Performance and optimization of microchannel condensers
Heun, Matthew Kuperus
This item is only available for download by members of the University of Illinois community. Students, faculty, and staff at the U of I may log in with your NetID and password to view the item. If you are trying to access an Illinois-restricted dissertation or thesis, you can request a copy through your library's Inter-Library Loan office or purchase a copy directly from ProQuest.
Permalink
https://hdl.handle.net/2142/20421
Description
Title
Performance and optimization of microchannel condensers
Author(s)
Heun, Matthew Kuperus
Issue Date
1995
Doctoral Committee Chair(s)
Dunn, William E.
Department of Study
Mechanical Science and Engineering
Discipline
Mechanical Engineering
Degree Granting Institution
University of Illinois at Urbana-Champaign
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
Engineering, Mechanical
Language
eng
Abstract
This study is the first to document the condensation heat transfer performance of small diameter, microchannel tubes in crossflow heat exchange, and this study provides the first systematic evaluation of the effect of port shape on microchannel tube performance. Furthermore, this study is the first to suggest methods for improving microchannel heat exchanger designs.
We collected experimental data for flat, multiport tubes with hydraulic diameters in the range of 0.6 mm $\leq\rm D\sb{h}\leq$ 1.5 mm. The port shapes considered were circles, squares, triangles, enhanced squares, and small squares. We found that established relationships describe single-phase circular-tube heat transfer and pressure drop behavior in microchannel tubes. Circular-tube correlations are appropriate length scales. The wavy flow correlation of Dobson (1994) was found to predict accurately condensing heat transfer in flows predicted to wavy. A slightly modified form of the Dobson (1994) annual flow correlation was found to predict accurately condensing heat transfer in flows predicted to be annular.
An analytical study of methods to improve microchannel condenser design was performed. We found that volume minimization is a comprehensive and reasonable objective for the suboptimization analysis. As condenser volume is reduced, system charge, condenser mass, and material costs all decrease.
Refrigerant-side circuiting flexibility is the key that unlocks the potential of the microchannel technology. With unconstrained refrigerant circuiting, smaller port diameters always lead to reduced condenser volume. However, the pressure-drop effect drives optimal condenser designs toward many tubes of short length, and the crossflow-heat-exchanger effect drives optimal condenser designs toward many tubes of short length and few ports.
We found that port shape significantly impacts condenser designs. To achieve reduced internal volume, the order of preference for port shapes is circle, square, and triangle. To achieve minimized external volume, the order of preference for port shapes is triangle, square, and circle.
Use this login method if you
don't
have an
@illinois.edu
email address.
(Oops, I do have one)
IDEALS migrated to a new platform on June 23, 2022. If you created
your account prior to this date, you will have to reset your password
using the forgot-password link below.
