PRE BOARD PIPE 5

50問 • 1年前

問題一覧

An air compressor consumed 1200 kw-hr per day of energy. The electric motor driving the compressor has an efficiency of 80%. If indicated power of the compressor is 34kw. Find the mechanical efficiency of the compressor.

85%

Find the enthalpy of water 212F and 14.7 psi dryness for factor is 30% use the approximate enthalpy formula of liquid.

471 Btu/lb

Find the heat needed to raise the temperature of water from 80^C to 100^C with 60% quality. Consider an atmospheric pressure of 101.325 kpa. Use the approximate enthalpy formula of liquid.

1,647.29 kj/kg

Find the mass of carbon dioxide having a pressure of 20 psia at 200F with 10ft^3 volume.

1.24 lbs

To what height will a barometer column rise if the atmospheric conditions are 13.9 psia and 68 degF and barometric fluid is ethyl alcohol ? Note: @ 68degF; Pv=138.5 lbf/ft^2 and specific gravity of 0.79 for ethyl alcohol.

453.53 in.

To what height will a barometer column rise if the atmospheric conditions are 13.9 psia and 68 degF and barometric fluid is mercury ?

2.36 ft/s

A rectangular duct has a dimension of 0.25 m by 2m. Determine the equivalent diameter of the duct.

0.40 m

A pressure difference of 400 Pa is available to force 20 degC air through a circular sheet-metal duct 450mm. In diameter and 25m long. At 20 degC, p=1.204 kg/m^3 and take friction factor, f=0.016. Determine the velocity.

89.68 ft/s

Compute the pressure drop of 35 degC air flowing with a mean velocity of 5 m/s in a circular sheet-metal duct 100 mm in diameter and 25m long. Use a friction factor, f= 0.04 and p=1.3799 kg/m^3.

431.22 Pa

A coil has an inlet temperature of 70 degF and outlet of 80 degF, if the mean temperature of the coil is 130 degF, find the bypass factor of the coil.

0.83

Compute the specific volume of an air- vapor mixture in cubic meters per kilogram of dry air when the following conditions prevail; t = 40 degC, w = 0.015 kg/kg, and P=100 Kpa

0.99 m^3/kg

The speed of a centrifugal pump is doubled. By what factor does the pump head change?

What is the power ratio of a pump and its 1/5 scale model if the ratio of heads is 4 to 17

200

An impulse wheel at best produces 125 HP under a head of 2.0 ft. by what percent should the speed increased for a 290 ft-head?

17.5%

A double-overhung impulse-turbine installation is to develop 20,000 hp at 275 rpm under a net head 100 ft. determine the specific speed.

4.34

In order to predict the behavior of a small oil pumps, tests are to be made on a model using air. The other pump is to be driven by a 1/20 HP motor at 1800 rpm and a 1⁄4 HP motor is available to drive the air pump at 600 rpm. Using specific gravity of oil at 0.912 and density of air constant at 0.076 lb/ft^3, what size model should be built?

The model should be 10 times as large as the oil pump

A centrifugal pump (efficiency 88%) lifts water through a total height of 40 m from reservoir to discharge. Pumping is through 300 m of 75mm diameter pipe at the rate of 20 liter/sec. if pipe friction factor f= 0.025, what horsepower is required?

32.2 KW

A piston positive- displacement pump (PDP) has 6-in diameter and a 2.5-in stroke. Is crankshaft rotates at 300 rpm. Calculate its output at 94 percent volumetric efficiency.

11.53 cfm

The diameter of the discharge pipe is 8 in. and that of the intake pipe is 10 in. the pressure gage at discharge reads 32 psi, and vacuum gage at the intake reads 12 in HG, if the discharge flow rate = 4.0 ft^3/s of water and the brake power horsepower is 49, find the efficiency. The intake and the discharge are at the same elevation.

82.1 %

A model pump delivering water at 180 degF (w= 60.6 lb/ft^3; p(vapor) = 7.54 Psia) at 900 gpm and 2500 rpm begins to cavitate the inlet pressure and velocity are 13 psia and 22 fps. Find the required NPSH of a protype which is 4 times larger and runs at 1100 rpm.

63.5 ft

A A 26-hp delivers 475 gpm of gasoline (w= 42.5 lb/ft^3) at 20 deg C with 78% efficiency. what pressure rise result across the pump?

