TIEC管内插入螺旋线强化一次空气传热的研究

提出了在管式间接蒸发冷却器（TIEC）管内插入螺旋线以强化一次空气传热的方法，并通过实验探讨了风量、风量比、温度、螺旋线插入物对换热效率及流体阻力的影响．结果表明，插入螺旋线换热器与光管换热器相比，换热效率可提高25％～34％，但一次空气流动阻力只增加了4％～15％．     

蒸发冷却＋辐射供冷空调系统的设计

根据蒸发冷却和辐射供冷的热湿处理空调特性,利用焓湿图分配其热湿负荷．计算辐射供冷水侧的供回水温度、流量、供冷能力等．给出了蒸发冷却新风的送风状态点和送风量的求解结果,并给出了冷源设备的选型方法．     

SWFF60型微细分级机的性能试验

介绍了用于特种水产饲料加工的SWFF60型微细分级机的特点，主要研究了微细分级机的转子转速，系统风量，二次进风量及环隙截面风速对分级性能的影响。     

改良D.T.蒸脱机的实践应用

改良后的Ｄ．Ｔ．蒸脱机可同时适用菜籽预榨浸出脱溶粕、大豆一次浸出粕的生产，其结构是在Ｄ．Ｔ．型蒸脱机的基础上，根据物料的特性，对设备进行一些合理的改进。改良后的设备结构简单、制造容易、操作方便、降低能耗、所得成品粕指标符合国家标准。经过我院的探讨与实践，以初步收到预期的效果。     

大型竖管降膜蒸发器液体分布装置的研究

介绍了适用于大型竖管降膜蒸发器的多层喷淋盘式分布器的结构，对组成分布器的分布盘及初始分布装置的主要参数进行了分析，提出了设计、计算的公式和依据，并通过实验进行了验证。     

大米微粉碎工艺特点及参数

介绍了大米（碎米）微粉碎工艺特点及在米微粉的开发价值，计算民微粉碎循环气流网路的总风量和总阻力，说明利用一台风机和循环气流网络，在对设备和物料进行降温、冷却的同时，能完成对物料输送、分级及产品收集等任务。空气能量利用率高。     

机械通风干燥谷物单位风量的选择

本文提出在某一地区大气条件下，对于某种粮食采用机械通风降水，单位风量的计 算与选择。在对粮食进行通风干燥过程中，根据进入粮堆热量、粮食水分气化所需要的热量 和粮食自身温度升降所需要的热量之间的热平衡关系，再根据单位风量和通风时间的函数关 系，以及机械通风干燥粮食的天数最多不能超过粮食的安全储藏天数这一原则，来计算和选 择略高于允许的最低单位风量，作为机械通风干燥粮食的单位风量。     

五金制品抛光粉尘治理的系统设计

从五金制品抛光粉尘的特性出发,根据抛光工艺、工件材料等提出粉尘捕捉方式和粉尘治理采用的形式,详细介绍捕捉技术及风量计算、治理系统风机选择及相应的风压、风量计算和辅助设施设置原则。对设计关键技术进行详细论述,对抛光粉尘治理有着重要的指导意义.     

四效压力蒸发的热经济性

节能降耗是企业界永恒的话题。围绕着这一主题的各种探索和举措层出不穷。糖厂蒸发站的热力方案有好多种，比如，从蒸发效数上讲，有三效、四效、五效蒸发，从末效汁汽的状态上分，有压力蒸发和真空蒸发，有带零效罐的系统，有带浓缩罐的方案等．方案各有利弊，评价见仁见智．笔者在此根据银川糖厂的生产实践，谈谈四效压力蒸发的热经济性．1国内外发展趋势五效真空蒸发的特点是：对汽温度高，可以充分利用．抽对汽量可大幅度后移，蒸汽利用系数高，故而热经济性圩．一般认为比四效低真空系统节约生蒸汽6％左右．且运行平稳，调往容易．但一…     

浅谈宾馆厨房的空调通风设计

阐述了宾馆厨房空调通风设计的一般原则及通风系统采用形式，包括送风、排风系统设计、送风量的计算及排烟罩的选择等。     

蒸发式冷凝器的设计计算

针对蒸发式冷凝器的换热过程同时存在显热和潜热交换,计算过程比较复杂且方法较多的情况,介绍一种简单实用的蒸发式冷凝器的设计计算方法,通过基本参数计算、盘管设计、水系统设计和风系统设计,进行系统设计计算,得出换热量、传热面积、淋水量、水泵功率和风机功率等设计参数,该方法适用于常规蒸发式冷凝器的设计计算。     

