1To increase the thermal efficiency of Rankine cycle
______at which heat is rejected from the working fluid in the condenser.
a. increase the average temperature
b. decrease the average temperature
c. limit the average temperature
d. temperaturw approaches zero
2Lowering the operating pressure of the condenser automatically lowers the temperature of the steam
and thus the temperature at which
a. heat is rejected
b. heat is added
c. pressure is rejected
d. temperature is added
3The overall effect of lowering the condenser pressure is an _______in the efficiency of Rankine cycle.
a. increase
b. decrease
c. remains constant
d. none of these
a. increase
4To take advantage of the increased efficiencies at low pressures
the condenser of steam power plants usually operate well below the
a. gage pressure
b. vacuum pressure
c. atmospheric pressure
d. absolute pressure
5The average temperature at which heat is added to the steam can be increased without increasing the boiler pressure by_______the steam to high temperature
a. subcooling
b. reheating
c. saturating
d. superheating
d. superheating
6Superheating the steam to higher temperatures decreases the moisture content of the steam at the _________.
a. turbine inlet
b. compressor inlet
c. compressor exit
d. turbine exit
d. turbine exit
7Presently the highest steam temperature allowed at the turbine inlet is about______________. Ceramics are very promising in this regard
a. 600⁰C
b. 620⁰C
c. 640⁰C
d. 660⁰C
b. 620⁰C
8Another way of increasing the average temperature during the heat addition process is to____________the operating pressure of the boiler.
a. increase
b. decrease
c. constant
d. none of these
a. increase
9Raises the average temperature at which heat is added to the steam raises the
a. pressure
b. temperature
c. heat addition
d. thermal efficiency of the cycle
d. thermal efficiency of the cycle
10The lower efficiencies of nuclear power plants is due to the_______ used in those plants for safety reasons.
a. higher maximum temperature
b. lower maximum temperature
c. considerate temperature
d. allowable maximum temperature
b. lower maximum temperature
11The average temperature during reheat process can be increased by _________the number of expansion and reheat stages
a. increasing
b. decreasing
c. maximizing
d. none of thess
a. increasing
12The incorporation of the single reheat in a modern plant improves the cycle efficiency by ________by increasing the average temperature at which heat is added to steam
a. 1 to 2%
b. 2 to 3%
c. 3 to 4%
d. 4 to 5%
d. 4 to 5%
13As the number of stages is increased
the expansion and reheat process approached an _______at the maximum temperature
a. isentropic process
b. isothermal process
c. isobaric process
d. adiabatic process
14In a Reheat cycle
the optimum reheat pressure is about _________of the maximum cycle pressure
a. one-eight
b. one fourth
c. one half
d. one third
15The main purpose of reheating is to _______ of the steam at the final stage of expansion
a. reduce the moisture content
b. limit the pressure
c. limit the moisture content
d. none of these
a. reduce the moisture content
16Is to transfer heat to the feedwater from the expanding steam in a counter flow heat exchanger built into the turbine
a. heat exchanger
b. regeneration
c. boiler
d. reheater
b. regeneration
17The device where the feedwater is heated by regeneration is called
a. Regenerator
b. Recuperator
c. Diabatic
d. Toxic
a. Regenerator
18Regeneration also provides a convenient means of dearating the feedwater to prevent
a. boiler explosion
b. boiler scale production
c. boiler corrosion
d. compressor damage
c. boiler corrosion
19An open feedwater heater is basically a mixing chamber
where the steam from the turbine mixes with the feedwater exiting the
a. turbine
b. pump
c. boiler
d. condenser
20The thermal efficiency of the Rankine cycle_________as a result of regeneration.
a. increases
b. decreases
c. remains constant
d. none of these
a. increases
21The cycle efficiency increases further as the number of feedwater heater is
a. increased
b. decreased
c. remains constant
d. none of these
a. increased
22____________in which heat is transferred from the extracted steam to the feedwater without any mixing taking place
a. open feedwater heating
b. condenser rejection
c. boiler addition
d. closed feedwater heating
d. closed feedwater heating
23A_______allows the liquid to be throttled to a lower pressure region but traps the vapor.
