粮食烘干机生物质热风炉系统研究与应用

针对现有燃煤热风炉燃烧不充分、燃烧效率低、尾部烟气NOx浓度高、烟尘堵塞换热器等问题,对生物质热风炉进行热风炉改造,安装凝渣换热系统、余热回收系统、环保除尘系统、自动上料系统改造,便热风炉在运行过程中不仅具有高效、低氮燃烧以及解决结焦挂壁等优势,还具有良好的经济指标与环境指标。同时对存在的问题进行了积极的分析。     

茶叶生产工艺中高效供热系统的研制与应用

醇基燃料热风炉为涪陵地区自主研制的新型供热系统,以空气为加热介质,采用燃烧醇基(甲醇加催化剂)为主体配置燃料,以火焰间接加热方式,可通过电脑界面控制,燃烧室与换热器合为一体。通过在茶叶杀青、干燥、提香工茶叶生产工艺中的应用,取得了明显效果。该系统操作简单、成本低廉、无环境污染危害,提升产品质量,综合经济效益提高26%以上,并已获得国家发明专利。     

粮食烘干机系统的常见故障分析及处理方法

我国地域广阔，粮食的收获季节从南到北有很大差别，由于南方气候潮湿，而北方气温较低，粮食收获后不能自然干燥，需要烘干。国家粮食主管部门对粮食烘干一直非常重视，近20年来投资兴建了大量的烘干设备，这些设备绝大部分为塔式烘干机，其最基本配置为：一台有换热器的燃煤热风炉、一台塔式干燥机、一台斗式提升机、一台塔下出粮皮带机和必要的清理设备及电控设备，     

鸡骨草种子发芽试验条件的研究

按《国际种子检验规程》（ISTA）1996版中发芽试验和GB／T3543．4-1995《农作物种子检验规程》发芽试验的要求对鸡骨草种子发芽试验的条件进行研究。初步得出鸡骨草种子发芽试验的技术规程、幼苗鉴定技术、幼苗发育类型编码，为鸡骨草种子检验提供参考。     

地铁用间接蒸发冷却器换热性能影响因素

为解决地铁站冷却塔设置难题,提出了一种采用低速电机驱动旋转布水装置的间接蒸发冷却器,在两种布置方式下,对其换热性能进行了单因素实验,并运用正交实验法对较优布置方式下影响换热器换热的因素进行了分析。结果表明：两种布置方式下,喷嘴与蒸发冷却器的间距、两组换热管束间距均存在最佳值,喷嘴双侧旋转布水优于单侧旋转布水;换热器平行气流布置且喷嘴双侧旋转布水为较优布置方式,此时,换热器换热量随喷水量、转速、空气速度、冷却水进口温度的增加以及喷水温度、空气温度的降低而增大,其中,冷却水进口温度对换热器换热影响最为显著,其他因素对其换热的影响从主到次顺序为：喷水量、空气温度、空气速度、喷水温度、转速、冷却水流量。     

金属热风炉煤耗试验及使用效果分析

在红绿茶初制加工中,烘干能耗尤其是煤耗占总成本消耗的比重较大。据我场近几年统计资料分析,初制煤耗约占主要物质消耗(鲜叶、煤、电)总成本的7％,其中烘干用煤占煤耗总量60％以上。因此,减少烘干煤耗是提高经济效益的重要途径。目前,国内已研制出立式三回程金属炉、喷流热管式热风炉等类型的高效节能炉。本场于1992年初引进一台RFL—80型无管式金属热风炉,试验情况如下。     

应用生物质燃料热风炉烘干小麦效果探讨

按照国家对完善粮食烘干配套设施的要求,为积极响应国家污染防治攻坚战和呼伦贝尔大气污染防治行动的号召,对烘干设备进行了环保改造,由生物质燃料热风炉代替了燃煤热风炉.经测试:烘干塔生产率提高11.31％,燃料成本和耗电成本合计降低0.39％,固体废弃物下降96.49％,颗粒物排放浓度为12.55 mg/m3,二氧化硫排放浓...     

