Suction duct and multiple suction ducts inside a shell of a flooded evaporator

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Solution Overview

Problem

Conventional suction ducts in heat exchangers often experience localized vapor flow phenomena and entrainment issues, leading to inefficiencies and pressure drop problems, especially in flooded-type evaporators used in HVAC and refrigeration systems.

Innovation Solution

The implementation of a suction duct with a strategically designed area schedule, featuring openings such as slots or geometric shapes, positioned above the tube bundle to direct vapor flow laterally and smoothly, avoiding liquid entrainment and promoting uniform vapor flow, and optionally extending along the longitudinal length of the shell with a side outlet configuration.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If conventional suction ducts are used in flooded evaporators, then vapor can be removed from the heat exchanger, but localized vapor flow phenomena and entrainment issues occur leading to pressure drop problems

Engineering Contradiction:

Improvevapor removal efficiencyVSAvoidpressure drop

Core Design Contradiction:

ProductivityVSLoss of energy

Solution Approach 1:

The suction duct incorporates an area schedule with non-uniform opening distribution along its length. The opening area varies at different positions to match the local vapor generation rate, creating locally optimized flow conditions that prevent localized vapor flow phenomena and reduce entrainment while maintaining efficient vapor removal throughout the evaporator

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent changes the geometric parameter of the suction duct by implementing a variable area schedule with specifically designed opening sizes and distributions. This parameter optimization allows the duct to adapt to varying vapor flow conditions along its length, reducing pressure drop while maintaining high vapor removal efficiency

Inventive Principle:

Principle #35Parameter changes

2Object-affected harmful factors

If suction duct is positioned high above tube bundle to avoid liquid entrainment, then liquid carryover is reduced, but vapor flow uniformity becomes difficult to maintain

Engineering Contradiction:

Improveliquid entrainmentVSAvoidvapor flow uniformity

Core Design Contradiction:

Object-affected harmful factorsVSStability of the object's composition

Solution Approach 1:

The area schedule creates different local characteristics along the suction duct length. Openings are strategically sized and positioned at different locations to address local vapor flow conditions, ensuring uniform vapor withdrawal while maintaining the high position necessary to avoid liquid entrainment from the tube bundle

Inventive Principle:

Principle #3Local quality

3Productivity

If traditional top outlet configuration is used, then vapor can be removed from shell, but vertical footprint is increased

Engineering Contradiction:

Improvevapor removal capabilityVSAvoidvertical footprint

Core Design Contradiction:

ProductivityVSLength of stationary object

Solution Approach 1:

The suction duct is configured to extend horizontally along the longitudinal axis of the shell rather than vertically. This dimensional reorientation allows vapor to be removed from the shell while minimizing the vertical footprint, accommodating space-constrained installations without sacrificing vapor removal capability

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

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 vapor flow uniformity, reduces localized currents and entrainment, and minimizes pressure drop, while optimizing vapor flow direction to match liquid flow, thereby improving the efficiency and performance of heat exchangers in refrigeration systems.

Implementation Method 1

vapor that is boiled off is drawn toward the top of the shell or to a relatively high position inside the shell

Methodology Applied

Scientific EffectVapor flow:

Implementation Method 2

The suction duct is disposed within the shell, and is located relatively high and above the tube bundle so as to not entrain liquid or droplets that may be splashing and spraying upward

Methodology Applied

Scientific EffectPhase separation:

Implementation Method 3

the area schedule configuration of the suction duct can have openings that are metered and/or have a density and/or have a geometry to optimize vapor flow inside the shell by obtaining uniform vapor flow from the evaporation off the tube bundle

Methodology Applied

Scientific EffectVapor flow uniformity:

Data Source

PatentUS10627139B2Suction duct and multiple suction ducts inside a shell of a flooded evaporator

Publication Date: 2020.04.21 TRANE INTERNATIONAL INC

AI summary

A suction duct is disposed within a shell and tube heat exchanger. The suction duct is located relatively high and above the tube bundle so as to not entrain liquid or droplets that may be splashing and spraying upward. The suction duct is configured with an area schedule in fluid communication with a flow path inside the suction duct. The flow path is in fluid communication with an outlet of the shell. This is advantageous relative to traditional top of the shell outlets which generally have higher vertical footprints. The area schedule of the suction duct can facilitate and/or maintain relatively smooth vapor flow within the shell. The area schedule can achieve vapor flows that have some uniformity along the length of the shell, which can manage and/or avoid localized vapor flow and/or local currents, such as where high velocity may be present and where entrainment can result.