Experimental and Theoretical Investigation of Annular Film Flow Reversal In a Vertical Pipe: Application To Oil Return In Refrigeration Systems

Mehendale, Sunil; Radermacher, Reinhard

doi:10.1080/10789669.2000.10391250

Cited by 12 publications

(4 citation statements)

References 3 publications

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“…They reported that minimum flow velocities ranging from 354 to 374 fpm (1.8 to 1.9 m/s) were required in the vertical upward suction lines when the system operated in the cooling mode. The oil return characteristic in vertical upward flows was also experimentally and theoretically investigated by Mehendale and Radermacher (2000) whereof the critical mass flow rates for preventing oil film reversal in a vertical pipe were estimated. Despite the efforts in improving oil circulation characteristics, some of the oil is unable to return to the compressor and retained in the components of AC and refrigeration system, especially the heat exchangers.…”

Section: Introductionmentioning

confidence: 99%

Oil retention in a microchannel type condenser and its effects on heat transfer rate performance and on the pressure drop

Yatim

Deokar

Cremaschi

2016

Science and Technology for the Built Environment

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Oil retention in a microchannel type condenser was measured and its effect on heat transfer rate performance and pressure drop were analyzed for refrigerants R410A and R134a condensation. The heat exchanger was a 2-pass aluminum louvered-fin type consists of multiports rectangular channels with hydraulic diameter of 0.06 inch (1.7 × 10 −3 m). The refrigerants and Polyolester oil mixtures were studied at saturation temperature from 85 to 130 • F (29 to 54 • C) and oil mass fraction (OMF) was varied from 0 to 6 wt.%. Oil retained in the condenser was found to be strongly dependent on the OMF and it was measured up to 11% of its internal volume. The oil retained for high mass fluxes were higher than those for low mass fluxes. The effect of mass flux on the oil retention was small for low OMFs but became more evident for OMFs of 3 wt.% and higher. The oil penalized the heat transfer capacity by as much as 10% when the OMF was 3 wt.%. For medium temperature of 105 • F (41 • C) the heat transfer capacities were fairly constant. Nevertheless, the high refrigerant-oil mixture viscosity of the liquid phase increased the pressure losses up to 19% compared to that in oil free conditions.

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Section: Introductionmentioning

confidence: 99%

Oil retention in a microchannel type condenser and its effects on heat transfer rate performance and on the pressure drop

Yatim

Deokar

Cremaschi

2016

Science and Technology for the Built Environment

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“…An experimental and theoretical investigation oil return characteristics in vertical suction risers was carried out by Mehendale and Radermacher (2000). The objective of this study was to determine the critical refrigerant mass flow rates required to ensure oil return and compare the results with predictions of Jacobs et al (1976).…”

Section: Studies For Determining Minimum Refrigerant Velocity For Oilmentioning

confidence: 99%

“…This limit incorporates the effect of liquid viscosity but does not account for effect of OCR on minimum mass flux. Mehendale and Radermacher (2000) proposed that the minimum mass flux limit should be the point at which liquid film reversal begins. They proposed that at the point of liquid film reversal, the wall shear stress would become zero.…”

Section: Vertical Pipementioning

confidence: 99%

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Oil retention and pressure drop of R1234yf and R134a with POE ISO 32 in suction lines

Sethi

Hrnjak

2014

HVAC&R Research

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In most of the refrigeration systems a small quantity of oil is carried out of the compressor by high velocity vapor leaving the compressor discharge in the form of a mixture with the refrigerant. The circulating liquid which is a mixture of oil and refrigerant has the highest viscosity in the suction line to the compressor due to which it has the highest potential for oil retention. R1234yf is a new alternative refrigerant of low global warming potential (GWP) which has been developed for automobile air conditioners as a drop-in replacement for R134a in order

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A numerical study on the oil retention of R410A and PVE oil mixture in multi heat pump system

Kim

2016

J Mech Sci Technol

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Experimental and Theoretical Investigation of Annular Film Flow Reversal In a Vertical Pipe: Application To Oil Return In Refrigeration Systems

Cited by 12 publications

References 3 publications

Oil retention in a microchannel type condenser and its effects on heat transfer rate performance and on the pressure drop

Oil retention in a microchannel type condenser and its effects on heat transfer rate performance and on the pressure drop

Oil retention and pressure drop of R1234yf and R134a with POE ISO 32 in suction lines

A numerical study on the oil retention of R410A and PVE oil mixture in multi heat pump system

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