池沸腾中纳米颗粒再悬浮、热稳定性及迁移现象的实验研究

IF 1.1 Q3 Engineering

Journal of Thermal Engineering Pub Date : 2022-10-26 DOI:10.18186/thermal.1194805

R. P. Bharathwaj, M. B. Varun Pradeep, P. Padmanathan, A. Satheesh, N. R. Devi

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引用次数: 0

摘要

纳米粒子已被证明在显热和潜热交换中同样有效。纳米颗粒在相变过程中的应用与纳米颗粒的迁移和再悬浮有关，我们现有的知识非常有限。本文通过实验研究了纳米颗粒在相变过程中的迁移率、稳定性和再悬浮。对迁移率的了解是衡量后续工艺中热和润滑增强的必要条件。采用超声搅拌技术制备了质量分数为0.05、0.1、0.2、0.4的Al2O3/Water和CuO/Water纳米流体。质量分数大于0.5%的纳米流体随着时间的推移稳定性较差，结块和沉淀现象明显且不可避免。纳米流体在接近饱和温度的温度下迅速不稳定和凝聚。在有核沸腾期间观察到团聚块的再悬浮，其中测试流体变得非常不均匀。CuO/水纳米流体的迁移比Al2O3/水纳米流体的迁移比Al2O3/水纳米流体小23%。当质量分数为0.05 wt%时，Al2O3/水的最大迁移率为17.8%。当纳米颗粒的分子尺寸和基液的大小相似时，发现最大的迁移。在相变体系中加入纳米颗粒是不可取的。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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An experimental study on resuspension, thermostability and migration phenomenon of nanoparticles in pool boiling

Nanoparticles have proven to be effective in sensible and latent heat exchanges alike. Applications of nanoparticles in phase change processes are associated with migration and resuspension of nanoparticles upon which our existing knowledge is very limited. This work experimentally investigates the migration ratio, stability and resuspension of nanoparticles during phase change. Knowledge on migration ratio is essential to gauge the thermal and lubricative enhancements in the subsequent processes. Al2O3/Water & CuO/Water nanofluids were prepared in four mass fractions (0.05, 0.1, 0.2, 0.4) using ultrasonic agitation technique. Nanofluids with mass fraction higher than 0.5% displayed poor stability over time also, agglomeration and sedimentation were pronounced and inevitable. Nanofluid destabilises and agglomerates rapidly at temperatures closer to saturation temperature. Resuspension of agglomerated chunks were observed during nucleate boiling where the test fluid became extremely nonhomogeneous. Migration ratio was found to commensurate with volume fraction where CuO/water nanofluid exhibited 23% lesser migration ratio than Al2O3/water nanofluid. Maximum migration ratio of 17.8% was observed for Al2O3/water with 0.05 wt%. Maximum migration was found when the molecular dimensions of nanoparticles and the base fluid are of similar magnitudes. It is inadvisable to involve nanoparticles in phase change systems.

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来源期刊

Journal of Thermal Engineering THERMODYNAMICS-

CiteScore

2.40

自引率

18.20%

发文量

审稿时长

4 weeks

期刊介绍： Journal of Thermal Enginering is aimed at giving a recognized platform to students, researchers, research scholars, teachers, authors and other professionals in the field of research in Thermal Engineering subjects, to publish their original and current research work to a wide, international audience. In order to achieve this goal, we will have applied for SCI-Expanded Index in 2021 after having an Impact Factor in 2020. The aim of the journal, published on behalf of Yildiz Technical University in Istanbul-Turkey, is to not only include actual, original and applied studies prepared on the sciences of heat transfer and thermodynamics, and contribute to the literature of engineering sciences on the national and international areas but also help the development of Mechanical Engineering. Engineers and academicians from disciplines of Power Plant Engineering, Energy Engineering, Building Services Engineering, HVAC Engineering, Solar Engineering, Wind Engineering, Nanoengineering, surface engineering, thin film technologies, and Computer Aided Engineering will be expected to benefit from this journal’s outputs.