73 psi

What type of turbine delivers 25,000 bhp at 500 rpm under a net head of 5350 ft

Impulse turbine

It is proposed to build a dam in a river where the flow rate is 10 m^3/sec and a 32-m drop in elevation can be achieved for flow through a turbine. If the turbine is 82% efficient, what is the maximum power that can be achieved? Specific gravity of river water is 0.998

2570 KW

How many poles should be a 60-Hz generator have, if it is connected to a turbine operating under a design head of 3000 ft with a flow of 82 cfs? Assume turbine specific speed and efficiency 3 and 84 percent respectively.

16 pole

How many identical turbines, operating at 139.0 rpm and 91% efficiency (specific speed = 5.4), are needed to exploit a head of 1200 ft and a flow of 1660 ft^3/s

3 turbines

Radial flow pump operating at maximum efficiency at a specific speed of 2500 is deliver 260 rpm against a head of 129 ft at a rotative speed of 2100 rpm find the required number of stages (I,e impellers)

4 stages

15 in. diameter fan operates at 1600 rpm and develops a head of 6 in. of water and delivers 120 cfm. What volumetric capacity for geometrically similar fan that will develop 6 in. of water at 1300 rpm?

181.8 cfm

Centrifugal pump at best efficiency point (BEP). Assume the pump characteristics are head, h= 7m , flow rate, Q = 19 liters/sec, and rotative speed n=1170 rpm. Find the specific speed in SI units.

0.71

A pump will be installed below the reservoir water surface with a required net positive suction head (NPSH) of 50 ft. the barometric pressure is 14.3 Psia and the vapor pressure is 0.5 psia. Assume friction losses in the intake piping are 5 ft. find the maximum allowable elevation of the pump relative to the water surface intake to avoid cavitation.

23.2 ft

Pump at its best efficiency (BEP) has a capacity of 10,500 gpm while developing a head of 60 ft and a rotative speed of 1450 rpm. What is the specific speed of the pump?

6892

A small pump serving as model, when tested in laboratory using water at 3600 rpm, delivered 3.0 cfs at a head of 125 ft. if the efficiency of this model pump is 84%. Predict the horsepower input to the prototype pump if it is develop the same heads as model pump and the model pump has scale ratio of 1:10. Assume the efficiency of the prototype pump is 90%.

47.30 HP

What is the resulting pressure when one pound of air at 0.3 psig and 200 degF is heated at constant volume to 800 degF?

28.6 psia

If If the specific weight of a liquid is 58.5 lbf per cubic foot, what is the specific volume of the liquid in cm^3/g?

1.0675 cm^3/g

What is the flow rate through a pipe 4 inches in diameter carrying water at a velocity of 11 ft/sec?

430.84 gpm

Assuming that there are no heat effects and no friction effects, find the speed of a 3220-lbm body after it falls 778 ft from rest

224 ft/sec

The work required to accelerate an 800 kg car from rest to 100 km/h on a level road;

308.6Kj

Air enters a nozzle steadily at 2.21 kg/m^3 and 30 m/s . What is the mass flow rate through the nozzle if the inlet area of the nozzle is 80 cm^2?

0.53 kg/s

What is the absolute pressure exerted on the surface of a submarine cruising 300 ft below the free surface of the sea? Assume specific gravity of sea water is 1.03

148.6 Psia

A cylinder weighs 150 lbf. Its cross0sectional area is 50 square inches, when the cylinder stands vertically on one end, what pressure does the cylinder exert on the floor?

0.258 bar

The specific weight of liquid is 60 lb/ft^3 what is the equivalent to Kn/m^3

9.420

A vertical column of water will be supported to what height by standard atmospheric pressure?

34 ft

An oil storage tank contains oil with specific gravity of 0.88 and depth of 20 meters. What is the hydrostatic pressure at the bottom of the tank in kg/cm^2?

1.67

A water temperature rise of 18 degF in the water cooled condenser is equivalent in degC to ---

10 degC

The absolute pressure at the bottom of a vertical column of water is 15.5 psia. What is the height of this column?

22 in

A bicycle tire has a volume of 600 cm^3. It is inflated with carbon dioxide to pressure of 551.43 Kpa _ 20 degC how many grams of CO2 are contained in the tire? R=0.18896 kj/kg-

5.98 g

What is the resulting pressure when one pound of air at 15 psia and 200 degF is heated at constant volume heated to 800 degF?

28.6 Psia

Steam turbine is receiving 1014 lbm/hr of steam, determine the horsepower output of the turbine if the work done by steam is 251 btu/lbm

100 HP

How many cubic meter is 100 gallons of liquid

0.3785 cu.m

A 10 kg block is raised vertically 3 meters. What is the change in potential energy.

294 J

How much does 30 lbm weigh in the moon (g=5.47 ft/s^2)

5.096 lbf

machine design 2

ユーザ名非公開 · 5問 · 2年前

machine design 2