基于性能曲面特性的干湿球温度允差等级划分

在试验结果的基础上,分析制冷量和能效比随干湿球温度的变化特性。用赤池信息量准则(Akaike information criterion,AIC)选取制冷量和能效比最优拟合三维曲面方程,求解制冷量和能效比随干湿球温度变化的梯度极值区间,以两者梯度极值区间内干湿球温度允差范围的并集为A级、现行干湿球温度允差为C级,以各级最大(最小)能效比变化率相等原则,对允差进行三级非线性划分。实例表明随着允差等级的升高,能效比最大变化率由5.19%缩减至1.04%,分级允差能够更加准确地判别房间空调器的能效等级,并给国家标准的修订提供参考。     

磁力泵驱动两相冷却环路的换热特性

为研究磁力泵驱动两相冷却环路的工作特性,特别是启动特性和换热性能随温差的变化规律,搭建了磁力泵驱动两相冷却环路的实验装置,并利用空气焓差法对其进行测试。结果表明:磁力泵驱动两相冷却环路启动迅速,在600 s内达到稳定状态,受蒸发器内液体过热的影响,启动过程中系统的压力和温度分布会产生微小波动;制冷量随温差的增大而增大,随制冷剂质量流量的增加呈先增大后减小的趋势。温差10℃时,系统最大制冷量为3.429 kW,能效比(EER)为12.94;温差25℃时,制冷量最大为9.241 kW,EER为29.7。     

柜式空调微通道蒸发器换热性能测试

设计并搭建了柜式空调用微通道蒸发器的性能实验测试平台,测试了微通道蒸发器扁管进出口端温度分布及蒸发器进出口温差、压差、输入功率、制冷量和系统能效比随环境舱温度(18~23℃)升高的变化,并与常规管翅式蒸发器进行了对比。结果表明,微通道蒸发器具有较好的制冷剂流量分配特性,提高了空调出风口温度分布均匀性;由于微通道蒸发器制冷剂充注量低于管翅式蒸发器,且流程也相对缩短,相同工况下,微通道蒸发器进出口压差比管翅式蒸发器降低了33.9%,输入功率降低了4.12%,制冷量提升了2.95%,系统能效比最高提高了6.69%。     

煤基/石油基火箭煤油高参数黏温特性与组分特性研究

为探究温度变化及组分变化对液体火箭推进剂黏度的影响规律,以煤基/石油基火箭煤油两种燃料为研究对象,获取两种燃料宽广温度和压力范围内的黏度数据,构建两种燃料“黏度-温度-压力”数学模型,大多数模型偏差都在5%的实验扩展不确定度范围内,能够精确预测燃料黏度随温度及压力的变化。黏温系数及等压黏度变化率的大小可反映不同燃料的黏温特性,对比结果表明,煤基煤油和石油基煤油的黏温系数和等压黏度变化率的绝对值相近,受温度影响程度几乎相同。根据运动黏度梯度,提供两种火箭煤油雾化燃烧效果最佳的临界预热温度。以灰色关联理论方法分析火箭煤油五组分烃类物质与黏度及黏度变化率的相关性,研究影响火箭煤油黏度的敏感组分因素。结果表明：单环烷烃对低温火箭煤油黏度指标影响最大,双环烷烃对高温火箭煤油黏度指标影响最大。     

太阳能喷射制冷系统临界冷凝特性实验研究

为了了解太阳能喷射制冷系统的系统性能随冷凝温度的变化规律,进而提出合理的系统运行控制策略,文中设计并搭建了太阳能喷射制冷实验研究平台,以HFC134a为制冷剂,对太阳能喷射制冷系统的临界冷凝特性进行了实验研究.研究表明:太阳能喷射制冷系统工作时,系统性能系数(COP)、制冷量和能效比(EER)等参数随着冷凝温度的升高呈...     

