Stirling Heat Engine:
A Stirling Heat Engine is defined as a machine used to provide power or refrigeration, operating on a closed cycle in which a working fluid is cyclically compressed and expanded at different temperatures.
A Stirling engine is a heat engine invented by Robert Stirling in 1816 and are used in submarines and auxiliary powered generators for yachts. Because of its potential to be more efficient than a regular engine, Stirling engines are being looked at as a potential alternative to diesel engines. They are also really quiet because they don’t use exhaust valves.
Unlike regular engines this uses the Stirling cycle. A fixed amount of gas is inside the Stirling engine, the cycle changes pressures of the gas causing it to work. unlike the regular combustion engines that make gas combust with a burst of energy over and over. By heating and cooling the gas inside the Stirling engine the temperature increases and decreases. By cycling heating and cooling the gas allows a piston to move the gas through cylinders. Pistons are pushed back and fourth when he gas is heated or cooled and the cycle happens again and again.
This cycle seems like a feasible way to reduce exhaust from regular engines but the actual use of this engine has some problems.
Because the two cylinders have to be heated and cooled by an external source of energy it takes a while for the engine to respond to changes in temperature and therefore would take a long time to start working. I could imagine on a cold New England morning starting your car would be a hassle if we used these types of engines.
Here is a great how it works video on Stirling engines :
Thermoelectric, or Peltier Cooling Modules:
used really commonly in refrigeration, cooling, and dehumidifiers. Thermoelectric is based on the Peltier effect is the presence of heating or cooling at an electrified junction of two different conductors and is named after Jean Charles Athanase Peltier in 1834.
This picture shows how wires are attached to sides of a battery using different types of wire, copper and bismuth, this is the Peltier effect. When current flows through the copper to the bismuth wire, heat is produced and vice versa creates cold.
The effect od this passing of thermal heat produces energy that is readily available for use. Implementation of Peltier’s heating and cooling effect that occurs when electric current goes through a conductor is used in many different modern day appliances like the refrigerator.
http://auto.howstuffworks.com/stirling-engine.htm
http://en.wikipedia.org/wiki/Thermoelectric_effect