Refrigerant-Side Tradeoffs in Microchannel Evaporators

Kulkarni, T.; Bullard, C.W.; Cho, K.

Permalink

https://hdl.handle.net/2142/12051 Copy

Description

Title

Refrigerant-Side Tradeoffs in Microchannel Evaporators

Author(s)

• Kulkarni, T.
• Bullard, C.W.
• Cho, K.

Issue Date

2002-06

Keyword(s)

microchannel heat exchangers

Abstract

The present study examined design issues of microchannel evaporators associated with the flow maldistribution caused due to header pressure gradient. The effects of mass flow maldistribution on microchannel heat exchanger were quantified by using a single port simulation model. Longitudinal headers as currently used with microchannel condensers may not be suitable for the applications with microchannel evaporators. Mass flow maldistribution was investigated by using well-known pressure drop and heat transfer correlations for two-phase flow, selected after comparing with the results obtained by using different correlations. It was found that mass flow maldistribution cannot be controlled by changing either port/header diameter or the refrigerant state at the inlet to the port, but only by minimizing pressure gradients along header. At the same time the need to avoid phase separation in the header places a lower bound on mass flux. The dependence of heat exchanger capacity on the diameter and the length of the longitudinal and radial headers and was investigated in detail. Results demonstrated that the requirement for inertially dominated flow in the inlet header severely limits the set of feasible evaporator geometries. Accordingly, alternative concepts for header design were suggested.

Publisher

Air Conditioning and Refrigeration Center. College of Engineering. University of Illinois at Urbana-Champaign.

Series/Report Name or Number

Air Conditioning and Refrigeration Center TR-198

Type of Resource

text

Language

en

Permalink

http://hdl.handle.net/2142/12051

Sponsor(s)/Grant Number(s)

Air Conditioning and Refrigeration Project 124

Owning Collections