Impact of Relative Humidity of Supply Gas on Temperature Distributions in Single Cell of Polymer Electrolyte Fuel Cell When Operated at High Temperature

For improving the performance of stationary PEFC （polymer electrolyte fuel cell） system, the cell operating temperature up to 90℃ will be preferred in Japan during the period from 2020 to 2030. To understand the operation of the PEFC system under relatively high temperature conditions, detail heat and mass transfer analysis is required. The purpose of this study is to analyze the impact of relative humidity of supply gas on temperature distribution on the backside of separator in single ceil of PEFC using Nation membrane at higher temperature e.g. 90℃. The in-plane temperature distribution when power was being generated was measured using thermograph with various relative humidity of supply gases. It was found that the in-plane temperature distribution at the anode was more even than that at the cathode irrespective of the relative humidity of supply gas at the anode and the cathode. The temperature elevated along gas flow through the gas channel at the cathode irrespective of relative humidity of supply gas at the anode and the cathode. The in-plane temperature distribution at the cathode was narrower with the increase in Tini irrespective of relative humidity of supply gas at the cathode, while it was not observed when changing the relative humidity of supply gas at the anode. When the relative humidity of supply gas at cathode decreased, the in-plane temperature distribution at the anode was wider compared to decreasing the relative humidity of supply gas at the anode. The study concluded that the impact of relative humidity of supply gas at both anode and cathode had little impact on the in-plane temperature distribution at the cathode.

Effects of Extreme Air Temperature and Humidity on the Insecticidal Expression Level of Bt Cotton

The higher survival rates of Helicoverpa amigera larvae were usually observed after adverse climate which was related to extreme temperature （T） and relative humidity （RH） stresses in transgenic Bacillus thuringiensis （Bt） cotton. The unstable resistance of Bt cotton to bollworms has been correlated with the reduced expression of CrylAc δ-endotoxin. The objective of this study was to investigate the effects of combined temperature and relative humidity stresses on the leaf CrylAc insecticidal protein expression during critical developmental stages. The study was undertaken on two transgenic cotton cultivars that share same parental background, Sikang 1 （a conventional cultivar） and Sikang 3 （a hybrid cultivar）, during the 2007 and 2008 growing seasons at the Yangzhou University Farm, Yangzhou, China. The study was arranged with two factors that consisted of temperature （two levels） and relative humidity （three levels）. The six T/RH treatments were 37℃/95%, 37℃/70%, 37℃/50%, 18℃/95%, 18℃/70%, and 18℃/50%. In 2007, the six treatments were imposed to the plants at peak flowering stage for 24 h; in 2008, the six treatments were applied to the plants at peak square, peak flowering, and peak boll stages for 48 h. The results of the study indicated that the leaf insecticidal protein expression in CrylAc was significantly affected by extreme temperature only at peak flowering stage, and by both extreme temperature and relative humidity during boll filling stage. The greatest reductions were observed when the stresses were applied at peak boll stage. In 2008, after 48 h stress treatment, the leaf Bt endotoxin expression reduced by 25.9-36.7 and 23.6-40.5% at peak boll stage, but only by 14.9-26.5 and 12.8-24.0% at peak flowering stage for Sikang 1 and Sikang 3, respectively. The greatest reduction was found under the low temperature combined with low relative humidity condition for both years. It is believed that the temperature and relative humidity stresses may be attributed to the reduced efficacy of Bt cotton in growing conditions in China, where extreme temperatures often increase up to 35-40℃ and/or decrease down to 15-20℃, and relative humidity may reach to 85-95% and/or reduce to 40-55% during the cotton growing season.

Effects of high temperature and high relative humidity drying on moisture distribution,starch microstructure and cooking characteristics of extruded whole buckwheat noodles

Drying is a key step in starch noodle production.The effects of high temperature(60,70,80°C)and high relative humidity(65%,75%,85%)drying(HTHD)on the moisture distribution,starch microstructure and cooking characteristics of extruded whole buckwheat noodles were investigated.Compared to the conventional hot-air drying(CHAD)at 40°C,the increase in drying temperature(60–80°C)and the decrease in relative humidity(85%–65%)significantly improved drying efficiency of the extruded noodles.By adjusting drying temperature and relative humidity,the rate of moisture migration in noodles and phase transition of starch could be appropriately controlled.The optimum drying parameters(T70H75,70°C drying temperature and 75%relative humidity)showed smooth and dense network structure,resulting in the lowest cooking loss(6.61%),broken rate(0%),highest hardness(1695.17 g)and springiness(0.92).However,the total flavonoid content(TFC)and the total phenolic content(TPC)reduced by 6.81%–28.50%and 7.19%–53.23%in contrast to CHAD,and the color of buckwheat noodles became darker through HTHD.These findings showed the potential of HTHD for increasing drying efficiency and improving buckwheat noodle quality.The appropriate drying parameters could maintain a balanced relationship between moisture migration in noodles and phase transition of starch,which resulted in better cooking quality for extruded whole buckwheat noodles.Such a study is valuable for regulating the process conditions of buckwheat-based foods and promoting its commercial utilization.

