Miniature low-vibration active cooling system with conical rotary compressor
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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 cryogenic temperatures below 123K while minimizing vibration and energy consumption.
Innovation Solution
A miniature conical rotary compressor with a high compression ratio of 1:2 to 1:20, operating with minimal vibration, is used in conjunction with a condenser, evaporator, and refrigerant to effectively cool to cryogenic temperatures by elevating the refrigerant's temperature and radiating excess heat into space.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a traditional reciprocating compressor is used, then cryogenic temperatures can be achieved, but vibration is excessive and distorts optical sensor images
Solution Approach 1:
The patent replaces the reciprocating mechanical motion of traditional compressors with a rotary screw mechanism. The conical rotary compressor uses continuous rotational motion of screw elements to compress the refrigerant, eliminating the reciprocating pistons and valves that generate harmful vibrations. This mechanical substitution maintains cryogenic cooling capability while reducing vibration to levels that do not distort optical sensor images.
Solution Approach 2:
The patent employs a conical geometry for the screw elements, where the diameter of the screw changes along its length. This geometric parameter variation creates a progressive compression ratio that is more efficient and generates less vibration compared to uniform cylindrical designs. The conical shape allows for smoother refrigerant compression and reduces mechanical shocks, thereby minimizing vibration while achieving the required cryogenic temperatures.
2Volume of moving object
If the compressor size is reduced to fit CubeSat constraints, then size requirements are met, but compression ratio drops below 1:1.5 and cooling efficiency decreases
Solution Approach 1:
The conical geometry of the screw elements fundamentally changes the compression parameters. By varying the diameter along the length of the screw, the system achieves a high compression ratio (1:2 to 1:20) within a compact volume. The progressive reduction in screw diameter creates increasing compression pressure along the length of the screw, enabling high compression ratios in a miniature package that would be impossible with uniform cylindrical screws.
Solution Approach 2:
The patent transitions from two-dimensional compression (cylindrical screws with uniform cross-section) to three-dimensional compression (conical screws with varying cross-section). This dimensional change allows the compression process to occur progressively along the length of the screw, maximizing the compression ratio within the limited space available in a CubeSat. The conical shape utilizes the third dimension (length) to achieve compression that would require much larger cylindrical components.
3Productivity
If more energy is allocated to the cooling system, then cooling performance improves, but available energy from solar panels is depleted and other satellite functions suffer
Solution Approach 1:
The conical screw geometry optimizes the thermodynamic parameters of the refrigeration cycle. The progressive compression ratio achieved through the conical shape improves the efficiency of heat transfer and reduces the work required by the compressor. This parameter optimization allows the system to achieve effective cryogenic cooling with lower energy consumption, preserving more power for other satellite functions while maintaining required cooling performance.
Solution Approach 2:
The conical rotary compressor design enables the system to achieve high compression ratios and efficient cooling with minimal external energy input. The geometric design of the conical screws creates efficient refrigerant flow patterns and heat transfer characteristics that reduce the energy required for compression. This self-optimizing geometry allows the cooling system to operate at high efficiency without requiring excessive power allocation, thereby supporting other satellite functions.
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 removal of tens of watts and cooling to cryogenic temperatures below 123K with reduced vibration, meeting the requirements for small satellite optical sensors while being compact and energy-efficient.
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 50 mm; b) a diameter of at least one of the inner element and the outer element is between 2 mm and 25 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 6001 and 20000 revolutions per minute.