| The open moisture excluding method is adopted in current bulk curing barn in China,and a large number of aroma components.etc of tobacco leaves are directly discharged from the excluding outlet,which leads to the quality reduction of baking tobacco leaves.Besides,a large loss of residual heat of the dehumidification airflow is brought about by the open type of dehumidification,which is discharged to the external environment and polluted the environment.Basing on this background,in order to explore the baking equipment with high quality and efficiency,high efficiency,energy saving and its dehumidification performance,this paper establishes a heat pump dehumidification system for closed hot air circulation bulk curing barn.By means of theoretical analysis,numerical simulation and experimental research,the feasibility of applying heat pump dehumidification technology for the dehumidification and recycling of bulk curing barn is analyzed.It also provides alternative and experimental fundamental for the upgrading of traditional bulk curing barn.This paper combines the existing barn structure form and tobacco leaf baking,and compares the advantages and disadvantages of several existing dehumidification methods,and draws the advantages of heat pump dehumidification technology,which is more suitable for dehumidification recycling of bulk curing barn and heat pump dehumidification drying technology.Theoretical analysis was carried out to investigate the form of the heat pump dehumidification system in the closed-type hot air circulation bulk barn.The system can retain the aroma substances in the moisture exhaust stream,and reduce the pollution to the environment.The temperature of the airflow after dehumidification is higher than the temperature of the open exhaust air inlet air,which plays the role of waste heat recovery and utilization.According to the relevant parameters of the primary heat pump dehumidification equipment,the physical model is established by Gambit,FLUENT is used for numerical simulation,Simulated cloud image is post-processed by Origin,and the dehumidification amount and the relevant parameters of the evaporator inlet and outlet under various working conditions of the heat pump dehumidification systemare simulated and calculated.And analyze the distribution law of the flow field in the evaporator.The results showed that the maximum simulated dehumidification amount was 26.32kg/h during the baking process of tobacco leaves,which could meet the requirements of dehumidification in the baking of bulk curing barn tobacco leaves,and the system dehumidification performance was good.Through experimental research,comparing and analyzing the consistency between the test results and the simulation results.The results show that the overall trend of experimental dehumidification under quasi-steady state condition is the same as that under simulated condition,and the relative error is less than 10%.The maximum experimental dehumidification under quasi-steady state condition is 26.56kg/h.The maximum sensible heat efficiency and latent heat efficiency are 79.14% and45.54% respectively,and the moisture evolution coefficient is about 2.06~2.31.The overall heat transfer performance of the system is good.By comparing and analyzing the baking effect of the closed-type hot air circulation heat pump dehumidification type bulk curing barn and the biomass type bulk curing barn,the dynamic investment payback period and net present value of the heat pump dehumidification system were calculated to evaluate the economic benefits.The results show that the closed-type hot air circulation heat pump dehumidification type bulk curing barn is superior to the biomass-type dense barn in terms of baking cost,energy consumption,appearance quality of dried tobacco leaves after baking,main chemical composition,sucking result and grade structure.And the dynamic investment payback period is only 4.3years,and the economic benefits are significantly improved. |
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