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Study on the Light and Temperature Environment and the Heat Transfer of the Tomatos in the Greenhouse

Author: WangQian
Tutor: SunZhiQiang
School: Henan Agricultural University
Course: Agricultural Biological Environmental and Energy Engineering
Keywords: Solar radiation Unit Conversion Active surfaces of the Canopy analysis Transmittance Extinction coefficient Thermocouple Conduct Convection Heat Transfer
CLC: S626
Type: PhD thesis
Year: 2007
Downloads: 293
Quote: 2
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Abstract


The enery relation of the biology and environment was payed much attention to by the ecologists after the ecology had been defined as a science of the relationship of the biology and the environment.D.M.Gates described the characteristic of energy exchange between the biology and environment,and he considered that the energy flowed not only in the organism but also in the physical environment.So all such things as radiation,convection, conduction,chemical and biology metabolism should be taken as energy flew.The energy ecology research in China started only in recent years.Though there are many people study in this field,only Wen Dazhong analyzed the energy flow of the agro-ecology system in northeast China.This is the most important content of this kind of research.Besides the Chinese Academy of Sciences did some research work in Benjing Datun Agro-ecology System Research Station,the purpose of the which is to study the relation between the environment factors,also between the crops and the environment factors,including to know the matter and energy cirvulation courses in the system during the different phases of the crops growth.Agriculture development demands more and more exactness control.The ASA, CSSA,SSSA raised the concept of Precsion Agriculture.The changed the traditional notion that the agriculture should be managed roughly,and demand a high level of the study of the relation between the crop and environment.This paper studied the energy flow of the radiation,conduction,convection and evapourtranspiration taking tomato （in greenhouse）as examples to support the energy flow study of the crop ecology. The main contents of this paper are below:（1）The light and the temperature environment of the tomato colony in greenhouse was studied.The rates of the light pass through the tomato canopy were measured using the Li-cor radiation instruments in and out the greenhouse.The canopy openness of the tomato canopy was analysered using the LAI-2000 canopy analyzer and the result shows the canopy openness is almost equal to the measured rates of the light penetrating into the tomato canopy.It demonstrates that the LAI-2000 canopy analyzer can be used in the greenhouse to measure the tomato colony structure.The light spectrum of solar radiation in the greenhouse was measured using the light spectrum analyzer.The results show that the maximum total solar radiation during clear days in the greenhouse is 550Wm-2,and 450 Wm-2during overcast days.The solar radiation environment in the house is good.As for the spectrum,the results are:a)the green light takes the maximum proportion in different weathers,b)the ultraviolet radiation is the more in clear days than in any other weathers,c)the red and orange light is more than the blue and the violet in clear days, whereas in the overcast days they are close to each other.It is an important factor of the qulity of plant procuct in greenhouse.（2）It studied the temperature difference of the different parts of the tomato and the air of the same hight above the ground in different weathers in the greenhouse,and it calculated the heat transfer of the tomato fruits and the convection heat transfer of the tomato colony.The results show that the temperature differences of the different parts of the tomato and the air of the same hight above the ground are obvious,and the biggest one is of the fruit,the second one is of the stem,the smallest one is of the leaf,and the temperatures of the fruit,stem and the leaf are all higher than the air temperatures of the same hight above the ground.The heat time constant of the tomato is about 172s.The maximum heat conduction of the tomato fruit is 1.29W,happens at 10:00 o’clock,which is about the 0.2%of the solar radiation in the greenhouse at noon.The heat convection at the clear day night is about -1W,which is losting heat.The lowest heat convection is -18.9W,which happens at 10:30.At 10:15 it changes to gain heat and get the highest heat convection of 34.9W at 13:30.At 18:30 it changes to be losting heat convection until the next morning.The daily change of the heat convection in the overcast day is the same,but the extent is samller.（3）The hidden heat transfer is clear because of the transpiration of the plant.Using the method of Penman-Monteith and the other specialist,it studied the hidden heat transfer of the tomato in greenhouse.The transpiration of the tomato in the greenhouse can be calculated with the radiation balance at he active surface of the tomato canopy,and the calculated results are consistent to that measured by other specialist using the Flow32 stem flux instrument.The daily diversification of the transpiration heat consuming of the tomato colony in different weather conditions is calculated using the method of Penman-Monteith.The heat consuming of the evaportranspiration in the clear day is obviously bigger than the heat conduct and the convection we mentioned above,but during the cloudy days it decrease to decades waits,which is of the same amount of the heat conduct and the convection.So,the cloudy,especially the continuous overcast days,the heat transfer of conduct,convection and radiation from the plant to the air is much more important.

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CLC: > Agricultural Sciences > Gardening > Horticultural ( protected cultivation ) > Vegetable Horticultural
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