红外辐射干燥谷物研究的进展

红外辐射干燥技术有众多的优点，在谷物干燥中的研究应用日益受到重视。介绍了红外辐射干燥谷物的研究进展情况，提出了研究方向。     

混流式粮食干燥机性能的模拟和参数分析

在中国农业大学的谷物干燥研究领域中，重点是数学模型和计算机模拟。从1985年至今，顺流式、逆流式、横流式以及混流式谷物干燥机的研究已经取得了成功。分析和讨论了空气温度、流速、风道中的风道尺寸对混流谷物干燥机的影响。发展了混流干燥机的模拟程序，着重提出了混流谷物干燥机中风道的设计，给出了最佳参数。     

谷物干燥品质的研究

谷物在干燥过程会出现不同程度的品质损伤。对谷物品质的影响因素主要有热风温度、干燥时间及风速。通过实验研究和大量的实际应用,总结出了从干燥工艺和结构方面改善谷物干燥品质的方法。     

红外干燥谷物机理分析

分析了小麦、玉米和水稻的红外吸收光谱，阐述了红外辐射干燥谷物的机理，并从原理上分析了红外干燥谷物的优势。     

新书介绍

《现代干燥技术》《现代干燥技术》由潘永康、王喜忠主编。该书是一本全面介绍干燥技术的工具书类专著。全书共有4篇47章：第1篇介绍干燥过程的计算方法、干燥的试验技术和测量方法；第2篇介绍各种干燥方法和干燥器，其中既介绍了隧道、厢式、带式、流化床、喷雾等传统型干燥器，也介绍了太阳能、冷冻、红外、微波、过热蒸汽等利用各种能源的干燥方法，对于近年来新发展的冲击流、对撞流干燥技术及声波、吸附、超临界流干燥等多种新型方法和干燥器也作了介绍；第3篇介绍了食品、水果、蔬菜、谷物、茶叶、中药饮片、药物、生物制品、乳品、染…     

辐射器辐射特性与谷物吸收特性研究

本文通过对辐射器辐射特性与谷物吸收特性的研究,为谷物辐射干燥系统参数的选择提供理论依据。根据辐射干燥理论,研究了不同辐射材料的辐射特性及不同条件下的辐射器强度特性;分析了不同谷物的吸收光谱,并对谷物辐射穿透性进行了研究。得出了辐射器辐射特性与谷物吸收特性之间的最佳匹配关系。     

《现代干燥技术》

《现代干燥技术》由潘永康、王喜忠主编。该书是一本全面介绍干燥技术的工具书类专著。全书共有４篇４７章；第１篇介绍干燥过程的计算方法、干燥的试验技术和测量方法；第２篇介绍各种干燥方法和干燥器，其中既介绍了隧道、厢式、带式。流化床、喷雾等传统型干燥器，也介绍了太阳能、冷冻、红外、微波、过热蒸汽等利用各种能源的干燥方法，对于近年来新发展的冲击流、对撞流干燥技术及声波、吸附、超临界流干燥等多种新型方法和干燥器也作了介绍；第３篇介绍了食品、水果、蔬菜、谷物、茶叶、中药饮片、药物、生物制品、乳品、染料、纤维物…     

谷物干燥工艺、设备现状及入世后的应对措施

分析了当前国内外谷物干燥工艺、设备研究和应用现状。谷物干燥是当前我国农业生产中的一个薄弱环节，与发达国家差距很大。存在的机械化干燥率低，干燥机普及率低的问题很突出，直接影响了我国谷物生产的效益和国际竞争力。针对这种状况提出了应对入世后谷物生产和经营面临挑战的措施。     

谷物干燥企业工艺优选模糊综合评价

我国现有谷物干燥工艺种类多，工艺性、经济性等指标繁杂，企业不容易选择。针对这一问题，运用多级模糊综合评价方法，对实际生产中有代表性的谷物干燥工艺进行综合评价，使得对工艺方案的评价具有准确性和客观性。通过建立数学模型，经过分析计算，结论基本合理，且本方法简单实用，为企业选择优良的生产工艺提供了理论依据。     

玉米低温真空干燥新技术研究与开发初探

通过实验探讨了玉米在真空低温条件下干燥的可能性，对真空干燥方法应用于谷物作了简单说明。     

Simulation of Grain Drying in Natural Convection Dryer

All the works so far on simulation of grain drying by natural convection of air presents conflicting reslts on the drying time forecast. In this work the models of Hukill, Thompson and Michigan are tested in same type of dryer. Appropriate equations are developed to correct the drying time, starting form the models of Thompson and Hukill. The solution of the equations of michigan model is developed on fintie difference and similarly and some speical technuques are utilized on the Thompson model. 53 test results are utilzed here to validate the simulation model of drying.     

