Tuesday, 28 June 2016: 11:00 AM-12:30 PM
Advances in Refrigeration Systems and Alternative Refrigerants
Chair:
Joseph A. Karnaz, CPI Fluid Engineering/Lubrizol
Technical Committee: 03.04 Lubrication
CoSponsor: 03.03 Refrigerant Contaminant Control
Lubricants are an essential component to effective operation of air conditioning and refrigeration compressors which are exhaustively studied by compressor engineers and tribology experts. But there are other aspects to lubrication effects beyond the compressor which can also be key to effective operation and performance of air conditioning and refrigeration systems. This seminar presents examples of how the lubricant circulated from the compressor into the system can affect system components, oil management and overall system performance with existing and alternate refrigerants.
1 Managing Lubricants in a Large Commercial Refrigeration System
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Danny Halel, Hussman Corporation |
Large commercial refrigeration systems have unique concerns/opportunities unlike those with a single compressor – single evaporator system. This seminar will discuss Lubricant Management from the outlet of the compressors through all components including the oil separator, receiver, valving, headers and suction and liquid lines as well as risers and back to the compressor.
2 Lubricant Management Heuristics and Impacts on System Chemistry, Valves and Other System Components
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Christopher Reeves, Sporlan Valve Division of Parker Hannifin |
Every component on the refrigerant side of a system comes into contact with the compressor’s lubricant. This lubricant plays a key role in the performance and life of thermostatic expansion, electric expansion, and solenoid valves. There are also interactions between the system lubricant and other system components such as piping, contaminant controls, and sealing surfaces. This presentation explores good lubricant management practices and the challenges this part of a refrigerant system faces when transitioning to new lower GWP refrigerants.
3 Lubricants in Heat Exchangers: A Slippery Slope
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Scott Wujek, Ph.D., Creative Thermal Solutions |
Once oil leaves the compressor, it circulates through all components before returning to the compressor to perform its primary lubrication objective. Oil induced wetting, foaming, and pressure drop impact heat exchanger effectiveness and pressure drop, sometimes in ways which are counterintuitive. Oil disproportionately accumulates in regions of the heat exchanger which have the greatest effect on distribution of refrigerant flow, therefore the impact of oil is much larger than its circulation ratio would suggest. Infrared photography and high speed videos are used to demonstrate changes in distribution and subsequent effect on heat exchanger and system performance.
4 Oil Separator Efficiency Rating Dilemma
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Kok-Hiong Kee |
When lubricant in the compressor circulates into the system, it may build up as a thin film on the internal surfaces of heat exchangers and acts as a thermal insulator. This robs the system of efficiency and increases energy consumption. In addition, refrigeration systems have a fixed volume so circulating oil competes with the refrigerant resulting in reduce cooling capacity. Oil separator technologies serve to regulate and minimize oil circulation by isolating the lubricant early in the discharge line and return it to the compressor. This study examines the performance of various oil separation technologies using controlled experiments.