Advantages and Disadvantages of Heat Engines

A heat engine is a system that transforms heat into mechanical energy. The heat engine is very useful for humans. A heat engine is used in jet planes. Heat engines have made travelling very easy and convenient. With the help of a heat engine, we can travel across the world in hours.

There are two types of heat engines: external combustion heat engines and internal combustion heat engines. There are three parts of a heat engine: hot reservoir, system and cold reservoir. Heat engines also produce pollution, so excessive usage is very harmful to human beings.

Let’s discuss what a heat engine is, the parts of a heat engine, the process of a heat engine, the advantages of a heat engine and the disadvantages of a heat engine.

What is a Heat Engine?

In terms of engineering and thermodynamics, a heat engine is a system that converts heat energy into mechanical energy. Mechanical energy can be used in machines. It works as a cyclic process. It works on the principle of heat and work relationships. While converting heat to work energy, the engine or system also rejects some heat energy. The energy goes from high temperature to low temperature.

There are two types of heat engines. The first is external combustion, and the second is internal combustion. In an internal combustion heat engine, the fuel is burnt inside the cylinder. This type of engine is common in cars. In an external combustion heat engine, the fuel is ignited outside the cylinder. The steam engine is an example of an external combustion heat engine. The parts of the heat engine are as follows.

Parts of a Heat Engine

• Hot reservoir:- The source of heat is known as a hot reservoir. The heat needed by the system is provided by the hot reservoir.

• System: – In the system, heat mixes with other gases or air that is a working substance, and the system heats up. For steam engines, the working substance is water, and for petrol vehicles, the working substance is petrol. Working substance absorbs the heat and expands it. The heat made in the system can be used in machines to work.

• Cold reservoir:- The rest of the heat which is left after the use of heat is sent to the sink is a cold reservoir. It works in the same manner as a bike engine. The bike engine generates heat that makes the wheels move and the rest of the heat goes out through the silencer. The sink absorbs heat as in the bike example. The atmospheric air also absorbs heat.

 Work done in a heat engine (W) can be calculated by

Given heat = Q₁

Rejected heat = Q₂

W = Q₁ – Q₂

The efficiency of the heat engine can be calculated by

The efficiency of heat engine = W/Q₁

Carnot’s theorem or principle makes the efficiency of the heat engine limited. The Carnot cycle is the most efficient heat engine cycle. The cycle consists of two adiabatic processes and two isothermal processes.

Advantages of a Heat Engine

• It is used in jet engines, petrol engines, diesel engines, gastroil engines and steam engines. It is very helpful for humankind.

• Heat engines are easy to use, and people use heat engines in their daily lives.

• It takes less time and energy. Heat engine saves energy and time. It has allowed travelling across the world in hours.

• Its cyclic process makes it more efficient than other processes. The engine converts heat into work, and the heat that can not be used by the engine is exhausted.

• It is also used to regulate temperature.

• Its high temperature leads to high efficiency.

• Many lives are saved with the help of heat engines. Whenever needed, humans can travel from one place to another swiftly.

Disadvantages of Heat Engine

• Heat engine efficiency is limited and cannot be used fully.

• Fuel is limited on earth. We are using fuel with heat engines excessively. Heat engines must be made more efficient so that the use of fuel in heat engines decreases.

• A heat engine is expensive as it does not use solid fuel such as coal, which is cheaper compared to diesel and petrol.

• As we all know, pollution is increasing day by day, and heat engines produce a good amount of pollution. That is why people are switching to electric vehicles. New technology is needed to decrease the level of pollution.

• A heat engine needs proper maintenance as it has multiple parts.

• One of the main drawbacks of an external combustion engine is it’s huge.

Conclusion

The heat engine is very useful for humans. It is useful in many works, for example, diesel and gasoline engines, jet engines, and steam turbines. Excessive usage leads to air pollution. There is a need to develop new technology that leads to more efficient heat engines and less pollution. The limited use of heat engines can improve human lives.