Thermal energy storage and thermodynamic properties of (E)-3-m-tolylbut-2-enoic acid as a medium temperature phase change material

Phase change materials (PCMs) that can store and release heat energy over the temperature range from 363 to 393 K are crucial for solar absorption cooling, and it is worthy to seek new solid-liquid PCMs candidates that melt and crystallize in this temperature range. In this paper, (E)-3-m-tolylbut-2-enoic acid (mTBEA) was applied as a PCM candidate. Its thermal energy storage properties and thermal stability were systematically investigated. The results showed that mTBEA melted at 382.9 ± 0.5 K and crystallized at about 364 K, with a melting enthalpy (Δ_fusH) of 138.4 ± 6.9 J g^?1 and showed good long-term cyclic stability and thermal stability. The supercooling of mTBEA was stabilized at about 20 K, indicating that the conservation condition of melted mTBEA could be simple. In addition, the melted mTBEA could release all the absorbed thermal energy upon crystallizing. Besides, mTBEA exhibited good thermal stability for it to be applied as PCM. Hence, mTBEA is a promising PCM candidate for solar absorption cooling. Furthermore, the heat capacity of mTBEA was measured by modulated temperature differential scanning calorimetry (MTDSC) over the temperature range from 198.15 to 431.15 K, and the molar thermodynamic functions, [H_T-H_298.15]_m and [S_T-S_298.15]_m, were calculated based on the fitted molar heat capacity data.     

Effectiveness of a cooling jacket with reference to physiological responses in iron foundry workers

Personal cooling garments (PCGs) have gained increased attention in recent years due to heat stress and strain in the working environment. The present study was conducted in hot environments of an iron foundry to evaluate the efficacy of a battery-operated PCG. Twenty-four workers were exposed to climatic conditions of 35.89?±?1.25?°C, 35% relative humidity during 90-min work with PCG and habitual clothing (HC). Mean weighted skin temperature was significantly lower by 4.84?±?1.05?°C compared with HC 0.38?±?1.02?°C (p?p?相似文献   

磨床冷却水循环处理技术

采用混凝斜管沉淀工艺，处理磨床使用后的冷却水，使之达到循环回用的指标，避免了水资源的浪费，减少了对环境的污染。运行实践说明，该系统的运行费用与节约的水及原料的费用大至相等，维护简单，有利于环境保护。     

我国城市污水回用作火电厂循环冷却水的研究

通过对我国城市污水回用作火电厂冷却水时的水质、水量、引起的问题及其处理技术、经济效益等方面的分析研究，说明了回用的可行性，并在此基础上提出了几点看法。     

Comparative thermodynamic performance analysis of a cascade system for cooling and heating applications

In this study, a comparative thermodynamic performance analysis of cascade system (CCS) for cooling and heating applications is presented and compared for different refrigerant couples. The CCS consists of the low-temperature cycle (LTC) and high-temperature cycle (HTC). The CO₂ was used as working fluid in LTC, whereas the HFE 7000, R134a, R152a, R32, R1234yf, and R365mfc refrigerants were used in HTC. The heating and cooling coefficients of performance (COP_ht, COP_cl) and exergy efficiency of CCS are investigated parametrically according to various factors such as the evaporator, condenser, and reference temperatures. After thermodynamic analyses are completed, the COP_cl of CCS is obtained as 1.802, 1.806, 1.826, 1.769, 1.777, and 1.835 for CO₂-HFE7000, CO₂-R134a, CO₂-R152a, CO₂-R32, CO₂-R1234yf, and CO₂-365mfc refrigerant couples, respectively. Furthermore, the heat exchanger has the highest exergy destruction rate, whereas the expansion valves have the lowest of exergy destruction rate.     

火电厂空冷机组水耗及煤耗性能分析

采用空冷机组是解决富煤贫水地区发电的有效措施,在中国西北部运用有着极为实际的意义,因此对中国燃煤电厂空冷机组的节水性能进行定量分析也具有现实意义。文章从国内外火电厂直接空冷机组与间接空冷机组发展的历史过程出发,在对近100个不同等级、不同冷却方式的火电项目样本进行统计分析的基础上,分别对直接空冷、间接空冷机组与常规火电机组的水耗及煤耗性能进行定量分析与比较,得出相应的水耗及煤耗结果,给出了水耗与煤耗的相关性,并给出相应的火电厂节水建议。     

高温矿井掘进工作面冰块降温数值模拟研究*

为确定冰块在矿井高温掘进工作面降温中的设计参数,以大红山铜矿西矿段高温掘进工作面为对象,开展通风降温和冰块降温下掘进工作面温度场变化的数值模拟,分析冰块量、摆放方式对掘进巷道工作面附近温度场的影响。结果表明:与只采用通风降温方案相比,增加冰块的降温方案降温效果明显;当冰块摆放方式相同时,冰块量越多,有效制冷时间越长,但增加到一定程度时有效制冷时间基本不变;冰块摆放方式对降温效果有显著影响,在相同的冰块量及同一水平摆放方式下,冰块摆放高度与风筒齐平时的降温效果最佳;当冰块量及垂直摆放方式相同时,距掘进工作面越远,掘进工作面附近温度场温度的分布越均匀,制冷空间越大。     

关于钢铁工业海水直接利用的技术探讨

在工业领域中钢铁工业是用水大户,临海建厂是未来中国钢铁产业布局的方向。向海洋要淡水,取之不尽、用之不竭。将海水直接利用于生产,可减少海水淡化成本、节约能源、降低钢铁企业生产成本。就钢铁企业的海水直接利用技术进行了初步的分析和探讨,可作为实际工程的参考。     

地面输油管道泄漏流散数值模拟

针对库区地面输油管道发生泄漏后油品流散行为的不确定性,建立了地面油品泄漏流散的三维CFD仿真模型,模拟了不同管道运行压力和不同泄漏孔径下油品在地面上的流散过程,得到了油品扩展速度关于泄漏流量的关系式和流散面积关于管道压力、泄漏孔径、流散时间的偏微分方程组。结果表明:流散面积随管道压力增大呈线性函数增大;流散面积随泄漏孔径呈三次函数变化,先减小后增大;在泄漏的开始阶段,流散面积随泄漏时间的变化随管道压力呈线性增长,在扩展达到稳定时,扩展速度随泄漏流量呈指数函数增大。     

双压入贴附送风在高温巷道掘进中的降温规律研究

为量化研究高温矿井深部开采掘进巷道在抽压混合通风中设备布置及风量分配对降温效果的影响规律问题,利用AN-SYS-FLUENT软件数值模拟掘进巷道通风降温模型.首先,提出双压入式混合贴附通风降温思路,并分别建立传统抽压混合通风与双压入式混合通风的巷道三维几何模型;然后,进行6组不同设备布置及风量分配的降温方案对比实验;最...