Magnetic Refrigerator Entropy Gradient for Higher Cooling Power
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Solution Overview
Problem
Conventional cooling devices, such as refrigerators, rely on gas coolants that have significant greenhouse effects, necessitating the development of environmentally friendly alternatives like magnetic refrigerators that utilize magnetocaloric effects for efficient cooling.
Innovation Solution
A magnetic refrigerator design incorporating a hot-end and cold-end heat exchanger with a magnetic material providing a temperature gradient, where the magnetic material's entropy change is controlled to satisfy the ratio k=Th/Tc=ΔSc/ΔSh>1, optimizing the entropy change to enhance cooling efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If conventional gas coolants are used in cooling devices, then cooling function is achieved, but greenhouse effects and environmental harm occur
Solution Approach 1:
The patent replaces the conventional mechanical compression-based cooling system with a magnetic field-based cooling system. The magnetic refrigerator uses magnetocaloric materials that undergo magnetic phase transitions to absorb and release heat, eliminating the need for harmful gas coolants and mechanical compressors, thus resolving the contradiction between environmental friendliness and cooling efficiency
Solution Approach 2:
The patent utilizes magnetic phase transitions of magnetocaloric materials (such as gadolinium and its alloys) to achieve cooling. When the magnetic field is applied or removed, the material undergoes phase transition, absorbing or releasing heat in the process. This phase transition mechanism provides efficient cooling without environmental harm, simultaneously addressing both concerns
2Productivity
If magnetic material content is increased to enhance cooling power, then cooling capacity improves, but device size and material cost increase
Solution Approach 1:
The patent applies local quality by creating a temperature gradient within the magnetic material structure. Different regions of the magnetic material are positioned at different temperatures, with the entropy change optimized at each temperature zone. This allows efficient use of magnetic material throughout the device, achieving high cooling power without requiring excessive material quantity
Solution Approach 2:
The patent optimizes the entropy change parameter of the magnetic material across the temperature range. By controlling the magnetic phase transition characteristics and entropy change distribution, the system achieves maximum cooling efficiency per unit of magnetic material, thereby improving cooling power without proportionally increasing material content
3Productivity
If temperature gradient is increased between hot-end and cold-end heat exchangers, then cooling efficiency improves, but entropy change distribution becomes non-uniform
Solution Approach 1:
The patent addresses the entropy change distribution issue by applying local quality principles. The magnetic material is structured such that different segments experience different temperature conditions, with the entropy change optimized for each local temperature zone. This creates a matched distribution where higher entropy change occurs where needed, maintaining stability while achieving efficient heat transfer
Solution Approach 2:
The patent introduces a spatial dimension to the entropy change distribution by arranging magnetic materials at different positions along the temperature gradient. The entropy change is distributed across multiple spatial locations rather than being uniform, allowing the system to maintain stable composition while achieving improved cooling efficiency through optimized heat transfer at each position
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 magnetic refrigerator achieves improved efficiency and cooling power by linearly varying the entropy change of the magnetic material between the heat exchangers, leading to increased cooling capacity without enlarging the device or increasing the magnetic material content, thus enabling a more efficient and environmentally friendly cooling solution.
Implementation Method 1
The magnetic refrigerator is cooled using magnetocaloric effects, which involves heating or cooling by changing a spin arrangement of a magnetic material according to a magnetic field.
Implementation Method 2
The magnetic material may change volume or mass between the hot-end heat exchanger and the cold-end heat exchanger to control an entropy change of Relationship Equation 1.
Implementation Method 3
a hot-end heat exchanger, a cold-end heat exchanger, a magnetic material arranged so as to provide a temperature gradient between the hot-end heat exchanger and the cold-end heat exchanger
Data Source
AI summary
A magnetic refrigerator, and a device including the same, include a hot-end heat exchanger, a cold-end heat exchanger, a magnetic material arranged so as to provide a temperature gradient between the hot-end heat exchanger and the cold-end heat exchanger, and a heat exchange medium, and satisfying the following Equation 1.k=Th/Tc=ΔSc/ΔSh>1 EQUATION 1In Equation 1, Th is a temperature of a hot-end heat exchanger, Tc is a temperature of a cold-end heat exchanger, ΔSh is an entropy change of a magnetic material at Th, and ΔSc is an entropy change of a magnetic material at Tc.