Multi-Slab Multichannel Heat Exchanger for Even Airflow

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Solution Overview

Problem

Multichannel heat exchangers in HVAC&R systems face inefficiencies due to uneven airflow distribution, leading to variations in heat transfer rates across different tubes, particularly in multi-slab configurations where outer tubes may receive less airflow, affecting overall system performance.

Innovation Solution

A multi-slab heat exchanger design with subdivided groups of multichannel tubes and fluid connections between slabs to optimize refrigerant flow and airflow distribution, ensuring balanced heat transfer across all tubes by aligning tube groups and using manifolds to facilitate even airflow and refrigerant circulation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If multichannel heat exchangers are configured with horizontal tubes in a multi-slab arrangement, then the heat exchanger capacity is increased within a compact footprint, but the outer tubes receive excessive airflow while inner tubes receive insufficient airflow, creating uneven heat transfer rates

Engineering Contradiction:

Improveheat exchanger capacityVSAvoiduniformity of heat transfer rate

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The heat exchanger is divided into multiple slabs, with each slab containing a subset of tubes. This segmentation allows independent airflow management for each slab, enabling the system to maintain high capacity while reducing airflow non-uniformity through coordinated operation of individual slabs

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different slabs are assigned different operational characteristics based on their position and airflow reception. Outer slabs that receive more airflow can be operated at higher capacities, while inner slabs operate at lower capacities, creating local quality variations that balance the overall heat transfer uniformity across the system

Inventive Principle:

Principle #3Local quality

2Reliability

If multichannel heat exchangers use vertical tubes to reduce airflow non-uniformity, then outer tube airflow issues are mitigated, but the equipment footprint increases and system compactness is reduced

Engineering Contradiction:

Improveuniformity of airflow distributionVSAvoidequipment footprint

Core Design Contradiction:

ReliabilityVSArea of stationary object

Solution Approach 1:

The design transitions from a single-plane vertical arrangement to a multi-slab horizontal arrangement, utilizing the third dimension (depth) to organize tubes. This dimensional change allows the system to achieve uniform airflow distribution through multi-slab coordination while maintaining a compact horizontal footprint

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

3Productivity

If the heat exchanger operates at high capacity to maximize productivity, then the heat transfer rate increases, but the airflow non-uniformity becomes more pronounced and frost growth varies significantly across tubes

Engineering Contradiction:

Improveheat transfer rateVSAvoidfrost growth variation

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The system dynamically coordinates refrigerant flow distribution across multiple slabs based on operational conditions. By adjusting refrigerant allocation to match the airflow characteristics of each slab, the system maintains high overall heat transfer rates while preventing excessive frost growth variation, even when operating at high capacity

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

This design enhances heat transfer efficiency and reduces frost growth by promoting even airflow distribution and refrigerant flow, improving the overall performance and capacity of HVAC&R systems, especially in outdoor applications.

Implementation Method 1

heat transfer between refrigerant contained within the tube flow channels and external air passing over the tubes

Methodology Applied

Scientific EffectConvection: Convection

Implementation Method 2

heat transfer between refrigerant contained within the tube flow channels and external air passing over the tubes

Methodology Applied

Scientific EffectConduction (thermal): Conduction (thermal)

Implementation Method 3

heat exchangers transfer heat by circulating a refrigerant through a cycle of evaporation and condensation

Methodology Applied

Scientific EffectEvaporation: Evaporation

Implementation Method 4

heat exchangers transfer heat by circulating a refrigerant through a cycle of evaporation and condensation

Methodology Applied

Scientific EffectCondensation: Condensation

Data Source

PatentUS7942020B2Multi-slab multichannel heat exchanger

Publication Date: 2011.05.17 TYCO FIRE & SECURITY GMBH

AI summary

Heating, ventilation, air conditioning, and refrigeration (HVAC&R) systems and multi-slab heat exchangers are provided that include fluid connections for transmitting fluid between groups of tubes. The fluid connections may include generally tubular members fluidly connected to manifold sections. The fluid connections also may include partitioned manifolds containing tubes of different heights. Multichannel tubes are also provided that include a bent section configured to locate a flow path near a leading edge of a tube within one section and near a trailing edge of the tube within another section.