水焓值法制冷量源装置的计量特性

水焓值法制冷量源能够应用于制冷量的量值传递,提供数值可测、可控的制冷量量值。首先提出了水焓值法制冷量源原理,并在该原理基础上设计和研制了制冷量源装置的物理结构。然后在空气焓值法实验室中对制冷量源进行了实验测量,由风机功率转化实验结果可知风机消耗功率完全转化为空气焓值的增加,并可通过焓差室测量。最后对制冷量源装置进行了稳定性研究和不确定度评定,由实验结果分析可知稳态运行30 min输出制冷量标准差为22.2 W（制冷量5251.9 W）,相对扩展不确定度为0.6%（k=2）。水焓值法制冷量源装置第一次从计量学角度实现了制冷量量值的溯源,输出量值可溯源至温度、压力、流量和电功率。     

炼厂气回收过程中分离技术的能效分析

针对炼厂气多目标回收工艺设计时缺乏理论指导的问题,本文系统阐述了分离过程能效比的概念,将气体分离过程中压力和温度变化导致系统与外界交换的能量统一用电功表示,得到了分离过程能耗与产品回收量间关系的定量表示方法;以某厂炼厂气回收过程为例,比较了不同分离技术和不同分离过程的能效比。当产品氢纯度要求不高（≥97%）时,采用变压吸附（PSA）工艺的能效比较高（0.86）,与膜分离工艺相比,提高了28%;当产品氢纯度要求较高（≥99.9%）时,采用膜分离-PSA工艺可以获得更高的能效比（0.54）,与PSA-膜分离工艺相比,能效比提高了40%。研究结果表明：分离过程的能效比可以用于评价不同分离技术或不同分离过程的能量效率,可用于指导不同分离技术的适用范围和多技术耦合工艺过程的设计,能够为炼厂气回收工艺设计提供一定的理论指导。     

凹凸棒土增强EVA/NBR阻燃复合材料的性能研究

以氢氧化镁（MH）和红磷（RP）为阻燃剂（FR）制备了乙烯醋酸乙烯共聚物/丁腈橡胶(EVA/NBR)阻燃复合材料,并将凹凸棒土（AT）引入到EVA/NBR阻燃复合材料中,以提高其力学性能、耐油性、燃烧性能及热稳定性。结果表明,含有10 份（质量份,下同）AT的阻燃复合材料,其拉伸强度为10.4 MPa,断裂伸长率为627.1 %;浸油后拉伸强度变化率从-29.3 %降低到-13.2 %,断裂伸长率变化率从-25.2 %降低到-8.6 %,且质量增大变化率从10.7 %降低到3.4 %;极限氧指数达到了32.2 %,UL 94垂直燃烧从无等级提高到V 0级;700 ℃时残炭量从29.3 %提高到35.6 %;浸油前后断面观察发现,加入AT后阻燃复合材料的断面更加致密。     

R290直线压缩机变工况制冷性能

根据电子冷却等应用需求,开发了小型制冷装置用R290直线压缩机样机,并开展了变工况性能试验研究。结果表明,在蒸发温度为8.0、2.7和-3.4℃三种工况下,直线压缩机在上死点位置的制冷量分别为1633.4、1417.4和943.4 W,COP分别为6.67、4.24和2.63,对应的循环效率分别为67.5%、70.9%和69.3%。蒸发温度2.7℃的设计工况循环效率最高,该工况下,当制冷量在35%～100%调节时,多变指数系数变化范围为0.968～0.983。在压缩机变容量调节过程中,气体等效刚度、固有频率与等效阻尼呈非线性变化,在上死点附近均存在极值点。     

回热器对双级压缩和复叠式压缩制冷系统影响的分析

为了研究回热器对双级压缩制冷系统和复叠式压缩制冷系统的影响,以R404A双级压缩制冷系统和R404A/R23复叠式压缩制冷系统为例,通过建立两种制冷系统的热力学模型和(火用)分析法,分析了回热器效率对压缩机排气温度、单位质量制冷量、制冷剂质量流量、系统制热能效比(COP)、系统总(火用)损、系统各部件(火用)损和系统(火用)效率的影响。结果表明,在双级压缩制冷系统中,当回热器效率ε 取0.1～0.9时,系统COP增大4.0%,系统的总(火用)损减少9.6%,而系统(火用)效率增大7.1%;在复叠式压缩制冷系统中,系统COP和系统(火用)效率随高温级回热器效率ε 增大而增大,随低温级回热器效率ε增大而减小,而系统总的(火用)损随高温级回热器效率ε 增大而减小,随低温级回热器效率ε 增大而增大。     

液氨球罐的消防设计

在国家标准规定的火灾危险性分类中 ,氨被列为乙类可燃气体 ,液氨球罐也被列为工艺装置的乙类单元 ,对此应引起有关化工企业的重视和采取必要的防火措施。在现行规范尚无如何对液氨球罐进行消防的情况下 ,参考地上立式储罐的消防规定 ,对某复合肥厂一座 40 0m3 液氨球罐所做的消防设计是一种可行的尝试 ,同时也说明应尽快对液氨球罐的消防设计作出明确规定     

