PRE BOARD PIPE 3

50問 • 1年前

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A pipe has a diameter of 4” at section AA, and a diameter of 2” at section BB. For an ideal fluid flow, the velocity is given as 1 ft/sec at section AA. What is the flow velocity at section BB?

4 ft/sec

Determine the average velocity through a circular section in which the velocity distribution is given if a v=Vmax[1-(R/Ro)^2]. The distribution is symmetric with respect to the longitudinal axis, r=0, Ro is the outer radius, Vmax is the velocity along the longitudinal axis.

Vmax/2

What is the pressure at point A in the tank if h=2 feet? (g=32.3 ft/sec2, and p=1.94 slug/ft3)

125 lbf/ft2

What is the power required to transfer 97,000 coulombs of charge through a potentials rise of 50 volts in one hour?

0.5 KW

An oxygen cylinder of volume 2.3 ft^3 has a pressure of 2200 psig and is at 50 degF. Determine the mass of oxygen in the cylinder.

28.66 Lbs

A reversible Carnot cycle requires 3 hp and extracts energy from a lake to heat a house. If the house is kept at 70 degF and requires 2000 btu per minute, what is the temperature of the lake?

36.29 degF

The journals of a shaft are 380 mm diameters, it runs at 150 rpm the coefficient of friction between journals and bearing is 0.02. if the average load on the bearing is 200 KN, find the heat generated per minute at the bearing.

501.375KJ

With three different quantities x,y, and z of the same kind of liquid of temperature 9,21 and 38 degC respectively, it is found that when x, and y are mixed together the resultant temperature is 17 degC and when y and z are mixed together the resultant temperature is 28 degC. Find the resultant temperature if x and z were mixed.

25.92 degC

A counter flow heat exchanger is designed to heat fuel oil from 45 degC to 100 degC while the heating fluid enters at 150 degC and leaves at 155 degC. Calculate the arithmetic mean temperature difference.

60 degC

A wall with an area of 10 m^2 is made of 2 cm thickness of white pine (k=0.113 W/m^2-C) followed by 10 cm of brick (k=0.649 W/m-C). the pine us in the inside where the temperature is 30 degC while the outside temperature is 10 degC. Assuming equilibrium conditions exist, what is the temperature at the interface between the two metals?

19.31 degC

How many watts will be radiated from a spherical black body 15 cm in diameter at a temperature of 800 degC?

5.34 KW

An insulated steam pipe located where the ambient temperature is 32 degC, has an inside diameter of 50 mm with 10 mm thick wall. The outside diameter of the corrugated asbestos insulation is 125 mm and the surface coefficient of still air , ho = 12 W/m^2-K. inside the pipe is steam having a temperature of 150 degC with film coefficient of hi = 6000 W/m^2-K. thermal conductivity of pipe and asbestos insulation are 45 and 0.12 W/m-K respectively. Determine the heat loss per unit length of pipe.

120 W

The surface temperature of the hot side of the furnace wall is 1200 degC. It is desired to maintain the outside of the wall at 38 degC. A 152 mm of refractory slice is used adjacent to the combustion chamber and 10 mm of steel covers the outside. What thickness of insulating bricks is necessary between refractory and steel, if the heat loss should be kept at 788 W/m^2?

220 mm

Hot gases at 280 degC flow on one side of a metal plate of 10mm thickness and air at 35 degC flows the other side. The heat transfer coefficient of the gases is 31.5 W/m^2-k and that of the air is 32 W/m^2-K. calculate the over all transfer coefficient.

15.82 W/m^2-K

A furnace wall consist of 35 cm firebrick ( k = 1.557 W/m-k) , 12 cm insulating refractory (k = 0.346) and 20 cm common brick ( k = 0.692 ) covered with 7 cm steel plate( k = 45 ) . the temperature at the inner surface of the firebrick is 1,230 degC and at the outer face of the steel plate is 60 degC. Atmosphere 27 degC. What is the value of the combined coefficient convection and radiation from the outside wall?

41.3 W/m^2-K

One insulated wall of a cold- storage compartment is 8m long by 2.5 high and consists of an outer steel plate 18 mm thick. An inner wood wall 22.5 mm thick, the steel and wood are 90 mm apart to form a cavity which is filled with cork. If the temperature drops across the extreme faces of the composite wall is 15 degC. Calculate the heat transfer per hour through the wall and the temperature drop across the thickness of the cork. take the coefficient of thermal conductivity for steel, cork and wood as 45, 0.045, and 0.18 W/m-k respectively.

