Abstract

Entropy and exergy analysis of a thermal system are the most powerful tools that can be employed to specify the optimum operating conditions of that system and utilization rate from the system. In the experimental thermal system in this work, entropy generation and exergy analyzes of GO–DW nanofluids have been carried out in straight copper pipes with constant heat load and 8 mm and 16 mm inner diameters. While the heat loads applied to the pipes are 250 W and 350 W, the range of fluid flow rate values in the pipes is 0.9 l/min–1.8 l/min. GO–DW nanofluids with 0.01% and 0.02% volumetric concentrations and DW have been used as working fluids in the pipes. The outcomes acquired from this work have been matched with the studies using different nanofluids in the literature and it has been noticed that the outcomes are reasonable and consistent. The results of the study have been presented at different GO–DW nanofluid concentrations in pipes with 8 mm and 16 mm inner diameters as thermal, friction and total entropy production, output exergy ratio and 2nd law efficiency. The obtained outcomes have exhibited that the lowest total entropy generation has been obtained for the 8 mm diameter pipe and the nanofluid with 0.02% GO–DW concentration. Besides, 2nd law efficiency is 12% higher for the 8 mm diameter pipe than 16 mm at flow rate of 1.2 l/min and 0.02% GO–DW nanofluid, and 350 W heat load.

中文翻译：

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不同直径直铜管 GO-DW 纳米流体实验热系统的熵和火用分析

摘要

热系统的熵和火用分析是最强大的工具，可用于指定该系统的最佳运行条件和系统的利用率。在本工作的实验热系统中，GO-DW纳米流体的熵产生和火用分析是在具有恒定热负荷、内径为8毫米和16毫米的直铜管中进行的。当施加到管道的热负荷为 250 W 和 350 W 时，管道中的流体流量值的范围为 0.9 l/min–1.8 l/min。体积浓度为0.01%和0.02%的GO-DW纳米流体和DW已被用作管道中的工作流体。这项工作获得的结果与文献中使用不同纳米流体的研究相匹配，并且注意到结果是合理且一致的。研究结果显示了内径 8 毫米和 16 毫米管道中不同 GO-DW 纳米流体浓度下的热、摩擦和总熵产、输出火用比和第二定律效率。获得的结果表明，8 mm 直径的管道和 0.02% GO-DW 浓度的纳米流体获得了最低的总熵产生。此外，在流量为 1.2 l/min、0.02% GO-DW 纳米流体和 350 W 热负荷下，8 mm 直径管道的第二定律效率比 16 mm 管道高 12%。