WorksheetsCHAPTER 19: RECENT BE QUESTIONS
Total questions: 105
Worksheet time: 53mins
A pump with capacity Q1 and head H1 is in series with another pump with capacity Q2 and head H2. What is the head developed if Q2 is less than Q1?
2 H2 H1
H2 + H1
H2 / H1
H2H1
At ordinary temperature what substance will behave as inert gas and will not react in the combustion process?
nitrogen
sulfur
hydrogen
carbon
Which of the following cycles is ideal for spark-ignition reciprocating engine?
Diesel cycle
Dual cycle
Rankine Cycle
Otto cycle
What is the relative humidity when the dew point and dry bulb temperature are equal?
110 %
0 %
100 %
50%
Reheating process is normally employed in steam plane when:
there is excess steam
subcooling is required
turbine undergoes excessive moisture
dehumidifying is required
Where does the final removal of water vapor in an absorption refrigeration system occur?
analyzer
generator
condenser
rectifier
If the average temperature liquid of power cycle during heat addition process is as high as possible, then the thermal efficiency of the cycle will:
increase
remain constant
decrease
zero
What is the temperature of lubricant at which it will ignite thus limit its application?
cold point
burning point
flash point
use point
What is the heat that is removed from the space to be cooled, which is the same as the heat absorbed by the cooling coils?
heating capacity
enthalpy
work compression
refrigerating effect
An air conditioning system in which water is chilled or cooled and which passes the evaporator coils is:
chilled water system
direct expansion
absorption
water circulation system
A multi-stage refrigeration system which is realizable in using different refrigerants is:
direct
cascade
flooded
vapor
Very large pipe diameter means a thicker wall and high cost. It also means:
zero pressure drop
high pressure drop
constant temperature
low pressure drop
Aside from maintaining appropriate temperature for food cold storage, how is desiccation minimized or decreased?
low oxygen
maintain humidity ratio
low air circulation
increase humidity ratio
During combustion process, only limited air is supplied and not enough to supply two molecule of oxygen per one molecule of carbon, then the product is:
hydration
carbon monoxide
carbonic acid
carbon dioxide
As far as combustion chamber design is considered, the maximum power output of a given engine can be increased by:
increasing combustion time
increasing combustion chamber volume
decreasing combustion chamber volume
providing small values
A water conservation device which employs both air and water is condensed a condenser and cooling tower combined into one is called:
shell and tube condenser
air-cooled condenser
water-cooled condenser
evaporative condenser
In order to perform efficiently, a power cycle must be communicated with the outside temperature of its surroundings and into one is called:
Kirchhoff’s Law
Second Law of Thermodynamics
Kelvin-Planck Law
First Law of Thermodynamics
Water is heated in a container. It expands and becomes less dense and lighter. It rises up the container because of its reduced density and is replaced by cooler air. As this process continues, the heat is transferred and disturbed all throughout. What is this mode of heat transfer called?
condenser
radiation
conduction
convection
When required, a regulator water valve in refrigerating system should be:
on the suction line on compressor line
in the water inlet
anywhere in the system
in the water outlet
When there is no work between the thermodynamic system and its surrounding, the quantity of net heat transfer is equal to:
total energy of an open system
temperature of an open system
temperature of a closed system
total energy of a closed system
In order to attain equilibrium in the condenser, the cooling tower range must be ____ with respect to temperature rise in the condenser.
greater
equal
less
zero
If ice will form in a solution of water and salt, then it is at a temperature called:
dew point
freezing point depression
boiling point depression
critical point
The flow of the convergent section of a nozzle is always subsonic. If the flow is subsonic then the Mach number is:
greater than unity
less than unity
near than unity
unity
One hundred twenty percent theoretical air was supplied for combustion. What is the equivalent excess equal to:
20 %
100 %
240 %
120 %
If Pi is the indicated horsepower and Pb is the indicated horsepower of a compressor, then what is mechanical efficiency, Em, equal to:
Em = Pb/Pi
Em = Pi/Pb
Em = Pb - Pi
Em = Pi - Pb
What is the least number of compressor a multistage system will use?
three
two
four
one
The relation between the Fahrenheit absolute scale and the Celsius absolute scale is:
R = 1.8 K
R = 32 °K
R = 3.2 °K
R = 18 °K
The sum of the internal energy and the product of pressure and specific volume is known as the:
enthalpy
entropy
total work
total internal energy
A refrigeration control that guards the compressor form overloads brought about by abruptly increases loads resulting from defrosting, warm products and others, is called:
safety valve
suction hold-back valve
solenoid valve
expansion valve
What does fossil-fuel fired power plants release, which in turn produces the key ingredient in acid rain?
nitrogen
sulfur emission
carbon monoxide
carbon dioxide
The fraction of the radiation energy incident on a surface which is absorbed by the surface is called:
Convection
Absorptivity
Emission
Radiation
Which of the following power plants uses energy from uranium to produce electric power?