磨皮对广州相思子种子发芽和幼苗生长的影响

为解除广州相思子种子硬实休眠状态,采用精白机对种子进行磨皮处理,通过发芽试验和幼苗生长实验探索磨皮处理对种子萌发和幼苗生长的影响。测定了不同磨皮时间处理的广州相思子种子损伤率、硬实率、电导率、吸水曲线、发芽势、发芽率、发芽指数、胚根伸长速度、胚芽生长速度、活力指数等指标,结果表明:与未磨皮的对照种子相比,磨皮处理120~180s的种子硬实率从91%降为0,24h吸水量提高46~62倍,发芽率从32.5%提高至92.0%~93.0%,根伸长速度和芽生长速度分别从3.66mm/d·粒、6.33mm/d·粒增加至6.41~6.90mm/d·粒、13.45~13.55mm/d·粒,同时造成种子损伤率达6.75%~8.25%,电导率提高9.8~10.5倍。说明通过磨皮处理,种皮透水性增强,种子吸水速率加快,但造成种子物理损伤,电解质外渗,为提高种子发芽率和幼苗质量,广州相思子种子适宜的磨皮处理时间为90~120s。     

基于SolidWorks二次开发实现蛇型管束的参数化建模

在间接加热式热风炉的参数化设计中,蛇型管束的行数和列数随着设计参数的变化而变化,使得间接加热式热风炉三维参数化建模比较困难。采用面向对象的编程语言VB,以SolidWorks为平台,对蛇型管束进行了三维参数化设计建模,可按照输入的设计参数自动生成蛇型管束的三维实体模型,绘图速度快且精度高,大大提高了设计质量,为其他复杂零件的参数化设计提供了可供参考的经验。     

农用小型移动式谷物干燥机的设计

阐述以秸秆为燃料的农用小型移动式谷物干燥机研究的背景和意义,分析该干燥机主要结构和工作原理,并对干燥塔和热风炉等主要部件进行设计计算,确定合理的结构参数与工作参数。样机性能试验表明,该干燥机能满足谷物干燥要求,而且操作方便,适合农户使用。     

Experimental Study of Ground-source Heat Pump Systems with Horizontal Heat Exchanger

This paper describes the double layer horizontal ground source heat pump systems constructed in 1998 with the buried depth of 0.9 m and 1.8 m. The program of study includes experimental equipments, heat exchanger size, testing meter and methods for data analysis. In addition, the heating and cooling performance at typical days are also illustrated. Among the influencing factors on the performance of the ground source heat pump systems, the parameter of heat exchanger and operation patterns of heat pump systems are analyzed.A heat transfer model has been set up for horizontal heat exchanger.     

Influence of Backfill on Performance of Ground Heat Exchanger

The physical and mathematical model of three dimensional unsteady coupled heat transfer in the ground heat exchanger is proposed, and corresponding numerical simulations for actual ground heat exchanger and operation condition are carried out. The computed results are compared with those of the thermal resistance test of the ground heat exchanger, which proves the correctness of the model and corresponding numerical methods. Then, the effects of thermal conductivity and specific heat of the ground backfill material on the ground heat exchanger are investigated, which provides theoretical guidance for the thermal response test and the engineering design of the ground heat exchanger.     

Numerical Analysis and Optimization of a Small Vehicle Heat Exchanger

This paper analyzes the fluid flow and heat transfer of the heat exchanger, and obtainsd the distribution of fluid field, heat field and pressure field in heat exchanger. According the analysis result, some modify measure is adopted, such as decreasing the number of tube bundle, the size of baffle plate and increasing the diameter of exchange heat tube. In the new heat exchanger, the resistance decreased 32.3%, is 103.2 Pa and the temperature of the exit is 130 K. The new heat exchanger satisfies the requirement of exchanging heat. The study indicates that adopting the numerical simulation method could get temperature, pressure and fluid - velocity of anywhere of the heat exchanger, and understand effecfing of structure parameter on fluid flied and heat flied of the heat exchanger. Therefore, it provides a new method for optimization design of heat exchanger.     

Heat Transfer Model and Application of Buried Tube Heat Exchanger for Ground Source Heat Pump

This paper introduces the theoretical basis and application method for heat transfer model of buried tube (pipe in pipe and U- type) heat exchanger for ground source heat pump, and a practical example is calculated. Then, the calculation results are analyzed and discussed. In particular, the correlation coefficient and calculation method of tube group exchanger is discussed; the method for determining known parameter and some basic data for main procedure GSHP.HTM is analyzed. The calculation formula and data sampling for JSW.HTM subroutine is introduced. At last, the problems in application of calculation procedure, to which should pay attention, are discussed.     

