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Research And Application On A New Heat Storage-Release System In Solar Greenhouse

Posted on:2014-06-02Degree:DoctorType:Dissertation
Country:ChinaCandidate:X W WangFull Text:PDF
GTID:1313330536962394Subject:Facilities crops
Abstract/Summary:PDF Full Text Request
Energy-saving solar greenhouse is an agricultural facility of Chinese characteristics.Its structure was innovated by scientists and farmers' continuous efforts over the past two decades.However it hasn't major innovative improvements and each improvement of solar greenhouse structure only designed by parameter optimization.We made a study of performance on solar heat storage system and its effect to environment in greenhouse after used combination of active and passive greenhouse heat storage.In this paper the main results as follows:1.One prefabricated full light and double effect solar greenhouse was designed.The parameter as follows: the length of 60 m,10 m span,height of 4.5 m,the back wall height of 4.4 m,before roof long of 11.2 m,20 cm wall thickness,greenhouse azimuth by west 5-8 °,after roof elevation Angle of 45 °.This greenhouse can increased inside daylighting of greenhouse.The greenhouse land utilization rate reached 85%,compared with common greenhouse land utilization increased by 15%.2.The many kinds of active heat storage system were designed and installed in solar greenhouse,for example double effective heat pump system,water curtain solar heat storage and release system,water bag solar solar heat storage and release system etc.By testing the performance of temperature and light,the results indecated that the rate of temperature increase significantly than the common greenhouse(temperature was rised to 25.8? in 3 hours),and illumination distribution more uniform than common greenhouse.Start active heat storage system,the average temperature of double effective solar greenhouse increased 3-5 ?than common greenhouse.3.When heat storage of double effective heat pump was started,it has certain cooling effect to the greenhouse environment,the closer the location of the heat pump units,cooling effect is more obvious,the average temperature dropped 1.94?.When heat storage of double effective heat pump was started,it can obviously improve the greenhouse environment temperature,minimum temperature of 3.54? higher than control greenhouse greenhouse at night.4.When heat storage of water curtain solar system was started,the temperature of storage water tank can rised to 35.7 ?,so decreased temperature of greenhouse about 1.88?.When heat release of water curtain was starting at night,the minimum temperature is higher 3.4 ? than control greenhouse.5.When heat storage and release of water bag curtain solar system was started,higher starting temperature(22 ?)is more storage heat 88901.317 KJ than lower starting temperature(18?).Collection efficiency is double the amount of low start-up temperature.At the same time,the energy efficiency ratio can recheaded 1:7.53 at starting temperature of 10?,the energy efficiency ratio can recheaded 1:8.58 at starting temperature of 8?.6.By comparison test of double effective heat pump?water curtain and water bag three heat storage and release solar system coordinate,the results were abtained that whether in the storage test or release test,the energy efficiency ratio of using heat storage of water curtain solar system is the highest(up to 1:20),and two double effective heat pump is the lowest(1:3.18).By the analysis of thermal efficiency,the thermal efficiency of running water curtain and two double effective heat pump at the same time is the highest,running 4 hours during the day can make the temperature of heat storage water tank increase by 19.39?,exothermic effect is obvious in evening,compared to control greenhouse,the temperature increased about 5.22 ?.7.The minimum temperature of ordinary brick package wall greenhouse that was installed a solar active system basically maintained at above 10? in winter,and the difference of the lowest temperature of that and control greenhouse can reach to 8.89? at night,and the maximum temperature difference can reach to 3.51? in cloudy evening,and the effect of continuous temperature compensation is obvious.The first harvest period of greenhouse of applicating active solar thermal storage was earlier than normal solar greenhouse by 9 days,the average fruit weight,the average yield per plant and total output were the highest,the total yield is higher than common greenhouse by 13%,and average weight,the average yield per plant were significantly higher than ordinary greenhouse.
Keywords/Search Tags:Solar greenhouse, Initiative storage and release heat, Double effective heat pump, Water cuitain, Water bag
PDF Full Text Request
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