Screw Compressor Demister Nesting for Compact Oil Separation

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Solution Overview

Problem

Existing screw compressors suffer from excessive oil droplets in the working medium discharge, particularly in certain operating conditions, necessitating improved oil separation and potentially compromising compact design.

Innovation Solution

A screw compressor design featuring a demister positioned upstream of the compressor outlet, where a jet of compressed working medium is directed to separate oil droplets, combined with a media-impermeable wall to prevent entrainment, and multiple demisters in series for enhanced separation, allowing for compact construction.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a demister is arranged in the interior space of the outer housing, then oil separation is improved, but the compressor size increases and compact design is compromised

Engineering Contradiction:

Improveoil separation efficiencyVSAvoidcompressor size

Core Design Contradiction:

ReliabilityVSVolume of moving object

Solution Approach 1:

The demister is integrated into the compressor outlet structure, with the outlet conduit passing through the demister element. This nesting approach allows the demister to be housed within the existing outlet pathway, eliminating the need for additional exterior space while maintaining effective oil separation functionality.

Inventive Principle:

Principle #7Nested doll (Nesting)

Solution Approach 2:

The demister function is merged with the outlet conduit structure, where the outlet conduit serves dual purposes as both fluid passage and demister support. This combination reduces the total component count and eliminates the need for separate demister housing, thereby maintaining compact dimensions.

Inventive Principle:

Principle #5Merging (Combining)

2Reliability

If multiple demisters are arranged in series, then oil separation efficiency is improved, but device complexity increases

Engineering Contradiction:

Improveoil separation efficiencyVSAvoiddemister arrangement complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The demister system is segmented into multiple functional zones within a single compact element. The outlet conduit passes through different sections of the demister structure, creating sequential separation stages without requiring multiple discrete demister components. This segmentation achieves enhanced separation efficiency while maintaining structural simplicity.

Inventive Principle:

Principle #1Segmentation

3Reliability

If the compressor outlet is oriented towards the demister, then oil droplets are effectively separated, but the internal space arrangement becomes more complex

Engineering Contradiction:

Improveoil droplet separationVSAvoidoutlet orientation arrangement

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

Instead of orienting the demister to face the outlet, the design inverts the arrangement by passing the outlet conduit through the demister element. This inversion simplifies the spatial arrangement by eliminating the need for complex angular orientations while maintaining effective oil droplet separation through the conduit-demister integration.

Inventive Principle:

Principle #13The other way round (Inversion)

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

The design effectively reduces oil droplets in the discharged medium while enabling a compact form factor by improving oil separation efficiency and ensuring reliable collection in an oil sump.

Implementation Method 1

Due to inertia, redirecting the oil droplets in the demister causes the oil droplets to not follow the gas flow of the working medium and strike the demister

Methodology Applied

Scientific EffectInertia: Inertia

Implementation Method 2

Larger oil drops can get stuck in the demister or, due to gravity, fall into an oil sump downstream of the demister

Methodology Applied

Scientific EffectGravity: Gravitation

Data Source

PatentUS20260049610A1Compressor, especially screw compressor, and refrigeration circuit with a compressor

Publication Date: 2026.02.19 BITZER KUEHLMASCHINENBAU GMBH

AI summary

The present invention relates to a compressor, in particular a screw compressor (2) for compressing a working medium, comprising an outer housing (10) with an inlet opening (11), an outlet opening (12) and a longitudinal axis (X), a drivable compression device (20) arranged in the outer housing (10) and having at least one rotatable rotor (25), and at least one compressor outlet (50), wherein the at least one compressor outlet (50) conducts the working medium compressed by the compression device (20) into an interior space (45) arranged in the outer housing (10), wherein a first demister (60) is arranged in the interior space (45), and wherein the at least one compressor outlet (50) is oriented towards the first demister (60) in order to cause the compressed working medium to flow to the first demister (60). Furthermore, the present invention relates to a refrigeration system (1) having a screw compressor (2).