Gas furnace
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Solution Overview
Problem
Gas furnaces face inefficiencies in heat transfer due to insufficient turbulence on the heat exchanger surface and non-uniform gas flow distribution, leading to reduced heat exchange performance and potential damage from direct flame contact.
Innovation Solution
The design incorporates a heat exchanger with a single-multiple return bend and multiple paths, featuring convex and concave portions to increase turbulence and uniformize gas flow, while preventing direct flame contact through gradual diameter changes and staggered concave formations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If concave portions are formed in the heat exchanger flow path to enlarge heat transfer area, then heat transfer area is increased, but turbulence on the surface is insufficient and heat transfer performance is not greatly improved
Solution Approach 1:
The patent employs curved flow paths with return bends instead of straight or simple concave paths. The combustion gas flows through curved sections that create centrifugal forces and enhance turbulence mixing between the gas and heat exchanger surface, significantly improving heat transfer coefficients and overall heat transfer performance.
Solution Approach 2:
The complex curved flow path with multiple return bends creates flow instability and turbulence that acts similarly to mechanical vibration, disrupting the boundary layer between the combustion gas and heat exchanger surface. This turbulence enhances convective heat transfer by continuously renewing the fluid particles in contact with the heat transfer surface.
2Loss of energy
If combustion gas flows through the heat exchanger, then heat exchange occurs, but temperature decreases and density increases causing slow flow rate and reduced heat exchange performance
Solution Approach 1:
The heat exchanger flow path is divided into multiple segments with return bends, creating a multi-pass configuration. This segmentation maintains smaller flow path lengths in each pass, preventing excessive temperature drop and density increase that would slow the flow. The combustion gas is continuously refreshed in each pass, maintaining better heat exchange performance throughout the entire heat exchanger.
Solution Approach 2:
The flow path design adapts to changing gas properties by using return bends that redirect flow when temperature and density change. The curved paths and varying cross-sections dynamically adjust the flow characteristics, maintaining adequate flow velocities even as the gas cools and densifies through the heat exchanger.
3Power
If flames contact the heat exchanger flow path, then combustion heat is transferred, but the flow path is damaged
Solution Approach 1:
The heat exchanger is positioned and configured to receive only combustion gas that has already been mixed with primary air and ignited in the combustion chamber. The flow path design ensures that the combustion gas enters the heat exchanger after the flame has stabilized, preventing direct flame contact while still capturing the thermal energy from the combustion process.
Solution Approach 2:
The combustion chamber acts as an intermediary between the fuel gas combustion and the heat exchanger. The combustion gas is fully mixed and stabilized in the combustion chamber before entering the heat exchanger flow path, serving as a buffer that prevents direct flame contact with the heat exchanger while still transferring the combustion heat effectively.
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 heat transfer area and turbulence, improving heating efficiency and durability by ensuring uniform gas distribution and preventing flame damage.
Implementation Method 1
a gas furnace is an apparatus that heats indoor air by exchanging air supplied to a room with a flame and a high temperature combustion gas
Implementation Method 2
the heat generated during the combustion of the fuel gas may not be effectively transmitted to the room air
Implementation Method 3
a combustion part in which a fuel gas is burnt to generate a combustion gas
Implementation Method 4
the turbulence on the surface of the heat exchanger is not sufficiently generated due to the simple shape or arrangement of the concave part or unevenness portion
Data Source
AI summary
A gas furnace is provided. The gas furnace includes a combustion part in which a fuel gas is burnt to generate a combustion gas, a heat exchanger having a gas flow path through which the combustion gas flows, a blower configured to blow air around the heat exchanger, and an inducer configured to discharge the combustion gas from the heat exchanger. The heat exchanger includes at least one single path in which a single gas flow path is formed a single-multiple return bend configured to communicate with the single path and convert a flow direction of the combustion gas, and at least one multiple path having a plurality of paths that communicate with the single-multiple return bend and form multiple gas flow paths.