Design And Application Evaluation Of Upwards Pulling Thermal Insulation System Inside Large Span Asymmetric Greenhouse

Greenhouse is a kind of building which uses daylighting and heat preservation materials as the whole or part of the enclosure structure for planting plants.In order to improve the heat preservation ability of greenhouse,multi-layer covering heat preservation and heat storage measures are usually adopted.The covering materials are divided into transparent and non transparent.The transparent materials have poor heat preservation ability,and the non transparent materials have better heat preservation ability.When rolled to the top of greenhouse in the daytime,the non transparent covering materials will cast a shadow band in the length direction of greenhouse to reduce the illumination of ground shadow parts The number and intensity of light,and the shadow position also shift with the change of the sun from sunrise to sunset,which has a certain negative impact on the growth quality and yield of large area crops in the northern part of the greenhouse.Based on the analysis of the evolution process of the roller shutter,combined with the use of more types of roller shutter in the current market,this paper analyzes the types of heat preservation quilt,the internal mechanical power structure and the external support system,uses the working principle of the sun shading system of the multi span glass greenhouse for reference,and relies on the 18m span asymmetrical double-layer heat preservation greenhouse as the test object,and judges a light and thin texture,good heat preservation and water absorption According to the working mode of "motor-reducer-coupling-transmission shaft-traction rope-counterweight shaft-heat preservation quilt",a set of large-spanasymmetric greenhouse pull-up type inner heat preservation quilt rolling curtain system including power device,transmission device,fixing device and protection device is designed.When it needs to be covered at night,the inner insulation is driven by the rolling curtain system to drive the transmission shaft to rotate forward,and the insulation is pulled up;when it does not need to be covered in the daytime,the rolling curtain system drives the transmission shaft to rotate backward,and the traction rope to reverse,so that the insulation is slid to the ground.After repeated tests and optimization of the system structure,the rolling curtain system runs stably with good effect and meets the production demand.In the test of temperature and light performance in winter,compared with the shed without heat preservation quilt,the inner heat preservation shed can increase the indoor temperature by 0.4?6.5?,especially in the cold weather at night,which can slow down the heat loss,effectively improve the minimum temperature in the shed and avoid the extreme situation;after opening the heat preservation quilt in the morning in the sunny weather,it can accelerate the temperature rise in the shed and keep the air humidity relatively stable throughout the day.Under the typical sunny conditions,the light in the south is the best,the middle is lower than the south,and the north is the worst.In addition,the light intensity in the inner heat preservation shed is higher than that in the outer heat preservation shed,the North-South distribution is more uniform,and the lighting performance is better,which can increase the light transmittance by aboutl2.22%.Based on the above temperature and light environment test,the results show that the upwards pulling thermal insulation system designed by this system can not only realize the transfer of the thermal insulation quilt from the outside to the inside,but also solve the problem of shadow on the ground during the day,increase the amount of light entering into the shed,increase the intensity of light,increase the indoor temperature,and play a positive role in the growth and yield of crops in the shed.