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3A1 > 401-450 > Flashcards

401-450 Flashcards

1
Q
  1. The total amount of heat, in kJ, that is absorbed by the water/steam in a boiler in a given period of time is called the _____________.

a. heat rate
b. factor of evaporation
c. equivalent evaporation
d. total enthalpy
e. latent heat of the transformation

A

a. heat rate

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2
Q
  1. The mass of water that would be evaporated in one hour, from feedwater at 100°C into dry saturated steam at 100°C, by the same amount of heat that is required, per hour, to produce steam at the actual boiler condition is called the _____________________.

a. heat rate
b. factor of evaporation
c. equivalent evaporation
d. total enthalpy
e. latent heat of the transformation

A

c. equivalent evaporation

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3
Q
  1. The ratio of the equivalent evaporation of the boiler to the actual steam flow rate is called the ____________.

a. heat rate
b. factor of evaporation
c. equivalent evaporation
d. boiler efficiency
e. boiler evaporation ratio

A

b. factor of evaporation

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4
Q
  1. A boiler of higher capacity will have a higher equivalent evaporation, regardless of the steam and water parameters.

a. True
b. False

A

b. False

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5
Q
  1. Boyle’s Law deals with a process that is:

a. Adiabatic
b. Constant pressure
c. Isothermal
d. Constant volume
e. Polytropic

A

c. Isothermal

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6
Q
  1. The Laws of Boyle and Charles can be combined and stated as the formula:

a. PV/T = a constant
b. P1 T1 = P2 T 2
c. P(V2 - V1)
d. PV x 2.3log V1 / V2
e. PVT = PVT

A

a. PV/T = a constant

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7
Q
  1. If the absolute pressure of a confined gas is constant, then the volume is:

a. Inversely proportional to the absolute temperature.
b. Directly proportional to the absolute pressure.
c. Inversely proportional to the mass.
d. Directly proportional to the absolute temperature.
e. Inversely proportional to the absolute pressure.

A

c. Inversely proportional to the mass.

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8
Q
  1. If the volume of a confined gas is constant then the absolute pressure is directly proportional to the absolute temperature according to:

a. Boyle’s Law
b. Bernoullis’ Law
c. Pascal’s Theory
d. The General Gas Law
e. Charles’ Law

A

e. Charles’ Law

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9
Q
  1. In the calculation of a constant temperature process the:

a. Pressure and temperature must be absolute.
b. Volume must be absolute.
c. Mass and temperature must be absolute.
d. Volume and temperature must be absolute.
e. Pressure and volume must be absolute.

A

a. Pressure and temperature must be absolute.

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10
Q
  1. Boyle’s Law is one of constant ___________.

a. mass
b. volume
c. pressure
d. temperature
e. flow

A

d. temperature

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10
Q
  1. If the volume of a confined gas is constant, then the absolute pressure is _______________________________.

a. directly proportional to the absolute mass
b. inversely proportional to the absolute temperature
c. inversely proportional to the absolute volume
d. directly proportional to the absolute temperature
e. directly proportional to the absolute volume

A

d. directly proportional to the absolute temperature

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11
Q
  1. In the formula of the general gas law, for a given mass of gas where PV = mRT, r is:

a. In degrees Rankine
b. A characteristic constant kJ/kg K
c. The gas expansion resistance
d. A reaction expansion
e. The thermal conductivity

A

b. A characteristic constant kJ/kg K

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12
Q
  1. The characteristic constant for a gas is given as ________________.

a. Kg/kPa/K
b. J/g C
c. KJ/Kg/C
d. Kg K
e. KJ/Kg K

A

e. KJ/Kg K

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13
Q
  1. Gases such as air, nitrogen and oxygen can be roughly defined as perfect gases because they:

a. Condense rapidly
b. Can expand without being heated
c. Remain in gaseous form because they are sufficiently removed from their condensation temperature.
d. Cannot be superheated
e. None of the above

A

c. Remain in gaseous form because they are sufficiently removed from their condensation temperature.

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14
Q
  1. The types of expansions or compressions that may be represented by pressure-volume diagrams are for:
1.     Constant pressure
2.     Constant temperature
3.     Adiabatic
4.     Constant volume
5.     Isothermal

a. 1, 2, 4
b. 1, 2, 3, 4
c. 3, 4, 5
d. 1, 2, 3, 5
e. 1, 2, 5

A

d. 1, 2, 3, 5

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15
Q
  1. An expansion or compression which occurs without heat transfer to or from the gas is:

a. Constant temperature
b. Isothermal
c. Adiabatic
d. Constant volume
e. Polytropic

A

c. Adiabatic

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16
Q
  1. Use of the equation PV = a constant, means the numerical result for a compression or expansion process will:

a. Decrease as the temperature varies.
b. Increase as the temperature varies.
c. Change from positive to negative for an increasing vacuum.
d. Be the same at any point in the process.
e. Be constant if pressure changes but not volume.

A

d. Be the same at any point in the process.

