Heat Exchanger With Perforated Microjet Tubes
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Solution Overview
Problem
Shell-and-tube heat exchangers face challenges in efficiently utilizing the entire heat exchange surface for hydrodynamic intensification due to the difficulty in uniformly distributing fluid jets, leading to reduced heat exchange efficiency and increased size and mass.
Innovation Solution
A heat exchanger design featuring concentric tubes with perforated and solid walls, where the perforation openings are less than 500 micrometres in diameter, allowing for the formation of microjets that intensify heat exchange while maintaining a large surface area and compact dimensions, with optional ribbing and auxiliary partitions for enhanced flow and mechanical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the number of tubes with perforated wall is increased to increase heat exchange surface usage, then the heat exchange intensification is improved, but the number of tubes with solid wall must be reduced which decreases the total heat exchange surface area
Solution Approach 1:
The invention places a perforated tube inside a solid tube, creating a nested configuration where the perforated tube is positioned within the inner diameter of the solid tube. This allows both tube types to coexist in the same spatial envelope, effectively doubling the heat exchange surface area while maintaining the jet perfusion capability on the outer solid tube surface.
Solution Approach 2:
The invention transitions from a two-dimensional arrangement (either perforated or solid tubes in separate positions) to a three-dimensional nested structure where perforated and solid tubes occupy different radial zones. This spatial reorganization allows simultaneous maximization of both jet perfusion effectiveness and total heat exchange surface area.
2Productivity
If jet inflow is used to intensify heat exchange by eliminating boundary layer, then heat exchange efficiency is improved, but uniform coverage of entire heat exchange surface with jets is very troublesome
Solution Approach 1:
The invention applies jet perfusion locally at the perforated tube surface while using the solid tube for conventional heat exchange. The perforated tube is strategically positioned and oriented to direct jets onto specific regions of the solid tube surface, creating localized intensification zones where boundary layer elimination is most beneficial without requiring uniform coverage of the entire heat exchanger.
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 achieves high energy transport efficiency, reducing the external dimensions and mass of the exchanger while maximizing heat exchange surface usage, allowing for effective heat transfer between various fluid pairs, including gases and liquids, and compensating for differences in heat exchange rates.
Implementation Method 1
as a result of the flow of the first fluid, microjets are formed in perforation openings
Implementation Method 2
the occurrence of a boundary layer of fluid at the surface of heat exchange
Implementation Method 3
an undesirable share of thermal conductivity in the mechanism for transferring heat through the partition increases
Implementation Method 4
Thermal conductivity is less efficient than convection
Data Source
Figure 1~3
Figure 4a~5
AI summary
A heat exchanger according to the invention comprises a shell (7) and at least one channel, located in its interior, with at least one perforated wall (5) adapted to carry a first fluid. The perforation of the wall is provided on at least a part of the surface of this perforated wall (5) so that, as a result of the flow of the first fluid, microjets are formed in the perforation openings. The shell (7) is adapted to carry a second fluid, and the said at least one channel has an additional solid wall (6) surrounding the perforated wall (5). A method for transferring heat between the first fluid and the second fluid according to the invention consists in that these fluids are introduced into the heat exchanger in which they are separated from each other by a partition, wherein the exchanger according to the invention is used therefore.