Double-Shell Phase Change Heat Exchanger for High Heat Flux Density
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Solution Overview
Problem
Existing gas water heaters suffer from low heat utilization efficiency due to low heat flux density and slow heat production, resulting in energy waste and irreversible losses from large temperature differences between high temperature gases and heated water.
Innovation Solution
A heat exchanger component with a double-shell structure, utilizing a liquid phase change medium and multiple heat exchange tubes, where high temperature flue gas flows through a cavity between the shells to enhance heat transfer, and a three-heating core system with a phase change heat exchanger to achieve efficient heat utilization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional finned tube heat exchanger is used with limited space heat transfer, then the structure is simple, but the heat flux density is low and heat utilization efficiency is poor
Solution Approach 1:
The patent introduces a phase change heat exchanger that utilizes phase transition (evaporation and condensation) of working fluid to achieve high heat flux density. The working fluid evaporates in the evaporation section absorbing heat from flue gas, then condenses in the condensation section releasing heat to heating water, dramatically improving heat utilization efficiency compared to conventional conduction-based heat exchangers
Solution Approach 2:
The heat exchanger is divided into distinct functional sections: evaporation section, condensation section, and liquid separation section. This segmentation allows each section to perform its specific function optimally, with the evaporation section focusing on heat absorption and the condensation section on heat release, thereby resolving the contradiction between structural simplicity and heat utilization efficiency
2Temperature
If high temperature flue gas flows through the heat exchanger, then heat transfer occurs, but the low velocity and laminar flow result in low heat flux density
Solution Approach 1:
The phase change process provides intense heat transfer coefficients that overcome the limitations of low flue gas velocity and laminar flow. The evaporation and condensation processes occur at high heat flux densities, enabling rapid heat production despite the slow-moving flue gas, thus resolving the contradiction between temperature transfer capability and productivity
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 solution significantly enhances thermal efficiency by achieving high heat flux density through boiling and condensation heat transfer processes, allowing for rapid heat production and energy savings in gas water heaters.
Implementation Method 1
the lower portion of the inner space of the inner shell is filled with a liquid phase change medium... achieving high heat flux density through boiling and condensation heat transfer processes
Implementation Method 2
through boiling and condensation heat transfer processes... the vaporized phase change medium contacts with the upper coiler and is condensed into liquid
Implementation Method 3
After the bottom heat exchange plate of the body is heated by the heat source, the flue gas rises from perimeter of the outside bottom of the inner shell along the flue gas passage and the heat is transferred to the heated fluid
Implementation Method 4
the flue gas rises from perimeter of the outside bottom of the inner shell along the flue gas passage and the heat is transferred to the heated fluid in the second heat exchange tube
Data Source
AI summary
A heat exchanger, comprising at least a double shell, wherein the lower portion of the inner space of the inner shell is filled with liquid phase change medium, and at least one coiler is provided in the upper portion. The heated fluid flows in the coiler. After the downstream side pipe of the coiler is pierced through the inner shell, at least one surrounding pipe is formed in the cavity between the double shells. The bottom heat exchange plate of heat exchanger of the inner shell is located above the heat source. The cavity between the two shells forms the flue gas passage. After bottom heat exchange plate of the inner shell is heated by the heat source, the flue gas rises from the bottom of perimeter of the inner shell along the flue gas passage and the heat is transferred to the heated fluid in the surrounding pipe. The heat device using the heat exchanger according to the present invention can significantly improve the efficiency of heat utilization.