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17
Q
  1. The pressure-volume diagram of a typical air compressor will have a curve drawn ____________________________.

a. as an adiabatic compression
b. as in an isothermal compression
c. approximately half way between the adiabatic and isothermal curves
d. almost as a straight line
e. from left to right in increasing value curved up

A

c. approximately half way between the adiabatic and isothermal curves

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18
Q
  1. In a constant pressure operation, as the temperature increases the __________________.

a. pressure increases
b. volume increases
c. volume decreases
d. pressure decreases
e. volume remains constant

A

b. volume increases

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19
Q
  1. A(an) ___________ process is one which has no temperature increase or decrease during the process.

a. adiabatic
b. otto
c. isothermal
d. polytropic
e. carnot

A

c. isothermal

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20
Q
  1. The curve for adiabatic expansion is __________ than for an isothermal expansion.

a. longer
b. steeper
c. higher
d. heavier
e. shorter

A

b. steeper

20
Q
  1. In calculations involving gases, absolute __________________ _______________ must be used.

a. temperatures and volumes
b. pressures and volumes
c. temperatures, pressures and volumes
d. temperatures and pressures
e. volumes

A

d. temperatures and pressures

21
Q
  1. The work done in a constant pressure expansion can be determined by:

a. P(V2-V1)
b. P(V1-V2)
c. (P1 V1 - P2 V2)/ r-1
d. PV x 2.3 log V1 / V2
e. P1 V1- P2V2

A

a. P(V2-V1)

22
Q
  1. If a calculation for work done is attempted using the formula for isothermal compression and a minus sign appears in the answer, it indicates the work _________________.

a. was done by the gas
b. was done on the gas
c. caused a vacuum to be formed
d. was done at a temperature below zero
e. was done in reverse

A

b. was done on the gas

23
Q
  1. An example of a constant pressure process is:

a. A steam engine with early cut-off.
b. A gas turbine process.
c. A steam turbine process.
d. An internal combustion engine process.
e. None of the above

A

d. An internal combustion engine process.

23
Q
  1. A perfect gas can be defined as a gas that ________________.

a. does not react chemically with other gases
b. is not poisonous
c. does not change its temperature ever
d. remains in its gaseous state under all external conditions

A

d. remains in its gaseous state under all external conditions

24
Q
  1. The person who discovered the relationship between volume and pressure of perfect gases under the condition of constant temperature was?

a. Jacques Charles
b. Albert Einstein
c. Robert Boyle
d. Isaac Newton

A

c. Robert Boyle

25
Q
  1. Absolute pressure can be defined as:

a. The pressure at which a perfect gas will turn to a liquid.
b. The sum of the gauge pressure reading plus atmospheric pressure.
c. The difference between the gauge pressure minus the atmospheric pressure.
d. A pressure constant used in the calculation of pressure volume equations.

A

b. The sum of the gauge pressure reading plus atmospheric pressure.

26
Q
  1. Before beginning any calculations involving perfect gases you must _________________.

a. ensure all the parameters are in the correct units
b. convert all the gasses to the same temperature
c. add 273° to both sides of the equation
d. add atmospheric pressure to both sides of the equation

A

a. ensure all the parameters are in the correct units

27
Q
  1. Experiments done by Jacques Charles produced two relationships for prefect gases, one for constant volume and one for constant pressure.

a. True
b. False

A

a. True

28
Q
  1. If the pressure of a perfect gas remains constant while its volume changes, then its temperature will _____________________.

a. remain constant
b. also change, in direct proportion to the pressure change
c. also change, but inversely proportional to the pressure change
d. change according to the law PVn = a constant

A

b. also change, in direct proportion to the pressure change

29
Q
  1. The General Gas Law is actually ___________________.

a. a new law that changes both Boyles and Charles laws
b. a new law that changes only Charles law
c. a new law that calculates any unknown conditions of pressure only
d. a combination of Boyles and Charles laws and is used when the three parameters of pressure, volume and temperature all change simultaneously

A

d. a combination of Boyles and Charles laws and is used when the three parameters of pressure, volume and temperature all change simultaneously

30
Q
  1. The equation P1V1 = P2V2 is called?

a. The characteristic equation of a perfect gas.
b. The characteristic constant of a perfect gas.
c. The perfect gas law equation.
d. The volume constant for perfect gases.
e. Boyle’s law.

A

e. Boyle’s law.

31
Q
  1. The Characteristic Constant of each perfect gas is ______________________.

a. the same for all perfect gases
b. the same for all gases if their temperatures are the same
c. the same for all gases if their pressures are the same
d. unique to that particular gas

A

d. unique to that particular gas

32
Q
  1. Compression requires that ________________________.

a. the gas be at absolute pressure and temperature
b. the work be done on the gas
c. the work be done by the gas
d. the gas will be at a constant volume

A

b. the work be done on the gas

33
Q
  1. To “expand a gas” means the gas is ___________________.

a. always at constant volume
b. always at constant pressure
c. always at constant temperature
d. able to perform useful work

A

d. able to perform useful work

34
Q
  1. If compression or expansion occurs with no change in the temperature of the gas, the process is called a(n)?

a. Adiabatic process
b. Polytropic process
c. Isothermal process
d. Constant volume process

