Keutenedjian Mady Carlos Eduardo, Reis Pinto Clara, Torelli Reis Martins Pereira Marina
School of Mechanical Engineering, University of Campinas, Mendeleyev St., 200-Cidade Universitária, Campinas 13083-970, Brazil.
Entropy (Basel). 2020 Jun 2;22(6):616. doi: 10.3390/e22060616.
This article proposes the utilization of the concepts of destroyed exergy and exergy efficiency for equipment and process performance indicators that are related to the current energy planning scenario in Brazil, more specifically with energy-efficiency labelling. Several indicators associated with these concepts are discussed, including one national program that is based on labeling the energy efficiency of several residential, commercial and industrial appliances. The grades are indicated in the equipment using values from A to G. This labeling system is useful for discriminating similar technologies used for the same function; nevertheless produced by different enterprises. For this complementary analysis, two types of refrigeration methods were compared, absorption and vapor compression; however, these energy indexes alone are not sufficient parameters to select among these two technologies, because their performance indexes definition are different. To address this, our research considers the second law of thermodynamics through exergy analysis as a proper sub-index to obtain a systematic comparison between these various indicators. It is significant to highlight that seldom research studies addressed to this problem so explicitly, in an actual governmental working solution, aiming at discussing to the society the advantage of the usage of the "quality of the energy" as a complementary index to governmental and personal choices. Results indicate that it is possible to use the destroyed exergy and exergy efficiency to help select the technology that better utilizes natural resources, considering the energy matrix of the country. Appliances for water heating and air conditioning were compared from energy and exergy viewpoint, where the last gave additional information about the quality of energy conversion process, giving a completely different trend from the energy analysis alone, without the necessity to think about the energy matrix. Later this issue is addressed from both points of view. Future studies may suggest an exergy based index. The energy efficiency suggests that electrical shower (values higher than 95%) are better than gas water heaters (83% ) in using natural resources, whereas the exergy efficiency shares similar magnitudes (about 3%). A related pattern is shown for the theoretical air conditioning systems. The vapor compression systems have an energy index higher than 3, and absorption systems lower than 1. For these circumstances, the exergy efficiency shows figures nearby 30%.
本文提出将㶲损失和㶲效率的概念用于与巴西当前能源规划情景相关的设备和工艺性能指标，更具体地说是与能源效率标签相关的指标。讨论了与这些概念相关的几个指标，包括一个基于对多种住宅、商业和工业电器的能源效率进行标签标注的国家计划。等级用A到G的值在设备上标明。这种标签系统有助于区分用于相同功能的类似技术，尽管这些技术由不同企业生产。对于这种补充分析，比较了两种制冷方法，即吸收式和蒸汽压缩式；然而，仅这些能源指标不足以在这两种技术中进行选择，因为它们的性能指标定义不同。为了解决这个问题，我们的研究通过㶲分析考虑热力学第二定律，将其作为一个合适的子指标，以便在这些不同指标之间进行系统比较。值得强调的是，在实际的政府工作解决方案中，很少有研究如此明确地针对这个问题，旨在向社会讨论使用“能源质量”作为政府和个人选择的补充指标的优势。结果表明，考虑到该国的能源矩阵，利用㶲损失和㶲效率有助于选择能更好利用自然资源的技术。从能源和㶲的角度对热水器和空调设备进行了比较，后者给出了关于能量转换过程质量的额外信息，呈现出与仅进行能量分析完全不同的趋势，而无需考虑能源矩阵。随后从两个角度探讨了这个问题。未来的研究可能会提出一个基于㶲的指标。能源效率表明，电热水器（值高于95%）在利用自然资源方面优于燃气热水器（83%），而㶲效率的数值相近（约3%）。理论空调系统也呈现出类似的模式。蒸汽压缩系统的能源指标高于3，吸收系统低于1。在这些情况下，㶲效率显示的数据接近30%。