Low-temperature combined with high-humidity thawing improves the water-holding capacity and biochemical properties of Portunus trituberculatus protein

This study compared the effects of conventional thawing methods(water immersion thawing(WIT,(25±1)℃),natural air thawing(AT,(25±1)℃,relative humidity(RH(65±2)per cent),refrigerator thawing(RT,4℃,RH(80±2)per cent)and low-temperature(LT)combined with high-humidity thawing LT,-1℃to 1℃(LT-1-1),2-4℃(LT2-4),5-7℃(LT5-7)and 8-10℃(LT8-10),RH>95 per cent)on the water-holding capacity,lipid oxidation and biochemical properties of Portunus trituberculatus(P.trituberculatus)myofibrillar protein.The results showed that WIT and AT significantly decreased the water-holding capacity while dramatically increasing lipid oxidation,protein oxidation and degeneration,resulting in serious P.trituberculatus quality deterioration.High humidity was beneficial for P.trituberculatus\.ha\A/\ng.The thawing time of P.trituberculatus under the conditions of LT2-4 was only 39.39 per cent of that of conventional air thawing at 4℃(RT),and the LT2-4 samples not only maintained better water-holding capacity but also had an obviously reduced degree of lipid oxidation,protein oxidation and denaturation.Thawed samples LT2-4 and LT5-7 provided better maintenance of P.trituberculatus quality than the LT-1-1 and LT8-10 samples.The best quality was exhibited after thawing at 2-4℃.The levels of thiobarbituric acid reacting substances,carbonyl content and surface hydrophobicity observably decreased in these samples,while the total sulfhydryl contents dramatically increased compared to those of conventionally thawed samples,indicating lower lipid oxidation and protein oxidation.Moreover,the Ca2+-ATPase activity of the sample thawed at 2-4℃(2.06 μmol Pi/mg prot/h)was markedly higher than that of samples subjected to WIT and AT.The product qualities observed after thawing at-1℃to 1℃,5-7℃and 8-10℃under LT were comparable to that observed by RT.Considering its thawing efficiency and product quality,LT is a suitable method for the thawing of P.trituberculatus,and the ideal thawing conditions were LT at 2-4℃.

Numerical Analysis of Temperature Distributions in Single Cell of PEFC by Heat Transfer Model Considering Vapor Transfer

Polymer Electrolyte Fuel Cell(PEFC)is required to be operated at temperature at 100℃ for fuel cell vehicle applications during the period from 2020 to 2025 in Japan.It is expected that micro porous layer(MPL)and thinner polymer electrolyte membrane(PEM)would enhance the power generation performance of PEFC at this temperature.The key objective of this study is to analyse the impact of MPL and thickness of PEM on the temperature distributions of interface between the PEM and catalyst layer at the cathode(i.e.,the reaction surface)in a single PEFC.A 1D multi-plate heat transfer model,considering vapor transfer,which is based on temperature data of separator measured using thermograph in power generation process.It is developed to evaluate temperature at the reaction surface.This study is investigated the effect of flow rate and relative humidity of supply gases on temperature distribution on reaction surface.The study reveals that the impact of flow rate of supply gas on temperature distribution on reaction surface is smaller with and without MPL.It is observed that the even temperature distribution on reaction surface as well as higher power generation performance can be obtained with MPL irrespective of thickness of PEM and relative humidity conditions.