Extending the potential of evaporative cooling for heat-stress relief

Factors were analyzed that limit the range of environmental conditions in which stress from heat may be relieved by evaporative cooling in shaded animals. Evaporative cooling reduces air temperature (Ta), but increases humidity. Equations were developed to predict Ta reduction as a function of ambient temperature and humidity and of humidity in cooled air. Predictions indicated that a reduction of Ta becomes marginal at humidities beyond 45%. A reduction of Ta lessens with rising ambient Ta. The impact of increasing humidity on respiratory heat loss (Hre) was estimated from existing data published on Holstein cattle. Respiratory heat loss is reduced by increased humidity up to 45%, but is not affected by higher humidity. Skin evaporative and sensible heat losses are determined not only by the humidity and temperature gradient, but also by air velocity close to the body surface. At higher Ta, the reduction in sensible heat loss is compensated for by an increased demand for Hre. High Hre may become a stressor when panting interferes with resting and rumination. Effects of temperature, humidity, air velocity, and body surface exposure to free air on Hre were estimated by a thermal balance model for lactating Holstein cows yielding 35 kg/d. The predictions of the simulations were supported by respiratory rate observations. The Hre was assumed to act as a stressor when exceeding 50% of the maximal capacity. When the full body surface was exposed to a 1.5 m/s air velocity, humidity (15 to 75%) had no significant predicted effect on Hre. For an air velocity of 0.3 m/s, Hre at 50% of the maximum rate was predicted at 34, 32.5, and 31.5° C for relative humidities of 55, 65, and 75%, respectively. Similar results were predicted for an animal with two-thirds of its body surface exposed to 1.5 m/s air velocity. If air velocity was reduced for such animals to 0.3 m/s, the rise in Hre was expected to occur at approximately 25° C and 50% relative humidity. Maximal rates of Hre were estimated at 27 to 30° C when ambient humidity was 55% relative humidity and higher. High humidity may stress animals in evaporative cooling systems. Humidity stress may be prevented by a higher air velocity on the body surface of the animal, particularly in sheltered areas in which the exposed body surface is reduced, such as mangers and stalls. This may extend the use of evaporative cooling to less dry environments.     

Study on thermal and evaporative resistances of multilayered fabric ensembles

The present work deals with the study on thermal and evaporative resistance of multilayered fabric ensembles meant for cold weather applications. Three-layered structure is used to study the thermal comfort properties. Knitted fabric and polytetrafluoroethylene coated fabrics were used in inner and outer layer, respectively. Needle punched fabrics produced from polyester fibre were used in middle layer. Fifteen different non-woven fabrics were produced according to Box and Behnken experimental design for three variables and three levels by varying mass per unit area, punch density and depth of needle penetration. The produced fabrics were evaluated for thermal and evaporative resistances with and without inner and outer layer fabrics. Thickness, air permeability, bulk density and porosity of the needle punched fabrics were studied. The properties of the fabrics were analyzed for statistical significance by using ‘Design-Expert’ statistical software. Artificial neural network model was developed to predict the properties of fabrics and validation of model was done with the testing data-set. The performance of prediction was evaluated by mean square error, mean absolute error percentage and correlation coefficient. It was concluded that the predicted properties of fabric correlated well with the experimental results.     

Evaporative water loss from dairy cows in climate-controlled respiration chambers

The effects of ambient temperature (AT) on total evaporative water loss from dairy cows at different relative humidity (RH) and air velocity (AV) levels were studied. Twenty Holstein dairy cows with an average parity of 2.0 ± 0.7 and body weight of 687 ± 46 kg participated in the study. Two climate-controlled respiration chambers were used. The experimental indoor climate was programmed to follow a diurnal pattern with AT at night being 9°C lower than during the day. Night AT was gradually increased from 7 to 21°C and day AT was increased from 16°C to 30°C within an 8-d period, both with an incremental change of 2°C/d. The effect of 3 RH levels with a diurnal pattern were studied as well, with low values during the day and high values during the night: low (day, 30%; night, 50%), medium (day, 45%; night, 70%), and high (day, 60%; night, 90%). The effects of AV were studied during the daytime at 3 levels: no fan (0.1 m/s), fan at medium speed (1.0 m/s), and fan at high speed (1.5 m/s). The medium and high AV levels were only combined with medium RH. In total, there were 5 treatments with 4 replicates each. The animals had free access to feed and water. Based on the water balance principle inside the respiration chambers, the total evaporative water loss from dairy cows at a daily level was quantified by measuring the mass of water in the incoming and outgoing air, condensed water, added water from a humidifier, and evaporative water from a wet floor, drinking bowl, manure reservoir, and water bucket. Water evaporation from a sample skin area was measured with a ventilated skin box, and water evaporation, through respiration with a face mask. The results show that RH/AV levels had no significant effect on total evaporative water loss, whereas the interaction effect between RH/AV with AT was significant. Cows at a high RH had a tendency for a lower increasing rate of evaporative water loss compared with cows at a low RH (0.61 vs. 0.79 kg/d per 1°C increase of AT). Cows at medium and high AV levels had a greater increasing rate than cows at low AV (0.91 and 0.95 vs. 0.71 kg/d per 1°C increase of AT, respectively). The increase of evaporative heat loss from dairy cows was mainly a result of the increase in evaporation (of sweat) from the skin. The skin water evaporation determined with the water balance method (less evaporation from respiration) and the ventilated skin box method showed no significant difference. The implication of this study is that cows at a high AT depend mainly on evaporative cooling from the skin. The ventilated skin box method, measuring only a small part of the skin during a short period during the day, can be a convenient and accurate way to determine the total cutaneous evaporative water loss from cows.     