a. vent
b. elbow
c. blow
d. trap
d. trap
24A closed feedwater heater is more ________ than the open feedwater heater
a. corrosive
b. dangerous
c. expensive
d. toxic
c. expensive
25Is the production of more than one useful form of energy(such as process heat and electric power) from the same energy source
a. Generation
b. Cogeneration
c. Simultaneous power reaction
d. none of these
b. Cogeneration
26Can be applied in steam turbine cycle (Rankine)
Gas turbine(Brayton) and combined cycle
a. Hydroelectric plant
b. Nuclear power plant
c. Cogeneration plant
d. Tidal power plant
27The overall thermal efficiency of a power plant can be increased by
a. binary reaction
b. extraction
c. Carnot cycle
d. Binary cycle
d. Binary cycle
28A____________is composed of two separate cycles
one at high temperatures(topping cycle) and the other at relative low temperatures
a. Carnot cycle
b. Binary cycle
c. Rankine cycle
d. Combustion cycle
29Combined cycles have a__________thermal efficiency than the steam or gas turbine cycles operating alone
a. higher
b. lower
c. limit
d. average
a. higher
30In a Rankine cycle with fixed turbine inlet conditions. What is the effect of lowering the condenser pressure
the pump work input will
a. increase
b. decrease
c. remains constant
d. none of these
31In a Rankine cycle with fixed turbine inlet conditions. What is the effect of lowering the condenser pressure
the turbine work output will
a. increase
b. decrease
c. remains constant
d. none of these
32In a Rankine cycle with fixed turbine inlet conditions. What is the effect of lowering the condenser pressure
the heat added will
a. increase
b. decrease
c. remains constant
d. none of these
33In a Rankine cycle with fixed turbine inlet conditions. What is the effect of lowering the condenser pressure
the heat rejected will
a. increase
b. decrease
c. remains constant
d. none of these
34In a Rankine cycle with fixed turbine inlet conditions. What is the effect of lowering the condenser pressure
the cycle efficiency will
a. increase
b. decrease
c. remains constant
d. none of these
35In a Rankine cycle with fixed turbine inlet conditions. What is the effect of lowering the condenser pressure
the moisture content at turbine exit will
a. increase
b. decrease
c. remains constant
d. none of these
36In an ideal Rankine cycle with fixed turbine inlet temperature and condenser pressure
what is the effect of increasing boiler pressure
37In an ideal Rankine cycle with fixed turbine inlet temperature and condenser pressure
what is the effect of increasing boiler pressure
38In an ideal Rankine cycle with fixed turbine inlet temperature and condenser pressure
what is the effect of increasing boiler pressure
39In an ideal Rankine cycle with fixed turbine inlet temperature and condenser pressure
what is the effect of increasing boiler pressure
40Is the amount of energy released when a fuel is burned completely in a steady flow process and the products are returned to the state of the reactants
a. heating value
b. reactor
c. combustion
d. none of these
a. heating value
41Higher heating value when H₂O in the product of combustion is in
a. solid form
b. vapor form
c. gas form
d. liquid form
d. liquid form
42Lower heating value when H₂O in the product of combustion is in
a. gas form
b. vapor form
c. liquid form
d. direct form
b. vapor form
43In the limiting case of no heat loss to the surroundings
the temperature of the products will reach a maximum
44The entropy of a pure crystalline substance at ________is zero
a. 0⁰F
b. absolute zero temperature
c. atmospheric zero temperature
d. none of these
b. absolute zero temperature
45Converted electric energy to chemical energy
a. fuel cells
b. converter
c. photovoltaic cell
d. generator
a. fuel cells
46A major application area of thermodynamics is
a. machining
b. refrigeration
c. compressor
d. heat and energy
b. refrigeration
47Devices which produce refrigeration are called
a. air-conditioner
b. heat pump
c. refrigerators
d. none of these
c. refrigerators
48The most frequently used refrigeration cycle is the
a. absorption
