【作者】 李阳；

【导师】 巩桂芬；

【作者基本信息】 陕西科技大学 ， 机械设计及理论， 2017， 硕士

【摘要】 传统干燥技术方式单一、效率低、能耗高,已经不能很好地满足现代社会生产的需求。近年来新兴的组合干燥技术将多种干燥方式分阶段结合起来,实现优势互补,使得干燥过程更加科学、更加高效和节能,因此受到了行业内学者和企业工作人员的广泛关注。果蔬热风真空组合干燥便是其中一种,它将热风干燥和真空干燥结合在一起,首先利用热风干燥去除果蔬中大量的自由水,然后利用真空干燥去除结合水,这样在提高干燥效率和节约能源的同时,也改善了成品的品质。尽管国内一些科研院校已经初步开发出了热风真空组合干燥装置,但都只是创造性地实现了热风干燥和真空干燥过程在同一台装置内部的完成,装置本身的能耗问题、操作条件的可控性问题以及在线监测和自动化控制等问题亟需解决,因此设计一套精密先进的试验装置对于这项技术的理论研究和产业推广尤为重要。基于上述原因,本硕士论文在陕西省科技厅工业攻关项目“热风真空组合干燥装置的设计研究(2014K07-19)”的资助下,利用实验室现有的中试装置进行试验研究和分析,总结现有装置的不足,进一步设计更加完善的热风真空组合干燥装置,具体研究内容如下:(1)干燥试验研究以柠檬、卷心菜等原材料为试验对象,分别进行单因素试验和正交试验研究,优化出各试验对象的最佳热风真空组合干燥工艺参数,为后续装置和自动化控制系统的设计提供理论和技术支持,同时在试验过程中分析总结现有中试装置存在的问题。(2)干燥装置设计针对试验过程中发现的问题设计新的干燥箱,以Solid Works为工具建立其三维模型,并用ANSYS Workbench对其进行CFD数值模拟,以验证所设计干燥箱的可行性。通过能量计算对装置太阳能系统的水箱和集热器重新进行计算选型,提高装置对太阳能的利用率。(3)干燥装置的控制系统设计结合试验过程添加相应的自动检测仪表,并以西门子S7-200 PLC控制器为硬件主体,MicroWIN为软件开发工具,开发装置的控制系统,改善试验过程的可视化操作问题,使新装置可以在线监测试验数据,减少试验过程的操作误差,为热风真空组合干燥试验研究提供更加精密的硬件平台。本硕士论文通过试验研究,优化出了柠檬、卷心菜等果蔬的最佳热风真空组合干燥工艺参数,并将其内嵌在设计的控制系统中;针对试验所反映出的装置问题,设计了旋转物料盘、锥形布风管、螺旋热水盘管等部件的结构,用Solid Works建立了干燥箱的三维模型,CFD数值模拟结果表明了设计的方案可行;通过计算将太阳能系统的水箱容量改为1m3,平板式集热器改用35支Φ58×1800 mm的全玻璃真空管式集热器代替;在原系统的基础之上添加了红外水分传感仪、上位机电脑、西门子S7-200 PLC等硬件,并以MicroWIN为软件开发平台,开发出了装置的控制系统。更多还原

【Abstract】 Traditional drying technology is unable to meet the needs of modern social production due to its simple way,low efficiency and high energy consumption.In recent years,the emerging combination drying technology has been widely concerned by scholars and business staff in the drying field,its drying process is more scientific,efficient and more energy saving.As one of them,hot-air vacuum combination drying not only accelerates the drying efficiency,saves energy,but also improves the quality of the products.It uses hot air drying to remove free water and vacuum drying to remove the bound water in fruits and vegetables.Although some domestic research institutions have developed equipment for hot-air vacuum combination drying,it’s just a simple realization of hot air drying and vacuum drying in the same equipment.The energy consumption of the equipment itself,the controllability of operating condition,the problems of on-line monitoring and automation are urgent to be solved.So to design a sophisticated and advanced test equipment is very significant for theory research and industry promotion of this technology.This thesis does experimental study,summarizes deficiency of the equipment and optimizes the equipment by using the test data.The thesis is with support of industrial project which is named "design and study of equipment for hot-air vacuum combination drying(2014K07-19)",and which is approved by Shaanxi province science and technology department.The specific contents are as follows:(1)Experimental studyThe optimum parameters of hot-air vacuum combination drying process for lemon and cabbage etc are optimized by single factor test and orthogonal test,it provids theoretical and technical support for the subsequent design of equipment.Meanwhile,problems existed in the pilot-pant are analyzed and summarized.(2)Drying equipment designDesign a new drying box respect to problems found in the process and establish its three-dimensional model by Solid Works,then use ANSYS Workbench CFD numerical simulation to verify the feasibility of the box.In order to improve the utilization rate of solar energy,the energy calculation is used to calculate the water tank and collector of solar energy system.(3)Design of control systemAdd the corresponding automatic detection instruments according to the test process and design control system using the SIEMENS S7-200 PLC controller as the main hardware,MicroWIN as software development tool.To solve the visual operation problem during drying process,make the new equipment can monitoring test data on-line,reduce the operation errors in the process,provid a more sophisticated hardware platform for the hot-air vacuum combination drying.In this master’s thesis,the best combination drying process parameters of lemon,cabbage etc are optimized and embedded in the designed automatic control system.The structure of the rotating material tray,conical air duct and spiral hot water coil are designed according to the problems reflected in the test and establish the three-dimensional model with SolidWorks.The result of CFD numerical simulation shows that the design scheme is feasible.The flat plate heat collector of solar system is replaced by 35 Phi 58×1800 mm all glass vacuum tube collector and water ank capacity is changed to 1m3 by calculation.The infrared moisture sensor,PC,SIEMENS S7-200 PLC and other hardware are added to the original system,and the control system is designed by using MicroWIN as the software development tool.更多还原