| Solar energy is the main energy of the solar greenhouses.The walls accumulate and store heat when the sun shines on at the daytime and release heat at nighttime to ensure a suitable temperature in the solar greenhouses during the night.However,due to the cold winter in the north,heat accumulated in the walls is not enough to resist the low temperature,resulting in insufficient temperature in the solar greenhouses at night and the growth of the plant is affected.Therefore,our team carried out the research on water circulation heat storage and release device with water as heat storage medium,developed Solar Energy Water-cycling Heat storage and release System and obtained two national patents(ZL 201210293846.X;ZL201310034606.2).But this system still has many disadvantages such as high cost and uneven water flow.In order to resolve these problems,this paper carried out the research on water circulation heat storage and release system with light,anti-aging and low-cost PE bubble film as collecting/dissipating material to provide theoretical and technical guidance for improving solar energy utilization and enhancing environmental control ability of solar greenhouse.The main results are as follows:1.Solar Energy Water-cycling Heat storage and release System was developedSolar Energy Water-cycling Heat storage and release System is mainly composed of a bubble plate heat collecting/ dissipating device(bubble plate),a heat storage device(water tank),a circulating water pump,a timing device,and water pipes.At the same time,a new type of water inlet device structure for the bubble plate was designed and used,which not only reduced the cost,but also ensured the uniformity of the water flow.2.The heat collecting/ dissipating device's structure of Solar Energy Water-cycling Heat storage and release System in solar greenhouses was studied.The effects of bubble plate with different colors,different bubble diameters,different water flow and whether or not benzene board is covered for insulation on the heat storage performance of Solar Energy Water-cycling Heat storage and release System were analyzed.The experimental results show that the heat storage performance of the black bubble plate is11% higher than that of the transparent bubble plate,but,the black bubble plate affects the uniformity of light nearby.In terms of the bubble diameter,the heat storage performance of 1cm bubble plate is 19%higher than that of 3cm bubble plate.Moreover,when the water flow rate is within the range of 40~60 L/min,the heat collecting efficiency of the bubble plate is the highest,which can reach about 80%.Compared with the control,the heat storage of the transparent bubble plate installing benzene board insulation cavity increased by 14.3%.Therefore,install benzene board insulation cavity can improve the heat storage performance of bubble plate.3.The operation effects of Solar Energy Water-cycling Heat storage and release System in solar greenhouses were studiedIn this test,the solar bubble plate was operated separately to observe its heat storage andheat release effect and compared with the performance of the solar solar panel.In the winter,in the solar greenhouse partition section,the test of the comparison of the operation effect of the bubble plate water circulation heat storage and discharge system is compared with the operation test of the solar water panel water circulation heat storage and discharge system under the condition of no partition,compared with the test.During the daytime,during the operation of the bubble plate,the water temperature of the water tank increased by 4.2°C on average,and the average heat storage capacity was 21.007 MJ.And the water temperature of the water tank reduced by 0.9°C,and the heat release was4.517 MJ during the nighttime,the air temperature can be rapidly increased by 1°C in the greenhouse partition.During the operation of the spring season,the water temperature of the tank increased by5.9°C during the operation of the water tank,and the heat storage capacity of the tank was29.609 MJ.In the comparative test of the operation effect of the solar water panel water circulation heat storage and discharge system,in the contrast test of the solar solar panel operation effect,under sunny conditions,the solar solar panel heat storage during the day is 24.696 MJ,and the solar bubble board heat storage during the day is 32.760 MJ,the solar thermal energy storage plate is 32.7% higher than the solar solar panel.During the nighttime heat release,the solar water tank water temperature decreased by 0.6°C,the heat release was 3.011 MJ;the solar bubble water tank water temperature decreased by 0.9°C,and the heat release was 4.517 MJ.Under cloudy conditions,the solar heat board has a heat storage capacity of 5.040 MJ during the day,and the solar bubble board has a heat storage capacity of 6.552 MJ during the day.The solar bubble board has a heat storage capacity 30% higher than that of the solar solar panel.During the nighttime heat release,the solar water tank water temperature decreased by 0.3°C,the heat release was 1.506 MJ;the solar bubble water tank water temperature decreased by0.7°C,and the heat release was 3.513 MJ.Therefore,the performance of the solar bubble plate water circulation heat storage and discharge system is better.Moreover,the solar water bubble water circulation heat storage system costs only about 55% of the solar panel.In the material cost study of the water circulation system,it can be found that the material cost of the solar bubble plate water circulation heat storage and discharge system is significantly lower than that of the solar sun plate water circulation heat storage and discharge system.Because the surface material cost of the collector/heat sink of the solar bubble plate water circulation heat storage and discharge system is low,and the solar bubble plate water circulation heat storage and discharge system uses a new water inlet structure,the new water inlet structure can effectively reduce the material cost.Therefore,the solar bubble plate water circulation heat storage and discharge system has high economic efficiency.The test results show that the suitable structure of the solar energy bubble water circulation heat storage and discharge system in the solar greenhouse is: the color of the collecting/heat dissipating device is black,the bubble diameter is 1cm,and the water flowinterval is controlled within the range of 40L/min~60L/min.Crops have higher requirements on the light radiation value,and the transparent bubble plate can be used to cover the benzene plate insulation cavity. |
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