Distribution of refrigerant and lubricant in automotive air conditioning systems

In automotive air conditioning (A/C) systems, the compressor lubricant is circulated throughout the system with refrigerant. At different oil concentrations, the circulating mixture exhibits different properties, which affects the characteristics of heat transfer, pressure drop and mass retention in each component. The purpose of this thesis is to measure and model refrigerant and lubricant mass distribution in each component of an automotive A/C system. Quick Closing Valve Technique (QCVT) combined with Remove and Weigh Technique is employed to measure the refrigerant mass, with an overall uncertainty within 2%. Three different techniques-Remove and Weigh, Mix and Sample and Flushing- are used to determine the mass of lubricant. The total mass of lubricant in the system is determined with 5% uncertainty in average. R134a and its new environmental friendly alternative R1234yf are used with PAG 46 oil as working fluid at different Oil Circulation Ratio (OCR), ranging from 2% to 4%. Experiments are conducted in two system, one with a fixed Orifice Tube (OT) and low pressure side accumulator, the other with a Thermal Expansion Valve (TXV) and a high pressure side receiver. In each system, R134a and R1234yf show similar results in terms of refrigerant and lubricant retention at I-35 steady state condition. An experimentally validated model is developed to estimate both refrigerant and oil retention in the microchannel condenser and plate-and-fin evaporator that are used in the experimental system.

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

2012

Author dc:creator

• Jin, Shenghan

Contributors dc:contributor

• Hrnjak, Predrag S.

• automotive air conditioning
• refrigerant retention
• lubricant retention

Statement dc:rights

• Copyright 2012 Shenghan Jin

Language dc:language

en

Handle dc:identifier

http://hdl.handle.net/2142/34290

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/34290