b. steam-jet
c. ammonia
d. vapor-compression
d. vapor-compression
49Heat flows in the direction of decreasing
a. pressure
b. temperature
c. volume
d. density
b. temperature
50The transfee of heat from temperature region to a high temperature one requires special device known as
a. refrigerator
b. air-consitioner
c. heat pump
d. humidifier
a. refrigerator
51Device which transfer heat from low temperature medium to a high temperature one is a
a. adiabatic
b. refrigerator
c. heat exchanger
d. heat pump
d. heat pump
52The objective of heat pump is to maintain a heated space at a
a. low pressure
b. high pressure
c. low temperature
d. high temperature
d. high temperature
53The capacity of refrigeration that can freeze 1 ton of liquid water at 0⁰C into ice at 0⁰C in 24 hrs is said to be
a. 1 ton of refrigeration
b. 1Mton of refrigeration
c. 1 EER
d. 1 ton of air-consitioning
a. 1 ton of refrigeration
54The COP of reversed Carnot increases as the difference between the two temperatures
a. increases
b. decreases
c. remains constant
d. none of these
b. decreases
55In an ideal Rankine cycle with fixed turbine inlet temperature and condenser pressure
what is the effect of increasing boiler pressure
56Is used as an oxidizer only in some specialized applications
such as cutting and welding
a. Pure gas
57In an ideal Rankine cycle with fixed turbine inlet temperature and condenser pressure
what is the effect of increasing boiler pressure
58During a combustion process
the components which exist before the reaction are called
a. reaction
b. combustion
c. reactants
d. product
59In an ideal Rankine cycle with fixed turbine inlet temperature and condenser pressure
what is the effect of superheating the steam to a higher temperature
60The components which exist after the reaction are called
a. results
b. products
c. mixture
d. none of these
b. products
61In an ideal Rankine cycle with fixed turbine inlet temperature and condenser pressure
what is the effect of superheating the steam to a higher temperature
62The fuel must be brought________ to start the combustion
a. below its ignition temperature
b. midway its ignition temperature
c. above its ignition temperature
d. above its maximum allowable
c. above its ignition temperature
63In an ideal Rankine cycle with fixed turbine inlet temperature and condenser pressure
what is the effect of superheating the steam to a higher temperature
64The minimum ignition temperatures if various substances in atmospheric air are approximately_________ for gasoline
400⁰C for carbon
65In an ideal Rankine cycle with fixed turbine inlet temperature and condenser pressure
what is the effect of superheating the steam to a higher temperature
66The total mass of each element is conserved during a
a. chemical emission
b. chemical transmission
c. chemical union
d. chemical reaction
d. chemical reaction
67In an ideal Rankine cycle with fixed turbine inlet temperature and condenser pressure
what is the effect of superheating the steam to a higher temperature
68The total number of moles is not conserved during a
a. chemical sublimation
b. chemical interaction
c. chemical reaction
d. chemical direction
c. chemical reaction
69In an ideal Rankine cycle with fixed turbine inlet temperature and condenser pressure
what is the effect of superheating the steam to a higher temperature
70The frequently used quantity in the analysis of combustion processed to quantify the amounts of fuel and air is called
a. fuel-air ratio
b. air-fuel ratio
c. combustion ratio
d. backwork ratio
b. air-fuel ratio
71Assume the mass flow rate is maintained the same
when a simple ideal Rankine cycle is modified with reheating
72A combustion process is complete if all the carbon in the fuel burns to CO₂
all the hydrogen burns to H₂O
73Assume the mass flow rate is maintained the same
when a simple ideal Rankine cycle is modified with reheating
74A combustion is ________is the combustion products contain any unburned fuel or components such as C
H₂
75Assume the mass flow rate is maintained the same
when a simple ideal Rankine cycle is modified with reheating