低压静电场协同低温高湿解冻对牛肉嫩度和持水性的影响

为探究低压静电场协同低温高湿解冻对牛肉嫩度和持水性的影响,本研究以牛背最长肌为试验材料,分析了低压静电场解冻(电压2500 V,温度4℃,相对湿度50%)、低温高湿解冻(温度4℃,相对湿度98%)、低压静电场协同低温高湿解冻(电压2500 V,温度4℃,相对湿度98%)与低温解冻(温度4℃,相对湿度50%)四种解冻方式对冷冻牛肉剪切力、质构、水分分布、水分含量、持水性、感官评价的影响。结果表明:低压静电场协同低温高湿解冻的解冻时间最短(804 min),其中解冻损失(2.06%)、蒸煮损失(26.09%)与离心损失(15.00%)显著低于其余三种解冻方式(P<0.05),垂直肌纤维剪切力值(95.46 N)和平行肌纤维剪切力值(41.69 N)最低,自由水含量最低,水分迁移较少,水分含量(68.31%)最高,嫩度品质最优,该解冻方式样品的组织状态、气味、弹性及色泽均最优(总体可接受度最高);综上,低压静电场协同低温高湿解冻加快了牛肉解冻速率、减少了汁液流失,改善了牛肉持水性和嫩度,品质最佳。本研究结果将为低压静电场协同低温高湿解冻技术在冷冻牛肉解冻的产业应用提供理论依据。

高干热现场环境下智能电能表可靠性验证方法

智能电能表通用技术规范要求电能表可靠寿命不低于16年,如何验证智能电能表可靠性不仅是行业亟需解决的现实问题,也是学术界面临的难点问题。文章在Weibull分布场合下给出了针对可靠寿命、平均寿命和失效率三项指标的可靠性验证抽样特性函数。结合高干热环境的加速效应,借助加速因子构建基于加速试验的电能表抽样特性函数,进而针对智能电能表的工程背景确定二参数抽样方案。在实验验证与分析中给出了高干热环境下智能电能表可靠性验证方案,在不同使用方风险、可接受的故障数条件下计算了试验样本容量与试验时间的组合,给出了表格和绘图,方便工程应用。对电力行业量测设备在高干热环境下开展可靠性验证具有示范作用。

不同时间的低温高湿暴露环境对运动主体血糖的影响分析

目的:探讨运动主体在不同时间的低温高湿暴露环境中血糖的变化规律。方法:采用文献资料法、实验法、数理统计法等研究方法,以低温雨雪冰冻天气作为实验模拟环境,以小鼠为实验对象。根据体质量随机分为常温常湿1.5 h组、低温高湿1.5 h组、常温常湿2 h组、低温高湿2 h组、常温常湿3 h组、低温高湿3 h组、常温常湿4 h组、低温高湿4 h组。各组连续间断暴露7天并禁食12 h后,第8天进行力竭游泳实验并测血糖。结果:与常温常湿组对比,低温高湿1.5 h、低温高湿4h组血糖浓度均升高,且低温高湿4 h组有显著性差异(P<0.01);低温高湿2h组、低温高湿3h组血糖浓度均下降,且低温高湿2 h组有显著性差异(P<0.05)。结论:在不同时间的低温高湿环境暴露下,小鼠的血糖浓度会出现不同的变化,其中低温高湿4 h组的血糖浓度变化最为显著,表明低温高湿环境对机体的血糖调节有明显影响,且暴露时间和强度是影响血糖变化的重要因素。本文研究对运动员、教练员或长期从事低温作业的人群掌握低温高湿环境下血糖的变化规律,合理调整饮食和运动计划具有一定的参考意义。

高黏度改性沥青材料在湿热环境下的路用性能评估

高黏度改性沥青在湿热环境下的路用性能试验评估结果表明,其具备优异的性能。在高温多雨的湿热地区,通过增强沥青与集料的黏结力,使用高黏度改性沥青可显著提升路面的高温稳定性和抗水损害能力。适量添加SBS和废胶粉,不仅增强了沥青的内聚力,还改善了其低温韧性,确保了路面的耐久性。在湿热条件下高黏度改性沥青的施工性能和易性良好,能够满足复杂环境下的施工要求。高黏度改性沥青在湿热环境下展现出卓越的路用性能,为提升道路安全性和舒适性提供了有力保障。

双冷源温湿度分控系统在上海某办公建筑项目的应用

首先对一种节能低碳的新型空调冷源技术——双冷源温湿度分控系统进行简要介绍,随后结合压焓图与焓湿图对双冷源温湿度分控系统的节能原理进行理论分析。再结合上海某办公建筑项目实际工程,分为单冷源系统、双冷源低温定频+中温系统以及双冷源低温变频+中温系统三个方案对冷水机房全年综合能效值EER与全年负荷进行数据对比分析,进一步验证双冷源温湿度分控系统能够显著提升冷水机房全年综合能效值以及双冷源系统低温侧采用初投资较低的定频机组节能效果更佳的结论。

