[Physics Class Notes] on Heat Engine Pdf for Exam

A heat engine is a device that turns heat into mechanical energy that can then be utilized to do work. It accomplishes this by lowering the temperature of a working substance from a higher state temperature. A heat source produces thermal energy, which raises the temperature of the working substance. The working material produces work in the engine’s working body while transferring heat to a colder sink until it reaches a low-temperature state. 

Using the qualities of the working substance, some of the thermal energy is turned into work throughout this process. Any system with a non-zero heat capacity can be used as the working substance, however, it is most commonly a gas or liquid. Some heat is generally lost to the environment during this process and is not converted to work. Friction and drag also render some energy ineffective.

Types of Heat Engine

Heat engines have been classified according to the concept that governs their operation. Despite the fact that all of the ideas come from Thermodynamics, each type of heat engine converts heat energy into mechanical work using a different principle. The following are examples of different types of heat engines found in thermodynamics:

1. Internal Combustion Engine- An internal combustion engine (ICE or IC engine) is a heat engine in which fuel is burned in a combustion chamber that is part of the working fluid flow circuit with an oxidizer (typically air). The expansion of the high-temperature and high-pressure gases produced by combustion acts directly on a component of an internal combustion engine. Pistons, turbine blades, a rotor, or a nozzle are usually the targets of the force. This force propels, moves, or powers whatever the engine is attached to by converting chemical energy into usable kinetic energy. For applications where engine weight or size are crucial, this has replaced the external combustion engine.

2. Stirling Engine- A Stirling engine is a heat engine that works by compressing and expanding air or another gas (the working fluid) at different temperatures in a cyclic pattern, converting heat energy to mechanical work. The Stirling engine, in particular, is a closed-cycle regenerative heat engine with a constant gaseous working fluid.

Parts of a Heat Engine-

There are 3 important parts of a heat engine, and they are:

1. Source- There must be an infinite thermal capacity source of heat that is kept at a constant high temperature so that whatever amount of heat is taken or added to it has no effect on its temperature.

2. Working Substance- It has to be some kind of substance that absorbs or rejects heat into the sink. This is the active ingredient.

3. Sink- There must be a finite thermal capacity sink, and it must be kept at a constant high temperature so that no quantity of heat is extracted or provided to it, and the temperature does not change.

What is an Ideal Heat Engine?

It’s impossible to build a heat engine that’s sole purpose is to absorb heat from a high-temperature environment and convert it all to work.

That is, there is no way to construct a heat engine that does not emit heat into the atmosphere.

Alternatively, it is impossible to create a heat engine with a 1.00 or 100% efficiency.

Conclusion

This is all about a heat engine, its different types, and how an ideal engine can be defined. Learn how an engine works and grab hold of the concept well.