Fuels

Question 1

The measurement requires complete combustion; that is, all carbon and hydrogen must be oxidized to
form ___________ and _________, respectively

Answer 1

CO2, H2O

Question 2

this corresponds to the heat of reaction when the latent heat of condensation of water is recovered

Answer 2

Gross Calorific Value (GCV)

Question 3

it is used to measure the heating value of a fuel and measurements are usually performed at temperatures in the range 288 to 298 K

Answer 3

calorimeter

Question 4

states of fuel

Answer 4

solid, liquid, and gaseous

Question 5

when one mole of H2 is burned, it produces ______ mole of water

Answer 5

one

Question 6

it is the total heat released when the fuel is burned and the water exits as vapor

Answer 6

NCV

Question 7

It can be calculated from the gross calorific value of the fuel and the heating value losses, neglecting heat input from the fuel and air.

Answer 7

thermal efficiency of combustion

Question 8

examples of secondary gaseous fuels

Answer 8

Blast Furnace Gas
Petroleum Gas
Producer Gas
Coal Gas
Coke-oven Gas
Carburetted Gas
Water Gas

Question 9

NCV only considers the first __________________

Answer 9

control volume

Question 10

common term for carbon particulates

Answer 10

soot

Question 11

This is observed to increase the apparent heat
release due to the?

Answer 11

latent heat of vaporization

Question 12

examples of primary liquid fuels

Answer 12

petroleum

Question 13

examples of secondary liquid fuels

Answer 13

Kerosene
Gasoline
Fuel Oil
Alcohol
Benzol
Shale Oil

Question 14

GCV and NCV of CO are equal because when burned completely, this does not produce ________

Answer 14

water

Question 15

examples of primary gaseous fuels

Answer 15

Natural Gas

Question 16

The presence of _____________________________ constitutes a calorific value loss

Answer 16

unburnt combustibles

Question 17

Though ________________ is a combustible element too but its presence in the fuel is considered to be undesirable.

Answer 17

sulfur

Question 18

GCV and NCV of ______ are equal because when burned completely, this does not produce water.

Answer 18

CO

Question 19

When water is in vapor form, the latent heat of vaporization of water is ________________

Answer 19

not recovered

Question 20

this is the total heat released when the fuel is burned and the water exits as liquid

Answer 20

GCV

Question 21

what are the cv losses

Answer 21

%CV loss due to unburnt combustible
%CV loss due to sensible heat
%CV loss due to uncondensed water

Question 22

_________ and __________ of CO are equal because when burned completely, this does not produce water

Answer 22

GCV, NCV

Question 23

The principal combustible elements of each
fuel are

Answer 23

carbon and hydrogen

Question 24

this measures % of the total calorific value of the fuel that can be used to generate power

Answer 24

Thermal efficiency of combustion

Question 25

examples of primary solid fuels

Answer 25

Coal Lignite Peat Wood

Question 26

If the product gases contain several percent H2O, considerably more than the saturation vapor pressure of water at that temperature, water will _______________ in the calorimeter

Answer 26

condense

Question 27

color of the flame in incomplete combustion

Answer 27

"yellow" warm

Question 28

The measured calorific value thus depends on the phase of the?

Answer 28

product water

Question 29

it is a measurement of how well the fuel being burned is being utilized in the combustion process

Answer 29

thermal efficiency of combustion

Question 30

The term ________________ is used to denote heat release due to combustion

Answer 30

calorific value

Question 31

This is observed to increase the ________________ release due to the latent heat of vaporization.

Answer 31

apparent heat

Question 32

thermal efficiency of combustion can be calculated from the gross calorific value of the fuel and the heating value losses, neglecting _______________ from the fuel and air

Answer 32

heat input

Question 33

Part of the heat generated by fuel combustion is absorbed by the flue gases which leave the chimney or stack at high temperature.

Answer 33

CV Losses due to Sensible Heat

Question 34

GCV is the total heat released when the fuel is burned and the water exits as?

Answer 34

liquids

Question 35

the following are important of a good fuel

Answer 35

- low ignition point - high calorific value - high burning efficiency - not produce harmful gases - produce least quantity of smoke (ash) and gases - be economical (cheaper) - be easy to store and convenient for transportation

Question 36

is a substance which releases heat energy on combustion

Answer 36

chemical fuel

Question 37

three requirements for combustion to take place

Answer 37

fuel, oxygen and heat

Question 38

this is negative in sign because combustion reactions are exothermic

Answer 38

Heats of combustion Hc

Question 39

fuels occur in nature called

Answer 39

primary fuels

Question 40

prepared fuels are called

Answer 40

secondary fuels

Question 41

examples of secondary solid fuels

Answer 41

Briquettes Coke Charcoal

Question 42

thermal efficiency of combustion can be calculated from the ________________________ of the fuel and the _______________, neglecting heat input from the fuel and air.

Answer 42

gross calorific value, heating value losses

Question 43

this corresponds to the case when the water is present as vapor

Answer 43

Net Calorific Value

Question 44

had these substances been completely burned, they would have given off additional heat

Answer 44

unburnt combustibless

Question 45

Heats of combustion Hc are negative in sign because combustion reactions are exothermic; by this equation, it can be said that calorific values have a _____________ sign.

Answer 45

positive

Question 46

NCV is the total heat released when the fuel is burned and the water exits as?

Answer 46

vapor

Question 47

Heats of combustion Hc are negative in sign because combustion reactions are?

Answer 47

exothermic

Question 48

The two measures of the enthalpy of combustion are generally specified in terms of the calorific value:

Answer 48

GCV and NCV