Subambient Cooling Air In-Leakage Estimation Using Pressure and Temperature

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Solution Overview

Problem

Subambient cooling systems face inefficiencies due to non-condensable gases like air leaking into the system, which decrease heat removal capability and require inefficient adjustments in coolant levels and heat exchanger active areas.

Innovation Solution

Measuring and storing data sets of various properties such as liquid level, temperature differentials, pressure differentials, and gradients within the cooling system to estimate air concentration and generate lookup tables for controlling and removing non-condensable gases, allowing for improved monitoring and operation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If non-condensable gases leak into the subambient cooling system, then the system continues to operate, but heat removal capability decreases

Engineering Contradiction:

Improvecontinuous operationVSAvoidheat removal capability

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

The system continuously monitors temperature differentials between the evaporator and condenser, and pressure differentials, to detect changes in heat transfer performance. When non-condensable gases accumulate, these measurements change, triggering feedback control that activates the air removal device to restore optimal heat removal capability

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The system uses its own operational parameters (temperature and pressure measurements during normal operation) to detect air accumulation and trigger self-correction through the air removal device, eliminating the need for external intervention or system shutdown

Inventive Principle:

Principle #25Self-service

2Loss of energy

If coolant levels are adjusted to compensate for air leakage, then heat transfer is maintained, but system complexity and operation difficulty increase

Engineering Contradiction:

Improveheat transfer efficiencyVSAvoidcoolant level adjustment

Core Design Contradiction:

Loss of energyVSEase of operation

Solution Approach 1:

The system replaces manual mechanical adjustment of coolant levels with an automated control system that uses temperature and pressure sensors to detect air accumulation and automatically activates the air removal device, eliminating the need for operator intervention and complex manual adjustments

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Loss of energy

If heat exchanger active areas are modified to compensate for air leakage, then heat removal capability is maintained, but device complexity increases

Engineering Contradiction:

Improveheat removal capabilityVSAvoidheat exchanger configuration

Core Design Contradiction:

Loss of energyVSDevice complexity

Solution Approach 1:

The system extracts and removes the non-condensable gases that are degrading heat transfer performance, rather than attempting to compensate for their presence by modifying heat exchanger geometry or adding complex multi-area configurations. This restores original design performance without structural changes

Inventive Principle:

Principle #2Taking out (Extraction)

4Difficulty of detecting and measuring

If traditional sensing methods are used to detect air leakage, then detection capability is limited, but measurement precision is insufficient

Engineering Contradiction:

Improveair concentration detectionVSAvoidair concentration measurement

Core Design Contradiction:

Difficulty of detecting and measuringVSMeasurement precision

Solution Approach 1:

The system uses temperature differential and pressure differential measurements as intermediary parameters that indirectly but precisely indicate non-condensable gas concentration. These intermediary measurements are more easily and precisely obtained than direct gas composition analysis, while still providing accurate detection of air leakage conditions

Inventive Principle:

Principle #24Intermediary (Mediator)

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

Enables longer, more efficient operation of cooling systems by accurately sensing and controlling air leakage, improving heat transfer coefficients and reducing the need for temperature adjustments, thus maintaining system performance.

Implementation Method 1

The condenser removes heat (thermal energy) while condensing the vapor

Methodology Applied

Scientific EffectHeat transfer: Conduction (thermal)

Implementation Method 2

The condenser removes heat (thermal energy) while condensing the vapor

Methodology Applied

Scientific EffectCondensation: Condensation

Implementation Method 3

The evaporator absorbs heat (thermal energy) from a source such as hot electronics

Methodology Applied

Scientific EffectHeat absorption: Conduction (thermal)

Implementation Method 4

The evaporator boils the liquid and feeds the liquid/vapor mixture to the condenser

Methodology Applied

Scientific EffectEvaporation: Evaporation

Data Source

PatentUS8055453B2Sensing and estimating in-leakage air in a subambient cooling system

Publication Date: 2011.11.08 RAYTHEON CO

AI summary

In certain embodiments, estimating air in a cooling system includes measuring a property that can be used to estimate the air to yield a plurality of measurements. The measurements are performed for different heat loads and for different concentrations of non-condensable gas in the cooling system. The measurements are stored a data set.