Abstract
3.1. INTRODUCTION
Heat transfer is a subject that deals with the generation, use, conversion, and
exchange of thermal energy between a system and its surroundings. At the
molecular level, we can visualize thermal energy by the motion of particles and
quantify it by the overall kinetic energy of all the particles. Heat transfer can
then be explained as an exchange of the kinetic energy among particles via
collisions or interactions. In a gas, the particles move faster, on average, under
higher temperatures and transfer their kinetic energy to particles at lower
temperatures through collisions. In a solid, the particles vibrate faster under
higher temperatures and transfer their kinetic energy to particles at lower
temperatures through molecular interactions.