Movable Liquid Injection Ports for Screw Compressor Temperature Control

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Solution Overview

Problem

Conventional liquid injection mechanisms in screw compressors have a fixed injection position, leading to unstable discharge gas temperatures and performance degradation due to excessive liquid injection or reduced injection when internal volume ratios change, causing increased compressor workload and vibration.

Innovation Solution

A screw compressor with movable liquefied liquid supply ports that adjust in the rotor shaft direction to communicate with tooth groove spaces near the discharge port, allowing for stable temperature control and efficient discharge gas cooling, reducing compressor workload and improving coefficient of performance (COP).

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If a fixed liquid injection port is used, then the structure is simple, but the discharge gas temperature becomes unstable when operating conditions change

Engineering Contradiction:

Improveliquid injection mechanism structureVSAvoiddischarge gas temperature stability

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The patent applies the dynamics principle by making the liquid injection port movable along the rotor shaft direction. The injection port is coupled to move with the internal volume ratio adjusting valve, allowing the injection position to dynamically change according to operating conditions. This resolves the contradiction by enabling temperature stability (reliability) without requiring a complex fixed multi-position system, as the single movable port adapts automatically.

Inventive Principle:

Principle #15Dynamics

2Device complexity

If liquid is injected at a fixed position connected to discharge portion, then the injection position is fixed, but liquid injection becomes disabled when internal volume ratio adjusting valve moves to low internal volume ratio side

Engineering Contradiction:

Improveliquid injection mechanism structureVSAvoidliquid injection adaptability to volume ratio changes

Core Design Contradiction:

Device complexityVSAdaptability or versatility

Solution Approach 1:

The liquid injection port is designed to move dynamically along the rotor shaft direction, coupled to the internal volume ratio adjusting valve. This allows the injection port to maintain proper positioning relative to the compression space regardless of the valve's position, enabling continuous liquid injection across all operating conditions without requiring multiple fixed ports or complex switching mechanisms.

Inventive Principle:

Principle #15Dynamics

3Device complexity

If liquid is injected with fixed injection port, then the structure is simple, but excessive liquid injection occurs when internal volume ratio adjusting valve moves to high internal volume ratio side

Engineering Contradiction:

Improveliquid injection mechanism structureVSAvoidliquid injection amount

Core Design Contradiction:

Device complexityVSQuantity of substance

Solution Approach 1:

The movable liquid injection port dynamically adjusts its position along the rotor shaft direction based on the internal volume ratio adjusting valve position. When the valve moves to high internal volume ratio side, the injection port automatically shifts to prevent excessive liquid injection, thereby controlling the liquid amount without requiring complex flow control mechanisms or multiple injection ports.

Inventive Principle:

Principle #15Dynamics

4Productivity

If unloader slide valve moves to suction side, then volume control is achieved, but liquid injection port connects to discharge portion causing increased compression power and vibration

Engineering Contradiction:

Improvevolume control capabilityVSAvoidcompression power

Core Design Contradiction:

ProductivityVSPower

Solution Approach 1:

The liquid injection port is coupled to move with the unloader slide valve along the rotor shaft direction. When the slide valve moves to the suction side for volume control, the injection port dynamically adjusts its position to remain properly positioned relative to the compression space, preventing connection to the discharge portion. This eliminates the harmful effects of increased compression power and vibration while maintaining volume control functionality.

Inventive Principle:

Principle #15Dynamics

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 movable liquefied liquid supply ports enable stable discharge gas temperature control and reduced compressor workload, enhancing reliability and COP by optimizing liquid injection based on changing operating conditions.

Implementation Method 1

a refrigerant liquid evaporates by removing heat of a compressed gas under compression

Methodology Applied

Scientific EffectEvaporation: Evaporation

Implementation Method 2

a refrigerant liquid evaporates by removing heat of a compressed gas

Methodology Applied

Scientific EffectHeat transfer: Conduction (thermal)

Data Source

PatentUS11333148B2Screw compressor and refrigeration device

Publication Date: 2022.05.17 MAYEKAWA MFG CO LTD

AI summary

A screw compressor according to an embodiment includes a rotor casing, a pair of screw rotors disposed in the rotor casing and engaging with each other, and a movable portion disposed so as to be movable in a rotor shaft direction of the pair of screw rotors. The movable portion includes liquefied liquid supply ports capable of supplying a liquefied liquid of a compressed gas toward tooth groove spaces formed by the pair of screw rotors.