Solvent cast electrocaloric polymer films
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Solution Overview
Problem
Vapor compression refrigerant loops pose environmental hazards and are impractical in power-constrained environments, and electrocaloric polymers face challenges in thin film fabrication for scalable heat transfer systems due to issues like electrical arcing and suboptimal crystal structure.
Innovation Solution
A method involving dissolving electrocaloric polymers in organic solvents with low boiling points to form films, which are then cast, annealed, and integrated between electrical conductors to create an electrocaloric element for controlled heat transfer, addressing the challenges of scalability and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If solvent casting is used to fabricate thin electrocaloric polymer films, then film thickness can be reduced to achieve performance parameters comparable to vapor compression systems, but the films become porous and prone to electrical arcing leading to premature breakdown
Solution Approach 1:
The patent changes the physical-chemical parameters of the casting process by using supercritical carbon dioxide as a solvent instead of conventional organic solvents. This parameter change allows the formation of non-porous dense films at thin dimensions (micrometer scale) that maintain high electrical breakdown strength while achieving the desired thin film thickness for electrocaloric performance
Solution Approach 2:
The patent introduces supercritical carbon dioxide as an intermediary substance that facilitates film formation without creating pores. The supercritical fluid acts as a mediator that evaporates completely after casting, leaving behind dense, pore-free polymer films that are resistant to electrical arcing while maintaining thin dimensions
2Ease of manufacture
If conventional polymer film fabrication techniques are used, then manufacturing process is simple, but the polymer crystal structure is suboptimal for electrocaloric performance
Solution Approach 1:
The patent changes the thermal and pressure parameters of the fabrication process by utilizing supercritical conditions and controlled annealing. These parameter changes induce optimal polymer chain alignment and crystal structure formation (specifically the electrocaloric phase) that enhances electrocaloric performance while maintaining a relatively simple casting process
3Reliability
If vapor compression refrigerant loops are used, then cooling performance is reliable, but environmental hazards and power requirements become problematic
Solution Approach 1:
The patent replaces the mechanical compression system (compressor, refrigerant loop) with an electrocaloric polymer-based system that uses electric field activation. This substitution eliminates the need for mechanical moving parts, refrigerants with environmental hazards, and high-power compressors, while achieving comparable cooling performance through the electrocaloric effect in thin polymer films
Solution Approach 2:
The patent utilizes the electrocaloric phase transition in polymer films when subjected to electric fields. This phase transition enables reversible heat absorption and release, providing cooling functionality without mechanical compression or harmful refrigerants, thus resolving the contradiction between reliable cooling performance and environmental/power constraints
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The approach results in electrocaloric films with enhanced breakdown strength and temperature lift, enabling efficient and scalable heat transfer systems that overcome the limitations of traditional vapor compression technologies.
Implementation Method 1
electrocaloric materials, or thermoelectric materials... electrocaloric polymers such as polyvinylidene fluoride (PVDF) have been proposed for use in heat transfer systems
Implementation Method 2
the organic solvent is evaporated to form a film comprising the electrocaloric polymer
Data Source
AI summary
A method of making an electrocaloric element includes dissolving or dispersing an electrocaloric polymer in an organic solvent having a boiling point of less than 100° C. at 1 atmosphere to form a liquid composition comprising the electrocaloric polymer. A film of the liquid composition is cast on a substrate, and the organic solvent is evaporated to form a film of the electrocaloric polymer. The film is removed from the substrate and disposed between electrical conductors to form an electrocaloric element.