508.24 KJ, 14.12 degC

A composite wall is made up of an external thickness of brickwork 110 mm thick inside which is a layer of fireglass 75 mm thick. The fireglass is faced internally by an insulating board 25 mm thick. The coefficient of thermal conductivity for the three are as follows; Brickwork Fireglass 1.5 W/m-k 0.04 W/m-k Insulating board 0.06 W/m-k The surface transfer coefficient of the inside wall is 3.1 W/m2-k while that of the outside wall is 2.5 W/m2-k. take the internal ambient temperature as 0 degC and the external temp. is 27 degC. Determine the heat loss through such wall 6 m high and 10 m lng.

330.10 W

A vertical furnace wall is made up of an inner wall of firebrick 20cm thick followed by insulating brick 15 cm thick and an outer wall of steel 1 cm thick. The surface temperature of the wall adjacent to the combustion chamber is 1200 degC while that of the outer surface of steel is 50 degC. The thermal conductivities of the wall material in W/m-k are firebrick, 10; insulating brick, 0.26; and steel,45. Neglecting the film resistances and contact resistance of joints, determine the heat loss per sq.m. of wall area.

1.93 W/m2

Steam is expanded through a nozzle of the enthalpy drop per kg of steam from the intial pressure to the final pressure is 60 kj. Neglecting friction, find the velocity of discharge and exit area of the nozzle to pass 0.20kg/s if the specific volume of the steam at exit is 1.5 m3/kg.

346.4 m/s, 866 m2

Steam with an enthalpy of 800 kCal/kg enters a nozzle with a velocity of 80m/s. Find the velocity of steam at the exit of the nozzle if its enthalpy is reduced to 750kCal/kg, assuming the nozzle is horizontal and disregarding heat losses. Take g=9.81 m/s 2 and constant J=427 kgm/kCal.

651.92 m/s

Steam enters the turbine stage with an enthalpy of 3628 Kj/kg at 70 m/s and leaves the same stage with an enthalpy of 2846 kj/kg and a velocity of 125 m/s. calculate the power if there are 5kg/s steam admitted at the turbine throttle?

4597.45KW

Steam is admitted to the cylinder of an engine in such a manner the average pressure is 120 psi. the diameter of the piston is 10 in. and the length of stroke is 12 in. what is the Hp of the engine when it is making 300 rpm?

171.4 Hp

What is the rate of evaporation of a water tube boiler if the factor of evaporation is 1.10, percent rating of 100% and the heating surface area is 250 m^2?

7,816.16 kg/hr

The heating value of fuel supplied in a boiler is 40,000 kj/kg. if the factor of evaporation is 1.10 and the actual specific evaporation is 10, what is the efficiency of the boiler?

62.70%

Two boilers are operating steadily on 91,000 kg of coal contained in a bunker. One boiler is producing 1591 kg of steam per hour at 1.2 factor of evaporation and an efficiency of 65% and another boiler produced 1364 kg of steam per hour and 1.15 factor of evaporation and an efficiency of 60%. How many hours will the coal in the bunker run the boiler if the heating value of the coal is 7,590 Kcal/kg?

230.80 hrs

A water tube boiler has a capacity of 1000 kg/hr of steam. The factor of evaporation is 1.3 boiler rating is 200%, boiler efficiency is 65% heating surface area is 0.91 m^3 per bo.Hp, and the heating value of fuel is 18,400 Kcal/kg. the total coal available in the bunker is 50,000 kg. determine the no, of hrs to consume the available fuel.

853.36 hrs

Diesel power plant consumed 1 m^3 of fuel with 30 Deg API at 27 degC in 24 hrs. calculate the fuel rate in kg/hr.

36.21

Diesel power plant consumed 1 m^3 of fuel with 30 Deg API at 27 degC in 24 hrs. calculate the fuel rate in kg/hr.

970 kg/m^3

A certain coal has the following ultimate analysis: C = 70.5% H = 4.5 % O2 = 6% N2 = 1.0 % S = 3.0 % Ash = 11 % Moisture = 4% A stoker fired boiler of 175,000 kg/hr steaming capacity uses this coal as fuel. Calculate the volume of air in m^3/hr with air at 60 degF (15.6 degF) and 14.7 psia (101.325 Kpa) the coal is burned with 30 % excess air. boiler efficiency of 70 % and factor of evaporation of 1.10.

212, 861.04 m^3/kg

A diesel electric plant supplies energy for meralco. During a 24 hr period, the plant consumed 200 gallons of fuel at 28 degC and produced 3930 KW-hr. industrial fuel used is 28 deg API and was purchased at P 5.50 per liter at 15.6 degC. What should be the cost of fuel be produced one KW-hr?

P 1.05

Fuel oil in a day tank for use of an industrial boiler is tested with hydrometer. The hydrometer reading indicate a S.G = 0.924 when the temperature of the oil in the tank is 35 degC. Calculate the higher heating value of the fuel.

48,352.13 Kj/Kg

A typical industrial fuel oil C16H32 with 20% excess air by weight. Assuming complete oxidation of the fuel, calculate the actual air-fuel ratio by weight.

