| Solar greenhouse because of its simple structure,good thermal insulation performance,high yield,in China’s agricultural field is favored,vigorously developed,widely used in agricultural production,especially in the north of China’s most widely used.In the actual production process,affected by the regional climate,the cold period in northern China is longer,and the amount of sunlight radiation is insufficient,resulting in the solar greenhouse can not play its role to the maximum extent.Crop development,growth and yield are closely related to its ambient temperature.There are many problems in solar greenhouse in north China,such as insufficient solar radiation,low heat storage and low night temperature.In view of this problem,the current research mainly focuses on the heating method of solar greenhouse.For solar greenhouse heating,the common methods such as fire passage heating,water heating boiler heating,biological heating,electric hot wire heating and hot blast furnace have highlighted the problems of uneven temperature,high maintenance cost,insufficient heat generation and low resource utilization in their respective heating links.Due to the limitation of material and technology,solar greenhouse in cold area is difficult to solve the problems of greenhouse heat preservation and heating.For the choice of heating mode,we should not only consider the heating effect,maintenance cost,but also consider China’s national conditions.At present,China’s energy system is at a critical stage of transformation.Accelerating the development of clean energy utilization will be of great help for China to accelerate energy transformation and achieve net zero emissions.In order to study the effect of air source heat pump on solar greenhouse heating,the dynamic heat load in solar greenhouse and the use of air source heat pump for greenhouse heating were numerically simulated in this paper,which provided theoretical and technical support for the popularization and application of air source heat pump.The conclusions are as follows:(1)The indoor and outdoor temperature and humidity monitoring system was established for the solar greenhouse in Zhengzhou during the heating season.The monitoring system arranged five monitoring points in the two representative sections of the solar greenhouse,respectively,and set one monitoring point outdoors,to monitor and record the distribution and variation of temperature and humidity in the solar greenhouse.It is found that in the heating period,the temperature in the greenhouse at night is below 10℃ for a long time.The maximum difference between measured outdoor temperature data and typical annual meteorological data is 2.17℃,the minimum difference is 0.03℃,and the average temperature error is ±0.3℃.(2)The building thermal load of the solar greenhouse is calculated to determine the heat required by the solar greenhouse,and the dynamic thermal load of the greenhouse during the heating period is simulated based on TRNSYS software.The results show that the maximum thermal load of the solar greenhouse in a heating period is 43.408 k W under the meteorological conditions of a typical year.The maximum difference with the calculated heat load is 1.64 k W,and the maximum heat index is72.35W/m2.(3)Inside the greenhouse temperature monitoring results show that the sunlight greenhouse during heating room temperature for a long time is not suitable for plants to grow within the temperature range,in order to ensure the sunlight greenhouse crops in this period to maintain good growth,guarantee the production,this article is based on TRNSYS software for the air source heat pump system for greenhouse heating system conditions are simulated.Based on the calculation results of greenhouse heat load,the selection of the air source heat pump was carried out according to the heat production of the air source heat pump.The heat production of the air source heat pump was determined to be 55.63 k W,the rated COP was 3,and the rated water supply temperature was 45℃.Based on the established dynamic heat load model of solar greenhouse,the air source heat pump system was added as the heating equipment for solar greenhouse heating.Under the condition of keeping the minimum indoor temperature at 12℃,the simulation results of TRNSYS software showed that the total energy consumption of the system was 6012.62 kwh during the heating period,and the COP of the air source heat pump was the highest at 3.06.The average COP was 2.87,the highest COP was 2.8,the average COP was 2.71,and the carbon dioxide emission was 3160.83 kg.The economic comparison between the system and the common heating system in terms of annual heating cost proves that the system is better in economy. |
