| The mash entering the cellar is an important process for liquor brewing,and the temperature and moisture of the mash are i mportant indicators that affect the fermentation quality of the mash.In the interval of two consecutive times of entering the cellar,the mash is affected by the temperature and humidity changes in the surrounding environment of the pit pool and the physi cal properties of the mash,causing the heat and moisture transfer phenomenon of the mash.In this paper,a multi-field coupling model of mash entering the cellar in hot season is established according to the law of heat and moisture transfer of mash.The finite element method is used to numerically solve the model,and the temperature and humidity controllable experiment platform is built to study the combination of theory and experiment.The temperature and humidity changes in the time interval of two consecutive times of entering the cellar of the fermented glutinous rice were compared and analyzed the simulation and experimental results,and the model was optimized.Based on the simulation results,this paper predicts the time and location of condensation,and formulates corresponding anti-condensation methods,and finally verifies the effectiveness of the anti-condensation methods through experiments.The main research work of this paper is as follows:(1)Taking the mash as the research object,the macr o-level method is used to analyze the existence mode and transfer mechanism of the moisture and heat in the mash,and the determination conditions for the mash condensation are established according to the condensation mechanism of the mash.Study the theo retical basis and process of the finite element method to solve the multi-field coupling problem,and introduce the COMSOL numerical simulation software.(2)Using the multi-field coupling theory method,the mathematical model of the multi-field coupling of the mash was established by studying the damp and heat transfer mechanism of the mash,and the numerical simulation of the anti-condensation of the mash was carried out.The physical properties of the mash are measured by physical experiment methods as the initial conditions of the model,and the temperature and humidity changes in the pit environment in the hot season are used as the boundary conditions for the simulation.The internal moisture-heat coupling law of the mash is simulated in the COMSOL numerical simulation software.(3)The temperature and humidity controllable experimental platform was designed and built,and the control system of the experimental platform was tested for uniformity,accuracy and error.Based on the experimental platform,the multi-field coupling model experiment of fermented wine was verified,and the mathematical model of multi-field coupling of fermented wine was optimized.Numerical simulation and actual measurement results show that the temperature and humidity of the upper mash is greatly affected by the environment of the pit during two consecutive times of entering the cellar.The temperature and humidity inside the mash varies slowly.The temperature and humidity field and the micro air flow field inside the mash An d there is obvious stratification.(4)According to the simulation results of the model,an anti-condensation method is formulated.The effectiveness of the anti-condensation method is verified by a combination of experimental means and simulation.The res ults show that: controlling the ambient temperature of the pit,the permeability of the mash,and the anti-condensation blocking material are beneficial to eliminate or delay the condensation of the mash.Provides guiding opinions for practical production.Based on the mechanism of humidity and heat transfer in fermented grains,this thesis verified the practicability and accuracy of the model by combining theory and experiment,which could effectively predict the time and location of condensation in fermented grains,and developed corresponding methods to prevent condensation in fermented grains. |
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