17.65 kg air/ kg fuel

A 640 BHP diesel engine uses fuel oil of 28 deg API gravity, fuel consumption us 0.65 lb/BHP-hr. cost of fuel is P 7.95 per liter. For continuous operation, determine the minimum volume of cubical day tank in cm^3, ambient temperature is 45 degC.

5,291,880cm^3

A 1.5 kg of wet steam at a pressure of 5 bar dryness 0.95 is blown into 70 liters of water of 12 degC. Find the final enthalpy of the mixture.

104.80Kj/kg

2.5 liters of superheated steam at 25 bar and 400 degC is expanded in an engine to a pressure of 0.1 bar when its dryness fraction is 0.9. find the final volume of the steam.

463.74 liters

One kilogram of wet steam at a pressure of 8 bar and dryness of 0.94 is expanded until the pressure is 4 bar. If expansion follows the law PVn=C, where n = 1.12, find the dryness fraction of the steam at the lower pressure.

0.9072

A group of 50 persons attend a secret meeting in room which is 12m wide by 10m long and a ceiling height of 3m. the room is completely sealed off and insulated. Each person gives off 150 Kcal per hour of heat and occupies a volume of 0.20 m^3. The room has an initial pressure of 101.3 Kpa and temperature of 16 degC. Calculate the room temperature after 10 minutes. Use R=0.287 Kj/kg-K and Cv=0.171 Kcal/kg-K.

33.1 degC

A single acting air compressor with clearance of 6% takes in air atmospheric pressure at a temperature of 85F and discharged pressure of 85 psia. The air handled is 0.25 ft3/cycle measured at discharged pressure. If the compression is isentropic, find the air HP of the compressor if rpm is 750.

96 HP

1.030 ft3/cycle

During a steady state operation, a gearbox receives 60kW through the input shaft and delivers power through the output shaft. For the gear box as the system, the rate of energy transfer is by convection. h=0.171 kW/m2K is the heat transfer coefficient, A=1m2 is the outer surface area of the gear box, Th=300K (27C) is the temperature and the outer surface, Tf=293K (20C) is the temperature of the surroundings away from the immediate vicinity if the gear box. Determine the power delivered to the output shaft in kW if the heat transfer rate is 1.2 kW.

58.8 KW

Determine the air fuel ratio on a molar basis for the complete combustion of octane with theoretical amount of air. (No given choices)

59.5 kgair/kgfuel

An adiabatic tank containing air used to power an air during times of peak power demand. The tank has a volume of 500m3 and contains air at 1000 kPa and 500K. Determine the mass remaining when the pressure reaches 100kPa.

672.73 kg

A pump in a municipality’s water supply system receives water from the filtration beds and pumps it up to the top of the water tower. The tower’s height is 35m, inlet piping of 2m below the pump’s intake. Temperature of water at 20C, measured at the bottom of the inlet and discharge from the pump. The mass flow rate through the pump is 100kg/s, diameter of the inlet piping is 25cm and the diameter of the discharge piping is 15cm. Determine the power required by the system.

33.77 KW

A mixture of 0.4lbm of helium and 0.2 lbm of oxygen is compressed polytropically from 14.7psi and 60F to 60 psia according to n=1. Determine the Polytropic work.

139 BTU

A mixture of 0.4lbm of helium and 0.2 lbm of oxygen is compressed polytropically from 14.7psi and 60F to 60 psia according to n=1.4. Determine the final temperature.

777.2 R

A pressure cooker operates by cooking food at a higher pressure and temperature than is possible at atmospheric conditions. Steam is contained in the sealed pot, with vent hole in the middle of the cover, following the steam to escape. The pressure is regulated by covering the vent hole with a small weight, which is placed slightly by escaping steam. The pressure is regulated by covering the vent hole with a small weight, which is displaced slightly by escaping steam. Atmospheric pressure is 100kPa, the vent hole area is 7mm2 and the pressure inside should be 250kPa. What is the mass of the weight?

0.107 kg

During takeoff in a spaceship, an astronaut is subjected to acceleration equal to 5 times the pull of the earth’s std.gravity. If the astronaut is 180 lb and takeoff vertical, what force does he exert on the seat?

4810.9 N

Determine the temperature for which a thermometer with degrees F is numerically twice the reading of the temperature in degrees C.

160

Calculate the air power of a fan that delivers 1200m3/min of air through a 1m x 1.5m outlet. Static pressure is 120mm WG and density of air is 1.18.

25.64 HP

A pump delivers a 20cfm of water having a density of 62 lb/ft3. The suction and discharge gage read 5 inHg of vacuum and 30psi respectively. The discharge gage is 5 ft above the suction gage. If pump efficiency is 70%, what is the motor power?

4.31 HP

machine design 2

ユーザ名非公開 · 5問 · 2年前

machine design 2