Ch9.1 Heat & Mass Transport Intro

Introduction

  • This chapter focuses on modeling heat conduction.
  • Formulate differential equations for heat and temperature of systems, and emphasize difference between them.
  • For many applications, it is of great importance to understand whether or not heat conduction is a factor to consider.

Humor



Sometimes I tuck my knees into my chest and lean forward.

That's just how I roll.

Heat and Temperature

  • Heat is a form of energy
  • Measured in Joules
  • Not determined directly by an instrument
  • A derived quantity

  • How hot or cold a body is
  • Measured in F, C, K, etc
  • Directly determined by thermometer
  • Is a fundamental quantity

Temperature

  • Reflects how much the molecules in a substance are moving.
  • At absolute zero, there is no motion at all.
  • In a solid state above absolute zero, molecules vibrate.
  • As a liquid they are flowing freely around unconstrained.
  • As a gas they fly around so much as to completely fill container with resulting impacts measured as pressure.

Main Types of Heat

  • Conduction
  • Convection
  • Radiation
  • Chemical reaction

Conduction

  • For our models, we will focus on conduction.
  • Conduction refers to the propagation of energy via collisions between excited particles.

Overview of Chapter 9 Heat Models

  • Chapter 9 introduces several modeling scenarios for heat.
  • The solutions are developed in Ch10 and in Ch11.
    • Cooling of a coffee cup
    • Hot water heater
    • Heat conduction through a wall
    • Insulated water pipe
    • Cooling fins (computer chips, motorcyle engines, etc)

Ch9.8 Mass Transport

  • In Ch9.8, we also look at diffusion models.
  • The diffusion models do not incorporate heat, but are readily seen as an application of common principles to a new context.