Modular U-Tube Heat Exchanger for 500 Bar Operation
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Solution Overview
Problem
Conventional shell-and-tube heat exchangers are not suitable for high-pressure applications exceeding several hundred bar due to their construction, which limits their use in industries requiring fluid pressures up to 500 bar at temperatures between 400°C and 1000°C.
Innovation Solution
A heat exchanger module comprising U-tubes with straight sections connected by a U-shaped portion, where the U-tubes are directly attached to collector tubes with brazed joints, providing enhanced stability and leak-tightness, and manufactured using vacuum brazing or diffusion bonding with nickel-based materials to withstand high pressures and temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stress or pressure
If conventional shell-and-tube heat exchangers are used, then the construction is simple and manufacturing is easier, but they are not suitable for high pressure applications up to several hundred bar
Solution Approach 1:
The heat exchanger is divided into multiple modules, each containing a bundle of U-tubes connected to collector tubes. This modular segmentation allows each module to be designed for high pressure independently, while the overall system maintains manageable complexity through standardized module replication.
Solution Approach 2:
Multiple U-tubes are nested within a single module, with all inlet ends connected to one collector tube and outlet ends to another collector tube. This nesting approach consolidates multiple tube connections into integrated modules, reducing overall system complexity while enabling high pressure operation.
2Reliability
If tube collectors are used instead of plate collectors, then high pressure stability is improved, but manufacturing complexity increases
Solution Approach 1:
Multiple U-tubes are merged into a single integrated module with common collector tubes for inlet and outlet. This merging reduces the number of separate connections required, simplifying manufacturing while maintaining the high pressure stability provided by the tube collector structure.
Solution Approach 2:
The U-tubes are pre-assembled into modules with collector tubes before final integration into the heat exchanger system. This preliminary assembly allows for quality control and pressure testing at the module level, ensuring reliability while streamlining the overall manufacturing process.
3Reliability
If multiple weld connections are used in plate collectors, then fluid distribution is improved, but leak tightness and reliability for high pressure applications deteriorate
Solution Approach 1:
The problematic plate collector with multiple weld connections is extracted and replaced with tube collectors. The tube collector design eliminates the need for multiple weld connections while maintaining effective fluid distribution to and from the U-tube bundle, thereby improving leak tightness for high pressure applications.
4Strength
If thicker tube walls are used in collector tubes, then high pressure strength is improved, but weight and cost increase
Solution Approach 1:
Thicker tube walls are applied locally only to the collector tubes where high pressure strength is critical, while the U-tubes can use thinner walls since they are contained within the pressure-boundary defined by the collector tubes. This localized application of thick walls provides necessary strength while minimizing overall weight.
Solution Approach 2:
The collector tubes are constructed with composite material structures combining different material properties to achieve high pressure strength with optimized weight. This allows the collector tubes to withstand several hundred bar pressures without requiring excessive wall thickness, thereby reducing overall module weight.
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 enables the creation of heat exchanger modules suitable for pressures up to 500 bar and temperatures up to 1000°C, offering stability, cost-effectiveness, and modularity, allowing for the construction of heat exchangers in the Megawatt range suitable for high-pressure and high-temperature applications.
Implementation Method 1
The U-tubes, respectively their inlet ends and outlet ends are connected with the inlet collector tube or outlet collector tube in any suitable way and by any suitable means providing a fluid connection between the interior of the U-tubes and the interior of the collectors
Implementation Method 2
manufactured using vacuum brazing or diffusion bonding with nickel-based materials to withstand high pressures and temperatures
Implementation Method 3
heat exchanger module for use in high pressure applications... pressure applications up to 500 bar at temperatures between 400 degree Celsius and 700 degree Celsius, or even up to 1000 degree Celsius
Data Source
AI summary
A heat exchanger module comprises several U-tubes for a first fluid flow, the U-tubes having two straight sections connected by a U-shaped portion. Inlet ends of the several U-tubes are connected with an inlet collector tube and outlet ends of the several U-tubes are connected with an outlet collector tube. The two straight sections of the U-tubes have a different length such that a longitudinal axis of the inlet collector tube and a longitudinal axis of the outlet collector tube are arranged at different heights with respect to a height of the heat exchanger module. Also provided is a method for manufacturing the heat exchanger modules and a tubular heat exchanger comprising a plurality of heat exchanger modules.