Engines

What is a Industrial Engine?

An engine or motor generally is a machine meant to convert one form of energy into mechanical energy. Heat engines, such as internal combustion engines, transform heat into work. Electric motors transform electrical power into mechanical motion, pneumatic motors utilize compressed air, and clockwork motors in wind-up toys employ elastic energy.

An engine employed in any branch of the industry is called an industrial engine. The application may be varied from a mechanical drive system, such as rock crushing equipment, or a typical irrigation pump. Many, but not all industrial engines have changeable speed capability.

Industrial Engine Parts

As will be discussed in the next part, industrial engines have diverse types, and each type has its own parts and design. However, in general, industrial engines consist of a mechanical part converting heat energy into mechanical power, either by rotating a shaft (e.g., steam or gas turbines) or by moving a reciprocating shaft (e.g., diesel engines). Furthermore, an exhaust system, which removes combustion products from the system, is an integral part of an industrial engine. In some applications, such as combined heat and power (CHP) and combined cooling, heat, and power (CCHP) systems, the moving part of the engine is directly connected to an electric generator, which converts the mechanical work of the engine into usable electric power.

In addition to the mentioned parts, most industrial engines have a fuel system in order to inject the fuel into the combustion chamber, lubrication systems to minimize friction loss of the moving parts, an air intake system to provide proper amounts of air for combustion, cooling systems to maintain various parts of the engine in descent thermal conditions to avoid thermal fatigue problems, and electrical systems, controlling various operating conditions of the engine. As a sample of industrial engines, typical parts of an industrial diesel engine are demonstrated in the following figure.

Industrial Engine Types

Various industrial engines are employed these days but generally can be classified into the following categories:

• Reciprocating steam engine: devised by J. Watt in 1769 - This engine receives mechanical power using the static pressure of the steam.
• Hot air engine (Stirling engine): invented by R. Stirling in 1816 - It is an external combustion engine with a closed cycle that repeatedly utilizes the working gas without any valve.
• Hot air engines (Ericsson engine): developed by J. Ericsson in 1839 - It is an external combustion engine with an open cycle with two valves at a supply cylinder and a power cylinder.
• Spark ignition engine (gasoline engine): invented by N. Otto in 1876.
• Steam turbine: proposed by C. Laval in 1883.
• Compression ignition engine (Diesel engine): developed by R. Diesel in 1892.
• Gas turbine for the airplane: invented by F. Whittle in 1930.
• Rocket engine: developed in Germany in 1944.

Industrial Engine Working Principles

The working principle of an industrial engine depends on the type of engine. At what follows, we are summarized basic operating principle of various types of industrial engines:

• Reciprocating steam engine - This engine receives mechanical power using the static pressure of the steam. Commonly, the steam engine includes a heater, a boiler, a piston, a cylinder, a condenser, and a water pump. An intake and an exhaust valve are placed on the top of the cylinder. In each cycle, the working gas with sufficient energy moves a reciprocating piston, resulting in the transformation of heat into mechanical energy.
• Hot air engine (Stirling engine) - It is an external combustion engine with a closed cycle that repeatedly utilizes the working gas without any valve.
• Hot air engines (Ericsson engine) - It is an external combustion engine with an open cycle with two valves at a supply cylinder and a power cylinder.
• Spark ignition engine (gasoline engine) - The gasoline engine is used extensively as the power source of automobiles. The principle of this engine is simple: a mixture of fuel and air is compressed in the cylinder at first, and the gas explodes by use of an ignition plug, which then generates the output power.
• Steam turbine - The steam turbine has rotating blades rather than the piston and the cylinder of the reciprocating steam engine. The steam turbine employs the dynamic pressure of the steam and transforms thermal energy into mechanical energy, though the reciprocating steam engine uses the static pressure of the steam.
• Compression ignition engine (Diesel engine) - The Diesel engine is an internal combustion engine like the gasoline engine and is used extensively as the power source of the automobile and the ship. The working principle is quite similar to that of a reciprocating steam engine.
• Gas turbine for the airplane - In a gas turbine, air, as the working fluid, is pressurized by a compressor and heated by the combustion energy of the fuel at first, resulting in a high temperature and pressure gas. The engine converts the energy of the working gas into the rotating energy of the blades, using the interaction between the gas and the blades.
• Rocket engine - The rocket engine takes a high temperature and pressure combustion gas from the fuel and an oxidizer in a combustor. The combustion gas becomes high speed with an adiabatic expansion through the nozzle and is flowed to the engine's rear, resulting in the production of force to move the rocket.
• Fuel cell - Above thermal engines convert the energy of the fuel to mechanical power using thermal energy. However, the fuel cell changes the fuel's chemical energy to electric energy directly. The fuel cell comprises the anode and the cathode, which are parted by an electrolyte layer. When the fuel is supplied to the anode, and the oxidizer is supplied to the cathode, it produces electric energy.