| Although the high altitude,low temperature,the high and cold region has the lighting conditions that abound in gifts of nature.Compared with the traditional thick soil wall solar greenhouse,the active heat storage solar greenhouse can provide more suitable environment for plant growth in winter,however,there are some problems in the greenhouse,such as the high temperature at noon,and it is difficult for the influence of airflow in greenhouse to reach the plant.Therefore,this thesis designed a kind of active heat storage cycle solar greenhouse with plant-to-plant air supply system,after construction is completed in the high and cold region,field tests are carried out during the cold winter season.The main results were as following:(1)The traditional thick soil wall solar greenhouse is one of the typical greenhouses in Qinghai region,but there are some problems such as low indoor temperature in winter and uneven airflow distribution.Compared to the thermal performance of the active heat storage solar greenhouse(G1)and the traditional thick soil wall solar greenhouse(G2),and the heat transfer characteristics of G1 was further analyzed.The results show that: during the test period(8 December to 25 December in 2021),the average temperature of G1 and G2 was higher than the outdoor 24.8 ℃ and 21.3 ℃ respectively;during the daytime(9:00-17:00),the average temperature of G1 and G2 was higher than the outdoor temperature 23.4 ℃ and 21.7 ℃,respectively;at night(17:00-9:00 the next day),it was higher 25.5 ℃ and 21.1 ℃ respectively.The average temperature of wall and soil in G1 was higher than that in G2,and also decreased with the increase of depth.(2)An active heat storage solar greenhouse with wall heat transfer duct and soil heat transfer duct is designed,at the same time,design a plant-to-plant air supply system,which consists of a plant-to-plant air duct and a outlet of a soil heat transfer air duct,design the different arrangement of plant-to-plant air ducts,and install and test in active heat storage solar greenhouse,the best air outlet is obtained by comparing the uniformity of the air outlet with that of the air flow at different heights.Compared and analyzed the thermal environment of two solar greenhouses with the same structure,the results showed that during the experiment period(January 1 to January 31 in 2023),the temperature changes of the two greenhouses on sunny and cloudy days as well as during the day and night were the same,and the difference was smaller,the trend of wall and soil temperature is also consistent.Install plant-to-plant air ducts in one greenhouse(G3),the other is the contrast greenhouse(G4),the test time of air duct between plants is 10 days(12 February-21 February in 2023).After the installation of plant-to-plant air ducts,when the temperature is too high at noon,it can reduce the temperature appropriately,and it can increase the temperature certainly at overcast day and night time.(3)Built the model of the test greenhouse by ANSYS software,simulating the airflow field in greenhouse,to verify the influence of plant-to-plant air supply system on greenhouse gas flow field by changing the air velocity of the outlet of the heat transfer duct in the greenhouse.The measured wind velocity at the outlet of the test greenhouse is 6.5m/s,the air velocity of outlet is 10 m/s,15 m/s,20 m/s in the simulation of air flow field.When the wind speed is 10 m/s,the air flow is even but it has little influence on the height plane of plant growth;when the wind speed is 15m/s,it has obvious influence on the air flow of the whole greenhouse,and the air flow is even;when the wind speed is 20m/s,it has obvious influence on the airflow of the whole greenhouse,but the wind is not uniform.Therefore,under the design of this kind of plant-to-plant air supply system,the most uniform wind speed is 15 m/s,which has a great influence on the greenhouse air flow field,at this time the wind speed around the plant is about 0.1 m/s. |
PDF Full Text Request