Diesel Plant
Geothermal Plant
Nuclear Plant
Hydroelectric Plant
Ice cubes added to a glass of water and stirred. Moisture starts to form on the outer surface of the glass. At this point, what is the temperature at the outer surface called?
critical temperature
surface temperature
dew point temperature
saturation temperature
The force when applied to a mass of one kilogram will give mass an acceleration of one meter per second for every second called:
Watt
Joule
Newton
Pascal
The kinetic energy of a moving fluid is used to isentropically compressed the fluid to state of zero velocity. The temperature of a moving fluid at the state zero velocity is called:
stagnation temperature
partial temperature
critical temperature
absolute temperature
The dew point temperature of the product of combustion in the saturation temperature that corresponds to the partial pressure of the ____ in the products.
SO2
H2O
N2
CO2
What do we call a device that is used to boiler operation that will stop the burner or at least send a signal to the operator if the water drops to a low level that is no longer safe?
safety valve
dead-weight valve
high water cut off
low water cut off
Dry analysis is a fractional analysis of the products of combustion which does not include:
water vapor
carbon dioxide
sulfur dioxide
carbon monoxide
The size of a reciprocating pump is stamped on the builder's plate 3" × 4" × 6'. The diameter of the liquid cylinder is:
5"
6"
3"
4"
One foot water is equal to:
0.4318 lb/in.2
68.3 lb/ft.2
0.8673 lb/in.2
62.43 lb/ft.2
The freezing point of R-22 is:
-109 °F
-252 °F
-256 °F
-211 °F
Which of the following is a type of evaporator?
shell-and-tube-condenser
sell-and-tube-water cooler
oil lantern rings
polyphase motors
For Brayton cycle, the result of regeneration is:
increase in thermal efficiency
decrease thermal efficiency
moderate thermal efficiency
low thermal efficiency
If the pressure exerted on a liquid is higher than the saturation corresponding to its temperature, the liquid is a:
saturated liquid
subcooled liquid
superheated liquid
highly superheated liquid
In a power driven pump, each piston stroke is displaced by 360º divided the ______.
revolution per minute
bore
length of the stroke
number of cylinders
If the air is compressed without discarding heat, then what do you call this kind of compression?
isobaric
isochoric
adiabatic
isothermal
If a gas posses internal energy, then it is due to its;
velocity
pressure and volume values
height from a certain datum level
molecular motion
The pressure of ammonia was detected in brine solution. How can ammonia be removed?
freeze the brine solution
heat the brine to a high temperature enough to free the ammonia
throw the brine solution
lower the temperature of the brine
What will happen when the pressure at any point inside a centrifugal pump goes below the vapor pressure corresponding to the temperature of the liquid?
turbulent flow
laminar flow
cavitation
priming
What does a negative Joule-Thompson coefficient means during a throttling process?
fluid pressure is constant
fluid temperature drop
fluid temperature rises
fluid pressure zero
For steam power plants, increasing the operating pressure of the boiler will:
increase thermal efficiency
decrease thermal efficiency
bring thermal efficiency to zero
make thermal efficiency constant
The ratio of the average load to that of the rated capacity of a plant is called:
output factor
demand factor
load factor
capacity factor
What is the method used to evaluate all welds performed on pressure parts of boiler tube materials?
hydrostatic test
Orsat analysis
vacuum test
radiographic test
If the pressure is disregarded in the various other components of a steam or gas power plants, the pressure rise in the pump or compressor is _______ to the pressure drop in the turbine.
inversely proportional
constant
equal
varying
What is the effect on saturated temperature if the pressure of the fluid is decreased?
there is no effect
saturation temperature decreases
saturation temperature remains constant
saturation temperature increases
If V3 is the cylinder volume after the combustion process of 8 Diesel cycle and V2 is its cylinder volume before combustion, then calculate the cut-off ratio, r.
r = V3 – V2
r = V2 – V3
r = V2/V3
r = V3/V2
Compare the temperature of discharge vapor refrigerant leaving the compressor for a superheated cycle and the saturated cycle, for the same condensing temperature and pressure.
there is no difference
higher, for the superheated cycle
higher, for the saturated cycle
lower for the Superheated cycle
A valve that releases steam from the boiler by opening at a pre-determined pressure in order to keep the steam pressure from rising more than the pressure from which the valve is set is called a
ammonia valve
stop valve
check valve
safety valve
What is the relationship of the capacity of a centrifugal pump, Q, to impeller diameter, D, when there are two impeller diameters in the same pump?