Numerical simulation and experimental investigations of air drawing model and air jet flow field model in wide slot positive pressure spunbonding process

An air drawing model of polymers and a model of the air jet flow field model in wide slot positive pressure spunbonding process are established. The air jet flow field model is solved by means of the finite difference method. The numerical simulation computation results of distributions of the air velocity match quite well with the experimental data. We find that the variation of the density and the specific heat capacity of polymer melt at constant pressure with polymer temperature have much effects on fiber diameter. The newly developed formulas were incorporated into a spunbonding theoretical model to predict the fiber diameter of nonwoven web. The air drawing model of polymer is solved with the help of the distributions of the air velocity measured by a Particle Image Velocimetry (PIV). The predicted fiber diameters agree with the experimental data well. It can be concluded that the higher air pressure, higher air velocity and air temperature can yield the finer fibers diameter. The higher inlet pressure and smaller jet angle will all cause higher x-axis position of air velocity and air pressure, which are beneficial to the air drawing of the polymer melt and thus to reducing the fiber diameter.     

PET板和金属板串联下的介电常数及其影响因素分析

含金属纤维纱线由金属纤维、普通纤维和空气的混合体构成,其介电常数的研究较为复杂。本文采用PET板、铜板和空气以不同方式进行串联,模拟含金属纤维纱线及其理想结构,推导出不同串联方式下介电常数的计算公式。同时,采用介电谱仪测试不同串联方式下的介电常数,表明测试结果和计算结果具有较好的一致性。实验条件下,串联复合体的介电常数随着金属含量增加而增加,随着空气含量和PET含量增加而减少。     

Fate modeling of phenanthrene with regional variation in Tianjin,China

A multimedia fate model with spatially resolved air and soil phases was developed and evaluated. The model was used for calculation of phenanthrene concentrations in air, water, soil, and sediment in Tianjin area and transport fluxes between the adjacent bulk phases under steady-state assumption. Both air and soil phases were divided into 3113 individual compartments of 4 km2 each to assess the spatial variation of phenanthrene concentrations and fluxes. Independently measured phenanthrene concentrations in air, water, and soil were used for model validation. The spatial variation in soil was validated using a set of measured phenanthrene concentrations of 188 surface soil samples collected from the area. Most data used either for model calculation or for model validation were collected during the last 5 years. As the results of the model validation, the calculated mean values for phenanthrene concentrations in various bulk phases are in fair agreement with those independently observed and are very close to those calculated using the model without spatial variation. The absolute difference between the calculated and the measured mean concentrations are 0.14, 0.48, and 0.13 log-units (mol/m3) for air, water, and soil, respectively. The spatial distribution patterns of phenanthrene in both air and soil were well modeled. Spatially, however, the model overestimated the soil phenanthrene level at low concentration range and underestimated it at high concentration range. The calculated distribution of phenanthrene in the air matches well with the emission from fossil fuel combustion, while the calculated distribution pattern in the soil is similar to that observed.     

Research on sound absorption properties of multilayer structural material based on discarded polyester fiber

Thermoplastic polyurethane was reinforced with discarded polyester fiber to develop excellent mechanical properties of fiberboard composites, by hot pressing and mixing method. The fiberboard was drilled and made as a perforated plate, which was then coupled with polyester fabric; so a multiple layer structural material with good sound absorption function was achieved. Sound absorption properties were studied by changing holes diameter, air cavity depth, and perforation ratio. Theoretical absorption coefficient was obtained through building analytical model and massive theoretical calculation. It was found that it has good agreement with the experimental results. Hence, the analytical model could be adopted to predict the sound absorption coefficient of multilayer structural composites.     

Dynamic modeling and simulation of bottom outlet air flow field in wide slot positive pressure spunbonding drawing process

The air jet flow has an important influence in wide slot positive pressure spunbonding process that not only includes the filament fiber diameter, crystallinity, and birefringence, but also the fiber web evenness. In this work, the air drawing model and the air jet flow field model of bottom outlet in spunbonding process are established and studied. The characteristics and regularities of the plane air jet flow in wide slot positive pressure spunbonding process are also demonstrated. It is simulated by means of the finite difference method. The numerical simulation computation results of distribution of the air velocity match quite well with the experimental data. The air drawing model of polymer is solved with the help of the distribution of the air velocity. The predicted filament fiber diameter, crystallinity, and birefringence agree well with the experimental data. It was found that higher initial velocity and initial temperature of air can yield finer fibers, and its effect was very significant. The results also reveal the great potential for this research in the computer-assisted design of spunbonding technology and equipment.