Development And Optimization Of A New Reduced Simplified Model Of Equilibrium Thermodynamics&Applied Technology Of High States Of Light And Temperature In Heliogreenhouse

Due to its particularity of structure, solar greenhouse is asuitable for protected horticulture facilities in an arid andsemi-arid region in northwest China. Solar greenhouse has alsogotten maximum development under the promotion of technicalinnovation in recent years. But，there are many problems in presentgreenhouse production which include less feasible structure，lowsolar radiation utilization rate， bad performance of heatpreservation and lack of theoretical research results．Based on thestudy of component and structure scheme, Different type of solargreenhouse has a specific similar structure and regularity. Andin addition, we can find the potential laws and to draw the rulesto value the uncertainty of the solar greenhouse system innorth-west of China. Then the suitable decision which can solvethe problem we faced in designing and operation management can bedrawn up out based on these foundations.The solar greenhouse environment factors which include solarradiation， air and surface temperature，temperature distributionand response behaviors of structure element, heat flux density ofstructure element, effect of soil temperature, and the cultivationmanagements in middle and late stages were measured continuouslyin four typical testing solar greenhouses in northwest region ofChina. And the solar greenhouse characteristics of thermalperformance were analyzed from the above measured data．The studyof characteristics of thermal performance may give the necessary theoretical basis for structure optimization，environment controland crop cultivation． In addition the solar greenhousecharacteristics of thermal performance and variation law of theillumination in the greenhouse were analyzed under the typical datesand the typical external climatic conditions according to themeasurement data．Firstly, detailed calculation method was appliedto the heat flux density of structure element and the thermalconsumption law. Secondly, based the comparative analysis of theheat flux density of different structure element, mainly heatdissipation way was be analyzed, and then the structure elementwhich should be improved can be found. The study of economicthickness of the greenhouse’ backwall has established a theoreticalanalyzing model on the basis of experimental study. Thirdly, thetransmission of solar radiation into the greenhouse can be acquiredaccording to the solar radiation inside and outside thegreenhouse．The law of thermal storage were analyzed and summarized.So we will found the way to overcome the drawbacks of the greenhousestructures.According to the concepts of classical heat transfer theory,the solar greenhouse thermal system is a very complicatedthree-dimensional、unsteady process of state thermal conduction,radiation and thermal convection. Based on the heat transfer lawof solar greenhouse, the simplified model of heat transfer in thesolar greenhouse was established and validated using fieldexperiment data （ΔQ=Qsun+Qprotect+Qlongwave+Qvent+Qsoil+Qground20）. The solargreenhouse is considered as a complete unit in the simplified modelof heat transfer. Then we grasp heat transfer law of solar greenhouseclearly. Thermal loss rate of the typical structure solar greenhousein daytime is80%, and the thermal loss rate at night is20%. Therate of the heat which loss by maintenance structure is65%indaytime, and the same rate is70%at night. The rate of the heatwhich loss by ventilation is35%in daytime, and the same rate is30%at night.Based on this established simplified model, we found that thesolar interception rate is relatively low. This paper studies and analyzes the experimental data by experiment comparison andlighting analysis method. Then it puts forward a new structuralmodel of high-performance greenhouse what is called a“solar-greenhouse with variable incidence angle”. It’s technicalperformance including lighting and structure are discussed andcompared theoretically. Through the research the variable structure,the solar-greenhouse with variable incidence angle is moreefficient in utilization of solar energy and raising temperature.Illumination in the greenhouse with variable incidence angle hasa great enhancement comparing with normal type. The increasing rateof lighting performance is25.6%. The mean indoor temperatureincreased roughly by3.6℃.Simplified model revealed that solar greenhouse has the problemof lack of thermal storage. Then it will lead to poor thermalinsulation properties. We developed the PCM wall structuregreenhouse. By researching their thermal properties by DifferentialScanning Celemeter （DSC）, for the new compound PCM composed ofNa₂SO₄·10H₂O and Na₂CO₃·10H₂O, the sample in t he mass proportionof4∶6is suitable for greenhouse. The phase transformationtemperature which divided into two stages meets the need of plantgrowth. During the application process, the phenomena of supercooling and phase segregation can’t be eliminated completely. Forthe new compound PCM composed of Na₂SO₄·10H₂O and Na2HPO4·12H₂O,the sample in the mass proportion of1.9∶7is suitable forgreenhouse. The phase transformation temperature remain stable,the phenomena of super cooling and phase segregation meet therequirements. Under the experimental conditions， The indoortemperature fluctuations of the PCM wall structure greenhouse is3.5℃lower than the temperature of the normal wall structure. Theindoor average temperature has increased by1.9degrees and canbe increased by5.8degrees.By researching thermal properties of the solar greenhouse, fourinnovative points well be realized. Firstly, based on the studyof characteristics of thermal performance, may give the necessarytheoretical basis for structure optimization，we grasp heat transfer law of solar greenhouse. Secondly, the simplified model of heattransfer in the solar greenhouse was established and validated usingfield experiment data. Accord to the simplified model of heattransfer in the solar greenhouse showed by the certain theory, Itmainly deals with theoretic investigation and practical study ofseveral typical solar greenhouse. Thirdly, in order to solve theproblem of the lower solar energy utilization ratio in thegreenhouse, we research and develop a new structural model ofhigh-performance greenhouse what is called a “solar-greenhouse withvariable incidence angle”. Through the research the variablestructure, the solar-greenhouse with variable incidence angle ismore efficient in utilization of solar energy and raisingtemperature. Illumination in the greenhouse with variable incidenceangle has a great enhancement comparing with normal type. Theincreasing rate of lighting performance is25.6%. Finally, in orderto solve the problem of the lower thermal storage performance inthe greenhouse, we developed the PCM wall structure greenhouse.Then the thermal storage performance of solar greenhouse wassignificantly increased. The theory is very practical in theexploration of the solar greenhouse structure and the managementof solar greenhouse.