Fuel Cell Heat Exchanger Pipes Variable Diameter Flow
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Solution Overview
Problem
Conventional fuel cell systems face inefficiencies in heat exchange, requiring additional fins or structures that increase pressure loss and hinder effective heat transfer, making it difficult to improve heat exchange efficiency without redesigning the system.
Innovation Solution
A fuel cell module design featuring a heat exchanger with annular oxygen-containing gas supply and discharge chambers and heat exchange pipes with varying diameters or cross-sectional areas, allowing for transition from laminar to turbulent flow, which enhances heat transfer efficiency and supports thermally self-sustaining operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If fins or additional structures are provided in the annular chamber to improve heat exchange efficiency, then heat transfer area increases, but pressure loss becomes large
Solution Approach 1:
The patent changes the geometric parameters of the heat exchange pipes by making the outer diameter vary along the length (larger at ends, smaller in middle section). This parameter variation creates turbulent flow conditions that enhance heat transfer efficiency without requiring additional fins, thereby avoiding the pressure loss problem associated with finned structures.
2Ease of manufacture
If the heat exchanger is designed with simple structure, then manufacturing cost decreases, but heat exchange efficiency is insufficient
Solution Approach 1:
The patent achieves improved heat exchange efficiency through parameter changes in the pipe geometry (variable outer diameter) rather than adding complex structures. This maintains manufacturing simplicity while enhancing heat transfer through turbulent flow generation, thus resolving the contradiction between simple structure and heat exchange efficiency.
3Temperature
If conventional cylindrical heat exchanger with coaxial plates is used, then structure is simple, but pressure loss increases when fins are added for improved heat efficiency
Solution Approach 1:
The patent departs from the conventional cylindrical heat exchanger design by implementing heat exchange pipes with variable outer diameter. This geometric modification generates turbulent flow that improves heat efficiency without requiring fins, thereby avoiding the pressure loss penalty associated with finned conventional designs.
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
The design improves heat exchange efficiency, reduces production costs, and allows for flexible operation under various conditions, achieving a compact and efficient thermally self-sustaining system.
Implementation Method 1
a heat exchanger for raising a temperature of the oxygen-containing gas by heat exchange with a combustion gas
Implementation Method 2
heat exchange pipes...supplying the combustion gas to a space between the heat exchange pipes
Implementation Method 3
a fuel cell stack formed by stacking a plurality of fuel cells for generating electricity by electrochemical reactions of a fuel gas and an oxygen-containing gas
Implementation Method 4
a reformer for reforming a mixed gas of water vapor and a raw fuel chiefly containing hydrocarbon to produce the fuel gas
Implementation Method 5
an evaporator for evaporating water, and supplying the water vapor to the reformer
Implementation Method 6
an exhaust gas combustor for combusting the fuel gas discharged from the fuel cell stack as a fuel exhaust gas and the oxygen-containing gas discharged from the fuel cell stack as an oxygen-containing exhaust gas to produce the combustion gas
Data Source
AI summary
A fuel cell module includes a first area where an exhaust gas combustor and a start-up combustor are provided, an annular second area around the first area where a heat exchanger is provided, an annular third area around the second area where a reformer is provided, an annular fourth area around the third area where an evaporator is provided. A plurality of heat exchange pipes are provided in the heat exchanger around a first partition plate. At least one of the heat exchange pipes has at least one constricted portion.