无溶剂体系脂肪酶催化合成阿魏酸双油酸甘油酯

对无溶剂体系中脂肪酶催化合成新型油脂抗氧化剂阿魏酸双油酸甘油酯进行了研究。以Novozym 435脂肪酶为催化剂,以阿魏酸乙酯和三油酸甘油酯为底物,合成阿魏酸双油酸甘油酯。探讨了减压旋转蒸发、底物比、温度、反应时间、酶的稳定性等因素对产率的影响。结果表明,无溶剂体系中,在110mg Novozym 435催化下,水活度小于0.01,转速为180r/min,底物比(阿魏酸乙酯∶三油酸甘油酯)为1∶2,温度为50℃,真空度为0.001MPa,旋转蒸发反应120h时的产率最高。固定化酶可反复使用多次,活性没有明显损失。     

利用蒸发冷却空调开展控温储粮试验

在拱板式高大平房仓的拱板间安装蒸发冷却空调开展控温储粮技术,解决拱板间的积热,以达到延缓仓内温度和上层粮温上升速度的目的。蒸发冷却空调主要利用水泵抽取水槽内的水,通过分水器均匀分布到特殊纤维制成的湿帘组件上,而大流量轴流风机的转动令仓外空气以极高速度穿过湿帘组件将湿气散发到空间,以增加空气中的湿度,通过正压促使空气流动,从而达到换气降温的效果。试验结果表明,利用低功率蒸发冷却空调,可以有效排除拱板间的积热,实现换气降温、节能、环保、绿色储粮的目的。     

魔芋精粉的加工设备

1.生产单机 (1)去皮机机械去皮机现有2种机型,一种是鼠笼圆滚筒式去皮机,去皮滚筒的直径和长度根据不同的生产量而有所不同,一般直径为500 mm～700 mm,长度为2 000 mm～3 500 mm,滚筒内嵌有多条尼龙毛刷,滚筒中有喷淋管,两组喷嘴以45°角向下喷水,滚筒的旋转速度一般为20 r/min～25 r/min,魔芋靠自身重量,与滚筒毛刷接触,在转动中毛刷与魔芋相对滑动,尼龙毛刷将魔芋皮刷掉,在喷淋水的作用下将泥沙和皮从毛刷的间隙排出.     

番茄果实与空气间对流换热研究

为了摸清番茄果实与空气间传热的对流换热系数,在人工气候室控温、控光环境下,测定了番茄果实不同风速时的表面温度与空气温度的温差,根据热平衡原理计算番茄果实表面的对流换热系数。用Porter和Mitchell模式计算对流换热系数,并计算了模式的回归系数。用称重法测定1 d中番茄果实水分损失量,分析了番茄水分损失产生的潜热交换量。结果表明,采样后24 h内番茄果实水分蒸发产生的潜热交换量平均为2.3 W/m2;番茄果实的对流换热系数随风速增加而线性增加。Porter的模式回归系数修正后,可用Porter公式计算对流换热系数。这为以后的对流传热分析提供了较为确切的热物性参数。     

高温高湿条件下鸡舍的通风管理

正高温高湿条件下保持鸡群生长舒适度的方法有两种:一是增加舍内风速达到风冷效应,二是使用湿帘降低舍温。这两种方法应首选增加舍内风速,促进鸡舍空气流动和加大空气交换总量,其次选择冷却降温。下面我们从鸡只的散热方式、蒸发冷却、温度与湿度、提高舍内风速等方面来讨论怎样做好高温高湿条件下鸡舍的通风管理。     

大米 豆粕和燕麦复合挤压工艺参数的研究

以大米、豆粕和燕麦为主要原料,研究物料含水量、机筒温度、螺杆转速和喂料速度对糊化度的影响。在单因素试验基础上,通过响应曲面法对挤压膨化工艺参数进行优化:物料含水量17.92%,机筒温度160.50℃,螺杆转速184.32 r/min,喂料速度21.99 r/min。     

杂粮加工中参数设置对挤压特性的影响

加工谷物早餐时,挤压膨化影响产品的感官评价、膨化度、糊化度的因素是多方面的,研究了原料成分、挤压膨化操作参数等因素的影响,主要考察物料含水量、机筒温度、螺杆转速、进料速度等参数对产品的影响。以膨化度、糊化度为考察目标进行了试验,最终确定最佳挤压工艺参数为:物料含水量16%,机筒温度设置为第3组,5个区温度分别为:80,90,110,130,165℃,螺杆转速为140r/min,进料速度为30r/min。     

