Abstract:

With the implementation of national policy on green and low-carbon development, the energy efficiency evaluation of heat exchangers is becoming more and more important. Based on the first law of thermodynamics, the typical methods and evaluation indicators for energy efficiency evaluation of heat exchangers are sorted out, and the characteristics of each evaluation method and indicator are analyzed. The evaluation methods mainly focus on factors such as heat transfer coefficient, pressure drop, heat load, and heat transfer area. For refrigeration, heating and liquid-liquid phaseless transformation heat exchange scenarios, fluid physical properties and heat exchanger types are relatively single, so the evaluation methods of energy efficiency indicator and energy efficiency have proposed clear energy efficiency grades. For the refining and chemical industry, it is difficult to use a single method for energy efficiency evaluation because of the complex physical properties of fluid and the diverse types of heat exchangers. In practical applications, it is suggested to conduct a comprehensive compare of heat transfer performance, pressure drop and heat exchange capacity per area based on the specific situation and similar structure type, and obtain energy efficiency evaluation results that have guiding significance for production and operation.

Key words: the first law of thermodynamics, heat exchanger, energy efficiency evaluation, heat transfer coefficient, heat transfer efficiency, Nu, power factor, quality factor

摘要： 随着国家绿色低碳政策的推行，热交换器的能效评价越来越重要。基于热力学第一定律，对热交换器能效评价的典型方法和评价指标进行了梳理，分析了各评价方法和指标的特点，评价方法主要聚焦于传热系数、压力降、热负荷、换热面积等因素。对于制冷系统、供暖系统及液-液无相变换热场合，工质物性和热交换器型式比较单一，能效指标和能源效率两种评价方法均提出了明确的能效划分等级。对于炼油及化工行业，介质物性复杂、热交换器型式多样，很难采用单一方法进行能效评价。在实际应用中，建议针对特定工位、同类型结构型式，对传热性能、压力降以及单位面积换热量进行综合比较，得出对生产运行具有指导意义的能效评价结果。

关键词: 热力学第一定律, 热交换器, 能效评价, 传热系数, 传热效能, 努塞尔数, 功率因子, 质量因子