Thermal conductivity of ethylene glycol at various temperatures

<strong>Thermal conductivity of ethylene glycol at various temperatures</strong> Junjie Chen Contributor: Junjie Chen, ORCID: 0000-0001-5055-4309, E-mail address: [e-mail], Department of Energy and Power Engineering, School of Mechanical and Power Engineering, Henan Polytechnic University, 2000 Century Avenue, Jiaozuo, Henan, 454000, P.R. China Ethylene glycol is mainly used for two purposes, as a raw material in the manufacture of polyester fibers and for antifreeze formulations. It is an odorless, colorless, flammable, viscous liquid. Ethylene glycol has a sweet taste, but it is toxic in high concentrations. Ethylene glycol is produced from ethylene, via the intermediate ethylene oxide. Ethylene oxide reacts with water to produce ethylene glycol. This reaction can be catalyzed by either acids or bases, or can occur at neutral pH under elevated temperatures. The highest yields of ethylene glycol occur at acidic or neutral pH with a large excess of water. Under these conditions, ethylene glycol yields of 90 percent can be achieved. The major byproducts are the oligomers diethylene glycol, triethylene glycol, and tetraethylene glycol. The separation of these oligomers and water is energy-intensive. Because the methanol is recycled, only carbon monoxide, hydrogen, and oxygen are consumed. The major use of ethylene glycol is as an antifreeze agent in the coolant in for example, automobiles and air-conditioning systems that either place the chiller or air handlers outside or must cool below the freezing temperature of water. In geothermal heating and cooling systems, ethylene glycol is the fluid that transports heat through the use of a geothermal heat pump. The ethylene glycol either gains energy from the source or dissipates heat to the sink, depending on whether the system is being used for heating or cooling. Pure ethylene glycol has a specific heat capacity about one half that of water. So, while providing freeze protection and an increased boiling point, ethylene glycol lowers the specific heat capacity of water mixtures relative to pure water. The freezing point depression of some mixtures can be explained as a colligative property of solutions but, in highly concentrated mixtures such as the example, deviations from ideal solution behavior are expected due to the influence of intermolecular forces. It's important to note that though pure and distilled water will have a greater specific heat capacity than any mixture of antifreeze and water, commercial antifreezes also typically contain an anti-corrosive additive to prevent pure water from corroding coolant passages in the engine block, cylinder heads, water pump and radiator. There is a difference in the mixing ratio, depending on whether it is ethylene glycol or propylene glycol. The use of ethylene glycol not only depresses the freezing point of aqueous mixtures, but also elevates their boiling point. This results in the operating temperature range for heat-transfer fluids being broadened on both ends of the temperature scale. The increase in boiling temperature is due to pure ethylene glycol having a much higher boiling point and lower vapor pressure than pure water, as is typical with most binary mixtures of volatile liquids. In the plastic industry, ethylene glycol is an important precursor to polyester fibers and resins. Polyethylene terephthalate, used to make plastic bottles for soft drinks, is prepared from ethylene glycol. Ethylene glycol is used in the natural gas industry to remove water vapor from natural gas before further processing. Thermodynamic temperature (degrees kelvin), Thermal conductivity (watts per meter-kelvin) 0.2549 280 0.2563 290 0.2576 300 0.259 310 0.2603 320 0.2616 330 0.263 340 0.2643 350 0.2645 288.15 0.2609 293.15 0.2695 353.15**不同温度下乙二醇（ethylene glycol）的热导率** 贡献者：陈俊杰，开放研究者与贡献者标识（ORCID）：0000-0001-5055-4309，电子邮箱：[e-mail]，单位：河南理工大学机械与动力工程学院能源与动力工程系，地址：中国河南省焦作市世纪大道2000号，邮编：454000。 乙二醇主要有两大应用方向：一是作为聚酯纤维生产的原料，二是用于防冻液配方。它是一种无臭、无色、易燃的粘性液体，味甜但高浓度下具有毒性。 乙二醇由乙烯经中间体环氧乙烷（ethylene oxide）制得：环氧乙烷与水反应可生成乙二醇，该反应可由酸或碱催化，也可在中性pH条件、高温环境下自发进行。在酸或中性pH且水大量过量的条件下，乙二醇产率最高，可达90%，主要副产物为二甘醇（diethylene glycol）、三甘醇（triethylene glycol）和四甘醇（tetraethylene glycol）等低聚物，分离这些低聚物与水需消耗大量能源。由于甲醇会被循环利用，因此仅消耗一氧化碳、氢气与氧气。 乙二醇的主要用途是作为冷却液中的防冻液，适用于将冷却器或空气处理器置于室外，或需要将介质冷却至水的冰点以下的汽车、空调系统等场景。在地热供暖与制冷系统中，乙二醇通过地热热泵实现热量传输：根据系统用于供暖还是制冷，乙二醇会从热源获取能量，或向热汇释放热量。 纯乙二醇的比热容（specific heat capacity）约为水的一半，因此尽管乙二醇水溶液能够提供防冻保护并提升沸点，但相较于纯水，其比热容会有所降低。部分混合溶液的凝固点降低（freezing point depression）可通过溶液的依数性（colligative property of solutions）解释，但在高浓度混合溶液中，受分子间作用力影响，其行为会偏离理想溶液。 需要注意的是，尽管纯水和蒸馏水的比热容高于任何防冻液与水的混合液，但商业防冻液通常还添加了防锈添加剂（anti-corrosive additive），以防止纯水腐蚀发动机缸体、气缸盖、水泵及散热器内的冷却液通道。乙二醇与丙二醇（propylene glycol）的混合比例存在差异。 使用乙二醇不仅可降低水溶液的冰点，还能提升其沸点，这使得传热流体的工作温度范围在温标的两端均得到拓宽。沸点升高的原因在于，纯乙二醇的沸点远高于纯水、蒸气压远低于纯水，这与大多数挥发性液体的二元混合物的特性一致。 在塑料工业中，乙二醇是生产聚酯纤维与树脂的重要前驱体，用于制作软饮料塑料瓶的聚对苯二甲酸乙二醇酯（Polyethylene terephthalate，PET）即由乙二醇制得。天然气工业中，乙二醇可在进一步加工前脱除天然气中的水蒸气。 本数据集包含的参数为：热力学温度（单位：开尔文，K）、热导率（单位：瓦每米-开尔文，W/(m·K)），具体实测数据如下： 280 K：0.2549 290 K：0.2563 300 K：0.2576 310 K：0.259 320 K：0.2603 330 K：0.2616 340 K：0.263 350 K：0.2643 288.15 K：0.2645 293.15 K：0.2609 353.15 K：0.2695