地下水渗流作用下地埋管间歇散热特性

为了探求地下水渗流对地埋管换热器间歇运行性能所产生的影响,基于移动的有限长线热源理论模型解析解,利用MATLAB软件编程计算,分析渗流对单钻孔地埋管换热器的影响。同时对比分析了连续和间歇运行情况下其周围土壤的温度响应特征和过余温度场分布特点。研究表明：埋管周围土壤的温度变化是由热流密度、土壤本身的热物性和实际渗流速度耦合作用影响的,而在间歇运行下其因素影响更加明显。     

微喷弥雾调控灌水技术对葡萄生理和产量的影响研究

旨在确定较优的微喷弥雾调控灌水技术方式。分析在不同微喷弥雾调控灌水技术方式下对葡萄枝条数、叶片数、节间长等生理指数和产量指标的影响。在不同弥雾微环境调控技术处理下,葡萄的各项生理指标均表现出一定的规律性,由于叶面积指数与叶片数、枝条数及单叶面积等有关,不同处理中WP4、WP5的叶面积指数最大,WP2和WP3居中,而对照CK处理最小。在产量的表现上,对照处理的产量为29275.5 kg/hm2,仅高于WP5（28591.5 kg/hm2）,WP3产量最高,为38313 kg/hm2,相比对照高出30.9%,其后是WP1、WP2和WP4,分别为33906 kg/hm2、33361.5 kg/hm2和32124 kg/hm2。葡萄微喷弥雾调控灌水技术在灌溉定额9150 m3/hm2,每天喷水1次,每次1~2 h,每次喷水量在105~120 m3/hm2时可以获得较高的葡萄产量。     

基于分子蒸馏技术紫苏油α-亚麻酸纯化效果的研究

为了探究分子蒸馏技术纯化紫苏油α-亚麻酸的可行性,筛选紫苏油提取方法的基础上,考察了蒸馏温度、蒸馏压力、刮板转速和进料速度4个因素对分子蒸馏技术纯化α-亚麻酸效果的影响。结果表明,紫苏油最佳提取法为超临界CO₂萃取法,α-亚麻酸纯化的首要影响因素是蒸馏温度,其次是蒸馏压力,再次是进料速度,最后是刮板转速。最佳纯化工艺：蒸馏温度220℃,蒸馏压力0.07 mbar,刮板转速375 r/min,进料速度1.0 d/min,该工艺条件下α-亚麻酸纯度达到97.42%。该方法有效提高了紫苏油α-亚麻酸的纯度,为高纯度α-亚麻酸的研究和利用奠定了理论基础。     

Spray Characteristics of a Two Phase Air water Nozzle for Indirect Evaporative Cooling

We present a two phase air water nozzle that can be applied to indirect evaporative cooling to improve the heat transfer efficiency of indirect evaporative coolers by improving the uniformity of the water film on the surface of the heat exchanger. The spray characteristics of a nozzle with a fan shaped orifice at various air and water pressure conditions was studied. The spray cone angle, the air water mass flow rate, and the relationship between the mass flow rate and the air water pressure ratio were obtained. The best air water pressure ratio and spray cone angle were also found.     

Subway Station Plate Evaporative Cooler Heat and Mass Transfer of Falling Film under Gas liquid Cross flow Condition

With the influence of the different gas Reynolds number and liquid Reynolds number on falling film heat and mass transfer of subway station plate evaporative cooler, the experiment was carried out by non contact infrared thermal imaging technology under gas liquid cross flow condition. The results indicated that during the increasing of liquid Reynolds number the thickness of liquid film increased and the temperature difference between liquid film inlet and outlet decreased in determined heating water temperature which weakened the heat transfer of liquid film. However, the increase of liquid Reynolds number strengthened the liquid film turbulence that enhanced heat transfer. Under the synergistic effect of these two factors, there was an optimal liquid Reynolds number which minimize thermal resistance and maximize heat and mass transfer coefficient of liquid film.     

Influence of Backfill Air Gap on Soil Temperature Recovery in Ground coupled Heat Pumps

Air gap may easily emerge in the progress of backfill in ground heat exchange due to field operation problems. The single U tube three dimensional numerical heat transfer model is set up and there are 3 kinds of backfill air gap assumptions for computational analysis, which are the most common situations in practical projects. Different air gap situations will have considerable effects on soil heat transfer, especially the factor of soil temperature recovery performance, which is investigated in this research, and there is practical project operating data for the comparison confirmation with the theoretical calculation results in inlet and outlet water temperatures. It can be concluded that the backfill air gap will increase the soil average excess temperature in the period of recovery inside the place where the air gap is, and degrade the heat transfer performance of the ground heat exchange.     

