Graphite Foam Shell-and-Tube Heat Exchangers for Low-Delta-T Transfer
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Solution Overview
Problem
Shell-and-tube heat exchangers have limited heat transfer efficiency, which hampers their performance in various industrial and thermal transfer applications.
Innovation Solution
The integration of thermally conductive foam heat transfer units, such as graphite foam, with the tubes, combined with liquid spraying and optimized tube configurations, enhances heat transfer efficiency. Additionally, the use of friction-stir-welding for tube connections and baffles to increase fluid path and residence time further improves efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional shell-and-tube heat exchanger configuration is used, then the structure is simple and economical to build, but heat transfer efficiency is limited
Solution Approach 1:
The patent introduces graphite foam, a porous material with high thermal conductivity, as a heat transfer enhancement unit. The foam's porous structure provides large surface area for heat exchange while maintaining structural integrity, directly addressing the heat transfer efficiency limitation of conventional smooth-tube designs without compromising manufacturability
Solution Approach 2:
The patent combines graphite foam with metal tube structures to create a composite heat transfer system. The graphite foam serves as the heat transfer enhancement medium while the metal tubes provide structural support and fluid conduit functions, achieving high efficiency through material synergies while remaining economical to manufacture
2Productivity
If graphite foam heat transfer units are integrated with tubes, then heat transfer efficiency is significantly enhanced, but device complexity increases
Solution Approach 1:
The graphite foam is divided into discrete heat transfer units that can be individually installed on tube bundles. This segmentation allows for modular assembly, simplifying the integration process and reducing overall device complexity while maintaining the heat transfer efficiency benefits of the foam structure
Solution Approach 2:
The graphite foam acts as an intermediary heat transfer medium between the tube surface and the shell-side fluid. This intermediary layer enhances heat transfer by providing a large surface area for thermal exchange, while the foam's flexible structure adapts to tube configurations, minimizing the increase in device complexity
3Productivity
If liquid spraying is used to maximize energy transfer, then evaporator efficiency is increased, but device complexity and operational complexity increase
Solution Approach 1:
The liquid spray system uses dynamic spraying mechanisms that can adjust spray patterns, coverage area, and liquid distribution based on operational conditions. This dynamic capability maximizes evaporator efficiency by optimizing heat transfer while keeping the spray system relatively simple through adaptive control rather than complex fixed infrastructure
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 described configuration significantly enhances heat transfer efficiency, making the heat exchangers suitable for low thermal driving force applications, power generation, and non-power generation applications like refrigeration and cryogenics, while being inexpensive and corrosion-resistant.
Implementation Method 1
The foam of the heat transfer units can be any thermally conductive foam material that enhances heat transfer, for example graphite foam
Implementation Method 2
The heat exchanger employs spraying of liquid to maximize the energy transfer through the use of large surface/volume ratio of the sprayed liquid
Data Source
AI summary
Shell-and-tube heat exchangers that utilize one or more foam heat transfer units engaged with the tubes to enhance the heat transfer between first and second fluids. The foam of the heat transfer units can be any thermally conductive foam material that enhances heat transfer. In an embodiment, a liquid distribution unit is employed that sprays a fluid to maximize the energy transfer through the use of large surface/volume ratio of the sprayed fluid. The spraying can be used in combination with or separately from the foam heat transfer units. Also, the tubes can be helically twisted around the liquid distribution unit so that the sprayed fluid impinges on the tubes. The shell-and-tube heat exchangers described herein are highly efficient, inexpensive to build, and corrosion resistant. The heat exchangers can be configured as an evaporator, a condenser, or for single phase cooling or heating thermal transfer applications.