Incorporation of indolinospirooxazine on ethylene-vinyl acetate copolymer to produce a intelligently temperature-regulated nonwhite cool material

Cool materials that adjust cooling efficiency according to sunlight intensity are needed because people have different needs for cooling at different times. Several colors of commercial microencapsulated photochromic powder were melt blended with ethylene-vinyl acetate copolymer in a two-roll mill at 90 °C to prepare the photochromic films of corresponding colors. Pink photochromic films [the organic photochromic compound is indolinospirooxazine (NISO)] were selected to continue the following variable experiment due to its best performance in the indoor cooling test. The pink photochromic films change color as well as transmittance according to the intensity of sunlight, thereby achieving an intelligent cooling effect. A maximum decrease around 10 °C was observed in natural environment when the addition amount of pink photochromic powder reaches 2.0 phr under strong sunlight and all films did not show cooling effect under weak sunlight. This material can be covered on buildings to regulate the indoor temperature. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48887.     

制冷剂充注量对微通道蒸发器换热性能影响的实验研究

以微通道换热器作为柜式空调蒸发器,设计并加工了微通道蒸发器(MCE,扁管和翅片均为铝材),搭建实验测试系统。研究了三种入口形式(Z-Inlet, Y-Inlet, U-Inlet)、五种制冷剂充注量(800~1600 g)下微通道蒸发器的表面温度分布、制冷量(Q)、输入功率(Pin)和能效比(EER),并与管翅式换热器(FTE,铜管-铝翅片)进行对比分析。结果表明,Z-Inlet形式MCE内部制冷剂行程基本相同,流量分配较均匀,其表面温度分布比较均匀,换热效果最佳;Z-Inlet形式MCE的制冷量和EER最高,与另外两种形式相比,制冷量和EER最高分别提高了8.8%和5.7%;MCE的制冷量和EER比FTE大,制冷量平均超出了11%,最高达13.3% (约600 W),EER平均提升了9.36%,最大约为12.4%;此外MCE的EER达到峰值对应的制冷剂充注量与FTE相比减少了200 g。     

Statistical methodology for setting legal allowances for nutrient contents of bagged fertilizer materials in the State of North Carolina

The process of establishing investigational allowances for fertilizer materials is reviewed. All sources of variation incurred in taking, preparing and analyzing an official sample of fertilizer are considered. The importance of both theoretical and practical considerations is discussed. Use of the techniques described is illustrated using a set of data involving five grades of commercial fertilizer. Sampling was by a hierarchical scheme. Estimates of variance components from these data were used in the estimation of the investigational allowances. Economic losses to the State of North Carolina, the farmers, and the manufacturer were estimated using various assumed prices and legal allowance establishment procedures. Setting the investigational allowances at 2.33 standard errors is confirmed.     

Effect of surface heat transfer coefficient gradient on thermal shock failure of ceramic materials under rapid cooling condition

A rapid thermal processor (RTP) device as well as quenching technique is employed to systematically investigate the effect of surface heat transfer coefficient (h) gradient on thermal shock failure of a hot-pressed ZrB₂-based ceramic. Two typical kinds of quenchant with different surface h gradients during quenching tests, water and boiling water, are used for this study. When water as the cooling medium, two different cooling modes of indirect contact cooling by RTP device and direct contact cooling by quenching are also studied. The experimental results and related numerical simulations illustrate that surface h gradient plays an important role in thermal shock failure. This study confirms the previous presumption that the combination of body temperature gradient and surface h gradient leads to thermal stress damage and thermal shock failure. Under water quenching condition, water phase changes form bubbles randomly and produce great surface h gradient. Accordingly, critical body temperature gradient (V(max)_c) is small (~ 270?°C?s^?1). Under aqueous polymer quenching condition, the introduction of polymer chains into water lowers the random formation of steam bubble and mediates the surface h gradient. The corresponding V(max)_c hence become larger (~ 500?°C?s^?1). Under boiling water quenching condition, there is no surface h gradient and V(max)_c is even larger (> 600?°C?s^?1). This study provides useful complementary information for understanding the thermal shock behavior and gives suggests for predicting materials performance in actual service.     

A new coke-slaking procedure

A method of simultaneous coke cooling and classification is described. The method consists of two stages: (1) dry cooling from about 1000 to 650°C; (2) water-jet cooling in drums from 650 to around 200°C. At the same time, coke of size class <25 mm is isolated and stabilized. The coke may be divided into two size classes. There is no need for a separate sorting structure. The coke is characterized by high strength and by low and constant moisture content; it does not break down to dust.     