Pressure Drop and Evaporative Heat Transfer Characteristics of Air-water Bubbling Flow

A new kind of evaporative heat transfer experiment for the cooling process of condensers is conducted. The test coil is immersed in an air-water bubbling layer. The air-water two-phase flow passes through the heating tubes of the coil. Due to the motion of the air bubbles in the water, a thin water film forms on the surface of the heating tubes. As the air bubbles passing by the tubes the water is evaporated into the air. The tubes of coil reject heat to the water film, and the evaporation of the water film then rejects heat to the air bubble stream. This heat transfer mode significantly increases the heat transfer coefficient between tubes and air. The consumption of the power of a water pump can be decreased. Moreover, the airflow rate required is less than that of an air-cooled condenser.The pressure drop of air through air-water bubbling layer and the heat transfer between the tubes and water are experimentally investigated in the paper. The results show that the factors affecting the pressure drop and the heat transfer coefficient involve the pore geometry of sieve plate, the height of the air-water bubbling layer, the air flow rate through the sieve plate and the heat flux of tubes. The heat transfer coefficient between tube and water is two times larger than that of falling film of water on the outer surface of tube.     

乙二醇蓄冷库的设计和性能

为探讨乙二醇作为蓄冷剂的蓄冷库用于果蔬贮藏保鲜的可行性,研究人员设计了包含制冷循环系统、蓄冷剂循环系统和保鲜库制冷系统三个循环的乙二醇蓄冷库。按照国家标准冷库热工性能试验方法对研制的蓄冷库的围护结构传热系数、冷风机制冷量、耗电量和库内温度波动等冷库性能进行了分析,结果表明,研制的乙二醇蓄冷库,围护结构传热系数为0.20 W/(m2·℃),冷风机制冷量5.4 kW,耗电量35.48 kW·h·d-1,库内温度不均匀性2.8℃,平均温度波动±1.0℃,达到了果蔬贮藏保鲜设施的技术要求。     

STUDY ON HEAT TRANSFER MATHEMATICAL MODEL BETWEEN BILLETS AND ROLLERS FOR THE SECONDARY COOLING ZONE IN BILLET CONTINUOUS CASTING

A mathematcal model of heat transfer between the billet and the roller for the seeondary cooling zone in billet continuous casting is established. By means of the simulated test,a regres sion relation between the heat flow from the billet into the roller and the surface temperature and cast ing speed and spray water density obtained. The calculated theoretical values for change of surface temperature are in agreement with the measured data, these studies may contribut to the quantitative analysis and the calculation of the heat transfer of the secondary cooling zone.     

Measurement method for spray cooling characteristics of industrial nozzle

In order to study the cooling characteristics of the nozzle, a test platform is designed and developed for spray cooling feature measurement based on unsteady state heat conduction. By heating and keeping Q215 metal samples up to some surface temperature, a series of temperature data are collected by S7-200 modules during spray force cooling. Through Visual C++6.0 and Matlab interface programming, a series of regression equation with thermodynamic property versus temperature, such as density, specific heat capacity, and thermal conductivity etc., and with temperature versus sample time are obtained. The surface heat transfer coefficient and spray cooling feature of nozzle can be indirectly measured by the regression equations. The relation between surface heat transfer coefficient versus temperature, spray pressure and water intensity are investigated by means of the testing equipment. The experiment result shows the method is feasible and can be used in spray cooling feature measurement for all kinds of nozzle.     

Analysis of coupled heat transfer between freezing soil,water and horizontal heat exchange tube

The research object is the coupled heat transfer effect between freezing soil,water and horizontal heat exchange tube,use finite volume numerical method to dispersed solving for continuity equation and heat transfer equation of unsaturated freezing soil,gives part of the temperature fields and freezing percentage distribution graphs,and analyzes the reason of the coupled heat transfer.The analysis result shows that:the temperature field of freezing soil are some horizontal lines parallelling to the ground surface.The peak value of solid-liquid phase change region appears in the upper part where there is backwater pipe,the low value appears in the place where there isn't horizontal heat exchange tube.The horizontal heat exchange tube makes the freezing front deviate towards the ground surface.The arrangement difference of inlet and outlet position of horizontal heat exchange tube will effect the size and position of the phase change region of freezing soil.Arranging the backwater pipe at one side or middle position is the optimized mode.     

Dynamic Heat Transfer Analysis of a Water Storage Roof

On the basis of analyzing the complicate heat and humid exchange between the outdoor air and the water layer of the roof,the authors obtained a heat transfer model and it's transmit matrix. The temperature and heat flux responses of the internal roof surface is greatly lowered than that of non-water layer roof. It can be concluded that the maintenance of a water layer on the roof is a good way to resist the fluctuation of outdoor temperature and significantly reduce the cooling load of a building.