Introduction to Internal Combustion Engines.pdf & Fuels and Combustion Part I.pdf

INTERNAL COMBUSTION ENGINE

Is a heat engine that converts chemical energy in a fuel into mechanical energy, usually made available on a rotating output shaft.

EXTERNAL COMBUSTION ENGINE

Combustion takes place outside the mechanical engine system.

SPARK IGNITION (SI)

Starts the combustion process in each cycle by use of a sparkplug. The sparkplug gives a high-voltage electrical discharge between two (2) electrodes which ignites the air-fuel mixture in the combustion chamber surrounding the plug.

COMPRESSION IGNITION (CI)

Starts when the air-fuel mixture self ignites due to high temperature in the combustion chamber caused by high compression.

four stroke cycle

experiences four (4) piston movements over two (2) engine revolutions for each cycle.

two-stoke cycle

has two (2) piston movements over one (1) revolution for each cycle.

L-head

Valve in Block

I-head

Valve in Head,

F-head

One Valve in head and one in block

T-head

Valves in block on opposite sides of cylinder

RECIPROCATING

Engine has one or more cylinders in which pistons reciprocate back and forth. The combustion chamber is located in the closed end of each cylinder. Power is delivered to a rotating output crankshaft by mechanical linkage with the pistons.

ROTARY

Engine is made of a block (stator) built around a large non-concentric rotor and crankshaft. The combustion chambers are built into the nonrotating block.

Single Cylinder

Engine has one cylinder and piston connected to the crankshaft.

In-Line

Cylinders are positioned in a straight line, one behind the other along the length of the crankshaft

V-Engine

Two banks of cylinders at an angle with each other along a single crankshaft. The angle between the banks of cylinders can be anywhere from 15 to 120 degrees, with 60-90 degrees being common.

2 to 20

V engines have even number of cylinders from “blank” more. V6s and V8s are common automobile engines, with V12s and V16s found in luxury and high-performance vehicles

Opposed Cylinder Engine

Two (2) banks of cylinders opposite each other on a single crankshaft (a V engine with a 180 degree V). There are common on small aircraft. Often called as flat engines.

W-engine

Same as V engine except with three banks of cylinders on the same crankshaft. Not common, but some have been developed for racing automobiles. Usually 12 cylinders with about a 60 degree angle between each bank.

Opposed Piston Engine

Two pistons in each cylinder with the combustion chamber in the center between the pistons

Radial Engine

Engine with pistons positioned in a circular plane around the central crankshaft. The connecting rods of the pistons are connected to a master rod which, in turn is connected to the crankshaft.

Naturally Aspirated

No intake air pressure boost system

Supercharged

Intake air pressure increased with the compressor driven off of the engine crankshaft

Turbocharged

Intake air pressure increased with the turbine-compressor driven by the engine exhaust gases

Carbureted

A device that mixes air and fuel for ICE in the proper air fuel ratio for combustion.

Multipoint Port Fuel Injection

One or more injectors at each cylinder intake.

Throttle Body Fuel Injection

Injectors upstream in intake manifold.

Air Cooled

Direct air cooling without an intermediate liquid.

Liquid Cooled, Water Cooled

Waste heat is transferred from a closed loop of water pumped through the engine to the surrounding atmosphere by a radiator

Fuel

is any substance, natural and artificial which upon combustion releases heat energy.

Primary Fuels

Occurs in nature as such. Ex. Coal, Petroleum, Natural Gas

Secondary Fuels

Derived from primary fuels. Ex. Coke, Gasoline, Coal Gas

Solid Fuels

– such as coal, coke, wood, charcoal, bagasse, coconut shells, rice husks, and briquetted fuels

Peat

– starting stage of coal formation and is not useful in power plants

Lignite

– is the youngest form of coal. It is soft and ranges in color from black to shades of brown.

Sub-bituminous coal

– after millions of years, continued pressure and temperature convert lignite into sub-bituminous coal.

Bituminous coal

– is harder and blacker than lignite and sub-bituminous coal

Anthracite

– is the most mature coal and thus has the highest carbon content of any type of coal.

Liquid Fuels

– such as crude petroleum and its distillates (gasoline, alcohol, kerosene, diesel, bunker and other fuel oils)

Gaseous Fuels

– such as natural gas, artificial gas, blast furnace gas, liquefied petroleum gas (LPG), methane, acethylene and propane)

Combustion

– synonymous with oxidation and is the union of oxygen with combustible materials

PROXIMATE ANALYSIS

– indicates the percentage by weight of the fixed carbon , volatiles, ash, and moisture content in coal.

Fixed Carbon

– is the solid fuel left in the furnace after volatile matter is distilled off. Fixed carbon gives a rough estimate of heating value of coal.

Volatile matter

– are the methane, hydrocarbons, hydrogen and carbon monoxide, and incombustible gases like carbon dioxide and nitrogen found in coal. Typical range is 20-35%

Ash Content

– is an impurity that will not burn. Typical range is 5-40%

Moisture Content

– decreases heat content per kg of coal. Typical range is 0.5 to 10%. The loss in weight of the sample is found out and the percent moisture is calculated

Sulphur Content

– Typical range is 0.5-0.8%. Affects clinkering and slagging tendencies, corrodes chimney and other equipment and limits exit flue gas temperature.

ULTIMATE ANALYSIS

– is an analysis of the composition of fuel which gives, on mass basis, the relative amounts of carbon, hydrogen, oxygen, nitrogen, sulfur, ash and moisture.

12 g

44 g of CO2 contains ___ of Carbon

2 g

18 g of water contains ___ of Hydrogen

32 g

233 g of BaSO4 contains ___ of Sulphur

Higher Heating Value of Gross Calorific Value

– is the heating value obtained when the water in the products of combustion is in the liquid state.

Lower Heating Value or Net Calorific Value

– is the heating value obtained when the water in the products of combustion is in the vapor state