| Aiming at the problems of low temperature indoor and night in winter,poor heat preservation and storage capacity of back wall,low temperature and cold damage of the main protected vegetables and other outstanding issues in the South Xinjiang,this paper designs a set of Water-curtain and Floor-heating System for Chinese solar greenhouse based on the typical Chinese solar greenhouse in the South Xinjiang,with the goal of taking full advantage of clean solar energy to adjust the greenhouse climate.Its working principle is that part of the solar energy which will reaches the back wall of the greenhouse in the daytime is collected,transformed and stored in the deep soil at the bottom of the plant cultivation tank and the Floor-heating System by water cycles,and the heat stored energy is released to realize the space-time transfer of solar energy,improve the temperature of the plant root area and the indoor air temperature,and reduce the probability of low temperature and cold damage,so as to eliminate the winter of the Chinese solar greenhouse in the Southern Xinjiang low carbon greenhouse heating technology which is provided by low-temperature stress in winter night.First of all,the main design and material selection of four parts of Water-curtain collector,Floor-heating pipe storage/release device,circulating water pump and bucket are carried out.The innovative design idea of Water-curtain and Floor-heating System is to make heat to be stored directly in the deep soil at the bottom of the plant cultivation tank by using small volume of water,improving the soil temperature and air temperature at the same time,so as to realize the matching combination of agricultural cultivation measures and facility environment regulation.In the early stage,different heat-absorbing materials,diversion Water-curtain layer,pipeline selection,bonding process,Floor-heating pipe material,etc.were applied.Through design schemes,0.12mm thick carbon black PVC salt film was selected as the heat-absorbing layer,0.5cm thick silk wool as the diversion Water-curtain layer,thermoplastic and organic solvent as the bonding process,PE Floor-heating pipe as the storage/heat release device,0.75KW submersible pump as the operation power of the system and the test material with a bucket volume of 0.5m3 finally form an efficient and low-cost Chinese solar greenhouse Water-curtain and Floor-heating System.Secondly,according to the designed and installed Water-curtain and Floor-heating System,the temperature increase experiment of Chinese solar greenhouse in winter was carried out.Through the measurement and analysis of the air temperature and humidity,soil stratification temperature,indoor solar radiation,back wall surface temperature,system water temperature,system power consumption and outdoor temperature and other indicators in the greenhouse G1 and G2,the micro environment of the system and the back wall surface temperature measured in the greenhouse were studied,based on the analysis of the thermal environment,the performance of heat collection,the performance of heat storage/release and the performance of energy consumption.The system was optimized and designed.The specific conclusions are as follows:1.Micro environment change of Chinese solar greenhouse.Typical sunny days,the system can increase the temperature of greenhouse air by 5.6?in daytime and 2.1?in nighttime;typical cloudy days,the system can increase the temperature of greenhouse air by 2.4?in daytime and 2.0?in nighttime.Soil temperature,typical sunny days,the average temperature of each layer of soil at surface in the daytime is higher than that in the groove,and the average temperature of each layer of soil at 10-60cm is G1>G2.The maximum soil temperature at 40cm ground heating pipe in the test groove is 28.6?.The heat storage effect of the system is obvious.At night,the average temperature of each layer of soil at surface-60cm in the groove is G1>G1>G2>G2,and the heat release effect of the system is obvious;typical cloudy days,the root temperature is G1>G2 The temperature of G1 soil surface-30 cm was significantly higher than that of G2,which indicated that the heat stored in Greenhouse Soil and air in the day before the system could effectively alleviate the low temperature in cloudy days.2.The surface temperature of the back wall and the change of the collecting and releasing heat are measured in the Chinese solar greenhouse.The Water-curtain collector affects the normal absorption of solar radiant heat on the back wall surface.The temperature of the back wall surface covered in the daytime is significantly lower than the relative position of G2.The unit area heat collection is reduced by 7.01MJ·m-2,and the accumulated heat collection is reduced by 175.26 MJ,but the surface temperature G1 of the back wall at the uncovered position is significantly higher than the relative position of G2;at night,the surface temperature G1 of the back wall is generally higher than G2,but the heat release per unit area of the back wall covered by G1 is reduced by 1.29 MJ·m-2,and the cumulative heat release is reduced by 32.13MJ.3.System performance.The system has a heat collection capacity of 100.30MJ,a heat collection capacity of 4.91MJ per unit area,an average heat collection efficiency of 40.72%,a heat storage capacity of86.68MJ,a cop of 6.19,and an energy saving rate of 81.4%compared with electric heating.Finally,with the system is optimized through comprehensive analysis,the list of relevant supporting equipment of the standard Chinese solar greenhouse Water-curtain and Floor-heating System is given,with the total cost of installing a system is about 2200 RMB?excluding labor?.Under the condition of sunny day,the Water-curtain and Floor-heating System has the advantages of large heat collection and high heat storage in the daytime,and high heat emission at night.The effect of temperature increase in Chinese solar greenhouse is obvious,and the low temperature in greenhouse can be alleviated in cloudy day. |
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