Thermodynamics

Posted by admin on February 9, 2018 in Articles

1. Energy – The capacity for producing an effect or doing work.
a. Forms of Energy
1. Stored
0. Potential energy – energy stored by virtue of stresses existing in a system. Commonly related to the work done against gravity in elevating the object from some arbitrary reference plane to some higher level.
1. Internal energy – the energy in a substance associated with the random motion, rotation, and vibrations of a substances molecules. Thermal energy is the stored internal energy within a substance.
2. Kinetic energy – the energy in a substance that is dependent upon the bodys mass and velocity.
3. Chemical energy – the energy stored in chemical bonds that is released in chemical reactions.
b. Flow work – the energy necessary to maintain a steady flow of a
stream of fluid. c. Energy in Transition
1. Heat – energy which is transferred from one region to another by reason of a temperature difference.
2. Mechanical work – force applied through a distance.
B. Fundamental Laws of Thermodynamics
1. The First Law of Thermodynamics (Conservation of Energy) – Energy can be neither created nor destroyed, but only transformed. The heat from the burning fuel in our engines and boilers does nothing to turn the propeller shafts. It must be applied to turbines or pistons to make them move, and they in turn will spin the shafts. We dont gain any energy from this transformation. In financial terms, we cant make a profit. In fact, we cant break even, which leads to…
2. The Second Law of Thermodynamics (Thermal Efficiency) – No engine, actual or ideal, can convert all the heat supplied to it into work. Some heat is lost (not converted to work) as it is applied to the turbines and pistons, and more is lost as they spin the propeller shafts. It has to go somewhere, though, and it does. This lost heat becomes friction of the moving metal parts, and it must be carried away by cooling systems.
3. There are three important rules to remember about heat and…