Thermodynamics is a branch of physics that studies the transformation of heat into work.

Heat is the disorderly movement of the molecules of a body.

For labor, we must give meaning to the movement by forcing the molecules to move in one direction with a machine. So give the order to matter.

That is when the invention of the steam engine that the nature of the Heat, Labor and the temperature have become real puzzles to solve.

Nicolas Leonard Sadi Carnot was the first to lay the foundations for the functioning of thermal machines.

The theoretical implications of the findings go well beyond the theory of operation of the engines and affect both the Cosmos that the constitution of matter and chemistry.

However, the validity of the principles of thermodynamics is limited to the macroscopic world.

This site does a small part of this science: the performance appraisal cycle engines that convert heat into work.

To convert heat into work, you can change the volume of a body by heating or by cooling and use this change to push on another body.

For example, if one heats a metal bar, the length of the bar increases.

One can imagine a device that would use the increase to produce useful work.

If we replace the bar with a gas, it can push a piston.

In a turbine, a gas is relaxed and set speed.

Steam turbines are used in power generating so-called "thermal". They allow the conversion of kinetic energy of steam into mechanical energy.

A distinction is made between conventional thermal power (coal, oil, gas) and nuclear power. Yet the only way to produce heat is different. The transformation of heat into work is done by a steam turbine in the same operating principle.

Improve the performance of these engines is an important economic issue.

There are now central to combined-cycle that a yield of 60%.

Often, and in my opinion wrongly, that this return is a maximum possible.

1. Run the engine fuel-lean, that is, use excess air. It is well known that fuel-lean running improves the efficiency. In the old days, under cruising conditions, the engines always ran lean – about 15% excess air -- this was economical. So what happen to change this? The problem is the three-way (CO, UHC, NOx) catalyst used on engine exhausts. This only works if the engine air/fuel ratio (by mass) is stoichiometric (chemically correct). For gasoline this ratio is 14.6:1. The engine computer, acting in concert with the engine air flow sensor, electronic fuel injectors, and exhaust oxygen sensor, maintains the stoichiometric ratio for most of your driving. Only at this ratio can the catalyst both oxidize the CO and UHC (to CO2 and H2O) and chemically reduce the NOx (to N2). (UHC = unburned hydrocarbons.) What humankind needs is a lean-NOx catalyst. Then we could have increased efficiency and continue to be clean!

Also needed are ways to improve lean flammability in gasoline engines. That is, the ability to burn real lean is limited by the fuel. If the gasoline-air mixture is too lean, the flame will not have enough speed to get across the cylinder in the time permitted by the engine RPM the driver wants, or the flame will not even start – the cylinder misfires, and then the catalyst has to oxidize a huge amount of UHC and thus may overheat (which might mean you have to buy a new catalyst).

2. Higher compression ratio. Here, we are limited by autoignition of the gasoline – knock. That is, if the gasoline engine compression is above about 10.5, unless the octane number of the fuel is high, knocking combustion occurs. This is annoying and if persistent, damage to the engine can occur. Thus, gasoline engines are limited in their efficiency by the inability of the fuel to smoothly burn in high compression ratio engines.

However, the diesel engine is not subject to this limitation. It runs at high compression ratio. In part, this explains its high efficiency. It also runs lean, and its pumping work is low, further increasing its efficiency over the gasoline engine. Humankind needs quiet, smoke-free, odor-free diesels!
We need new cycles put into practical use. An example is the Atkinson cycle. This has a smaller compression ratio than expansion ratio. This means TC is reduced since the burnt gas cool as they expand, making the cycle efficient. We throw away less waste heat via the exhaust.
Run the engine at optimum conditions, meaning low friction (modest engine speed) and low pumping work (air throttle more open). Try to approach the "pushing-the-pistons" efficiency of 35%. This already is happening in some stationary piston engines – large, slow, piston engines used at pipeline compressor stations, for example. Also, this is an important characteristic of the engines used in the hybrid gasoline-electric vehicles. Let the gasoline engine in the hybrid gasoline-electric power plant only run with good throttle opening and modest RPM. An example of one type of commercially available hybrid engine.