微波干燥玉米籽粒的试验研究

针对玉米热风干燥中存在的问题。运用自制的微波干燥试验设备。采用不同的质量比功率和加热时间及配套的工艺流程。研究了玉米微波干燥特性及干燥条件对干燥品质、能耗的影响；分析了微渡干燥玉米过程中单位质量功耗、温度、平均失水速率与玉米籽粒发芽率、爆腰率和淀粉得率的关系；确定了影响微波干燥玉米的工艺参数和玉米微波干燥的合理工艺流程。研究结果表明：玉米微波干燥主要处于恒率干燥阶段，应用微波技术既能快速而经济地对玉米籽粒进行干燥，又能保持其种用价值，且有利于改善其品质。     

MATHEMATICAL SIMULATION OF TEMPERATURE AND MOISTURE FIELDS WITHIN A GRAIN KERNEL DURING DRYING

ABSTRACT

Non-linear partial differential equations are presented for two dimensional heat and mass transfer within a single grain kernel during drying. In this model, the moisture evaporation inside the kernel is considered. The moisture is assumed to diffuse to the outer boundary of the kernel in liquid form and evaporate on the surface of the kernel. The influence of temperature and moisture content on grain properties is also considered in the simulation. The Non-linear partial differential equations are solved using the finite element method and simulation data is verified on a thin layer dryer for wheat kernels. The comparison shows that the simulated results have a high accuracy with average relative error of about 5%. The results of the finite element analysis can be used for grain quality evaluation, drying simulation studies and stress analysis of grain kernel.     

THIN LAYER AND DEEP BED DRYING OF LONG GRAIN ROUGH RICE

ABSTRACT

The paper presents new data for thin-layer drying characteristics of Thai long grain rough rice measured under various conditions of drying air temperature (35 to 60?°C), drying air relative humidity (30 to 70 % ) and the initial moisture content of rough rice (20 to 40 % dry basis). Empirical equations were developed using the instantaneous weight, the weight loss and drying time, with temperature, relative humidity and initial moisture content of rough rice as the independent variables. A computer program was developed to simulate the deep-bed drying process. The thin-layer drying equation developed before was used in the computer simulation. Experimental data from the fixed bed dryer were compared with the results from the calculation.     

SIMULATION OF THE HEAT AND MOISTURE TRANSFER PROCESS DURING DRYING IN DEEP GRAIN BEDS

ABSTRACT

Grain drying is a simultaneous heat and moisture transfer problem. The modelling of such a problem is of significance in understanding and controlling the drying process. In the present study, a mathematical model for coupled heat and moisture transfer problem is presented. The model consists of four partial differential equations for mass balance, heat balance, heat transfer and drying rate. A simple finite difference method is used to solve the equations. The method shows good flexibility in choosing time and space steps which enable the simulation of long term grain drying/cooling processes. A deep barley bed is used as an example of grain beds in the current simulation. The results are verified against experimental data taken from literature. The analysis of the effects of operating conditions on the temperature and moisture content within the bed is also carried out     

Performance of Single and Multi-stage Spouted Bed Drying Systems

ABSTRACT

A mathematical model is developed to predict the performance of single-stage and multi-stage drying systems using spouted beds. The model uses unsteady state analysis for batch operation to simulate the steady state operation of a continuously fed spouted bed. A parametric study is carried out to study the effect of the following parameters on the performance of a single-stage grain drying system: air flow rate per unit mass of the grain in the bed, ambient air temperature and humidity, initial and target moisture contents, the residence time in the bed, and the effectiveness of the heat exchanger to recover the thermal energy in the exhaust air. The parametric study is also extended to investigate the effect of these parameters (except ambient air temperature and humidity) on the performance of the multi-stage system. In addition, the number of stages is also included in the latter study. The results are presented in terms of charts which may be adopted for the design of such systems.     

DESICCANT GRAIN APPLIED TO THE STORAGE OF SOLAR DRYING POTENTIAL

Sorption storage of solar heat using a layer of wheat as the desiccant was analyzed by means of a deep-bed drying model. Intended to be applied to solar-assisted in-storage drying of agricultural bulk materials, the probability of the persistence of unfavorable weather periods was quantified statistically for Potsdam for the month of August, as an example. Simulation results demonstrate that a relative humidity of the drying air of 65 % can be maintained day and night for weeks without combustion of fossil fuels. Using a simple strategy of control, periods with insufficient solar radiation can be bridged over. The desiccant grain is not endangered by mold growth as a matter of principle. Simple solar air heaters can be used to avoid economic losses due to overdrying and to reduce the danger of decay to a minimum even at unfavorable climatic conditions.     

DESICCANT GRAIN APPLIED TO THE STORAGE OF SOLAR DRYING POTENTIAL

ABSTRACT

Sorption storage of solar heat using a layer of wheat as the desiccant was analyzed by means of a deep-bed drying model. Intended to be applied to solar-assisted in-storage drying of agricultural bulk materials, the probability of the persistence of unfavorable weather periods was quantified statistically for Potsdam for the month of August, as an example. Simulation results demonstrate that a relative humidity of the drying air of 65 % can be maintained day and night for weeks without combustion of fossil fuels. Using a simple strategy of control, periods with insufficient solar radiation can be bridged over. The desiccant grain is not endangered by mold growth as a matter of principle. Simple solar air heaters can be used to avoid economic losses due to overdrying and to reduce the danger of decay to a minimum even at unfavorable climatic conditions.