Applied Study Of Transmission Concentrated Solar Energy Collector In Forage Drying

According to traditional forage storage process in our country, during drying forage dry matter loss. Forage nutrient retention rate is low in the field. Post harvest forage effective nutrient retention rate is only50%. In the process of harvesting forage (alfalfa) dry matter loss reached30%.The annual forage loss is large. In the forage harvesting season,the natural drying although saving money, but the quality of the products is low and the waste is rich in nutrition. By means of high temperature fast drying equipment on forage drying, the quality of the products is high, but the cost is high and the environment is polluted. Therefore in the forage harvesting, the drying process to produce high quality hay grass has become the most important preparation process. Starting from the solar energy forage drying wet harvest technology, the consumption of energy and nutrients losses are mainly considered.This paper presents a new method using the transmission type solar air collector dry forage. In the solar energy collector applied to forage drying field, from the application of basic theory, the photothermal conversion efficiency, economy and forage drying equipment design, drying process, the following research works are carried out:(1) According to the Finel lens optical principle,3D models transmission focus Finel lens is established. Through the lens model, incident angle, focal length error, tracking error and machining error are calculated. Effects of these factors on the ratio of lens and energy distribution of focusing light on the plate absorber is drawn. Finel lens fabrication process is described. And the experiments are carried out to study the optical performance and receiving angle. Theoretical analysis and experimental results show that:When the absorber openings size is5cm and openings receiving angle is within±0.4°, absorber can obtain higher optical efficiency.(2) Absorber is designed.Half round, arc, triangle and square four different geometries of the absorber is studied from two aspects of theory and experiment. Optical properties and thermodynamic properties of four kinds of absorber is displayed. Triangle absorber shows better optical efficiency and small heat loss. Therefore the square and triangle absorber was selected for the structure optimization analysis. The optimization results show that the triangular absorber accept focus light opening depth in4cm is best when the flat Finel lens as a condenser. Receive focus light opening depth of square absorber is the best in the2cm. According to the optimization results, two kinds of length6.4m absorber are made.(3) Daylighting area25.6m2transmission concentrated solar energy air collector is developed. Solar air collector comprises a heat collector box, frame support and control gear. Through the single-chip microcomputer control system, the collector can be single axis sun tracking accuracy. When the collector box is designed combined plate Finel lens and triangle focusing absorber, the performance of solar collector is the best. In one hour, the collector internal air drying temperature from ambient temperature rise to the highest temperature201℃. Collector air drying performance parameters are0.3℃m2/W. In the heat collector box, flow field distribution is uniform. In the heating box temperature and air flow distribution is uniform. A high numerical regional does not appear. The collector has reasonable structure.(4) The collector of fixed and single axis tracking is analyzed array arrangement. Optimal array collector distance is calculated. The theoretical design calculation formula is established. Provide a method to calculate the array to the collector in the practical engineering application and design(5) Through the construction of transmission type solar drying bale characteristics test equipment, the drying characteristics of bale was done. The test results show it have a great relationship between distribution of surface temperature distribution inside alfalfa bale and drying air flow. But also distribution changes in moisture content and drying air flow has a very close relationship. Drying is non-uniform in the bale internal. The performance test on the drying equipment show grass wet harvest technology can reduce the loss of dry matter nearly30%. Effective nutrient content of forage such as crude protein, crude fat is saved and preserved rate increased from50%to90%.