Cooling circuit

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Solution Overview

Problem

Existing cooling circuits for refrigeration machines face inefficiencies in heat dissipation during compression, leading to high final compression temperatures, which can damage compressors and limit their application, and current methods like air flow cooling or refrigerant injection are not effective in managing partial load operations or pressure levels.

Innovation Solution

A cooling circuit with a refrigerant compressor, a heat exchanger, and a supply unit featuring a high-pressure pump and injector that supplies refrigerant at pressures significantly above the delivery pressure of the compressor, ensuring efficient cooling by injecting refrigerant directly into the working space, allowing for adjustable injection points and pressures to manage compression temperatures and partial load conditions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If refrigerant compressors are not actively cooled, then the structure is simpler, but the final compression temperature becomes very high causing long-term damage to the compressor

Engineering Contradiction:
Improvecooling system structureVSAvoidcompressor durability
Core Design Contradiction:
Device complexityVSReliability

Solution Approach 1:

The refrigerant compressor cools itself by using a portion of the compressed refrigerant to cool the suction gas before it enters the compression chamber. The motor and power electronics are also cooled by the refrigerant, creating a self-cooling system that eliminates the need for external cooling devices while maintaining compressor durability.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The refrigerant serves multiple functions: it is the working medium for compression, the cooling medium for the suction gas, and the cooling medium for the motor and power electronics. This multi-functionality eliminates the need for separate cooling systems while improving overall system efficiency.

Inventive Principle:
Principle #6Universality (Multi-functionality)

2Temperature

If vapor injection is used to reduce compression temperature, then the final compression temperature decreases, but the device complexity increases due to additional injection components

Engineering Contradiction:
Improvefinal compression temperatureVSAvoidinjection system complexity
Core Design Contradiction:
TemperatureVSDevice complexity

Solution Approach 1:

The injection system is integrated into the existing compressor structure, with the injection port combining the refrigerant supply line and the injection function into a single component. This merging reduces the number of separate parts while maintaining the temperature control function.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The injection port acts as an intermediary component that introduces cooled refrigerant vapor into the compression chamber during the compression process. This intermediary mechanism effectively reduces compression temperature without requiring complex external cooling systems.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Reliability

If the refrigerant is injected at pressure between discharge and suction gases, then the injection is more effective, but the control precision for partial load operations decreases

Engineering Contradiction:
Improveinjection effectivenessVSAvoidpartial load control precision
Core Design Contradiction:
ReliabilityVSEase of operation

Solution Approach 1:

The injection pressure is dynamically adjusted based on the compressor's operating conditions. The system automatically adapts the injection parameters to match the current load, ensuring optimal injection effectiveness across all operating ranges while maintaining precise control for partial load operations.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The control system monitors the compressor's operating parameters and adjusts the injection pressure and timing accordingly. This feedback mechanism ensures that the injection remains effective under varying load conditions while maintaining precise control for partial load operations.

Inventive Principle:
Principle #23Feedback

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

This solution effectively reduces final compression temperatures, enhances efficiency, and allows for precise control of refrigerant injection, thereby extending the compressor's application range and improving partial load operation without the limitations of traditional methods.

Implementation Method 1

The supply unit has a high-pressure pump and an injector. The supply unit is designed to supply refrigerant from the refrigerant reservoir to the working chamber via the injector at a pressure above a discharge pressure of the refrigerant compressor

Methodology Applied
Scientific EffectCompression: Compression

Implementation Method 2

The injector is designed to distribute the refrigerant within the working chamber and/or to spray the refrigerant onto a refrigerant compressor wall of the refrigerant compressor that delimits the working chamber

Methodology Applied
Scientific EffectFluid spray: Fluid Spray

Implementation Method 3

spraying the refrigerant onto a refrigerant compressor wall... that delimits the working chamber

Methodology Applied
Scientific EffectEvaporative cooling: Evaporative Cooler

Implementation Method 4

The cooling circuit further comprises a heat exchanger with a fluid collection chamber. The heat exchanger is connected to a pressure chamber of the refrigerant compressor

Methodology Applied
Scientific EffectHeat exchange: Heat Exchanger

Implementation Method 5

supplying essentially single-phase refrigerant from the refrigerant reservoir to the working chamber by means of the injector

Methodology Applied
Scientific EffectPhase change: Phase Change

Data Source

PatentEP3978836B1Cooling circuit
Publication Date: 2024.11.27 HOCHSCHULE KARLSRUHE
  • EP3978836B1 patent drawingFigure 1
  • EP3978836B1 patent drawingFigure 2

AI summary

A cooling circuit (100) is proposed. The cooling circuit (100) comprises a refrigerant compressor (102) with at least one working chamber (104), a heat exchanger (106) with a fluid collection chamber (108), wherein the fluid collection chamber (108) is configured to form a refrigerant reservoir, and a supply unit (114). The supply unit (114) is connected to the fluid collection chamber (108) and the refrigerant compressor (102). The supply unit (114) includes a high-pressure pump (116) and an injector (118). The supply unit (114) is configured to supply refrigerant from the refrigerant reservoir to the working chamber (104) by means of the injector (118) at a pressure above the discharge pressure of the refrigerant compressor (102).