Mixed Ester Dielectric Fluid for Transformer Cooling
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Solution Overview
Problem
Conventional dielectric insulating liquids in transformers, such as mineral oils, are poorly biodegradable and pose environmental and safety risks due to their low flash points and high fire hazards, while natural vegetable oils lack the necessary properties like viscosity, low-temperature performance, and oxidation stability required for modern transformer applications.
Innovation Solution
The use of mixed esters of polyhydric alcohols, specifically trimethylolpropane esters, esterified with a combination of linear saturated fatty acids and partially unsaturated fatty acids from vegetable oils, which provide improved viscosity, low pour point, high flash and fire points, and oxidation stability, while being biodegradable and derived from renewable sources.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If natural vegetable oils are used as insulating liquid, then biodegradability and flash point are improved, but viscosity and low-temperature properties deteriorate
Solution Approach 1:
The patent uses composite materials by combining polyhydric alcohols (such as trimethylolpropane) with fatty acids to create ester-based insulating liquids. This composite approach allows the material to achieve both environmental benefits (biodegradability, high flash point) and functional performance (appropriate viscosity, low-temperature fluidity) that neither component alone could provide.
Solution Approach 2:
The patent applies parameter changes by systematically varying the molecular structure of the esters - specifically changing the type of polyhydric alcohol, the chain length of fatty acids, and the degree of unsaturation - to optimize the balance between viscosity, pour point, and oxidation stability. This allows tuning of physical properties while maintaining the core benefits of vegetable-based insulating liquids.
2Object-affected harmful factors
If natural vegetable oils are used as insulating liquid, then flash point is improved, but oxidation stability deteriorates
Solution Approach 1:
The patent changes chemical parameters by selecting specific fatty acid compositions (controlling saturation levels) and polyhydric alcohol structures to inherently improve oxidation stability. Additionally, antioxidants are added as supplementary measures, but the primary improvement comes from the molecular structure design of the esters themselves, which resists oxidation while maintaining high flash point.
3Ease of manufacture
If viscosity is reduced by mixing vegetable oils with thinner base oils, then low-temperature properties are improved, but flash point deteriorates
Solution Approach 1:
Instead of mixing vegetable oils with petroleum-based thinner oils (which would compromise flash point), the patent creates composite esters from polyhydric alcohols and fatty acids. This composite material inherently provides both low viscosity and high flash point, eliminating the need to compromise fire safety for improved low-temperature performance.
Data Source
AI summary
The invention relates to compositions including esters of polyvalent alcohols that are esterified with fatty acids, partially unsaturated, from plant oils, and to the use thereof as cooling and insulating fluids for transformers.