Q is directly proportional to the square of the ratio of D
Q is inversely proportional to the ratio of D
Q is directly proportional to the ratio of D
Q is inversely proportional to the square of the ratio of D
If Wt is the turbine shaft work of a gas turbine unit, Wc is its compressor shaft work and Q is the heat supplied in duel, then determine its thermal efficiency.
Q / (Wt + Wc)
Q / (Wt + We)
(wt + We) / Q
(Wt - Wc) / Q
The schedule number of a pipe, N, indicates the thickness of the pipe wall. If the allowable stress of the pipe is S, then what is the internal pressure equal to?
N−S
N/S
N×S
S/N
What is the pressure present inside the casing of an impulse turbine?
vacuum
atmospheric pressure
above atmospheric
zero
In order to remove the fly ashes from the flue gas, which of the following must a power plant be equipped with?
condenser
demineralizer
electrostatic precipitator
desulphurization plant
If Hs is the total suction head of a pump, Hp is its suction surface pressure, and Hf is its suction friction head, then calculate the total suction head, Ht.
Ht = Hs - Hp - Hf
Ht = Hs + Hp - Hf
Ht = Hs + Hp + Hf
Ht = Hs - Hp + Hf
The constant spending of certain percentage of circulated water in a cooling tower in order to prevent accumulation of dissolved mineral solids and other impurities in the condenser water is called
approach
drift
range
bleed-off
What process is employed when the turbine steam power plants experience excessive moisture?
reheating
supercooling
subcooling
freezing
A company is interested to produce a water turbine wherein only little energy is required or necessary because the guide vanes are to be controlled. The turbine must be a:
gas turbine
propeller turbine
Kaplan turbine
Francis turbine
If Et is the total net energy generated by a plant in a certain period of time and Er is the rated net energy capacity of the plant during the same period of time then what is the plant operating factor?
Er - Et
Et / Er
Et - Er
Er / Et
If W is the work output of a heat engine and H is the total heat input of an engine, then determine its thermal efficiency, e.
e = H/W
e = W/H
e = W×H
e = 1 - (W - H)
Which of the following is converted to mechanical energy by a water.
Internal energy
kinetic energy
potential energy
hydraulic energy
What must be the value of the available Net Positive Suction Head (NPSH) of a centrifugal pump compared to its require NPSH to avoid losing priming?
available NPSH lesser than required NPSH
available NPSH equal than required NPSH
available NPSH greater than required NPSH
available NPSH constant at all times
What type of fuel is used with stationary power plants where gas is available by pipeline?
gaseous fuels
solid fuels
coal
liquid fuels
Wb is shaft work of an engine and Wi is the indicated work of an engine. If mechanical friction is present in the engine mechanism, then:
Wb is equal to Wi
Wb is less than Wi
Wb is proportional to Wi
Wb is greater then Wi
What is the saturation pressure at the critical temperature, or the lowest pressure in which a substance can be in the liquid state at its critical pressure?
external pressure
critical pressure
condensing pressure
evaporation pressure
What is the significance of a high dielectric strength of lubricating oil?
oil is thick
oil is contaminant-free
oil is thin
oil is not clean
Theoretically, what is the effect of the compressor clearance on horsepower?
varies in direct proportion
increase power
decrease power
there is no effect
Compare the refrigerating effect per unit mass of refrigerant circulated for a superheated cycle that produces useful cooling and a saturated cycle, for the same vaporizing and condensing temperature.
lower for a superheated cycle
greater for a saturated cycle
the same
greater for a superheated cycle
It is important to take some moisture from the air to dehumidify it if the relative humidity reaches high levels. To do this, it requires cooling the air:
at wet-bulb temperature
above its dew point temperature
at critical temperature
below its dew point temperature
What does enthalpy measure in a substance?
its coldness
its heat content
its humidity
its dew point
Pneumatic tools are powered by:
natural gas
air
electricity
steam
The pump will not cavitate if the available Net Positive Suction Head (NPSH) is:
less than the required NPSH
equal or lesser than the required NPSH
equal or greater than the required NPSH
zero compared to the required NPSH of 1
A water-tube condenser has a total of 60 tubes. If these are two passes, then compute the number of tube per pass.
