Refrigerator Lubricant Composition for Refrigerant Phase Stability

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Solution Overview

Problem

Lubricants for refrigeration systems using unsaturated fluorinated hydrocarbon refrigerants face challenges in maintaining stability and compatibility, leading to phase separation issues that affect the efficiency and lifespan of refrigerators, particularly in air-conditioning systems for cars where the refrigerant must operate across a wide temperature range without phase separation.

Innovation Solution

A lubricant composition utilizing a polyoxyalkylene glycol derivative as the base oil with specific properties, including a hydroxyl number of 5 mgKOH/g or less, kinematic viscosity of 2 to 50 mm2/s at 100° C., and molecular weight of 500 or more, combined with additives such as extreme pressure agents and antioxidants, is used in conjunction with a refrigerant containing unsaturated fluorinated hydrocarbon compounds, ensuring compatibility and stability across varying temperatures.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional lubricants are used with unsaturated fluorinated hydrocarbon refrigerants, then the refrigeration system can operate, but phase separation occurs between the refrigerant and lubricant leading to insufficient lubrication and reduced system lifetime

Engineering Contradiction:
Improvesystem lifetimeVSAvoidphase separation
Core Design Contradiction:
ReliabilityVSStability of the object's composition

Solution Approach 1:

The patent applies parameter changes by carefully controlling the hydroxyl number (5 mgKOH/g or less) and molecular weight (500 or more) of the polyoxyalkylene glycol derivative base oil. These parameter optimizations ensure compatibility with unsaturated fluorinated hydrocarbon refrigerants, preventing phase separation and maintaining reliable operation throughout the system's lifetime.

Inventive Principle:
Principle #35Parameter changes

2Productivity

If the refrigerant and lubricant are used together in the compression refrigerator, then the system can function, but phase separation occurs at extreme temperatures affecting efficiency and component protection

Engineering Contradiction:
Improvesystem efficiencyVSAvoidtemperature-dependent phase separation
Core Design Contradiction:
ProductivityVSStability of the object's composition

Solution Approach 1:

The patent utilizes parameter changes by optimizing the base oil's molecular weight (500 or more) and hydroxyl number (5 mgKOH/g or less) to maintain phase compatibility across extreme temperature ranges from -20°C to 40°C, preventing efficiency loss and component damage.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent employs composite materials by formulating a lubricant composition that combines polyoxyalkylene glycol derivative base oil with specific additives including antioxidants and extreme pressure agents. This composite formulation ensures stable performance and prevents phase separation under varying temperature conditions.

Inventive Principle:
Principle #40Composite materials

Data Source

PatentUS20100175421A1Lubricant composition for refrigerator and compressor using the same
Publication Date: 2010.07.15 IDEMITSU KOSAN CO LTD

AI summary

Provided is a lubricant composition for a refrigerator, which is characterized by using a substance mainly containing a polyoxyalkylene glycol derivative and having a hydroxyl number of 5 mgKOH/g or less, as a base oil. Also provided is a compressor using such the lubricant composition for a refrigerator. The lubricant composition for a refrigerator is used for a refrigerator which uses a refrigerant having a specific structure such as an unsaturated fluorohydrocarbon and being usable in current air-conditioning systems for cars or the like. The lubricant composition for a refrigerator exhibits excellent compatibility with the refrigerant, while having excellent stability. The compressor uses such the lubricant composition for a refrigerator.