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End User Outlook
Extended failures associated with high-temperature and pressure heat exchangers.
1.2 Challenges associated with high pressure High-pressure conditions introduce a distinct set of challenges that necessitate rigorous material selection and mechanical design. Heat exchangers operating at high pressures must withstand significant tensile stresses. Materials must be selected for their ability to maintain strength under repeated loading and unloading cycles, known as fatigue resistance. Highpressure systems are prone to failure if materials lack sufficient fatigue resistance, leading to cracks and, ultimately, failure. Ensuring the structural integrity of high-pressure heat exchangers is complicated by the difficulty of inspecting components for defects. Non-destructive testing techniques such as ultrasonic and radiographic inspection are essential to detect flaws before they lead to failure. As operating pressures increase, the size and weight of the heat exchanger also increases due to the need for thicker walls and stronger materials. This necessitates careful consideration of material costs, transportability, and ease of installation.
1.3 Impact on physical properties and heat transfer The increase in temperature and pressure has a profound effect on the physical properties of the fluids passing through the heat exchanger.
• For gases, as temperatures rise, viscosity and thermal conductivity increase in most cases, which improves convective heat transfer. However, a significant decrease in gas density at high temperatures can negatively impact convective heat transfer. Conversely, liquids generally benefit from the reduction in viscosity at high temperatures, enhancing their convective heat transfer properties
• Under high pressure, gases exhibit increased density and thermal conductivity, leading to improved heat transfer, especially in dense-phase gas flows. However, liquids, being largely incompressible, show relatively minor changes in their heat transfer properties with increasing pressure.
Design considerations To overcome the challenges posed by high temperatures and pressures, various design innovations and materials suited for these applications must be incorporated in the thermal and mechanical design of these heat exchangers.
2.1 Material selection High-temperature heat exchangers often require the use of advanced alloys such as Inconel 625,
Correlation between common challenges and performance of heat exchangers.
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