Analysis And Experimental Study On Oscillation Drying Process Of Biomass

As a kind of clean and renewable energy, the fact that biomass energy plays an important role in the whole energy system has attracted the attention of the world. However, before biomass energy utilization, drying of biomass must be done. It is a complex process by coupling heat and mass transfer, and along with the internal moisture phase transition. Different drying process will lead to different drying rates, drying energy consumption and dried product quality. Compared with general drying process, oscillation drying has the advantages of high efficiency and energy saving potential. In this paper, the oscillation drying process of biomass is respectively analyzed by numerical simulation and experimental research.Firstly, for the single particle potatoes, a mathematic model based on non-equilibrium thermodynamics theory was established to describe the heat and mass transfer in the drying process of potato granules. Fortran program was compiled to solve the discrete equations, so we obtained the numerical solution of drying process. According to the calculated results of radial distribution of temperature and humidity, the mechanism of oscillation drying was analyzed. It is also obtained that when the cycle of high and low temperature oscillation is fixed a value, the rate of entire process is largest, and energy saving. Great amplitude of oscillation will lead to consume low energy consumpution to reach well wet removal effect in the low temperature section, but it should not be too large. On-off ratio has an optimal value.Then, a test system for biomass oscillation that has high precision control of the drying medium moisture content, flow rate, high and low temperature of inlet air temperature, on-off ratio was designed and constructed.Finally, the drying model of potato slices was verified reasonable by using the drying experimental system. Under the same condition, rice husk was dried by constant temperature and oscillation situation, respectively. And it was found that oscillation drying had the advantages of efficiency, energy saving potential. On this basis, considering the drying rate and drying energy consumption at the same time, the influence of single factor on the drying characteristics of rice husk oscillation drying was studied. The result shows that the drying medium moisture content and flow rate have obvious effect on early drying process, but almost no effect on the later. High temperature of oscillation section should be as high as possible, and low temperature section is neither too high nor too low,10～15℃ higher than ambient temperature is optimum, on-off ratio should be set greater than 1, and the concrete optimal value set should be comprehensively considered.So, under the external condition control section, constant temperature drying is dominant. But oscillation drying is dominant in internal resistance control section, it can consume lower energy consumption to achieve higher drying rate and more thorough drying effect. In this paper, the numerical and experimental results can provide relevant references for the design of drying device.