THERMAL ENGINEERING OVERVIEW

Terminology description

 Following disciplines are important in thermal engineering aspects.

• Thermodynamics: Basic relationship of work and heat along with system properties are thermodynamic process
• Thermal transformation systems: The thermal system converts thermal energy in to mechanical energy. For instance gas turbines, internal combustion engines, steam engines, steam turbines and steam power plants.
• Mass transfer: Transport of mass from one place to other is referred as mass transfer.  For instance evaporation of liquid to vapor and diffusion of impure materials from specific points.
• Heat transfer: transport of heat from one medium to other medium is referred as heat transfer. For instance radiation, convection and conduction are thermal energy transfer forms.
  • Radiation: Heat transfer is by electromagnetic waves
  • Convection: Transfer of heat from particle to fluid
  • Conduction: Transfer of heat from high temperature solid region to low temperature solid region

History of thermal engineering

Till 17^th century thermal energy has least bothered attention. The first accepted thermal energy theory was Phlogiston theory of heat. This Phlogiston theory was given by Stahl and he states that less weight particle are vaporized by combustion. Unsuccessful attempt of Stahl was overcome by Caloric theory proposal in 18^th century. Specific heat is referred as calorific content which increases the temperature of substance by 1 ºC. With this heat of conduction concept was explored.

Ingendhousz of 1789 and Rumford of 1792 analyzed metals relative conductivity when metal rods coated with wax are kept in hot water. Heat release by friction is not covered under calorific theory. Calorific theories explain thermal energy is a part of mechanical energy form as mechanical equivalent of heat exists. Joule measured calorific values during 1840 to 1849. The principle of steam engine was given by Pepin in 1681. But first expansion steam engine was proposed by Watt in 1763. Later in 19^th century, refrigeration and automobile system was introduced with the application of thermal energy.

Questions:

• What are classical prospective of thermal engineering?
• What are thermal engineering disciplines?
• What are applications of thermal energy?