断块油田古近系原油特征对比及分类评价

断块油田由于断裂输导体系丰富,原油往往来自于多个生烃凹陷或多套烃源岩,从而使得成熟度不同的油性混杂。这不仅造成原油归类难度大,而且使原油成熟度评价困难,因此需要使用比往常更多指标进行了综合分析。此次选取了断裂体系丰富的断阶带上的多个油田,使用原油碳同位素、族组分、异构烷烃,以及很多非常规的甾类和萜类化合物指标,对多层位多区域的原油进行了归类,并对原油成熟度评估。测试发现原油的δ~(13)C在Es3层段较高,Es1较低,Ed最低。从族组分上看,饱和烃比例最大,即以优质原油为主。通过各类标志物分析可将原油可分3类,Ⅰ类油δ13C较轻,Pr占优势,Ts/Tm值约1.9,C_(27)、C_(28)、C_(29)甾烷呈L或V型,属于成熟油,来自Es3段生烃母质;Ⅱ类油δ~(13)C也较轻,Pr含量比Ph高,Ts/Tm小于1.0,甾烷呈V型或倒L型,来自Es1下段生烃母质,综合评价部分属于成熟原油,部分属于低成熟重质油;Ⅲ类油则为性质介于两者之间的混合型原油,总体评价为高成熟度优质原油。     

An experimental study of the air-side particulate fouling in fin-and-tube heat exchangers of air conditioners

An experimental study was conducted to investigate the chronological performance variation such as pressure drop across a heat exchanger and cooling capacity due to the air-side particulate fouling of fin-and-tube heat exchangers for air conditioner evaporators used. Thirty samples of air conditioners used in the field such as inns, restaurants, and offices are collected in chronological order of use. This study was intended to provide factual long-term fouling data under actual operating conditions. It was found that the important parameters to influence the fouling of heat exchangers are the concentration and size of indoor pollutants, the filter efficiency, the hydrophilicity of fin surfaces, fin spacing, and the structure of fins. The pressure drop of heat exchangers increases from year to year due to the deposition of indoor pollutants larger than 1 Μm in size and increases up to 44% in the samples used for 7 years. Also, the air-side particulate fouling degrades the cooling capacity by 10-15% in the samples used for 7 years.     

Time and Space Uniformity of Indoor Bacteria Concentrations in Chicago Area Residences

The objective of this article is to assess spatial and temporal variation of indoor gram-positive bacteria and Staphylococcus sp. in 20 urban residences. At each residence, air was sampled at one outdoor site and four indoor sites (rooms) to assess spatial variation and once each season for five consecutive seasons to assess temporal variation. All temporal and spatial comparisons were performed using data obtained by the Andersen sampling technique. A secondary objective of this study is to evaluate relationships among several sampling methods used to measure bacteria levels; since differences in the measured concentrations are expected, the focus is to discern if corresponding measurements relate to each other. Not surprisingly, comparisons among the four sampling systems revealed statistically significant differences, although levels correlated relatively well. Using data only from the Andersen samplers, we conclude that seasonal variation is residence dependent with typically higher summer levels, but a clear pattern of variation could not be established. Room-to-room difference is not statistically significant, but the basement levels render the basement a distinct microenvironment. Indoor concentrations exceeded corresponding outdoor concentrations 75% of the time. Staphylococcus accounts for approximately 27% of the average indoor bacteria levels. The highest levels of gram-positive bacteria are found in the kitchen. The presence of multiple indoor sources with variable emission rates in multiple indoor locations results in bacteria levels that vary with time and space.     

泡沫镍板冷却特性的实验研究及数值模拟

以泡沫镍板为研究对象，采用实验与数值分析方法，研究了泡沫镍板在冷却过程的基本特性。实验结果表明，在泡沫镍板生产线正常运行期间，整个冷却过程可视为稳态过程，镍板各部分温度基本保持不变。较大温度梯度主要集中在两处，第一是还原性气体入口处，第二是高温水冷段的前半段。数值分析表明，改变镍板的运动速度时，第一温度梯度随着镍板运动速度的增加而增加，第二温度梯度随着速度的增加而减少，二者出现的位置也相应变化；改变高温水冷段水温时，水温升高引起第二温度梯度减小，对其他位置的温度场影响较小。