouse thermal environment, the author proposed solar greenhouse heating system based on the use of burning-cave and discussed the structure and working principle of the system. Through the detailed design of each part of the system, the research group built the system in Fuyu City, at the same time, the author designed experimental program of system and tested it during the heating period. The experimental results showed that the average temperature of the experiment greenhouse was 3.92 ? higher than greenhousel and 12.23 ? higher than greenhouse2. The average soil temperature of experiment greenhousel was 1.2? higher than greenhousel, which showed that the heating effect of solar greenhouse heating system based on the use of burning-cave was obvious. The indoor environmental factors (CO2, air humidity, wind speed) were tested and the data were analysed judging by relevant national standards, which showed that the use of the system would not inhibit the growth of the plants. The author makes theoretical analysis of the thermal characteristics of the system by using the test data, which showed that the active heat storage device can improve 22.8% of the utilization rate of the solar system, distribution ratio of three kinds of energy utilization system is that the biomass energy is greater than the solar energy and that the solar energy is greater than the geothermal energy, and the system is feasible from the effect of the system and thermal characteristics.Finally, whether a system can be applied to the actual project, mainly depends on the economy of the system, whether it is in line with the national policy and other evaluation indicators. The author makes use of the test data of the system to analyze the energy saving rate, ecological benefit, plant nutrition quality and economy of the system. The results show that compared with electrically heated system, the energy saving rate of the system by solar greenhouse heating system based on the use of burning-cave is 82.9%, and the carbon dioxide emissions is 278.1kg during a heating period of system operation. Compared with the greenhouse heating system using a hot water heating system, it reduced carbon dioxide emissions for 673.19 kg, which is in line with China's energy-saving emission reduction policies. In this paper, the nutrient quality of Chinese cabbage under the action of solar greenhouse heating system based on the use of burning-cave is simulated and analyzed by using the model of radiant heat product. The results show that vitamin, cellulose, soluble sugar, soluble protein simulation value of experimental greenhouse is 4.66higher, 0.72%higher,0.05higher,0.04higher than the greenhousel, and therefore can be indicated that the system is conducive to the accumulation of nutrient substance of Chinese cabbage. Through the comprehensive evaluation of economic system, the annual cost and present value of solar greenhouse heating system based on the use of burning-cave in the experiment solar greenhouse respectively are lower than that of the hot air heating system and the boiler hot water heating system. According to the production experience, payback period can be calculated in accordance with the annual production benefit of 800 Yuan and 10% annual interest rate of loans, The payback period of solar greenhouse heating system based on the use of burning-cave is 2.7a, which is 0.2a lower than that of the hot air heating system and 0.3a lower than that of the boiler hot water heating system, Therefore, the economic evaluation of solar greenhouse heating system based on the use of burning-cave is better than that of traditional energy heating system.This research conducts experimental research and theoretical analysis of the traditional indoor thermal environment of solar greenhouse and concludes its problems. According to the problems, the author designed solar greenhouse heating system based on the use of burning-cave, and explained the feasibility and practicality of the system in respect of experimental tests, theoretical analysis and comprehensive evaluation, which provides the reliable basis for the practical use of solar greenhouse heating system based on the use of burning-cave.