Centrifugal refrigerant compressor system

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Solution Overview

Problem

Existing refrigerant compressors face challenges in efficiently managing capacity control during part-load operating conditions, particularly in maintaining flow angles and velocities similar to full-load design conditions, which affects stability and efficiency.

Innovation Solution

A centrifugal refrigerant compressor system with a first and second impeller, incorporating a recirculation flow path and an economizer flow path that introduce fluid into the main flow path through ports, either adjacent to the return channel between the impellers or downstream of the second impeller, to stabilize operation and improve efficiency by injecting fluid from these paths to maintain optimal flow conditions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If variable inlet guide vanes and variable-geometry diffusers are used to improve capacity control during part-load conditions, then flow angles and velocities can be maintained similar to full-load design conditions, but device complexity increases

Engineering Contradiction:
Improvestability during part-load operationVSAvoidmechanical components
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent removes the variable inlet guide vanes and variable-geometry diffusers from the system, replacing complex mechanical adjustment mechanisms with a simpler recirculation flow path that achieves similar stability benefits without the mechanical complexity

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent introduces a recirculation flow path as an intermediary mechanism that allows refrigerant to be redirected and reintroduced into the main flow path, achieving flow stabilization during part-load conditions without requiring variable geometry components

Inventive Principle:
Principle #24Intermediary (Mediator)

2Reliability

If recirculation flow path is implemented to improve capacity control, then stability during part-load conditions is enhanced, but device complexity increases due to additional ports and flow paths

Engineering Contradiction:
Improveoperational stabilityVSAvoidflow path configuration
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The recirculation flow path serves multiple functions: it stabilizes flow during part-load conditions, enables capacity control, and eliminates the need for variable geometry components, achieving multiple benefits through a single integrated approach

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

Solution Approach 2:

The patent changes the operational parameters by redirecting recirculation flow at different rates depending on load conditions, using the same recirculation path to achieve capacity control across varying operating conditions without mechanical adjustment

Inventive Principle:
Principle #35Parameter changes

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 configuration enhances the stability and efficiency of the compressor during part-load conditions, extends the operating range, and reduces the likelihood of surge conditions, while also simplifying the mechanical components by eliminating the need for inlet guide vanes and variable geometry diffusers.

Implementation Method 1

a first impeller, and a second impeller downstream of the first impeller

Methodology Applied
Scientific EffectCentrifugal force: Centrifugal Force

Implementation Method 2

Fluid from a recirculation flow path and an economizer flow path is introduced into a main flow path of the compressor by way of the at least one port

Methodology Applied
Scientific EffectFluid injection: Injector

Data Source

PatentEP3069089B1Centrifugal refrigerant compressor system
Publication Date: 2020.08.05 DANFOSS AS
  • EP3069089B1 patent drawingFigure 1~3
  • EP3069089B1 patent drawingFigure 4~6
  • EP3069089B1 patent drawingFigure 7~9

AI summary

One exemplary embodiment of this disclosure relates to a centrifugal refrigerant compressor system. The system includes a condenser, an evaporator, and an economizer between the condenser and the evaporator. The system further includes a centrifugal compressor having a first impeller and a second impeller downstream of the first impeller. The compressor includes at least one port. Fluid from a recirculation flow path and an economizer flow path is introduced into a main flow path of the compressor by way of the at least one port.