76Is an obvious reason for incomplete combustion
a. insufficient carbon
b. insufficient air
c. insufficient nitrogen
d. insufficient oxygen
d. insufficient oxygen
77Assume the mass flow rate is maintained the same
when a simple ideal Rankine cycle is modified with reheating
78The minimum amount of air needed for the complete combustion of fuel is called the
a. actual-fuel air
b. theoretical air
c. 50%air
d. 90 percent air
b. theoretical air
79Assume the mass flow rate is maintained the same
when a simple ideal Rankine cycle is modified with reheating
80The theoretical air is also referred to as the chemical correct amount of air
or
a. 120% theoretical air
b. 50% theoretical air
c. 0% actual air
d. 100% theoretical air
81Assume the mass flow rate is maintained the same
when a simple ideal Rankine cycle is modified with reheating
82Theoretical air is also known as
a. actual air
b. exact theoretical air
c. zero excess air
d. stoichiometric air
d. stoichiometric air
83How do the following quantities change when the simple ideal Rankine cycle is modified with regeneration? The turbine work output will
a. increase
b. decrease
c. remains the same
d. none of these
b. decrease
84The amount of air in excess of the stoichiometric amount is called
a. excess air
b. excessive air
c. controllable air
d. excess theoretical air
a. excess air
85How do the following quantities change when the simple ideal Rankine cycle is modified with regeneration? The heat added will
a. increase
b. decrease
c. remains the same
d. none of these
b. decrease
86Amount of air less than the stoichiometric amount are called
a. excess air
b. inefficiency of air
c. incremental air
d. deficiency of air
d. deficiency of air
87A commonly device to analyze the composition of combustion gases is the
a. Volumetric analyzer
b. Gravimetric analyzer
c. Orsat analyzer
d. none of these
c. Orsat analyzer
88How do the following quantities change when the simple ideal Rankine cycle is modified with regeneration? The heat rejected will
a. increase
b. decrease
c. remains the same
d. none of these
b. decrease
89How do the following quantities change when the simple ideal Rankine cycle is modified with regeneration? The cycle efficiency will
a. increase
b. decrease
c. remains the same
d. none of these
a. increase
90Is the difference between the enthalpy of the products at a specified state and the enthalpy of reactants at the same state for a complete reaction
a. chemical energy of reaction
b. enthalpy of reaction
c. internal energy of reaction
d. kinetic energy reaction
b. enthalpy of reaction
91How do the following quantities change when the simple ideal Rankine cycle is modified with regeneration? The moisture content at turbine exit will
a. increase
b. decrease
c. remains the same
d. none of these
c. remains the same
92Represents the amount of heat released during a steady flow combustion process when 1 kmol of fuel is burned completely at a specified temperature and pressure
a. chemical energy of reaction
b. enthalpy of reaction
c. internal energy of reaction
d. enthalpy of combustion
d. enthalpy of combustion
93Any material which can be burned to release energy is called a
a. fuel
b. gas
c. coal
d. uranium
a. fuel
94Enthalpy of formation is the enthalpy of a substance at a specified state due to its
a. energy composition
b. chemical composition
c. internal energy of reaction
d. enthalpy of reaction
b. chemical composition
95Hydrocarbon fuels are primarily consist of
a. oxygen and nitrogen
b. hydrogen and carbon
c. air and fuel
d. helium and sulfur
b. hydrogen and carbon
96A gasoline is treated as Octane_____
a. C₁₂H₁₈
b. C₄H₈
c. C₈H₁₈
d. C₁₄H₃₀
c. C₈H₁₈
97A___________is treated as dodecane
C₁₂H₂₆
a. Alcohol fuel
b. Solid fuel
c. Methane fuel
d. Diesel fuel
98The gaseous hydrocarbon fuel natural gas is sometimes treated as ___________
CH₄
a. methane
b. propane
c. ethane
d. trochane
99A chemical reaction during which a fuel is oxidized and a large energy is released is called
a. reaction
b. combustion
c. oxidation
d. chemical reaction
b. combustion