An assessment of fin-tube thermal contact resistance in round-tube-plain-fin heat exchangers

Fin-and-tube heat exchangers are used in a wide variety of applications. Heat exchangers with expanded tubes are economical, but a drawback is the potentially large contact resistance between tubes and fins. Previous studies have investigated this topic under the exclusion of air-side convection. The present work is more realistic, because the contact resistance is evaluated in the presence of air-side convection. The goal of this experimental work is to determine the contribution of the contact resistance to the overall heat transfer resistance in round-tube-plain-fin heat exchangers. The four samples have copper tubes with two different expansion ratios and aluminum fins with collars of two different lengths. The heat exchangers were examined in a wind tunnel under dry and frosted conditions to determine the contact resistance. The frosted heat exchangers are used as a baseline, because frost growth bridges the gaps between fins and tubes. The contact resistance was much higher for the unexpanded heat exchangers – about 30-60% of the overall resistance, whereas expanded heat exchangers exhibited a contact resistance of about 10-30% of the overall resistance.

Name thesis:degree_name

M.S.

Level thesis:degree_level

Thesis

Discipline thesis:degree_discipline

Mechanical Engineering

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2015

Author dc:creator

• Cortes, Maria

• Contact resistance
• Fin-tube heat exchanger

Statement dc:rights

• Copyright 2015 Maria Cortes

Language dc:language

en

Handle dc:identifier

http://hdl.handle.net/2142/78523

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/78523