Tubular Membrane Header Sealing for Pressure-Resistant Heat Exchangers
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Solution Overview
Problem
Sealing membrane tubes in tubular heat exchangers is challenging due to their small size and large number, leading to issues like poor adhesion, uneven gaps, and limited water flow rates, which affect heat and mass transfer properties and working pressure, limiting the versatility and applicability of these exchangers.
Innovation Solution
A tubular membrane assembly with a header, tubular membrane, and fitting that forms a fluid-tight connection, using potting to secure the membrane to the header, allowing for flexible and small cross-section membranes to withstand pressures up to 50 psi, and includes a support system to maintain spacing and prevent leaks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If membrane tubes are sealed using traditional methods (welding, rolling, braising, gluing, or potting), then the heat exchanger can be assembled, but the seal strength is insufficient leading to leaks and limited working pressure
Solution Approach 1:
The patent uses a composite sealing system combining multiple materials: the membrane tube material (e.g., PTFE, polypropylene), sealant material (adhesive compound), and potting material (epoxy or similar). This multi-material approach creates a sealing structure where each material contributes its specific properties - the membrane provides structural integrity, the sealant provides initial bonding, and the potting material provides final encapsulation and pressure resistance, collectively achieving reliable sealing at high working pressures.
Solution Approach 2:
The patent applies sealant to the membrane tube before inserting it into the tube sheet, creating a preliminary bonding layer. This preliminary action ensures that the membrane tube is pre-sealed to the tube sheet before the potting material is applied, preventing leaks during assembly and providing a foundation for the final high-pressure sealing capability.
2Reliability
If multiple small membrane tubes are sealed individually, then each tube can be secured, but the process is time-consuming and labor-intensive
Solution Approach 1:
The patent merges multiple sealing operations into a single integrated process. Instead of sealing each membrane tube individually through multiple separate steps, the combination of sealant application, tube insertion, and potting material application creates a unified sealing system that secures multiple tubes simultaneously, dramatically improving assembly productivity while maintaining consistent seal quality across all tubes.
Solution Approach 2:
The potting material serves multiple functions automatically: it encapsulates the membrane tubes, provides additional sealing, bonds the tubes to the tube sheet, and protects the assembly. This self-service approach eliminates the need for separate operations for each of these functions, streamlining the assembly process.
3Area of moving object
If membrane tubes are made flexible with small cross-section to increase surface area, then heat and mass transfer efficiency improves, but adhesion to tube sheet deteriorates
Solution Approach 1:
The patent addresses the adhesion problem by using composite sealing materials specifically designed to bond flexible, small-cross-section membrane tubes to the tube sheet. The sealant and potting material formulations are selected to provide strong adhesion to the membrane tube material (such as PTFE or polypropylene), enabling reliable connection of flexible tubes that provide high surface area for heat and mass transfer.
Solution Approach 2:
The sealant and potting material act as intermediary substances between the flexible membrane tube and the rigid tube sheet. These intermediary materials bridge the compatibility gap between the flexible tube material and the tube sheet, providing strong bonding while accommodating the flexibility and small cross-section of the membrane tubes, thus enabling both high surface area and strong adhesion.
4Adaptability or versatility
If inconsistent or flexible tubes are used to increase adaptability, then configuration flexibility improves, but gap uniformity deteriorates causing leaks
Solution Approach 1:
The sealant and potting material serve as intermediary substances that fill and seal the gaps between flexible membrane tubes and the tube sheet. These intermediary materials compensate for variations in tube consistency and flexibility, maintaining gap uniformity and preventing leaks even when tubes have slight manufacturing variations or flexible configurations, thus enabling configuration flexibility without sacrificing manufacturing precision.
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 assembly provides a durable, flexible, and efficient heat exchanger with variable spacing, enabling high heat and mass transfer surface area, and allows for modular configuration and repair/replacement of membranes, enhancing performance and applicability under pressure.
Implementation Method 1
tubular membranes that facilitate heat transfer between two fluids
Implementation Method 2
potting of the header keeping the tubular membrane connected to the header body
Data Source
AI summary
In one aspect, a tubular membrane assembly is provided for a heat exchanger. The tubular membrane assembly includes a header having a header body, a tubular membrane, and a fitting connecting the tubular membrane to the header body. The fitting is configured to form a fluid tight connection between the fitting and the tubular membrane. The tubular membrane assembly further includes potting of the header keeping the tubular membrane connected to the fitting.