PIPE 2 Flashcards
(23 cards)
In Refrigeration, how do you call a heat exchanger in
which low-pressure refrigerant boils or vaporizes, thus
absorbing heat that was removed from the refrigerated
area by the cooling medium (water)?
a) Evaporator
b) Chiller
c) Cooler
d) Flooded Evaporator
b) Chiller
In an ideal standard Brayton cycle, 1.5 kg/s of air at 101
kPaa and 27 oC is compressed isentropically to a certain
pressure and temperature after which the is added until
the temperature becomes 1027 oC. Isentropic expansion
occurs in the turbine. Determine the net power produced
by the cycle.
a) 629.56 kW
b) 592.65 kW
c) 529.76 kW
d) 579.26 kW
c) 529.76 kW
In an air standard Otto cycle, the clearance volume is 12
% of the displacement volume. What is the thermal
efficiency?
a) 57 %
b) 59 %
c) 58 %
d) 60 %
b) 59 %
It is a type of refrigeration system where only part of the
circulated refrigerant is evaporated, with the remainder
being separated from the vapor and then recirculated.
How do you call this system?
a) Absorption refrigeration system
b) Vacuum refrigeration system
c) Vapor-compression refrigeration system
d) Flooded refrigeration system
d) Flooded refrigeration system
In an air-standard Brayton cycle, air enters compressor
at 1 bar and 15 oC. The pressure leaving the compressor
is 0.6 MPaa and maximum temperature of the cycle is
1000 oC. What is the maximum net work, in kJ/kg?
a) 319.52
b) 392.51
c) 315.29
d) 352.19
d) 352.19
How do you call the ice formation on a refrigeration
system at the expansion device, making the device
inoperative?
a) Ice formation
b) Freeze-up
c) Freezing
d) Pump-down
b) Freeze-up
What is the clearance volumetric efficiency of an
ammonia compressor designed with 4 % clearance and
operating between condenser temperature of 30 oC (psat
= 1.1672 MPaa) and evaporator temperature of 4 oC (psat
= 497.48 kPaa)?
a) 93.61 %
b) 93.68 %
c) 96.31 %
d) 96.83 %
c) 96.31 %
In a lithium bromide solution absorption refrigeration
system, which of the following is the function of
water?
a) Refrigerant
b) Absorbent
c) Coolant
d) Analyzer
a) Refrigerant
The percent rating of water tube boiler is 200 %, factor
of evaporation is 1.10, and heating surface is 400 ft2
.
Determine the rate of evaporation, in kg/hr.
a) 1831
b) 1831
c) 1138
d) 1813
c) 1138
In the absorption refrigeration system, is a pressure
vessel mounted above the generator through which
the vapor leaving the generator pass. How do you call
this component?
a) Absorber
b) Analyzer
c) Rectifer
d) Reflux
b) Analyzer
A Carnot cycle is represented by a rectangle in a Ts
diagram that operates between temperature limits of
300 oK and 650 oK. Inscribed within a rectangle is a
ellipse of maximum major and minor axes, represents a
cycle and operating at the same temperature limits.
Considering that the major axis of the ellipse is two
times that of its minor axis. Determine the thermal
efficiency of the cycle represented by an ellipse.
a) 44.88 %
b) 48.48 %
c) 43.66 %
d) 46.36 %
a) 44.88 %
Determine the critical radius in cm for an asbestos-
cement covered pipe [kasb = 0.208 W/m-oK]. The external heat-transfer coefficient is 1.5 Btu/h-ft2 oF.
a. 2.44 cm
b. 2.55 cm
c. 2.66 cm
d. 2.22 cm
a. 2.44 cm
A hiker carried an Aneroid barometer from the foot of
Mount Banahaw to the camp of the NPA leader Ka Roger.
On the foot of the mountain, the barometer reads
30.150 inches of Hg, and on the camp, which is nearly at
the top of the mountain it reads 28.607 inches of Hg.
Assume that the average air density (atmospheric) was
0.075 psf, estimate the height of the mountain, in ft.
a) 1455.54
b) 1545.54
c) 1554.54
d) 1455.55
a) 1455.54
In the absorption refrigeration system, it is the inlet part
of the condenser, cooled by a separate circuit of
cooling water or strong aqua. It condenses a small part
of the vapor leaving the bubble column and returns it as
a liquid to the top of bafe plate. This ensures that the
vapor going to the condenser is lowered in temperature
and enriched in ammonia. What is this component?
a) Reflux
b) Analyzer
c) Rectifier
d) Absorber
c) Rectifier
In a geothermal power plant, the mass flow rate of
ground water is 4000 kg/s and the quality after throttling
is 20%. If the turbine power is 80 MW, what is the
change in enthalpy of steam at the inlet and outlet of
the turbine?
a) 120 kJ/kg
b) 100 kJ/kg
c) 200 kJ/kg
d) 150 kJ/kg
b) 100 kJ/kg
Determine the partial pressure of CO2 for the following
analysis of gas mixture by weight at 101 kPaa and 25 oC:
CO2 = 35 % and N2 = 65 %.
a) 25.75 kPaa
b) 27.55 kPaa
c) 52.75 kPaa
d) 52.57 kPaa
a) 25.75 kPaa
Which of the following is a scale of temperature in which
the melting point of ice is taken as 0deg and the boiling point of water is 80deg?
a) Reaumur Scale
b) Carrene Scale
c) Genetron Scale
d) Frigorie Scale
a) Reaumur Scale
A certain coal has the following ultimate analysis by
weight. C = 67 %, Ash = 5 %, Moisture = 8 %, N = 6 %,
H = 3 %, Sulfur = 7 %, O = 4 %. Calculate the higher
heating value in Btu/lb.
a) 15 179
b) 11 579
c) 17 519
d) 19 517
b) 11 579
What is the amount of heat energy required to raise the
temperature of one pound of water one degree
Fahrenheit. It is 1/180 of the heat required to raise the
temperature of one pound of water from 32 to 212 oF at
constant atmospheric pressure of 14,696 psi absolute.
a) Specifc heat
b) British thermal unit
c) Calorie
d) Sensible heat
b) British thermal unit
How do you call the mixtures or substances that are
used in laboratory methods of producing a drop in
temperature? The most common example is the mixture
of ice and salt.
a) Calorifc mixture
b) Water-ammonia mixture
c) Frigorifc mixture
d) Hygroscopic mixture
c) Frigorifc mixture
If an airplane is flying at an altitude of 4800 ft, what is
the approximate atmospheric pressure at the said
altitude?
a) 12.34 psi
b) 14.7 psi
c) 13.24 psi
d) 14.32 psi
a) 12.34 psi
It the maximum temperature of any gas or vapor at
which it may be condensed into a liquid; above this
temperature, it is impossible to condense regardless of
the pressure applied. How do you call this temperature?
a) Saturation temperature
b) Superheated temperature
c) Critical temperature
d) Dew point temperature
c) Critical temperature
