Variable speed magneto-caloric thermal diode assembly
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Solution Overview
Problem
Conventional heat pump systems using fluid refrigerants face efficiency limitations, environmental concerns, and operational impracticality across varying ambient temperatures, while magneto-caloric materials offer higher theoretical efficiency but require cost-effective and practical equipment solutions.
Innovation Solution
A magneto-caloric thermal diode assembly with a magneto-caloric cylinder and stacked thermal stages, each containing magnets and non-magnetic rings, driven by a variable speed motor to rotate relative to the cylinder, facilitating heat transfer through the magneto-caloric effect across a range of temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If magneto-caloric materials are used in heat pump systems, then theoretical Carnot cycle efficiency is significantly higher, but equipment complexity and cost increase due to requiring relatively large and expensive magnets
Solution Approach 1:
The magneto-caloric material is divided into multiple discrete beads or segments that are distributed around the circumference of the cylinder. This segmentation allows the system to achieve the desired thermal effect while reducing the total volume of magneto-caloric material required, thereby decreasing the size and cost of associated magnets while maintaining or improving efficiency.
Solution Approach 2:
The patent employs a nested structure where magneto-caloric beads are positioned within a cylinder that rotates relative to stationary magnets. The thermal stages are stacked axially within the same cylindrical space, creating a compact nested arrangement that reduces overall equipment size and complexity while preserving the high efficiency benefits of magneto-caloric materials.
2Loss of energy
If magneto-caloric materials are used in heat pump systems, then theoretical Carnot cycle efficiency is significantly higher, but practical cost competitiveness decreases due to expensive magnets
Solution Approach 1:
By segmenting the magneto-caloric material into discrete beads distributed circumferentially, the system requires smaller individual magnets positioned at strategic locations rather than large continuous magnet structures. This reduces the total volume and cost of magnetic materials while maintaining the high efficiency heat transfer performance.
Solution Approach 2:
The patent uses relatively small amounts of magneto-caloric material in bead form rather than large blocks, and positions limited numbers of magnets strategically. This approach reduces the quantity of expensive materials required, making the system more cost-competitive despite the inherent cost of magneto-caloric materials and magnets.
3Device complexity
If conventional fluid refrigerant heat pumps are used, then equipment simplicity is maintained, but efficiency is limited to about forty-five percent or less of maximum theoretical Carnot cycle efficiency
Solution Approach 1:
The patent replaces the conventional mechanical compression and expansion system with fluid refrigerant with a magneto-caloric system that uses magnetic field application and removal to drive heat transfer. This substitution eliminates the need for compressors and expansion valves, maintaining relative equipment simplicity while achieving significantly higher Carnot cycle efficiency through the magneto-caloric effect.
4Adaptability or versatility
If refrigerant-based systems are used, then operational range is limited, but adaptability to different ambient temperatures is insufficient
Solution Approach 1:
The patent employs multiple thermal stages with different magneto-caloric materials that have different Curie temperatures, allowing the system to operate effectively across a wide range of ambient temperatures. By changing which thermal stage is active based on ambient conditions, the system maintains high efficiency and reliability across diverse temperature environments that would be impractical for conventional refrigerant systems.
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 system achieves efficient heat transfer and temperature regulation, overcoming the limitations of fluid refrigerant-based systems with improved efficiency and adaptability across ambient temperature ranges.
Implementation Method 1
the magnetic moments of MCMs become more ordered under an increasing, externally applied magnetic field and cause the MCMs to generate heat. Conversely, decreasing the externally applied magnetic field allows the magnetic moments of the MCMs to become more disordered and allow the MCMs to absorb heat
Data Source
AI summary
A magneto-caloric thermal diode assembly includes a magneto-caloric cylinder. Each of a plurality of thermal stages includes a plurality of magnets and a non-magnetic ring. The plurality of magnets is distributed along a circumferential direction within the non-magnetic ring in each of the plurality of thermal stages. A variable speed motor is coupled to one of the magneto-caloric cylinder and the plurality of thermal stages. The variable speed motor is operable to rotate the one of the magneto-caloric cylinder and the plurality of thermal stages relative to the other of the magneto-caloric cylinder and the plurality of thermal stages.