A

c. Isothermal process

35
Q
  1. A gas is compressed adiabatically from 200 kPa to 700 kPa. The index of compression for the gas is 1.37 and the volume decreases from 3.5 m3to 1.403 m3. How much work is done in compressing the gas?

a. 752.4 kJ
b. 742.4 kJ
c. 762.4 kJ
d. 742.2 kJ

A

c. 762.4 kJ

36
Q
  1. A gas at 1000 kPa gauge pressure and 30°C is transferred from a cylindrical vessel 1.5m in diameter and 3m long to another cylindrical vessel 2.5m in diameter and 5m long. If the new gauge pressure is 150 kPa, calculate the new temperature. Note: Assume atmospheric pressure to be 100 kPa for this calculation.

a. 35°C
b. 45°C
c. 318°C
d. 328°C

A

b. 45°C

37
Q
  1. A perfect gas is compressed under conditions of constant temperature to a volume of 30 m3. If the final pressure of the gas is 450 kPa gauge, and the initial volume was 135 m3, what was the initial pressure? (Assume atmospheric pressure to be 101.3 kPa)

a. 122.5 kPa gauge
b. 21.2 kPa gauge
c. 223.8 kPa gauge
d. 101.3 kPa gauge

A

b. 21.2 kPa gauge

38
Q
  1. What mass of air can be held in a storage cylinder at 95°C and 1500 kPa absolute pressure, if the tank volume is 9.5 m3?

a. 134.92 kg
b. 144.1 kg
c. 154.9 kg
d. 522.6 kg
e. 725 kg

A

a. 134.92 kg

39
Q
  1. Find the characteristic constant for a gas if 112 kg of the gas has a volume of 5.7m3 when the pressure is 1500 kPa absolute and the temperature is 42°C.

a. 0.2436 kJ/kgK
b. 0.261 kJ/kgK
c. 0.271 kJ/kgK
d. 0.274 kJ/kgK
e. 0.291 kJ/kgK

A

a. 0.2436 kJ/kgK

40
Q
  1. 0.25m3 of a gas at 4000 kPa gauge pressure is expanded until the pressure is 500 kPa gauge. If expansion is polytropic with n = 1.35 find the final volume the gas will occupy. Note: Assume atmospheric pressure = 100 kPa

a. 1.03m3
b. 1.24m3
c. 1.30m3
d. 1.33m3
e. 1.47m3

A

a. 1.03m3

41
Q
  1. 1.45m3 of air at 100 kPa and 12°C is compressed to 950 kPa while following the law PV1.34 = °C. Taking R for air = 0.287 kJ/kgK, find the final volume of air and the mass of air compressed.

a. V2 = 0.27m3 and mass = 1.77 kg
b. V2 = 0.42m3 and mass = 3.55 kg
c. V2 = 0.27m3 and mass = 42.1 kg
d. V2 = 0.42m3 and mass = 57.5 kg

A

a. V2 = 0.27m3 and mass = 1.77 kg

42
Q
  1. An engine cylinder 160 cm in diameter is supplied with a constant working pressure of 1500 kPa absolute. How much work is done in 120 strokes if the stroke length is 0.45 meters and the clearance space is 0.25 m3.

a. 117 MJ
b. 118 MJ
c. 119 MJ
d. 116 MJ

A

b. 118 MJ

43
Q
  1. 10.4m3 of air is compressed at a constant temperature to 5.1m3 and 750 kPa absolute. Calculate how much work is done on the gas, assuming atmospheric pressure to be 100 kPa.

a. 2727 kJ
b. 2850 kJ
c. 3051 kJ
d. 3089 kJ

A

a. 2727 kJ

44
Q
  1. How much work is required to compress 75 kg of air isothermally @ 205°C if the compression ratio is 8.5 to 1? Use R for air = 0.287kJ/kgK

a. 9443 kJ
b. 15238 kJ
c. 22019 kJ
d. 24039 kJ

A

c. 22019 kJ

45
Q
  1. 24,500 kJ of work is done in a cylinder when 115 kg of a perfect gas is expanded isothermally @ 210°C from 0.035m3 to 0.35. Find the characteristic constant for this gas.

a. 0.192 kJ/kgK
b. 0.198 kJ/kgK
c. 0.421 kJ/kgK
d. 0.441 kJ/kgK

A

a. 0.192 kJ/kgK

46
Q
  1. A gas expands adiabatically from 1025 kPa to 225 kPa, with an expansion index of 1.42. If its volume increases from 1.5 m3 to 4.05 m3, find the amount of available work performed.

a. 441.02 kJ
b. 883.9 kJ
c. 1281.1 kJ
d. 1491.07 kJ

A

d. 1491.07 kJ

47
Q
  1. How much work is done on a 9kg mass of a perfect gas that is heated from 15°C to 175°C if the process follows the law PVn = 1.45. The characteristic constant for this gas is 0.325 kJ/kgK.

a. 322.76 J
b. 322.76 kJ
c. 1040 J
d. 1040 kJ

A

d. 1040 kJ

3A1 (12 decks)

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