Gear Pump for Two-Phase Ammonia Cooling in Microgravity
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Solution Overview
Problem
Current heat exchange devices for space applications, particularly those using two-phase loops, face challenges such as high power consumption, large size, high cost, and sensitivity to pressure drops in microgravity environments, making them unsuitable for long-term space missions like satellite thermal control, especially when using low viscosity and corrosive fluids like ammonia.
Innovation Solution
A gear pump design with external spur gears and a housing that minimizes friction and wear, using non-metallic and ceramic materials for bearings and a corrosion-resistant coating, allowing for efficient and reliable pumping of low viscosity fluids like ammonia, with a drive speed of less than 250 revolutions per minute to maintain constant flow rates and reduce vibrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a centrifugal pump is used for two-phase coolant loop, then the pump can operate in microgravity, but it has high power consumption, large bulk, high cost, and sensitivity to pressure drop variations
Solution Approach 1:
The patent replaces the centrifugal pump's rotodynamic mechanical system with a positive displacement gear pump mechanism. The gear pump uses meshing gears to directly displace and move the coolant fluid, eliminating the need for high-speed rotation and centrifugal forces. This mechanical substitution reduces power consumption while maintaining effectiveness in microgravity environments, as the gear pump's positive displacement mechanism is less sensitive to gravitational variations.
2Productivity
If a positive displacement pump with many moving parts is used, then pumping performance is improved, but wear and service life become problematic
Solution Approach 1:
The patent extracts and eliminates unnecessary moving parts from the positive displacement pump design. The gear pump features fixed gears that rotate on stationary bearings, removing reciprocating pistons, deformable components, and complex valve mechanisms. This reduction in moving parts minimizes wear points while preserving the positive displacement pumping action, thereby improving reliability and service life for space applications.
3Productivity
If gear pump speed is increased to improve flow rate, then productivity increases, but vibrations and wear increase
Solution Approach 1:
The patent optimizes the gear pump's operational parameters, specifically the rotational speed, to balance productivity and reliability. By operating at controlled speeds within an optimal range, the pump achieves sufficient flow rates for space thermal control while minimizing vibrations that could affect sensitive equipment and reducing wear on gears and bearings. This parameter optimization is critical for long-duration space missions.
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 gear pump design ensures reliable, long-term operation (10-15 years) with minimal wear and vibrations, maintaining high hydraulic performance and flow rates over a wide temperature range, suitable for space applications, while being compact and energy-efficient.
Implementation Method 1
a gear pump comprising: a housing, at least two pinions with external spur teeth in meshing cooperation with each other
Implementation Method 2
means for coupling at least one of the pinion shafts to a drive motor suitable for driving the latter in rotation at a speed of less than 250 revolutions per minute
Implementation Method 3
said heat transfer fluid at least partially changing state on contact with at least part of said heat exchange means
Implementation Method 4
heat exchange means with at least one cold source and at least one hot source external to the circuit
Data Source
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AI summary
The method involves using a corrosive coolant i.e. ammonia, partially at a liquid state and a vapor state, where viscosity of the coolant is less than water. The coolant is driven in a circuit i.e. conduits, by displacement using pumping, where the circuit comprises heat exchange units including evaporator exchanger and condenser exchanger groups with a cold source and a hot source external to the electronic circuits. A state of contact of the heat exchange units is changed by the coolant. An independent claim is also included for a diphasic type heat exchange device comprising a gear pump.