Objective 01: Heat Engines

Question 1

What is one of the most important applications of thermodynamics?

Answer 1

Heat Engines

Question 2

What does a Heat Engine do?

Answer 2

Converts Heat energy to Mechanical energy

Question 3

What are the 3 main elements of a Heat Engine?

Answer 3

1. Source of high temperature heat input
2. Cyclic process that acts on a working fluid
3. Low temperature heat sink

Question 4

How do Heat Engines usually obtain a source of high temperature heat input?

Answer 4

Combustion of a fuel

Question 5

What do Heat Engines use Working Fluids for?

Answer 5

To produce work

Question 6

Why do Heat Engines require a low temperature heat sink?

Answer 6

To reject heat to

Question 7

Can a Heat Engine operate in reverse?

Answer 7

Yes

Question 8

What are 3 examples of a Heat Engine working in reverse?

Answer 8

1. Refrigeration Device
2. Air Conditioner
3. Heat Pump

Question 9

How do Heat Engines convert energy from heat to mechanical work?

Answer 9

The alternate supply and rejection of heat to and from the working fluid in the engine cylinder

Question 10

How do Heat Engines maintain work output?

Answer 10

Repeatedly supplying and rejecting heat to and from the working fluid

Question 11

Is there a relationship between the quantities of heat involved and the amount of work produced?

Answer 11

Yes

Question 12

To engage in the cyclical process, what must Working Fluids be capable of at the end of each cycle?

Answer 12

Returning to their original state

Question 13

What is the work performed by Heat Engines equivalent to?

Answer 13

The difference between the heat supplied and the heat rejected

Question 14

What are the 5 types of Heat Engines according to the Thermodynamic Cycle they use?

Answer 14

1. Carnot Cycle
2. Rankine Cycle
3. Otto Cycle
4. Diesel Cycle
5. Brayton Cycle

Question 15

Carnot Cycle

Answer 15

Theoretical thermodynamic cycle with the highest possible efficiency

Question 16

What is the Rankine Cycle applicable to?

Answer 16

Steam Plants

Question 17

What is the Otto Cycle applicable to?

Answer 17

Spark Ignition Engines

Question 18

What is the Diesel Cycle applicable to?

Answer 18

Compression Ignition (Diesel) Engines

Question 19

What is the Brayton Cycle applicable to?

Answer 19

Gas Turbines

Question 20

What are the 2 types of Heat Engines according to the nature of the Working Fluid?

Answer 20

1. Gas Cycle

2. Vapour Cycle

Question 21

What is the main Working Fluid used by the Gas Cycle?

Answer 21

Air

Question 22

How does the Gas Cycle work?

Answer 22

1. Fuel is combusted with atmospheric air
2. Heat of combustion heats and expands the air
3. The available energy in the air is used to perform work
4. The air and combustion products are released to atmosphere

Question 23

Which Thermodynamic Cycles are Gas Cycles?

Answer 23

1. Otto
2. Diesel
3. Brayton

Question 24

What is special about the Brayton Cycle as a Gas Cycle?

Answer 24

It is the only gas cycle that is not restricted to using only air as the Working Fluid

Question 25

What is the Working Fluid used by the Vapour Cycle?

Answer 25

Condensable Vapour which is in the liquid phase during part of the cycle

Question 26

What is the most common Working Fluid used by the Vapour Cycle?

Answer 26

Steam

Question 27

Which Thermodynamic Cycle is a Vapour Cycle?

Answer 27

Rankine Cycle

Question 28

Is a refrigeration cycle considered to be a Vapour Cycle?

Answer 28

Yes