试验型太阳能锯材干燥窑的计算机控制系统

本文讨论试验型高效太阳能干燥窑采用微机控制系统和探讨利用太阳能干燥的优点.控制系统主要包括个人计算机和一个数据采集装置,执行大量的测量和控制功能.监测的干燥变量有木材含水率、收集器温度、干燥窑温度和相对湿度.记录放在地磅上3.2m3的木材堆垛的重量以监测含水率.木材湿度和平衡温度的连续监测采用控制系统,使它在太阳能干燥运转过程中达到两个测量干燥变量(干燥梯度)的目标值.开发该控制系统与相似的太阳能干燥窑的半自动系统控制相比较.     

Computerised data-acquisition and control system for an experimental pressure steam dryer for lumber

The microcomputer based data-acquisition and control system employed in an experimental pressure steam drying kiln and the advantages of using this approach in wood drying research are discussed. The tasks of the system include measuring all relevant parameters, performing real-time control and storage onto magnetic media.     

Experimental pressure steam dryer for lumber

This article describes the design and construction of an experimental kiln suitable for operation at pressure steam drying conditions of temperatures up to 130°C, pressures up to 300 kPa and air velocities up to 10 m·s^?1. The kiln could also be utilized for low, medium and high temperature convective wood drying at atmospheric pressure. It is, therefore, extremely suitable for the determination of the basic drying behaviour of wood under various combinations of temperature/pressure/air velocity, using full-sized sample boards of 2.1 m length.     

粮食烘干机温度控制系统的设计

设计一套粮食烘干机温度控制系统,以粮食烘干机水分测量系统为前置,用于谷物类粮食烘干过程中的变温控制.温度控制核心为STM32F103C8T6单片机,依靠步进电机驱动单元对可控硅调压器完成功率控制.绘制出PCB(Printed Circuit Board)板的布局布线,完成控制系统制作并进行联调测试.基于粮食烘干机水分测...     

Performance of a solar-heated,forced-air,fully automated lumber dryer

A 3.5 m³, external collector type kiln has been designed and constructed to dry green lumber to M.C. low enough for use in furniture. The kiln uses a hot air transfer-circulation system and its ratio of collector area to lumber capacity is 2.9 m²/m³. The kiln is equipped with a fully automated supervisor system. The energy efficiency and performance of the solar kiln have been evaluated through a series of operational tests. The solar collectors operate at 71 to 75% efficiency, while the drying chamber at an efficiency of 46%. The kiln has been found able to use 33% of the available solar energy for lumber drying, Control system has been proved able to run the process to the drying gradient required by any given species of wood. The performance of the dryer, evaluated by direct comparison with air drying, is satisfactory in respect of the final moisture content and drying time. A final M.C. of 10% was attainable at all times of the year.     

真空冷冻干燥在线测试系统设计与测试

为获得真空冷冻干燥过程的含水率与温度实时数据,监控干燥过程,提出了一种新型真空冷冻干燥在线测试系统并开展了试验测试。该系统由单片机、应变式压力传感器、热电阻、模数转换模块、OLED屏等部件组成,采用无线数据传输,设计中进行了温度修正与减振设计。试验测试表明,该系统可用于真空冷冻干燥过程中质量、含水率、温度的实时测量,且质量在5～50g范围内,测量值与实际值的相对偏差为-1.6%～2.7%,在-40～40℃范围内温度测量偏差在±3%以内,具有较好的精度。     

Mathematical modeling and computational fluid dynamics simulation of cabinet type solar dryer: Optimal temperature control

The mathematical model for determination of auxiliary energy required to maintain set air temperature in the drying chamber is proposed for cabinet type solar dryer. The model is developed considering the heat exchanges across the dryer control volume with solar radiation intensity and set temperature as input. The sole purpose is to minimize the auxiliaries. The computational fluid dynamics (CFD) technique is used to simulate the air flow inside the drying chamber for different operating conditions. The simulations results for the temperature are very close to the results from mathematical model. The dryer configuration discussed in illustrative example found to have minimum auxiliary consumption at 45°C with total auxiliary expense of 97.3 kWh per day. When applied to full calendar year, the optimum temperature is found to be function of ambient temperature and solar radiation intensity. The results obtained from mathematical model are found to be in well agreement with simulation results. The simulation results provide a region with 1.2 m to 1.6 m on X-ordinate, 0.8 m to 1.0 m on Y-ordinate and 0.7 m to 1.2 m and 3.7 m to 4.3 m on Z-ordinate where average temperature can be sensed. It helps in modulating the auxiliary input/s in integration with solar heat.     

