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Портал Begell Электронная Бибилиотека e-Книги Журналы Справочники и Сборники статей Коллекции
Journal of Enhanced Heat Transfer
Импакт фактор: 0.562 5-летний Импакт фактор: 0.605 SJR: 0.175 SNIP: 0.361 CiteScore™: 0.33

ISSN Печать: 1065-5131
ISSN Онлайн: 1026-5511

Выпуски:
Том 27, 2020 Том 26, 2019 Том 25, 2018 Том 24, 2017 Том 23, 2016 Том 22, 2015 Том 21, 2014 Том 20, 2013 Том 19, 2012 Том 18, 2011 Том 17, 2010 Том 16, 2009 Том 15, 2008 Том 14, 2007 Том 13, 2006 Том 12, 2005 Том 11, 2004 Том 10, 2003 Том 9, 2002 Том 8, 2001 Том 7, 2000 Том 6, 1999 Том 5, 1998 Том 4, 1997 Том 3, 1996 Том 2, 1995 Том 1, 1994

Journal of Enhanced Heat Transfer

DOI: 10.1615/JEnhHeatTransf.2017020547
pages 197-220

THE IMPACT OF FIN DEFORMATION ON FLOW BOILING HEAT TRANSFER AND PRESSURE DROP INMICROFIN TUBES

Sunil S. Mehendale
Michigan Technological University, Houghton, Michigan 49931, USA

Краткое описание

In air-conditioning and refrigeration (HVACR) equipment, microfin or internally grooved tubes are commonly used to enhance the thermal performance of evaporators and heat pumps. Such tubes are mechanically expanded by a mandrel into a fin pack to minimize the thermal contact resistance between the tube and the air side fins. However, tube expansion also deforms the inner enhancements to varying degrees, which degrades the in-tube thermal performance. Extensive published data on boiling heat transfer coefficients and pressure drop in pristine microfin tubes exist. However, there is lack of knowledge about the influence of microfin deformation on the thermal-hydraulic performance of microfin tubes. This brings into question the use of pristine tube data for designing HVACR heat exchanger equipment. In this work, we first present an analysis of the changes in the internal surface area of microfin tubes arising from tube expansion. A computational model of a coaxial tube heat exchanger is then used to estimate the changes in thermal-hydraulic performance of the expanded microfin tube. In-tube flow boiling of R-410A at 300 kg/m.s2 and 0°C saturation temperature, a condition typically encountered in HVACR applications is simulated. The tube heat transfer rate is degraded with increasing fin deformation, and the loss can be up to 5% for a tube with 10% fin deformation. The refrigerant pressure drop decreases by up to about 6% due to the increase in tube cross-sectional area and the loss in tube surface area caused by mechanical expansion of the tube.