Gas Cooler Pressure Control for Gas Loop Detection

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Solution Overview

Problem

Cooling plants with heat rejecting heat exchangers face inefficiencies due to 'gas loop operation', where measurement faults in pressure and temperature lead to suboptimal energy use, reducing cooling capacity and increasing compressor load without detection by existing systems.

Innovation Solution

A method to monitor and adjust the gas pressure in the heat rejecting heat exchanger, identifying high compressor capacity levels over time to detect gas loop operational mode and increase pressure to shift the operating point away from inefficient isothermal curves, thereby improving energy efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If gas cooler control is used with standard pressure and temperature measurement, then the controller believes the system is operating at optimal conditions, but the actual cooling capacity is dramatically reduced and energy efficiency is severely degraded

Engineering Contradiction:
Improvepressure and temperature measurement accuracyVSAvoidcooling capacity
Core Design Contradiction:
Measurement precisionVSProductivity

Solution Approach 1:

The patent introduces an intermediary parameter (compressor capacity indicator) that indirectly reflects the actual thermodynamic state of the system. Instead of relying solely on direct pressure and temperature measurements that may be faulty, the system uses the compressor's electrical power consumption as a mediator to detect gas loop operation and infer the true operating condition.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The system implements feedback by continuously monitoring the compressor capacity indicator and comparing it against expected values for optimal operation. When the indicator shows values corresponding to gas loop operation, the system generates a signal to alert operators or automatically adjust control parameters, creating a closed-loop detection mechanism.

Inventive Principle:
Principle #23Feedback

2Productivity

If the controller increases compressor capacity to 100% in response to detected inefficiency, then the system attempts to maintain cooling output, but energy consumption increases and the gas loop condition persists undetected

Engineering Contradiction:
Improvecooling capacity maintenanceVSAvoidcompressor energy consumption
Core Design Contradiction:
ProductivityVSUse of energy by moving object

Solution Approach 1:

The patent applies preliminary action by detecting gas loop operation conditions before they lead to severe energy waste and performance degradation. By monitoring the compressor capacity indicator and detecting the characteristic pattern of gas loop operation early, the system can alert operators to take corrective action before the system enters a sustained inefficient state.

Inventive Principle:
Principle #10Preliminary action

3Ease of operation

If standard control systems are used without gas loop detection, then the system operates continuously, but it cannot distinguish between optimal and inefficient operating modes

Engineering Contradiction:
Improvecontinuous operationVSAvoidoperating mode information
Core Design Contradiction:
Ease of operationVSLoss of information

Solution Approach 1:

The patent uses a metaphorical 'color change' approach by generating distinct signals or alerts that indicate different operating modes. When gas loop operation is detected through the compressor capacity indicator, the system produces a specific warning signal that clearly distinguishes this inefficient mode from normal optimal operation, making the operating state information visible to operators.

Inventive Principle:
Principle #32Color changes

Data Source

PatentEP2764303B1Method for controlling gas pressure in cooling plant
Publication Date: 2021.06.16 DANFOSS AS
  • EP2764303B1 patent drawingFigure 1
  • EP2764303B1 patent drawingFigure 2

AI summary

A method for monitoring gas pressure in a heat rejecting heat exchanger in a cooling circuit is disclosed. In the heat rejecting heat exchanger, pressure is controlled by means of a control unit, said control unit controlling at least one valve. The present capacity of one or more compressors in the cooling circuit compared to a maximum capacity of the one or more compressors is established. The maximum capacity may be the rated capacity of the compressors, or it may be a maximum capacity under the given circumstances and/or the given operating conditions. If the present capacity of the one or more compressors is at least at a level corresponding to a pre-set percentage of the maximum capacity, a period of time elapsed from a point in time where the compressor capacity reached said level is established. If the established period of time has a duration which is longer than a pre-set period of time, then it is concluding that the cooling medium is in a gas loop operational mode. Detecting a gas loop operational mode in an easy manner allows an operator or a controller to adjust operation of the cooling plant in such a manner that the cooling medium is brought out of the gas loop operational mode, thereby increasing the energy efficiency of the cooling plant.