Two-Phase Refrigerant Cooling With Gas-Phase Control
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Solution Overview
Problem
Cooling systems for aircraft using two-phase refrigerants face challenges in maintaining reliable operation at low ambient temperatures due to refrigerant condensation at cold walls, leading to reduced refrigerant availability and potential system failure, necessitating overdesign and increased refrigerant usage to prevent condensation.
Innovation Solution
A cooling system with a detection device to monitor refrigerant state and a control device that adjusts temperature and pressure to maintain the refrigerant in a gaseous state, using heating devices and pressure control valves to prevent condensation, allowing for efficient operation with minimal refrigerant and reduced system size and weight.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If insulation of tubing is increased to prevent refrigerant condensation at low ambient temperatures, then reliability is improved, but device complexity and weight increase
Solution Approach 1:
The patent changes the physical state parameter of the refrigerant from two-phase (liquid-gas mixture) to superheated gas phase. By ensuring the refrigerant is fully vaporized and heated above its dew point temperature, the system eliminates condensation issues without requiring excessive insulation or increased refrigerant quantities. This parameter change resolves the contradiction by improving reliability through phase control while avoiding the complexity and weight penalties of over-insulation.
Solution Approach 2:
The patent replaces the mechanical/physical approach of thick insulation with a thermal process approach - actively heating the refrigerant to superheated conditions. Instead of relying on passive insulation to prevent heat transfer that would cause condensation, the system actively controls the refrigerant temperature to remain above the dew point, substituting insulation-based protection with process-based control.
2Reliability
If amount of two-phase refrigerant is increased to compensate for condensation losses, then reliability is improved, but weight increases
Solution Approach 1:
The patent changes the refrigerant state from two-phase to superheated gas phase, which fundamentally alters the system's refrigerant requirements. By maintaining the refrigerant in a superheated state (temperature above dew point), the system prevents condensation in the tubing, eliminating refrigerant losses. This allows the system to operate reliably with minimal refrigerant quantity, directly resolving the contradiction between reliability and weight.
Solution Approach 2:
The patent converts the potential harm of condensation (which would cause refrigerant loss and system failure) into a benefit by using the heating process that prevents condensation. The same thermal energy that could potentially cause unwanted phase changes is instead used to maintain the refrigerant in a stable superheated state, turning a risk into a reliability-enhancing mechanism while minimizing refrigerant quantity and weight.
3Productivity
If tubing cross section is reduced for lower installation volume and weight, then productivity is improved, but refrigerant flow control becomes more difficult
Solution Approach 1:
The patent changes the refrigerant phase from two-phase flow to single-phase superheated gas flow. This parameter change fundamentally improves flow characteristics - superheated gas has consistent density and viscosity, making it much easier to control through small tubing cross sections. The elimination of phase change uncertainties and condensation issues allows for efficient flow management in compact tubing, resolving the contradiction between productivity (smaller tubing) and ease of operation.
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
Ensures reliable operation of the cooling system at low ambient temperatures by preventing uncontrolled condensation, maintaining an even distribution of gaseous and liquid refrigerant, and avoiding the need for overdesigning the cooling circuit or excessive refrigerant usage, thus maintaining system efficiency and reducing the risk of failure.
Implementation Method 1
A signal indicative of the state of aggregation of the refrigerant in a portion of the cooling circuit which connects the refrigerant outlet of the evaporator to the refrigerant inlet of the condenser is detected and output
Implementation Method 2
the temperature and/or the pressure of the refrigerant in the portion of the cooling circuit which connects the refrigerant outlet of the evaporator to the refrigerant inlet of the condenser is controlled in dependence on the signal indicative of the state of aggregation of the refrigerant
Implementation Method 3
using heating devices and pressure control valves to prevent condensation
Implementation Method 4
using heating devices and pressure control valves to prevent condensation
Implementation Method 5
the two-phase refrigerant circulating in the cooling circuit is a refrigerant, which upon releasing cooling energy to a cooling energy consumer is converted from the liquid to the gaseous state of aggregation
Implementation Method 6
is then converted back to the liquid state of aggregation
Data Source
AI summary
A cooling system particularly suitable for use on board an aircraft includes a cooling circuit allowing circulation of a two-phase refrigerant therethrough. An evaporator in the cooling circuit has a refrigerant inlet and a refrigerant outlet. A condenser in the cooling circuit has a refrigerant inlet and a refrigerant outlet. A detection device is configured to output a signal indicative of the state of aggregation of the refrigerant in a connecting portion of the cooling circuit which connects the refrigerant outlet of the evaporator to the refrigerant inlet of the condenser. A control device is configured to control at least one of the temperature and the pressure of the refrigerant in the connecting portion of the cooling circuit in dependence on the signal output by the detection device such that the refrigerant in the connecting portion of the cooling circuit is maintained in its gaseous state of aggregation.