Experimental Study of Flow and Heat Transfer in Heat Exchanger with Small Channels

The experimental study of the flow resistance and heat transfer characteristics are conducted for water and ethylene glycol solution (66% Wt) flowing in the heat exchanger with small rectangular microchannels . The heat exchanger having the channels of 0.4 mm in width, 2.0 mm in height, and 20 mm in length is heated by a hearing rod at the bottom surface, the upper and two side surfaces are adiabatic. During experiments, the Reynolds number are ranged from 2 to 2 500. The experimental results show that the flow friction factor decreases and Nusselt number increases with increasing Reynolds number for water and ethylene glycol solution. At a fixed Reynolds number, the Nusselt number for ethylene glycol solution with larger Prandtl number is greater than that for water. Meanwhile, the correlations of flow resistance and heat transfer in the heat exchanger with small channels are obtained for engineering application.     

A Thermodynamic Criteria for Evaluation of Heat Exchanger Performance

The concept of loss rate of available energy was introduced for evaluating heat exchanger performance. At the same time, the general expression of loss rate of available energy was obtained for heat exchangers of several typical. And NL criteria was recommended for evaluation of the loss rate of available energy of heat exchanger. Then. the influences of inlet temperatures ratio, heat capacity ratio of fluids, the number of heat transfer units and flow patterns of heat exchanger on ,VL criteria were also discussed.     

Analysis of Sewage-water Heat Exchanger withthe Function of Auto-de-fouling

A sewage-water shell-tube heat exchanger with the function of de-fouling was proposed and designed for sewage-source heat pump. Its new simulation program which relies on a distribution parameter computational method was set up. Then the model was solved with the method of Matrix Control. Based on the model, the distribution of bilateral fluid temperature were studied, under the conditions of different flow rates and heat exchange area before and after the de-fouling. Results showed that there will be heat anti-transfer phenomenon if the heat exchanger area is bigger than need and the region of this phenomenon was point out. Setting the function of auto-de-fouling in shell-tube heat exchanger and reducing the equipment's volume accordingly can make the sewage-water heat exchanger run in the best conditions.     

The Key Parameters Method of Calculating Geothermal Heat Exchanger Length

The geothermal heat exchanger is the key component of ground coupled heat pump systems. We discuss the key parameters method of calculating geothermal heat exchanger length based on line source theory. Typical meteorological year data is used to determine the hottest month, the coldest month and annual average surface temperature. The building hourly load can be obtained by introducing the concept of equilibrium temperature. The cooling fraction and the heating fraction then can be calculated using building hourly load and performance parameters curve fit of a water source heat pump unit. The method for selecting the hottest and lowest entering fluid temperature and calculating the borehole and ground thermal resistance is given. A vertical U tube heat exchanger length calculation procedure is proposed.     

A Three-Dimensional Numerical Model and Experimental Research for U-Tube Ground Heat Exchanger in Heating Operation

In terms of the theory of a transient energy balance on the finite controlled volume, in this paper, a transient three-dimensional heat transfer model for the simulation of a single vertical U-tube ground heat exchanger based on finite-difference methods is systematically proposed. The model is also compared with experimental results during the heating operation in winter. What's more,based on test data and domestic and foreign literature, the equations to determine the undisturbed ground temperature for wet and heavy soil in Chongqing are presented. These formulae are essential conditions to calculate the heat transfer model.     

Analysis of the Ground Adjustment Ability of the Ground Source Heat Pump Systems in Winter

Based on an actual ground source heat pump system in hot summer and cold winter area, the system operation parameters were tested for 6 years under the state of using cooling tower for cooling in summer but the ground heat exchanger and fire pool for heating in winter. A three dimensional (3D) tube group model was established, and the thermal balance analysis and calculation of the ground temperature distribution around the ground heat exchanger were conducted by the numerical calculation. According to the comparison between the test data and the theoretical results, the influencing factors of the ground adjustment ability were obtained.