Polyol Ester Lubricant for Fluorinated Olefin Refrigerants
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Solution Overview
Problem
Existing refrigeration systems face challenges with phase separation and viscosity reduction due to the miscibility of fluorinated olefin refrigerants with traditional polyol ester lubricants, leading to decreased performance and efficiency, especially when using hydrofluoro-olefin refrigerants like R-1234ze.
Innovation Solution
A polyol ester lubricant composition with a specific blend of alkylcarboxy esters of pentaerythritol, di-pentaerythritol, and tri-pentaerythritol oligomers, optimized to maintain high viscosity and miscibility with hydrofluoro-olefin refrigerants across a wide temperature range, preventing excessive refrigerant solubility and phase separation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional polyol ester lubricants are used with fluorinated olefin refrigerants, then the lubricant provides good low temperature flow properties and thermal stability, but the refrigerant excessively dissolves in the lubricant causing viscosity reduction and phase separation
Solution Approach 1:
The patent modifies the chemical composition parameters of the polyol ester lubricant by specifying precise weight percentage ranges of different ester components (monoesters 20-40%, diesters 10-30%, triesters 30-60%, oligomers 5-20%). This compositional parameter optimization reduces refrigerant solubility while maintaining low-temperature flow properties and thermal stability, preventing excessive viscosity reduction.
Solution Approach 2:
The patent creates a composite lubricant formulation by blending multiple polyol ester types (monoesters, diesters, triesters, and oligomers) with specific molecular weight ranges and structural characteristics. This composite approach balances miscibility control with lubrication performance, preventing phase separation while maintaining reliability across operating temperatures.
2Ease of operation
If the lubricant viscosity is reduced to improve flow properties, then low temperature operation is enhanced, but lubrication effectiveness and wear protection deteriorate
Solution Approach 1:
The patent applies local quality by assigning different functional roles to specific lubricant components: lighter monoesters and diesters provide low-temperature flow enhancement, while heavier triesters and oligomers maintain viscosity and wear protection at operating temperatures. This distributed functional approach optimizes both flow properties and lubrication effectiveness across the temperature range.
Solution Approach 2:
The patent creates a dynamic viscosity response by formulating a blend where lighter components (monoesters, diesters) facilitate cold-start flow, while heavier components (triesters, oligomers) provide thermal thickening at operating temperatures. This dynamic behavior ensures adequate flow at low temperatures while maintaining sufficient viscosity for wear protection during normal operation.
3Object-affected harmful factors
If fluorinated olefin refrigerants are used to reduce global warming potential, then environmental performance is improved, but miscibility with traditional lubricants increases causing performance degradation
Solution Approach 1:
The patent changes the chemical parameters of the lubricant by specifying molecular weight ranges (e.g., oligomers with 10-50 repeating units) and compositional ratios that optimize the balance between miscibility and phase stability. This parameter optimization allows the use of environmentally friendly fluorinated olefin refrigerants while preventing excessive dissolution and phase separation.
Solution Approach 2:
The patent formulates a composite polyol ester system that combines components with varying polarities and molecular weights. This composite structure creates a lubricant that is sufficiently miscible with fluorinated olefin refrigerants to prevent stratification, yet maintains compositional stability and prevents excessive refrigerant dissolution across the operating temperature range.
Data Source
AI summary
High viscosity working fluids comprising a fluorinated olefin refrigerant, such as a hydrofluoro-olefin refrigerant, and a high viscosity polyol ester comprising a select mixture of alkylcarboxy esters of pentaerythritol, di-pentaerythritol, tri-pentaerythritol and pentaerythritol oligomers are provided.