Heat Exchangers: Fundamentals and Design Analysis - Lecture 1

Jul 3, 2024

Heat Exchangers: Fundamentals and Design Analysis

Lecture 1: Introduction and Overview

Lecturer

  • Professor P. K. Das from the Department of Mechanical Engineering, IIT Kharagpur
  • Course jointly taught by Professor A.R. Das from the Cryogenic Engineering Centre, IIT Kharagpur
  • Three Teaching Assistants (TAs) to assist participants via forum

Course Structure

  • Jointly conducted by two instructors, lectures will be swapped between them.
  • TAs will be available to answer queries and facilitate understanding.
  • The course will have interactive sessions with participants.
  • Key Topics to be covered:
    • Introduction to heat exchangers (current lecture)
    • Basic thermal and hydraulic analysis
    • Variety of heat exchanger types
    • Enhanced heat transfer and compact heat exchangers
    • Plate fin heat exchangers and direct contact heat exchangers
    • Regenerators and heat pipes
    • Microscale heat exchangers
    • Phase change heat exchangers
    • Heat exchanger testing and network synthesis
    • Discussion of fouling, mechanical design, and manufacturing techniques (indirectly covered)

Basic Overview

  • Definition of Heat Exchanger: Device used to transfer thermal energy between two or more fluids, solid surfaces, particulate solids, etc. (source: Kays and London)
  • Wide variety in application and design; can be small or gigantic.
  • Core principle involves two fluids exchanging heat due to a temperature difference while being physically separated by a solid wall (for indirect exchangers).

Types of Heat Exchangers

  1. Indirect-Contact Heat Exchanger

    • Example: Two-fluid tube-in-tube exchanger
    • Commonly involves two fluids that are separated by a solid boundary.
    • Example: Cooling hot gas using a cold fluid passing through an annular space.
    • Type: Indirect (fluids don't mix)

  2. Direct Contact Heat Exchanger

    • Example: Sprinkling cold water into hot gas.
    • Fluids mix during heat exchange.

  3. Storage Type (Regenerative) Heat Exchanger

    • Uses an intermediate medium for transferring energy.
    • Example: Rotating wheel heat exchangers used in power plants.
    • Intermediate medium temporarily stores heat and then releases it to another fluid.

Heat Exchanger Representation as a Control Volume

  • Mass, Momentum, and Energy Balances: Applying fundamental conservation laws.
  • Common assumptions: No heat generation within the exchanger, insulated boundaries, no work input/output, and no external energy interactions.

Historical Context

  • Early principles traced back to cooking methods and home heating (e.g. stone heating by Vikings, Roman hypocaust system for heating baths and rooms).
  • Early examples illustrate fundamental heat exchange concepts that have evolved into modern applications.

Conclusion

  • Overview of the course content and the introduction to the vast field of heat exchangers.
  • Emphasized historical evolution and diverse application in industries today.
  • Question and queries can be discussed with TAs in the provided forums.