6C
15
3C
2
If Ev is the volumetric efficiency of a reciprocating pump, then determine SLIP which represents all losses of capacity given in percentage of the displacement.
1/Ev
1−1/Ev
1−Ev
Ev+1
What is the relationship of the horsepower of a centrifugal pump, Hp, to the impeller speed, S, if the pump is at two different rotative speeds?
Hp is inversely proportional to the cube of the ratio of S
Hp is directly proportional to the ratio of S
Hp is inversely proportional to the ratio of S
Hp is directly proportional to the cube of the ratio of S
What is likely to occur when sections of the impeller of a centrifugal pump are handling vapor and other sections are handling liquid?
erosion of the pump
high head and low capacity
excessive vibration
complete failure to operate
When vapor compression takes place on one side of the piston and one during one revolution of the crankshaft, then the compressor is:
double-acting
four-cycle
two-revolution
single-acting
In Stirling and Erickson Cycles, the efficiency can be increased by:
compressibility
superheating
regeneration
subcooling
Which of the following is used to control refrigeration compressor capacity?
dehumidifier
check valve
solenoid valve
unloader
During a cooling and dehumidifying process, sensible and latent heats are removed in the cooling coil. If Hs is the sensible heat and Ht is the total heat transferred, then determine the coil sensible factor.
Ht−Hs
Hs−Ht
Ht/Hs
Hs/Ht
Based on PSME code, what should be provided in each stream outlets if two or more boilers will be connected in parallel?
relief and check valves
non-return and shut-off valves
expansion and shut-off valves
expansion and check valves
The diesel cycle is the ideal cycle for a:
absorption
steam-jet
compression-ignition engine
gas turbine
If a Carnot cycle is at the same maximum and minimum temperatures as a Rankine cycle, then how would you compare the efficiency of a Rankine cycle to that of the Carnot cycle?
efficiency is the same
higher efficiency
efficiency is the higher, by 30%
lower efficiency
Compute the wall gain load of a load storage room when A is the outside surface area of the wall, D is the temperature differential across the wall, and U is the overall coefficient of heat transition.
AU/D
D/N
A/UD
AUD
If m is the mass of dry air and H is the specific enthalpy of the water vapor in air and r is the humidity ratio, then determine the latent heat of any dry air.
m/(r−H)
r/(H−m)
(m−r)/H
m(r×H)
When an electric motor nameplate indicates a "100-kw electric motor," then what does a 100 kW rating refers to?
thermal energy input
thermal energy output
electrical power output
mechanical power output
For a hydraulic power to be transmitted at its maximum what should be the value of loss of head due to friction if H is the total available head?
11H
31H
41H
5H
The ratio of the average load during a certain time to peak the load occurring during the same period of time is called:
demand factor
capacity factor
load factor
output factor
Based on the PSME Code, what should be the effective temperature of the air to be maintained for comfort cooling at an air movement from 0.0761 to 0.127 meter per second?
25 - 29 degrees
35 - 39 degrees C
20 - 24 degrees C
30 - 34 degrees C
Past Board Question If R is the delivery rate of a pump, H is the total pumping head and e is the efficiency of the pump, compute the power required to drive the pump.
R/H×e
1−(R+H)/e
(R×H)/e
(h−R)/e
Past Board Question There are three basic boiler types, namely:
water-tube, horizontal tube and cast-iron boilers
cast-iron, fire-tube and water tube boilers
fire-tube, cast-steel and water tube boilers
HRT, fire-tube and Marine Boilers
Past Board Question The amount of heat necessary to bring up the temperature of a unit mass of a substance through a unit degree is called:
specific volume
thermal heat
total heat
specific heat
Past Board Question What is the specific gravity of an oil which has a Baumé reading of 28 degrees F?
0.215
0.562
0.886
0.774
Past Board Question If C is the capacity of the compressor in a refrigeration system and F is the heat rejection factor, calculate the condenser load L.
L=F−C
L=F/C
L=C×F
L=C/F
Past Board Question Based on the PSME Code, what should be the humidity of air to be used for comfort cooling?
75% - 80% relative humidity
50% - 60% relative humidity
60% - 70% relative humidity
70% - 75% relative humidity
Past Board Question What is the cause of pressure drop in the boiler, condenser and the pipings between different components? Because of this drop, steam leaving the boiler is at a lower pressure.
positive slip
fluid friction
negative slip
low thermal efficiency
