Effect of oil on R134a distribution in the microchannel heat exchanger with vertical header

Yang Zou; Pega S. Hrnjak

doi:10.1016/j.ijrefrig.2013.09.037

Effect of oil on R134a distribution in the microchannel heat exchanger with vertical header

Yang Zou, Pega S. Hrnjak

Mechanical Science and Engineering

Research output: Contribution to journal › Article › peer-review

Abstract

This paper presents refrigerant R134a and oil (PAG 46) mixture upward flow in the vertical header of microchannel heat exchanger (compared to pure R134a and R410A), and its effect on distribution. The mixture enters into the header through the five tubes in the bottom pass and exits through the five tubes in the top pass representing the flow in the heat pump mode of outdoor heat exchangers in reversible systems. The quality was varied from 0.2 to 0.8 and the mass flow rate from 1.5 to 4.5 kg h^-1 per tube. The oil circulation rate (OCR) was varied from 0% to 4.7%. It was found that at low OCR, e.g. 0.5%, the distribution was worse than pure R134a, whereas at high OCR, the distribution was improved and better than pure R134a in some cases. This was due to sufficient oil would create a lot of foams and enlarge the liquid region in the header based on the visualization.

Original language	English (US)
Pages (from-to)	201-210
Number of pages	10
Journal	International Journal of Refrigeration
Volume	40
DOIs	https://doi.org/10.1016/j.ijrefrig.2013.09.037
State	Published - Apr 2014

Keywords

Microchannel heat exchanger
Refrigerant and oil distribution
Two-phase flow
Vertical header

ASJC Scopus subject areas

Building and Construction
Mechanical Engineering

Online availability

10.1016/j.ijrefrig.2013.09.037

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title = "Effect of oil on R134a distribution in the microchannel heat exchanger with vertical header",

abstract = "This paper presents refrigerant R134a and oil (PAG 46) mixture upward flow in the vertical header of microchannel heat exchanger (compared to pure R134a and R410A), and its effect on distribution. The mixture enters into the header through the five tubes in the bottom pass and exits through the five tubes in the top pass representing the flow in the heat pump mode of outdoor heat exchangers in reversible systems. The quality was varied from 0.2 to 0.8 and the mass flow rate from 1.5 to 4.5 kg h-1 per tube. The oil circulation rate (OCR) was varied from 0% to 4.7%. It was found that at low OCR, e.g. 0.5%, the distribution was worse than pure R134a, whereas at high OCR, the distribution was improved and better than pure R134a in some cases. This was due to sufficient oil would create a lot of foams and enlarge the liquid region in the header based on the visualization.",

keywords = "Microchannel heat exchanger, Refrigerant and oil distribution, Two-phase flow, Vertical header",

author = "Yang Zou and Hrnjak, {Pega S.}",

note = "Funding Information: The authors are grateful for the sponsor and support from Air Conditioning and Refrigeration Center at the University of Illinois at Urbana-Champaign and the support from Creative Thermal Solutions. Copyright: Copyright 2014 Elsevier B.V., All rights reserved.",

year = "2014",

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doi = "10.1016/j.ijrefrig.2013.09.037",

language = "English (US)",

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journal = "International Journal of Refrigeration",

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AU - Zou, Yang

AU - Hrnjak, Pega S.

N1 - Funding Information: The authors are grateful for the sponsor and support from Air Conditioning and Refrigeration Center at the University of Illinois at Urbana-Champaign and the support from Creative Thermal Solutions. Copyright: Copyright 2014 Elsevier B.V., All rights reserved.

PY - 2014/4

Y1 - 2014/4

N2 - This paper presents refrigerant R134a and oil (PAG 46) mixture upward flow in the vertical header of microchannel heat exchanger (compared to pure R134a and R410A), and its effect on distribution. The mixture enters into the header through the five tubes in the bottom pass and exits through the five tubes in the top pass representing the flow in the heat pump mode of outdoor heat exchangers in reversible systems. The quality was varied from 0.2 to 0.8 and the mass flow rate from 1.5 to 4.5 kg h-1 per tube. The oil circulation rate (OCR) was varied from 0% to 4.7%. It was found that at low OCR, e.g. 0.5%, the distribution was worse than pure R134a, whereas at high OCR, the distribution was improved and better than pure R134a in some cases. This was due to sufficient oil would create a lot of foams and enlarge the liquid region in the header based on the visualization.

AB - This paper presents refrigerant R134a and oil (PAG 46) mixture upward flow in the vertical header of microchannel heat exchanger (compared to pure R134a and R410A), and its effect on distribution. The mixture enters into the header through the five tubes in the bottom pass and exits through the five tubes in the top pass representing the flow in the heat pump mode of outdoor heat exchangers in reversible systems. The quality was varied from 0.2 to 0.8 and the mass flow rate from 1.5 to 4.5 kg h-1 per tube. The oil circulation rate (OCR) was varied from 0% to 4.7%. It was found that at low OCR, e.g. 0.5%, the distribution was worse than pure R134a, whereas at high OCR, the distribution was improved and better than pure R134a in some cases. This was due to sufficient oil would create a lot of foams and enlarge the liquid region in the header based on the visualization.

KW - Microchannel heat exchanger

KW - Refrigerant and oil distribution

KW - Two-phase flow

KW - Vertical header

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Effect of oil on R134a distribution in the microchannel heat exchanger with vertical header

Abstract

Keywords

ASJC Scopus subject areas

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