Study On Drying Process And Application Optimization Of Alfalfa

For the drying temperature,the relative humidity of hot air and the wind speed,the experimental research on the drying characteristics of alfalfa by hot air and the nutritional quality of alfalfa hay was carried out in the laboratory.Under the conditions that the drying temperature is60 ℃～90 ℃,the relative humidity of hot air is 20%～35%,and the speed of hot air is 2 m/s～5 m/s,the time required for alfalfa to dry to safe water content increases with the increase of drying temperature.It decreases with the increase of the drying wind speed,and increases first and then decreases with the increase of the relative humidity of the hot air.When the drying temperature is 90°C,the whole drying process is reduced speed drying.The color difference of alfalfa leaves before and after drying increased with the increase of hot air temperature,the decrease of relative humidity and the decrease of wind speed.The soluble protein content of alfalfa decreased with the increase of hot air temperature and relative humidity,and first increased and then decreased with the increase of drying wind speed.Using the experimental data,10 common drying kinetic models were fitted and compared,and it was found that the Logarithmic model was the best drying kinetic model for analyzing the changing law of water ratio during hot air drying of alfalfa.The orthogonal experiment range method was used to analyze the effects of drying temperature,relative humidity of hot air and air speed on the time required for drying alfalfa to safe water content,the color difference of alfalfa leaves before and after drying,and the content of soluble protein.Using the response surface method,single-objective and multi-objective optimizations were carried out on the time required to dry alfalfa to safe water content,the color difference of alfalfa leaves before and after drying,and the content of soluble protein,and the drying process parameters corresponding to the highest comprehensive evaluation of alfalfa hay were obtained.In Sunan Yugu Autonomous County,Gansu Province,the three-yearold alfalfa was evaluated with nutritional indicators such as effective crude protein content,total digestible nutrients,fiber digestion rate within 30 hours,and in vitro dry matter digestibility within 30 hours.The nutritional quality characteristics of different parts of alfalfa and the effect of different flowering,harvesting time and stubble on the nutritional quality characteristics of alfalfa hay were studied.It was found that the nutritional quality of alfalfa in the budding stage was higher than that in the early and full flowering stages.Compared with stems,alfalfa leaves at the budding stage had higher nutritional quality.Compared with the alfalfa harvested in the first crop,the alfalfa harvested in the second crop had higher effective crude protein and total digestible nutrients at the budding stage,early flowering stage and full flowering stage,but the fiber digestion rate within30 h was slightly lower.An experimental study was carried out on the intubation hot air alfalfa drying device.In order to solve the problems found in the process of experimental research,a numerical model of the intubation bale drying system was constructed,and the established model was verified with the experimental results.On the basis of verifying the correctness of the established numerical model,the optimization study of the opening size of the insertion tube was carried out.