Thermodynamic definitions

Question 1

How do Gasoline Engines - 4 stroke - operate ?

Answer 1

Four stroke engines operate with a cycle that has 2 complete revolution per complete cycle

Question 2

How do Diesel Engines operate ?

Answer 2

• also uses the 4-stroke cycle
• differs in its ignition system, engines uses heat generated by compressions to auto-ignite

Question 3

What is the gas turbine ?

Answer 3

It has a very good power to weight ratio and is thus used for aircraft propulsion

Question 4

Why are combined cycle gas turbines used ?

Answer 4

The ease of natural gas handling alongside quick spin up times make it economically viable

Question 5

Thermodynamics

Answer 5

The science of energy

Question 6

First law of thermodynamics

Answer 6

That energy cannot be created or destroyed but can only change forms

Question 7

Second law of thermodynamics

Answer 7

It asserts that energy has a quality as well as a quantity and actual processes occur in the direction of decreasing quality of energy

Question 8

System

Answer 8

A quantity of matter or a region in space chosen for study

Question 9

Surroundings

Answer 9

The mass or region outside the system

Question 10

Boundary

Answer 10

The real or imaginary surface that separates the system from its surroundings

Question 11

Closed system

Answer 11

A fixed amount of mass, and no mass can cross its boundary

Question 12

Open system

Answer 12

Both mass and energy can cross the boundary of a control volume

Question 13

Intensive properties

Answer 13

Those that are independent of the mass of a system, temperature, pressure and density

Question 14

Extensive properties

Answer 14

Those whose values depend on the size of the system

Question 15

Specific properties

Answer 15

Extensive properties per unit mass

Question 16

Equilibrium

Answer 16

A state of balance

Question 17

Thermal equilibrium

Answer 17

If the temperature is the same throughout the entire system

Question 18

Mechanical equilibrium

Answer 18

If there is no change in pressure at any point of the system with time

Question 19

Phase equilibrium

Answer 19

If a system involves two phases and when the mass of each phase reaches and equilibrium level and stays there

Question 20

Chemical equilibrium

Answer 20

If the chemical composition of a system does not change with time, that is, no chemical reactions occur

Question 21

State postulate

Answer 21

The state of a simple compressible system is completely specified by two independent, intensive properties

Question 22

Isothermal process

Answer 22

A process during which the temperature remains constant

Question 23

Isobaric process

Answer 23

A process during which the pressure remains constant

Question 24

Isochoric process

Answer 24

A process during which the specific volume remains constant

Question 25

Cycle

Answer 25

A process during which the initial and final states are identical

Question 26

Quasistatic or quasi-equilibrium process

Answer 26

When process proceeds in such a manner that the system remains infinitesimally close to an equilibrium state at all times

Question 27

Steady-flow process

Answer 27

A process during which a fluid flows through a control volume steadily

Question 28

Zeroth law of thermodynamics

Answer 28

If two bodies are in thermal equilibrium with a third body, they are also in thermal equilibrium with each other

Question 29

Ice point

Answer 29

A mixture of ice and water that is in equilibrium with air saturated with vapor at 1 atm pressure

Question 30

Steam point

Answer 30

A mixture of liquid water and water vapor in equilibrium at 1 atm pressure

Question 31

Pressure

Answer 31

A normal force exerted by a fluid per unit area

Question 32

Absolute pressure

Answer 32

The actual pressure at a given position it is measured relative to absolute vacuum

Question 33

Gage pressure

Answer 33

The difference between the absolute pressure and the local atmospheric pressure

Question 34

Vacuum pressures

Answer 34

Pressures below atmospheric pressure

Question 35

Pascal’s law

Answer 35

The pressure applied to a confined fluid increases the pressure throughout by the same amount