Double-pipe heat exchanger

Definition

A double-pipe heat exchanger is a type of heat exchanger consisting of one pipe inside another, allowing two fluids to exchange heat while flowing in opposite directions. This design enhances heat transfer efficiency due to the counterflow arrangement, where the hot fluid transfers its heat to the cold fluid through the pipe walls. The simplicity of its construction makes it a popular choice for various applications in industries such as chemical processing and HVAC systems.

5 Must Know Facts For Your Next Test

1. The double-pipe heat exchanger operates on the principle of conduction and convection to facilitate heat transfer between two fluids.
2. This design can be configured in either parallel flow or counterflow arrangements, with counterflow generally providing better performance.
3. Double-pipe heat exchangers are often used for heating or cooling processes due to their simplicity and effectiveness in small to medium-scale applications.
4. Maintenance and cleaning of double-pipe heat exchangers are relatively easy compared to other types, making them user-friendly.
5. The overall effectiveness of a double-pipe heat exchanger can be influenced by factors such as flow rates, temperature differences, and the properties of the fluids involved.

Review Questions

• How does the counterflow arrangement in a double-pipe heat exchanger enhance its performance compared to parallel flow?
  • In a double-pipe heat exchanger, the counterflow arrangement allows the hot and cold fluids to flow in opposite directions, which creates a larger temperature gradient between them throughout the length of the pipes. This maximizes the average temperature difference, leading to improved heat transfer efficiency. In contrast, parallel flow tends to have diminishing temperature differences as both fluids exit at similar temperatures, resulting in less effective heat exchange.
• Evaluate the advantages and disadvantages of using double-pipe heat exchangers in industrial applications.
  • Double-pipe heat exchangers offer several advantages, including simplicity of design, ease of maintenance, and low manufacturing costs. They are effective for small to medium-scale applications. However, they have limitations in terms of capacity; they may not be suitable for high-temperature or high-pressure operations compared to more complex designs like shell-and-tube exchangers. Additionally, their thermal performance can diminish with increased fluid flow rates.
• Design an experiment to compare the thermal performance of a double-pipe heat exchanger versus a shell-and-tube heat exchanger.
  • To compare thermal performance, set up an experiment where both types of heat exchangers are subjected to identical inlet temperatures and flow rates for both hot and cold fluids. Measure temperature changes at various points along each exchanger and calculate the overall heat transfer coefficients. Analyze the data to determine which design achieves greater efficiency under similar conditions. Factors such as material properties and fluid characteristics should also be considered in your analysis for a comprehensive comparison.

Related terms

Counterflow: A flow arrangement in which two fluids move in opposite directions, maximizing the temperature difference and improving heat transfer efficiency.

Shell-and-tube heat exchanger: A more complex type of heat exchanger consisting of a series of tubes, where one set carries the hot fluid and the other carries the cold fluid, typically used in high-capacity applications.

Heat transfer coefficient: A measure of the heat transfer rate per unit area per unit temperature difference between the two fluids in a heat exchanger.