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Diesel Fuel Injection Systems > 190203b Combustion Process And Starting Aids > Flashcards

190203b Combustion Process And Starting Aids Flashcards

0
Q

What are four causes of an engine burning oil

A

Worn piston rings, excessive crank pressure, worn valve guides or a defective turbocharger

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1
Q

Blue exhaust smoke is a result of what

A

Of an engine burning oil

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2
Q

Black exhaust smoke can be the result of what to conditions

A

A lack of air for the metered amount of fuel, an excess amount of fuel

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3
Q

And engine creating excessive exhaust manifold heat should have what installed before the turbo

A

Pyrometer. Extremely high engine combustion temperatures will damage engine components. (1200*F)

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4
Q

Black exhaust smoke is an indication of what

A

That there is not enough oxygen for proper combustion

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5
Q

What is the primary cause of white smoke

A

There is a lack of heat for ignition and combustion

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6
Q

What are two mechanical faults causing white smoke

A

Incorrect ignition timing and poor atomization of fuel. (and coolant being burnt)

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7
Q

What can be done to reduce ignition delay

A

Warming the engine, preheating the air, preheating the fuel, retarding the injection timing (usually just for starting), atomizing the fuel better (raising injection pressure by injecting more fuel just for starting)

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8
Q

A longer ignition delay period will result in what?

A

A louder and more pronounced knock

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9
Q

What are the four basic stages of combustion

A

Ignition delay, flame propagation, direct combustion and post combustion

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10
Q

How many degrees ATDC will the most force be (optimum crank angle)

A

25° ATDC

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11
Q

Which of the four basic stages of combustion creates the sound of combustion knock

A

Combustion knock is caused by the delay period

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12
Q

What is the stage of combustion from the time when fuel is initially injected to when the fuel is actually ignited

A

Ignition delay

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13
Q

What is the stage of combustion that the flame moves rapidly through the fuel accumulated during the delay period

A

Flame propagation

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14
Q

What is the stage of combustion where the remainder of the fuel charge is injected and burned

A

Direct combustion

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15
Q

What is the stage of combustion from the end of injection to the end of combustion

A

Post combustion

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16
Q

Diesel fuel must be in what form to ignite

A

Gaseous

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17
Q

TQ. What three things must a diesel engine have for complete combustion

A

Correct amount of air, correct quantity of fuel injected at the proper time and sufficient heat for ignition of the fuel

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18
Q

What’s the term for the chemical process of burning a fuel.

A

Combustion

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19
Q

At sea level how many pounds of air is needed to burn 1 pound of diesel fuel

A

20

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20
Q

What’s the temperature increase approximately in Fahrenheit, for every one psi of pressure developed

A

2°F (and 300 psi should be considered minimum compression pressure for combustion)

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21
Q

What’s the average diesel engine compression ratio

A

21 1/2 : 1

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22
Q

The intake Manifold heaters are designed for

A

Pre heat intake air with a coiled heating element and located at entrance to the intake manifold

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23
Q

What is the function of glow plugs

A

They heat the pre-combustion chamber and surrounding air, and will be sufficient heat for combustion.

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24
Q

The shape of the piston crown causes the air to spin at high velocity and mix thoroughly with the injected fuel, this is referred to as what ?

A

Piston induced squish.

25
Q

The inlet ports in a two-stroke cylinder liner are cut on an angle in order to ?

A

Create turbulence.

26
Q

What’s the pressure range of indirect injection ?

A

400 - 2000 psi or 2758 - 13790 kPa.

27
Q

Where is a single hole injector used ?

A

In precombustion chambers.

28
Q

List four advantages to a precombustion chamber ?

A
  1. lower emissions
  2. smooth combustion
  3. needs less atomization of fuel
  4. will burn a wide range of fuels
29
Q

List five advantages of an open combustion chamber.

A
  1. simple design
  2. good mixing of air & fuel
  3. higher combustion pressures
  4. better fuel economy
  5. easier starting
30
Q

List three disadvantages of an open combustion chamber.

A
  1. fuel must be well atomized
  2. higher pressure injection required (more expensive)
  3. needs lots of turbulence (more expensive)
31
Q

In a given volume of air, density is a measurement of the?

A

Oxygen concentration

32
Q

The period of time from when fuel is injected to when ignition of the fuel actually occurs is referred to as?

A

Ignition delay

33
Q

The factors affect the ignition delay period are?

A

Injection timing, air temperature and fuel quality

34
Q

As altitude and air temperature increase, air will have?

A

Decreased density

35
Q

Depending on the grade, the auto ignition temperature of diesel fuel ranges from?

A

500-700°F or 260- 370°C

36
Q

Low compression pressure could cause?

A

Hard starting and white exhaust smoke

37
Q

Low sulphur diesel fuels are being used to reduce emissuing of?

A

SOx

38
Q

Due to the danger of _________ emissions, engines being run indoors should be equipped with a properly vented exhaust system.

A

CO

39
Q

Black exhaust smoke could be the result of?

A

A plugged air filter

40
Q

The formation of smog is the result of?

A

HC, NOx and sunlight

41
Q

Open combustion chamber designs?

A

Utilize direct injection

42
Q

Turbulence is an open combustion chamber to ensure that?

A

The fuel mixes thoroughly with air

43
Q

Precombustion chambers require a glow plug to?

A

Preheat the combustion chamber

44
Q

As compared to an open combustion chamber, a precombustion chamber will?

A

Have lower combustion pressures, burn a wide range of fuels, have lower injection pressures

45
Q

Fuel heaters should be thermostatically controlled because?

A

High fuel temperatures will cause a loss of horsepower.

46
Q

List 4 methods used to assist starting a diesel at low ambient temperatures

A

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

47
Q

Starting fluid should not be used in combination with engines which have?

A

Glow plugs or manifold heater

48
Q

List 3 factors that are necessary for combustion in a deal engine

A

Correct amount of air, correct amount of fuel at the proper time, susufficient heat for ignition

49
Q

One type of coolant heater is the immersion type where is it normally located

A

In a expansion plug bore, or access cover leading to water jacket that surrounds the cylinders

50
Q

Why is a Circulating type coolant heater more effective than a immersion type?

A

Because the cylinder block and components are heated evenly

51
Q

A fuel fire type coolant heater is a efficient heater design to

A

Raise the temperature of coolant close to engine operating temperature

52
Q

Lubricating oil heaters lower the oils viscosity and improves what?

A

Oil flow to critical components during cold starts

53
Q

Why are heaters used in some fuel systems?

A

To heat the fuel prior to filtration when ambient temperatures approach the cloud point of the fuel

54
Q

Starting fluids generally contain two hydrocarbon compounds, what are they?

A

Diethyl ether and Heptane

55
Q

For every 10°F(5.56°C) increase in fuel temperature above 100°F(37.8°C), what percentage of power will be lost?

A

A 1% power loss will occur

56
Q

Starting fluid should not be used in combination with what?

A

An intake manifold heater or glow plugs

57
Q

For maximum effectiveness, where should the fuel heater be installed?

A

For maximum effectiveness fuel heaters should always be installed upstream of the first point to filtration

58
Q

Fuel heater should be thermostatically controlled to what temperature?

A

Fuel heaters should be thermostatically controlled to 140°F(60°C). This is particularly important with electronically controlled Diesel engines that use fuel to cool the electronic control module (ECM)

59
Q

What is the auto ignition temperature of diesel fuel?

A

500 F to 700 F

260 C to 370 C

60
Q

What are the three stages of combustion?

A

ignition delay
flame propagation
direct combustion
post combustion

Diesel Fuel Injection Systems (8 decks)

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