Stirling freezer
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Solution Overview
Problem
Existing Stirling freezers have limited cooling capacity and efficiency due to small heat exchange areas, refrigerant loop losses, and reliance on high-temperature heat sources, which hinder rapid cooling and effective temperature control across multiple cold zones.
Innovation Solution
A Stirling freezer design featuring multiple Stirling cooling modules with passive displacers, a piezoresistive unit, and an electric motor-driven piston, eliminating the refrigerant loop and allowing for adjustable pressure and displacement control to enhance cooling efficiency and flexibility in cold end arrangement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If a single cold zone is used in the Stirling freezer, then the structure is simple, but the heat exchange area and heat transfer rate are too small
Solution Approach 1:
The patent divides the cooling system into multiple independent cold zones (first cold zone, second cold zone, etc.) instead of using a single cold zone. Each cold zone has its own heat exchanger and can operate independently, thereby increasing the total heat exchange area and heat transfer rate while maintaining manageable structural complexity through modular design
2Loss of energy
If refrigerant is used to deliver heat in the loop, then heat can be transported, but coldness loss occurs in the loop and freezing performance is reduced
Solution Approach 1:
The patent extracts and eliminates the refrigerant loop from the cooling system. Instead of using refrigerant to transport heat, the system directly uses the Stirling engine's working gas (air or inert gas) to provide cooling at multiple cold zones, thereby eliminating coldness loss in the refrigerant loop and improving freezing performance
3Speed
If only one Stirling engine is used as power source for multiple cooling modules, then the structure is simple, but the cooling rate is limited and rapid cooling cannot be achieved
Solution Approach 1:
The patent divides the power source into multiple independent Stirling engines (first Stirling engine, second Stirling engine, etc.), with each engine driving a corresponding cooling module. This segmentation allows each engine to independently control its associated cold zone, thereby achieving rapid cooling and improved cooling rate while maintaining modular structural simplicity
4Ease of operation
If multiple cooling modules are arranged in a straight line without pressure drop control, then the arrangement is simple, but phase difference cannot be controlled and cooling effect deteriorates
Solution Approach 1:
The patent introduces pressure drop control devices (such as flow resistors or adjustable valves) at specific locations in the pipeline connecting each cooling module to its Stirling engine. This allows independent control of the phase difference for each cooling module by adjusting the local pressure drop, thereby optimizing the cooling effect of each zone while maintaining a relatively simple overall arrangement
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
This design increases heat exchange area and transfer rate, reduces coldness loss, enables rapid cooling, and operates independently of high-temperature heat sources, providing consistent and customizable cooling effects across multiple cold zones.
Implementation Method 1
The piston is driven to compress air in the cylinder to form a compressed air
Implementation Method 2
The cold end absorbs thermal energy of the cold end space to form a low-temperature environment in the cold end space
Implementation Method 3
A thermal insulating layer is provided between the cold end space and the hot end space
Implementation Method 4
The passive displacer is reciprocally, movably disposed in the pipe to partition the pipe into a cold end and a hot end
Data Source
AI summary
A Stirling freezer includes a cabinet body, at least one power unit, a pipeline, and a plurality of Stirling cooling modules. The cabinet body has a refrigerating space, a cold end space, and a hot end space. The power unit is connected to the pipeline. The Stirling cooling modules each include a pipe and a passive displacer. The passive displacer is reciprocally, movably disposed in the pipe to partition the pipe into a cold end and a hot end. The cold end is located in the cold end space. The hot end is located in the hot end space. The hot end is connected to the pipeline. The cold end absorbs thermal energy of the cold end space to form a low-temperature environment. Air flows between the cold end space and the refrigerating space, so that the refrigerating space also forms a low-temperature environment.