Uploaded by Lawrence Catipay

# PIPE Solving Problems 1

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```Solve the following problems correctly and systematically. Write your solutions and final answers
separately on any clean white paper, scan or take pictures of it then submit your file/s in this
activity.
1. A Carnot engine operates between 800R and 1000R. What is the thermal efficiency?
2. A 10 m3 vessel contains 5 m3 of liquid water and 5 m3 of saturated water vapor at 100kpa.
Calculate the internal energy of the system using the steam tables.
3. 3.0 lbm of air are contained at 25 psia and 100 &deg;F. Given that Rair = 53.35 ft-lbf / lbm-&deg;F, what is
the volume of the container?
4. Twenty grams of oxygen (O2) are compressed at a constant temperature of 30&deg;C to 5 % of their
original volume. What work is done on the system?
5. The pressure drop across a turbine is 30 psi. The flow rate is 60 gallons per minute. Calculate
the power output of the turbine.
6. A device produces 37.5J/cycle. There is one power stroke per cycle. Calculate the power
output if the device is run at 45 rpm.
7. Compute the percent rating of a water tube boiler if the heating surface area is 500 m2 and the
developed boiler horsepower is 750?
8. A vessel with a volume of 1 cubic meter contains liquid water and water vapor equilibrium at
600 kPa. The liquid water has a mass of 1 kg. Using the steam tables, calculate the mass of the
vapor.
9. A four-stroke, direct injection diesel engine of 4 in. bore x 4.5 in. stroke develops 45 Hp at full
load and 8 Hp when running at idling load. Engine speed is 2,200 rpm. Compute the
mechanical efficiency.
10. A cylinder and a piston arrangement contain saturated water vapor at 110 &deg;C. The vapor is
compressed in a reversible adiabatic process until the pressure is 1.6 MPa. Determine the work
done by the system per kilogram of water.
11. Ideal Oxygen is throttled at 140degF from 10 atm to 5 atm. What is the temperature change?
12. Gas is enclosed in a cylinder with a weighted piston as the top boundary. The gas is heated
and expands from a volume of 0.04 m3 at a constant pressure of 200 kPa. Calculate the work
done by the system.
13. Assume the total heat of vaporization (per gram) of water can be used to supply the energy
needed to tear 1 g of water molecules apart from each other. How much energy is needed per
molecule for this purpose?
14. An isobaric steam generating process starts with saturated liquid at 20 psia. The change in
entropy is equal to the initial entropy. What is the change in enthalpy during the process? (Hint:
Not all liquid is vaporized.)
15. Find the effective head of a reaction turbine that develops 500 BHP where flow through the
turbine is 50 cfs. Water enters at 20 fps with a 100 ft pressure head. The elevation of the
turbine above the tailwater level is 8ft.
16. A pipe of internal diameter 6 units carries water with a depth of 3 units under the influence of
gravity. Calculate the Hydraulic radius.
17. A steam generator produces saturated steam at 100 psia from saturated liquid at 14.7 psia. If
the heat source is a bath at 340F that produces 800 BTU/lbm, which of the following is true?
18. If air is at a pressure of 3200 lbf/ft2, and at a temperature of 800&deg;R, what is the specific
volume?(R = 53.3 ft-lbf/lbm-&deg;R, and air can modeled as an ideal gas)
19. What is the terminal velocity of a 2” diameter aluminum sphere falling in air? Assume that the
sphere has a coefficient of drag of 15, the density of aluminum is 5.12 slug/ft3, and the density
of air is 0.00234 slug/ft3.
20. The 5” diameter cylinder shown below rotates at 3600 revolutions per minute. Air is flowing past
the cylinder at 100 ft/sec. How much is lift on the cylinder per unit length? The density of air is
0.00234 slug/ft3.
21. A 5m3 vessel initially contains 50 kg of liquid water and saturated water vapor at total internal
energy of 27,3000 kJ. Calculate the heat required to vaporize all of the liquid.
22. Water (ρ = 62.4 lbm/ft3) is flowing through a pipe. A pitot-static gage registers 3.0 inches of
mercury. What is the velocity of the water in the pipe?
23. A pump driven by an electrical motor moves 25 gal/min of water from reservoir A to reservoir B,
lifting the water a total head of 245 feet. The efficiencies of the pump and motor are 64% and
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84% respectively. What is the size of motor required?
A copper can of negligible heat capacity contains 1 kg of water just above the freezing point. A
similar can contains 1 kg of water just below the boiling point. Two cans are brought to into
thermal contact. Find the change in entropy of the system?
The atomic weight of hydrogen is 1gram per gram-atom. What is the mass of hydrogen atom?
In a gaseous mixture of 20 deg. C the partial pressures of the components are as follows:
Hydrogen, 200 mmHg; Carbon Dioxide, 150 mmHg; Methane, 320 mmHg; Ethylene, 105
mmHg. What is the total pressure of the mixture?
Air undergoes an isentropic compression from 14.7 psia to 180.6 psia. If the initial temperature
is 68 &deg;F and the final temperature is 621.5 &deg;F, calculate the work done by the gas.
Gas is enclosed in a cylinder with a weighted piston as the top boundary. The gas is heated
and expands from a volume 0.04 m3 to 0.1 m3. The pressure varies such that PV = C, and the
initial pressure is 200 kPa. Calculate the work done by the system.
A pump produces a head of 30 feet. The volumetric flow rate is 10 gallon per minute. The fluid
pumped is oil with a specific gravity of 0.83. How much energy does the pump consume in one
hour?
A 6” pump operating at 1770 rpm discharges 1500 rpm discharges 1500 gpm of cold water
(S.G. = 1.0) against an 80 – foot head at 85% efficiency. A homologous 8” pump is operating at
1170 rpm is being considered as a replacement. What is would be the new horsepower
requirement?
An engine burns a lighter of fuel each 12 minutes. The fuel has a specific gravity of 0.8 and a
heating value of 45 MJ/kg. The engine has an efficiency of 25%. What is the brake horsepower
of the engine?
The valve between a 9 liter tank containing gas at 5 atmospheres and a 6L tank containing gas
at 10 atmospheres is opened. What is the equilibrium pressure obtained in the 2 tanks at
constant temperature? Assume ideal gas behaviour.
How many kilograms of water at 0degC can a freezer with a coefficient of performance
of 5 make into ice cube 0degC with a work input of 3.6 MJ (one kilowatt-hour)?
Helium ( R = 0.4968 BTU/lbm-&deg;R) is compressed isothermally from 14.7 psia and 68&deg;F. The
compression ratio is 4. Calculate the work done by the gas.
For an ideal gas, what is the specific molar entropy change during an isothermal process in w/c
the pressure changes from 200 kPa to 150 kPa?
The surface of household radiator has an emissivity of 0.55 and an area of 1.5 m2. At what rate
is the radiation absorbed emitted by the radiator when its temperature is 50 deg. C.?
Calculate the theoretical density of copper given that the unit cell is face-centred cubic and the
lattice parameter is 361 A. The atomic weight of copper is 63.5 g/mole.
If 1 lbm of steam at 14.7 psia, 63 % quality is heated isentropically, at what pressure will it
reach the saturated vapor state?
200g of water are heated from 5C to 100C and vaporized at a constant pressure. The heat of
vaporization of water at 100C is 539.2 cal/g. The heat capacity at constant pressure, Cp is 1.0
cal/gK. Determine the total change in entropy.
It is required to pump water at 100 gal per min from a large reservoir to the surface of another
reservoir 400 feet higher. What horsepower of the motor to drive the pump, if the efficiency of
the pump is 70%?
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