Conical Rotary Compressor for Low-Vibration Satellite Cryocooling
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Solution Overview
Problem
Miniature cryocooling systems for small satellites face challenges in size constraints, vibration issues, and inefficiency, as existing systems fail to achieve the required cryogenic temperatures below 123K while minimizing vibration and energy consumption.
Innovation Solution
A miniature conical rotary screw compressor with a high compression ratio of 1:2 to 1:20, operating with minimal vibration, is integrated into an active cooling system, which includes a condenser, evaporator, and refrigerant, capable of elevating refrigerant temperature for effective heat radiation according to the Stefan-Boltzmann law.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a traditional reciprocating compressor or Stirling engine is used for active cryocooling, then cryogenic temperatures below 123K can be achieved, but excessive vibration is produced that distorts optical sensor images
Solution Approach 1:
The patent replaces the traditional reciprocating piston mechanism with a rotary screw compressor mechanism. The rotary motion of the screw elements eliminates the reciprocating motion that causes vibration, while still achieving the necessary compression ratio to reach cryogenic temperatures below 123K.
Solution Approach 2:
The patent changes the operational parameters by using a high compression ratio (1:2 to 1:20) in a rotary configuration. This allows the system to achieve the required temperature reduction without the vibration-generating reciprocating motion, as the continuous rotary compression maintains stability.
2Volume of moving object
If the cooling system is miniaturized to fit within 100 mm length and 40 mm height constraints, then it can be integrated into CubeSats, but the compression ratio is reduced to below 1:1.5 which prevents achieving cryogenic temperatures
Solution Approach 1:
The patent achieves a breakthrough by designing a conical screw compressor geometry that maintains a high compression ratio of 1:2 to 1:20 despite the miniaturized dimensions. The conical shape of the screw elements allows for efficient compression within the constrained volume, enabling cryogenic temperatures to be reached in a compact form factor suitable for CubeSats.
3Power
If more energy is allocated to the cooling system to remove tens of watts of heat, then cryogenic temperatures can be achieved, but the available solar panel energy is depleted that is needed for other satellite functions
Solution Approach 1:
The patent employs passive radiative cooling through black panels that utilize the Stefan-Boltzmann law. The compressed refrigerant naturally radiates heat to space without requiring additional active cooling components, reducing the energy burden on the satellite's power system while still achieving effective heat removal of tens of watts.
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 effectively removes tens of watts of heat and cools to cryogenic temperatures below 123K, meeting the requirements for small satellites while minimizing vibration and energy consumption, thus enhancing the signal-to-noise ratio of optical sensors.
Implementation Method 1
compressing the refrigerant in the conical rotary screw compressor, thereby heating the refrigerant
Implementation Method 2
the Stefan-Boltzmann law states that while the total energy radiated per unit surface area of a black body is linearly dependent on the surface area of the radiating panels, it depends on the fourth power of the black panels' thermodynamic temperature T
Implementation Method 3
removing heat from at least one component of the object into an evaporator
Data Source
AI summary
A system for cryocooling an optical sensor on a satellite to a temperature below 200K with minimal vibration comprising a miniature conical rotary screw compressor comprising an inner element configured to only rotate around a first stationary axis and an outer element configured to only rotate around a second stationary axis so that both elements revolve with minimal vibration; with at least one of a) a length of at least one of the inner element and the outer element is between 10 mm and 100 mm; b) a diameter of at least one of the inner element and the outer element is between 2 mm and 45 mm; c) a compression ratio of the rotary screw compressor is between 1:2 and 1:20; and d) a shaft speed of the conical rotary screw compressor is between 1001 and 20000 revolutions per minute.