Polyol Ester Compressor Oil for Low-GWP Refrigerant Stability
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Solution Overview
Problem
Lubricating oils for refrigerators using refrigerants with low global warming potential, such as unsaturated fluorinated hydrocarbons, face challenges in maintaining compatibility, sealing properties, and low friction coefficients while ensuring stability across a wide temperature range without phase separation, which affects the service life and efficiency of refrigeration systems.
Innovation Solution
A lubricating oil composition featuring a base oil made from a polyol ester compound derived from pentaerythritol, dipentaerythritol, trimethylolpropane, or neopentyl glycol, combined with specific additives, and used in conjunction with refrigerants like unsaturated fluorinated hydrocarbons, ensuring compatibility, low friction, and stability through controlled kinematic viscosity, acid value, and hydroxyl value, along with the use of engineering plastics or coated films in sliding members.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional lubricating oils are used with unsaturated fluorinated hydrocarbon refrigerants, then the system can operate, but phase separation occurs at extreme temperatures causing insufficient lubricity and reduced service life
Solution Approach 1:
The patent changes the chemical parameters of the lubricating oil by using polyol esters with specific molecular structures (polyhydric alcohols esterified with fatty acids) and controlling viscosity ratios between 0.7-1.3. This parameter optimization prevents phase separation at extreme temperatures while maintaining reliable operation and extended service life in refrigeration systems.
2Productivity
If the lubricating oil viscosity is reduced to improve heat exchange efficiency, then evaporator performance improves, but lubricity becomes insufficient causing seizing and reduced service life
Solution Approach 1:
The patent optimizes the viscosity parameter of the lubricating oil within the range of 2-50 mm²/s at 100°C and maintains a viscosity ratio between 0.7-1.3. This controlled parameter change ensures sufficient lubricity to prevent seizing while maintaining adequate heat exchange efficiency, thereby preserving both productivity and reliability.
3Object-affected harmful factors
If carbon dioxide is used as a refrigerant to reduce global warming potential, then environmental impact improves, but high pressure requirements make it incompatible with current car air conditioning systems
Solution Approach 1:
The patent develops lubricating oil compositions with specific viscosity ratios (0.7-1.3) and molecular characteristics that are optimized for refrigerants with low global warming potential. This parameter optimization enables compatibility with emerging eco-friendly refrigerants while maintaining adaptability to existing car air conditioning system constraints.
Data Source
AI summary
A lubricating oil composition for refrigerators comprising a base oil which comprises as a main component a polyol ester compound obtained from a polyhydric alcohol selected from among pentaerythritol, dipentaerythritol, trimethylolpropane, and neopentyl glycol and a C4 to C20 aliphatic monocarboxylic acid and which has an acid value of 0.02 mgKOH/g or less and a hydroxyl value of 5 mgKOH/g or less. A compressor using the lubricating composition. The lubricating oil composition is applicable to such refrigerators that use a refrigerant having a specific structure, such as an unsaturated fluorinated hydrocarbon compound, and being usable in current car air conditioner systems, and has excellent compatibility with the refrigerant, good sealing properties, capability of imparting a low coefficient of friction to sliding members and, yet, excellent stability. The compressor uses the lubricating composition.