低温高湿变温解冻库的研制与应用

为解决现有冻肉解冻库解冻速率慢、营养流失大、解冻过程氧化劣变严重等问题，研制了一种新型的低温高湿变温解冻库，该解冻库由绝热库体、蒸汽加热加湿系统、变频制冷系统和控制系统组成。通过各系统的协调运作，使库内温度始终维持在2-8℃，相对湿度始终保持在90％以上，从而实现冻肉解冻过程中的有效保鲜。同时通过低温高湿变温解冻库解冻20t冷冻牛肉的加热负荷、制冷负荷、加湿蒸汽量及总蒸汽量等工艺参数的优化计算，研制出用于冷冻肉解冻的20t低温高湿变温解冻库，并进行了生产验证试验，比较分析了该解冻库与常规4℃解冻库对解冻牛肉品质的影响。结果表明，该低温高湿变温解冻库解冻入库平均温度为-18℃的20t冷冻牛肉耗时约12h，加热负荷为95．94kw，制冷负荷为18．77kW，加湿蒸汽量为8．78g／s，需要总蒸汽量为49．19g／s；与常规4℃解冻库相比，低温高湿变温解冻库解冻汁液流失率、汁液蛋白含量及解冻牛肉蒸煮损失率分别显著降低了44．17％，21．61％及20．30％，解冻牛肉肌红蛋白含量显著增加了41．04％，高铁肌红蛋白含量显著降低了58．69％，硬度及咀嚼性分别显著增加了39．86N及15．11N，实现了冷冻牛肉的保鲜解冻。该研究为低温高湿变温解冻库的研制提供了参考，有利于解决冷冻肉解冻过程中的品质劣变问题。

猕猴桃低温动态高湿过饱和态贮藏工艺的试验研究

为了延长猕猴桃的贮藏寿命 ,提出了随着贮藏期的不同 ,对猕猴桃实行低温动态跟踪和高湿度过饱和态贮藏 ,依此原理进行了实验。结果表明 ,在低温动态和高湿过饱和态条件下贮藏的猕猴桃与常规贮藏工艺相比 ,果实的硬度比传统贮藏法高出 5 0 .96 N/cm2 ,保持良好 ,使猕猴桃的商品寿命延长 30 d以上 ;霉果率下降 3～ 5个百分点 ;果实失重率下降 8个百分点。

能源塔热泵技术在空调工程中的应用与分析

介绍了能源塔热泵技术的发展、原理和分类,分析了能源塔热泵的特点,简要阐述了能源塔热泵的关键技术问题、设计要点和运行管理方式。指出能源塔不同于冷却塔,用冷却塔代替能源塔会因为吸收低品位热源的能力不足而使能源塔热泵不能正常工作。将能源塔与其他空调方式进行了比较,认为在我国长江以南地区的新建建筑或既有建筑改造中,能源塔热泵是一种制冷制热设备的新选择。

高温干燥和高温高湿处理蚕丝织物的老化状况分析

研究不同温度、湿度条件下蚕丝织物的老化速度及老化程度,为科学制定丝绸文物保护和储藏技术方案提供依据。分别将蚕丝织物置于75、100、125和150℃的高温干燥及高温高湿环境中处理20 d,在不同处理时间取样测试蚕丝织物的力学性能、表面形貌、红外光谱和氨基酸含量。在高温干燥或高温高湿条件下,处理温度越高蚕丝织物的断裂强力下降速度越快、下降程度越高,丝纤维表面形貌的变化程度越显著,丝蛋白中的酪氨酸含量下降明显,且丝纤维酰胺Ⅰ区的吸收峰位向低波数方向移动。当温度达到125℃、150℃时,高温高湿处理蚕丝织物样品的—NH伸缩振动吸收峰峰形变窄且相对峰强度增大,丝蛋白中的天冬氨酸和苯丙氨酸的含量也明显下降;而高温干燥处理样品的变化不明显。研究结果表明:温度越深,蚕丝织物的老化速度越快,老化程度越深,并且高温高湿的影响更为明显。

不同地理种群玉米螟赤眼蜂对极端温湿条件的反应

在高温低湿(31℃,45%RH和34℃,45%RH)和低温低湿(16℃,45%RH和19℃,45%RH)不同温湿组合条件下,以亚洲玉米螟卵为寄主,研究了不同地理种群玉米螟赤眼蜂的寿命、生殖力和性比情况。结果表明,在31℃,45%RH条件下,北京种群和日照种群平均每雌分别寄生(17.60±1.70)粒和(17.44±1.46)粒,显著高于其他种群(p<0.05)。在19℃,45%RH条件下,广东广州种群寄生寄主卵数最多,平均每雌寄生(26.65±2.17)粒,与其他种群差异显著(p<0.05)。北京种群、日照种群和广州种群分别可以作为高温低湿和低温低湿条件下防治亚洲玉米螟的候选种群。

