Volute Blower Housing Geometry for Lower Furnace Pressure Drop

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Solution Overview

Problem

High efficiency residential furnaces face inefficiencies due to concentrated air flow through small areas of heat exchangers, leading to increased pressure drop and the need for larger blower motors, which decreases electrical efficiency and requires more space, making it difficult to maintain compact designs.

Innovation Solution

A blower housing with an exponentially increasing expansion angle along its volute-shaped outer wall, which enlarges the air outlet opening without increasing exterior dimensions, spreading air flow over a larger area of heat exchangers and converting velocity head to usable static pressure, reducing pressure loss and blower horsepower requirements.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If air flow is concentrated through small areas of heat exchangers, then heat transfer efficiency is improved, but pressure drop increases and blower motor size must be increased

Engineering Contradiction:

Improveheat transfer efficiencyVSAvoidpressure drop

Core Design Contradiction:

Use of energy by moving objectVSLoss of energy

Solution Approach 1:

The blower housing outlet is designed with non-uniform geometry where different regions have different expansion characteristics. The volute shape creates zones of varying flow velocity and pressure distribution, allowing optimal local heat transfer in different areas of the heat exchanger while managing overall pressure drop through strategic geometric variation.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent modifies the geometric parameters of the blower housing outlet, specifically implementing an exponentially increasing expansion angle in the volute section. This parameter change transforms the flow characteristics, spreading air flow over a larger effective area of the heat exchanger while maintaining heat transfer efficiency and reducing pressure drop.

Inventive Principle:

Principle #35Parameter changes

2Power

If blower motor size is increased to handle pressure drop, then air distribution capability is improved, but electrical efficiency decreases and space requirements increase

Engineering Contradiction:

Improveair distribution capabilityVSAvoidelectrical efficiency

Core Design Contradiction:

PowerVSUse of energy by moving object

Solution Approach 1:

By changing the geometric parameters of the blower housing outlet to an exponentially increasing expansion angle, the system achieves better air distribution capability without increasing motor power. The optimized geometry reduces flow resistance and improves pressure recovery, allowing smaller motors to achieve the same air distribution performance with higher electrical efficiency.

Inventive Principle:

Principle #35Parameter changes

3Area of stationary object

If blower housing exterior dimensions are increased to enlarge air outlet opening, then air flow distribution is improved, but furnace enclosure size increases

Engineering Contradiction:

Improveair outlet opening areaVSAvoidfurnace enclosure size

Core Design Contradiction:

Area of stationary objectVSVolume of stationary object

Solution Approach 1:

The patent employs a volute-shaped outlet geometry that utilizes three-dimensional spatial arrangement to achieve a large effective air outlet opening area without increasing the external footprint of the blower housing. The exponentially increasing expansion angle creates a spiral or curved flow path that expands the flow area internally while maintaining compact external dimensions, effectively using dimensional transformation to resolve the contradiction.

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 design enhances the efficiency of air distribution, reduces the size of the furnace enclosure, and achieves energy savings by distributing air flow more evenly across heat exchangers, lowering pressure loss and enabling the use of smaller motors while maintaining high efficiency in both 90+ and 80+ AFUE furnaces.

Implementation Method 1

The design of the blower housing also efficiently turns the velocity head of the air flow to usable static pressure at the housing air outlet

Methodology Applied

Scientific EffectVelocity head to static pressure conversion: Bernoulli Effect

Implementation Method 2

The enlarged outlet opening slows down and spreads out the air flow from the blower housing over a greater area of the secondary heat exchanger and the primary heat exchanger

Methodology Applied

Scientific EffectFlow expansion and velocity reduction: Diffusion

Data Source

PatentUS9513029B2High efficiency furnace/air handler blower housing with a side wall having an exponentially increasing expansion angle

Publication Date: 2016.12.06 REGAL BELOIT AMERICA INC

AI summary

An air distribution blower housing for an air handler such as a residential furnace is designed with a volute-shaped outer wall that has an exponentially increasing expansion angle in the direction of air flow through the blower housing for at least a portion of the volute-shaped outer wall length. This results in the blower housing having an enlarged air outlet opening that slows down and spreads out the air flow from the blower housing over a greater area of the furnace heat exchanger. The blower housing thereby enables less air pressure drop through the heat exchanger, which increases the efficiency of the blower motor operation. The design of the blower housing also efficiently turns the velocity head of the air flow through the housing to usable static air pressure at the housing air outlet.