Model And Experimental Study On Heat Transfer Of Resistive Heating Elements For Heating Cigarettes

With the acceleration of the global tobacco control movement,the tobacco industry has entered a new era of demand change and technological innovation,which has promoted the research and development of new tobacco products(heated nonburning cigarettes,e-cigarettes,oral cigarettes,etc.).Heated non-burning cigarettes not only contain tobacco ingredients to meet the needs of consumers to some extent,but also have the advantages of reducing tar and harm,and quickly become a research hotspot in the field of tobacco products at home and abroad.The heating cigarette consists of cigarette and heating device.The heating cigarette is made up of two parts of cigarette and heating device.Through controlling the temperature of heating element,the release,thermal degradation and evaporation of volatile organic compounds in tobacco can be controlled to product stable and controllable aerosol.Among them,the heating element as the heat source of the heating cigarette,the level of its performance plays a decisive role in the quality of the heating cigarette.Therefore,heating element and temperature control technology are the core of heating device design.In order to improve the performance of the heating device,this paper studies the temperature field distribution of the heating element and temperature control technology by combining theoretical analysis with experiment.The main research work is as follows:(1)Aiming at the problems of uneven heating and poor product consistency of domestic heating elements,the numerical simulation model of heating elements is constructed,and the material and structure of heating elements are simulated and analyzed,which provides a theoretical basis for the development and quality improvement of heating elements.Firstly,the heat transfer process and heat transfer mechanism of heating element are analyzed systematically from the generation and transfer mode of heat.Secondly,according to the coupling relationship between the physical fields,the control equations and boundary conditions of the simulation model are determined,and the mesh generation of the finite element simulation model is completed.Finally,the heating elements with different base materials,heating pastes and wiring forms are simulated and analyzed.According to the results of comparative analysis,the materials and structures with excellent performance are selected.A heating element with alumina ceramic as base material,platinum based resistance paste as conductive track,silver-palladium conductive paste as pad and metal silver as pin was designed.(2)A control strategy of high voltage constant voltage source preheating and low voltage constant voltage source constant temperature is proposed.The simulation and analysis of the control process are completed based on Ni Multisim software,which provides a new idea for the temperature control of heated cigarettes.Through the experimental research and analysis,the basic physical parameters of the heating element are obtained and analyzed,and the key parameters of the temperature control system are determined according to the temperature control requirements of the heating cigarette.According to the temperature control strategy of the heated cigarette,the temperature control circuit is designed by using the circuit simulation software.(3)The experimental platform was built to verify the performance of heating elements and control system.Based on the above numerical simulation model of the heating element,the three-dimensional model of the heating element under the condition of thermal electrical coupling is established by using the multi physical field finite element simulation software COMSOL multiphysics.The temperature variation of the heating element under different working conditions is obtained.The model can simulate the whole working process of the heating element and meet the control requirements.The simulation data are compared with the experimental data: In the preheating mode,the maximum error between the simulated value and the experimental value is 4.8%;under the constant temperature mode,the maximum error between the simulation value and the experimental value is 7.1%,and the results are in good agreement,and the error is within the acceptable range,which verifies the effectiveness of the model and simulation method.In this paper,the research and development of heating elements and temperature control technology in heating cigarettes are two major problems.The numerical simulation model of heating element is established,the temperature control circuit is designed,and the experimental platform is built for performance verification.The purpose of this paper is to provide technical support for the research and development of heating elements and further improve the overall performance of heating cigarette heating device.