Combustion Process and Starting Aids

Question 1

Air is composed of what?

Answer 1

79% nitrogen

21% oxygen

Question 2

What is the auto ignition temp of diesel?

Answer 2

500 - 700 F

Question 3

For every 1 psi of pressure developed, the air temp will increase?

Answer 3

2 F

Question 4

What is minimum compression pressure needed?

Answer 4

300 PSI

Ratio 16:1 will give about 350 PSI

Question 5

What are the four basic stages of combustion?

Answer 5

Ignition Delay, Flame Propagation, Direct Combustion, Post Combustion

Question 6

What is combustion knock?

Answer 6

Result of the ignition delay, the longer the delay the greater the knock

Question 7

Black smoke can be the result of what?

Answer 7

A lack of air for metered amount of fuel

An excess amount of fuel for amount of air engine can max supply

Question 8

Air pollution

Answer 8

Is the presence of enough contamination in the atmosphere to injure human, plant or animal life

Question 9

What are three major pollutants from an internal combustion engine?

Answer 9

Hydrocarbons (HC), Carbon monoxide (CO), and Oxides of nitrogen (NOx)

Question 10

Particulates may include

Answer 10

Lead, Sulphur compounds, and carbon

Question 11

Oxides of nitrogen are formed when?

Answer 11

When cylinder temperatures exceed about 2500 F

Question 12

Open Combustion Chamber design

Answer 12

Direct injection. Fuel is injected directly on top of the piston into the heated air. Injection pressures must be 2200 PSI or higher

Question 13

What are the two common methods of inducing air turbulence?

Answer 13

Shape of piston crown

Intake port design

Question 14

How is turbulence created in a two stroke engine?

Answer 14

The Inlet ports on the liner are usually cut on an angle to create a spiralling of air

Question 15

What are advantages of an open combustion chamber design?

Answer 15

Simple design, Good mixing of air and fuel, higher combustion pressures, better fuel economy, easier starting

Question 16

Disadvantages of an open combustion chamber design?

Answer 16

Fuel must be well atomized and of good quality, requires high pressure fuel injection system, requires fuel to be mixed thoroughly with air

Question 17

Pre-combustion chamber design

Answer 17

Fuel is injected into pre-combustion chamber. Injection pressures range from 400-2000 PSI. Hardened piston inserts may have to be used to protect piston

Question 18

What are advantages of a pre-combustion design?

Answer 18

Low emissions, Smooth combustion, requires less atomization of fuel, will burn a wide range of fuel

Question 19

Intake manifold heaters

Answer 19

Use a coiled heating element to preheat intake air. Commonly used on small displacement engines with open combustion chambers

Question 20

Glow plugs

Answer 20

heating element used to help increase the temp in a pre-combustion chamber

Question 21

What are the two types of coolant heaters?

Answer 21

Immersion type

Circulating type

Question 22

What is the purpose of fuel heaters?

Answer 22

Heat the fuel prior to filtration when ambient temperatures approach the cloud point.

Question 23

Starting fluids generally contain what two hydrocarbons?

Answer 23

Diethyl ether

Heptane

Question 24

What 3 factors are necessary for combustion in a diesel engine?

Answer 24

Correct amount of air
Correct amount of fuel at the proper time
Sufficient heat for ignition

Question 25

What are the 4 methods used to assist in starting a diesel engine at low ambient temperatures?

Answer 25

Heat the intake air
Heat the engine coolant
Heat the engine oil
Heat the fuel