无核紫葡萄太阳能干燥技术的研究

采用一种空气集热器-温室型太阳能干燥装置,在新疆石河子市的气候条件下验证了无核紫葡萄太阳能干燥的可行性,从2007年8月到10月间,进行了一系列的试验.试验表明:与自然晾晒相比,太阳能干燥周期缩短为原来1/3的时间,干燥质量也有大幅度的提高.     

实验型气流干燥机的应用评价

为减小卷烟产品研发成本,缩短研发周期,研制出实验型气流干燥机,并将其与500,5 000kg/h的HDT气流干燥机进行对比研究,以考察气流干燥机在卷烟产品生产中的尺寸放大效应。结果表明:实验型气流干燥机在固定气流速度时,气流温度与出口烟丝水分的关系可以用简化后的菲克第二定律的解析解方程来表达;气流干燥机设备尺寸越大,气流比越大,干燥气流温度越低,出口水分越稳定;为保持产品质量的一致,在应用实验型气流干燥机、500kg/h的HDT气流干燥机、5 000kg/h的HDT气流干燥机时气流温度应逐次降低。     

新型太阳能干燥装置在枸杞烘干中的应用

本文简要地介绍一种新型太阳能枸杞干燥装置结构形式。通过太阳能热利用原理计算推导出在太阳能集热器上的辐射强度,根据经验公式算出所需的集热器有效面积,通过实测得出每千斤枸杞所配置最佳面积。     

Effectiveness of the solar biomass hybrid dryer for drying and disinfestation of maize

The Solar Biomass Hybrid Dryer (SBHD) is a new technology developed in Ghana for grain drying and utilizes biomass (agro-residues, timber scraps, etc.) along with solar drying, and is especially useful for drying during rainy periods of the year when solar drying cannot be relied on. This study assessed the effectiveness of a 5.0-MT SBHD comprising a solar tent and a furnace for thermal drying and disinfestation of maize. Mortalities of adults of Sitophilus zeamais (Motschulsky), Tribolium castaneum (Herbst) and Cryptolestes ferrugineus Stephens were assessed. Additionally, mortalities of immatures of these three species were assessed. Internal and cage temperatures (°C) in the SBHD, sun drying (SD) and laboratory (control) were monitored, as were moisture content (MC) and thermally (stress) damaged kernels (TDK) (%). During the 7-h experiment, mean internal temperatures in the SBHD, SD and laboratory were 52.3 ± 1.0 °C, 41.4 ± 0.8 °C and 30.3 ± 0.2 °C, respectively. Similarly, temperatures in cages in the SBHD (49.5 ± 1.0 °C) were higher than those for cages in the laboratory (29.9 ± 0.2 °C) and SD (38.2 ± 0.6 °C). Reduction in the moisture content of maize dried using SBHD, SD and under laboratory conditions were 7.7, 5.2 and 2.9%, respectively. This corresponded to grain MC reduction rates of 1.1%, 0.74% and 0.4% per hour. There was 100% mortality of S. zeamais and C. ferrugineus adults achieved in only the SBHD; some immatures of all three species survived in all three treatments. However, survival of immatures was highest in the laboratory, followed by SD and lowest in the SBHD for all three species. Percent TDK was higher in the SBHD (6.7 ± 0.9) than SD (3.3 ± 0.3) and laboratory (2.7 ± 0.3). These data show that the SBHD is effective for both drying and disinfestation of grain.     

纸机干燥部循环润滑系统关键控制参数的研究

介绍了纸机干燥部循环润滑系统的组成,分析了水分和温度对纸机干燥部润滑油性能的影响,对纸机干燥部润滑系统中水分的危害进行了探讨,进一步提出了对纸机干燥部循环润滑系统关键参数进行控制的必要性和潜在价值。最后,对纸机干燥部润滑系统关键参数的控制进行了研究。