Economizer injection assembly and method

Solution Overview

Problem

HVAC systems with multiple compression stages experience mixing losses and efficiency drops due to the injection of vaporized flash refrigerant from economizers, as the injected refrigerant does not match the flow velocity and direction of compressed refrigerant, leading to pressure drops and turbulence.

Innovation Solution

Injecting vaporized flash refrigerant from an economizer into the refrigerant conduit between the first and second compression stages at a location with low static pressure, using an injection port and pipe configured to match the flow velocity and direction of the compressed refrigerant, and optionally employing a swirl control device to align the flow before entering the second compression stage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If vaporized flash refrigerant is injected into the refrigerant conduit between compression stages, then compressor efficiency is improved by reducing recompression needs, but mixing losses occur due to velocity and direction mismatch

Engineering Contradiction:

Improvecompressor efficiencyVSAvoidmixing losses

Core Design Contradiction:

Use of energy by moving objectVSLoss of energy

Solution Approach 1:

The injection port is designed with pre-conditioning features including a curved surface that aligns the injected refrigerant velocity and direction to match the compressed refrigerant flow before mixing occurs. This preliminary alignment reduces turbulence and mixing losses while maintaining the efficiency benefits of flash refrigerant injection

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The injection port incorporates localized geometric features including a curved injection surface and specific orientation angles that create optimal flow conditions only at the injection point. The local flow conditions are tailored to match the main refrigerant stream velocity and direction, reducing mixing losses without affecting other system components

Inventive Principle:

Principle #3Local quality

2Temperature

If flash refrigerant is vaporized in the economizer, then flash cooling is achieved improving system efficiency, but pressure drops occur due to mixing with compressed refrigerant

Engineering Contradiction:

Improveflash cooling temperatureVSAvoidpressure drop

Core Design Contradiction:

TemperatureVSStress or pressure

Solution Approach 1:

The injection port is designed to change the flow parameters of the injected refrigerant by matching its velocity and direction to the compressed refrigerant stream. The curved injection surface and optimized orientation transform the injected flow parameters to minimize pressure drops during mixing while preserving the flash cooling temperature benefits

Inventive Principle:

Principle #35Parameter changes

3Loss of energy

If injection port is positioned closer to first compression stage, then static pressure is lower reducing mixing losses, but flow velocity matching becomes more challenging

Engineering Contradiction:

Improvemixing lossesVSAvoidflow velocity matching

Core Design Contradiction:

Loss of energyVSSpeed

Solution Approach 1:

The injection port incorporates localized geometric features including a curved injection surface and specific orientation angles that create optimal flow conditions only at the injection point. The local flow conditions are tailored to match the main refrigerant stream velocity and direction, reducing mixing losses without affecting other system components

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The injection port is designed with pre-conditioning features including a curved surface that aligns the injected refrigerant velocity and direction to match the compressed refrigerant flow before mixing occurs. This preliminary alignment reduces turbulence and mixing losses while maintaining the efficiency benefits of flash refrigerant injection

Inventive Principle:

Principle #10Preliminary action

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 approach reduces mixing losses, such as pressure drops, and enhances the efficiency of the compressor by minimizing recompression of vaporized flash refrigerant, thereby improving the overall performance of the HVAC system.

Implementation Method 1

the economizer may vaporize a portion of the liquid refrigerant from the condenser (also known as flash refrigerant) to provide flash cooling

Methodology Applied

Scientific EffectFlash evaporation: Flash Evaporation

Implementation Method 2

the injection port may be configured to condition the vaporized flash refrigerant so that a flow velocity of the vaporized flash refrigerant matches a flow velocity of the compressed refrigerant in the refrigerant conduit

Methodology Applied

Scientific EffectFlow conditioning:

Implementation Method 3

mixed with compressed refrigerant from the first compression stage before flowing into the second compression stage

Methodology Applied

Scientific EffectMixing:

Data Source

PatentUS9816733B2Economizer injection assembly and method

Publication Date: 2017.11.14 TRANE INTERNATIONAL INC

AI summary

Embodiments provided herein are directed to systems and methods of re-injecting vaporized flash refrigerant from an economizer into a two-stage compressor. The injection can be through an injection port positioned after the first compression stage. The location of the injection may have a relatively low static refrigerant pressure. The injection port and/or an injection pipe of the economizer may be configured to pre-condition the vaporized flash refrigerant so that a flow velocity and/or direction of the vaporized flash refrigerant flow can be match a flow velocity and/or direction of the refrigerant in the refrigerant conduit.