Research On The Drying For Shilin Medium And Small Leaf White Tea Based On Solar Energy-Heat Pump

Under the background of the present serious energy crisis and environmental pollution,it is an significant measure to promote the development of low-carbon,energy-saving,high-efficiency and intelligent drying technology.As a clean,non-polluting renewable energy,solar energy has been gradually applied to various fields in conjunction with heat pump technology with good energy-saving effect.On the one hand,The combination of solar energy technology and heat pump technology can resolve the discontinuous and unstable defects of solar energy,and enhance the performance of the heat pump;On the other hand,the drying process can be monitored and controlled in real time,and the operating parameters of the system can be regulated according to the conditions of drying requirements,so as to bring about the continuity and standardization of the drying process of materials,thereby improving the quality of materials.Based on the issues existing in the production process of medium and small-leaf white tea in the high mountain tea area of Shilin,Kunming,this paper puts forward a solar-heat pump combined system.The research contents and conclusions are as follows:(1)A solar-heat pump combined system that can dry 15 kg of withered leaves at a time was designed.The operating principle and structural composition was determined according to the environmental conditions required in the white tea processing process,and the solar heat collection system was also decided according to the heat load required for white tea drying.Matching and selection of related components with the heat pump system.The system can control the withering conditions of white tea,and select drying modes such as solar drying,heat pump drying or solar-heat pump combination according to the specific conditions of the withered leaves.(2)The airflow field of the original box structure was numerically simulated by Fluent software.By adding variable sections with different inclination angles,the problem of poor airflow uniformity is solved.By comparing the wind speed values of the experiment and numerical simulation,the relative error of the two is between 4.62%and 8.62%,and the change trend is roughly the same.The results of the numerical simulation reflect the system airflow field distribution is reliable and reasonable.(3)A variable-section solar-heat pump system with an inclination angle of 15°was built inside the box,and the system was used to control withering and drying conditions.When the withering temperature is 24 ? 28°C,the humidity is 65% ? 75%,and the wind speed is 0.6 m/s,the color and content of internal biochemical components of the white tea produced are better than those that are naturally withered and dried indoors in overcast and rainy weather,and those that are naturally withered and dried indoors.indoor natural withering and drying in overcast and rainy days.(4)Taking 15 kg of withered leaves as the drying raw material,the performance of solar drying alone,heat pump drying alone,and combined solar-heat pump drying were studied and analyzed.Under the same drying temperature,the average heating coefficient is 5.81,when the solar drying is operated alone;the average heating coefficient is 3.22,when the heat pump is operated alone;when the water temperature in the solar water storage tank reaches 60 ? 62 °C,the combined average heating coefficient of drying is 3.68 ? 5.99.(5)The combination of solar energy and heat pump can realize the complete production and processing process of white tea.The operation process is highly controllable and not restricted by weather and environment,which significantly shortens the production and processing time of white tea.With high production efficiency and the improvement of quality,more economic value would be created,the investment payback period is 0.76 years,and the investment rate of return is 1.31.