氨基酸硒对桃设施栽培环境适应性的影响

探讨了硒提高桃适应设施栽培环境的效果,为提高设施桃的环境适应能力和改善果实品质调控技术提供依据。以4年生桃设施栽培的主栽品种中油4号油桃和春雪毛桃为试验材料,研究氨基酸硒对桃光合作用光响应曲线、二氧化碳响应曲线、温度响应曲线和蒸腾速率的影响。喷施氨基酸硒使设施桃的光补偿点和二氧化碳补偿点显著降低,表观量子效率和羧化效率显著提高,使设施桃净光合速率在高温条件下保持较高数值且呈平稳状态,显著促进了设施桃的蒸腾作用。喷施氨基酸硒显著增强了桃对设施弱光、二氧化碳浓度低、高温和高湿环境的适应能力,为设施桃品质的改善奠定了良好基础,因此,喷施氨基酸硒是一项切实可行的提高桃对设施环境适应能力的重要农艺措施。

地下微孔渗灌的节水机理及控制初探

田间试验结果证明，采用地下微孔渗灌技术，能显著提高作物的水分利用效率。如茄子、冬小麦的水分利用效率分别比对照提高１７．７％、４１．２％。并从理论上分析了地下微孔渗灌提高作物水分利用效率的机理是减少地面土壤物理蒸发。提出了应用ＤＴＳ－Ⅱ型土壤水分测控仪，可根据土壤湿度状况对地下微孔渗灌的灌水量实施控制。

高温环境下空气湿度对花期番茄生长及根系分泌的调节作用

以番茄品种“金冠5号”为试材,设置2个日动态温度(T)水平即日最高气温/日最低气温分别为32℃/22℃和38℃/28℃、3个空气相对湿度(RH)水平(50%±5%、70%±5%和90%±5%)和4个持续时间(3d、6d、9d和12d),并以25℃/15℃、50%±5%为对照(CK),分别测定各处理结束后0d、7d、14d、21d和28d时植株叶片的净光合速率(Pn)、植株总干重(Wtotal)、根系干重(Wroot)和活力(Rv)以及根系土壤中低分子量有机酸(LMWOAs)的类型和浓度,以探究高温环境下空气湿度对花期番茄生长及灾后恢复的调节机制。结果表明:(1)高温下植株的Pn和Rv下降,但根冠比和LMWOAs显著提高,且32℃处理下各指标值显著高于38℃,提高RH至70%可显著提高植株的Pn、Wroot和根冠比。(2)花期番茄主要分泌草酸和琥珀酸,高温下草酸、苹果酸、乳酸、乙酸和丙酸分泌量增加,酒石酸和甲酸分泌量减少。(3)环境温度和湿度均与LMWOAs呈显著负相关关系,Pn、Wroot、Wtotal和Rv与LMWOAs呈显著正相关。(4)高温下提高空气湿度至70%可增加Pn和Wroot,并促进根系分泌LMWOAs,有利于灾后番茄的恢复生长,但空气湿度达到90%则降低了叶片Pn和Wroot,加剧了高温对植株的损伤,不利于灾后恢复。因此,70%左右空气湿度可以在一定程度上缓解高温对番茄苗造成伤害。

家蚕胚胎期对高温干燥催青耐受性的遗传分析

本文运用完全双列杂交的方法 ,估测了家蚕在胚胎期对高温干燥催青条件耐受性的有关遗传参数。家蚕种对高温干燥催青的耐受性 ,在原种间和杂交组合间有明显差异。耐受性是一种遗传性性状 ,由遗传基因控制。经估算的广义遗传力大于狭义遗传力。有超显性现象。控制家蚕对高温干燥催青的耐受性的基因数目不少于两个。显性效应大于加性效应。显性效应为非单向性的。显性位点上的基因分布为不对称性。

宽温压力可变标准湿度发生器的研制

采用双温双压法原理研制了一套宽温度范围、测试室压力可变的标准湿度发生器。它能够测量发生温度范围为-50-90℃、相对压力范围为-50-0kPa、扩展不确定度为0．3％RH-0．8％RH（k=2）的5％RH-96％RH全量程相对湿度。其测试室尺寸为φ150mm×400mm，样气流量为5-30L／Min。通过设计高精度饱和器压力和流量自动调节装置，采用工控机与PLC相结合的操作控制方式，实现了全自动运行。冷镜式精密露点仪和重量法湿度计的实际测试结果均验证了其不确定度。