Design And Performance Optimization Of Heat Pump Drying System

At present,coal is still widely used in China to bake tobacco leaves,which not only causes pollution to the environment,but also wastes a lot of energy.As an environmentally friendly technology,heat pump technology has low operating energy consumption and high energy efficiency,but there are relatively few examples in the field of tobacco leaf baking.How to link heat pump technology to specific drying object characteristics remains to be studied.This article conducts research on the application of heat pump technology in tobacco leaf baking,in order to improve the adaptability of the heat pump drying system to the tobacco leaf baking process and save the energy consumption of baking.First,according to the tobacco leaf baking process,a composite heat pump drying system is established,and the system is divided into three operating modes: a large dehumidification phase,a stable drying phase,and a temperature drying phase.At the same time,three common heat pump working fluids are analyzed for typical working conditions and variable working conditions,and the best working fluid is selected from the aspects of condensing pressure,exhaust temperature,system COP,compression ratio,and heating capacity per unit volume.Secondly,in order to further study the performance of the compound heat pump baking room,compare it with a baking room that has been put into use,CYCLEPAD and DEST software are used to establish a thermodynamic model and a building model,and the thermodynamic performance,operating energy consumption and load of the system are analyzed.Compared with a baking room that has actually been put into use,the COP of the composite heat pump baking room system has increased by 8.77% on average,the average baking heat load has been reduced by 13.04%,and the average energy consumption has been saved by 14.64%.The difference between the average water lossrate of the two types of flue-cured tobacco leaves is about 4.22%,which indicates that the system does not affect the tobacco leaf curing process,thereby ensuring the quality of the tobacco leaf produced in a tobacco leaf curing cycle.In addition,through the analysis of the operation modes of the two heat pump drying systems,using two sets of heat pump units to alternately operate can not only meet the peak heat load of the drying,but also effectively reduce the operating energy consumption and prevent the heat pump units from running continuously for a long time,thereby increasing the unit's service life and reduce the unit failure rate.The research results in this paper provide a certain technical reference for the application of heat pump technology in flue-cured tobacco industry.