In a hydroelectric power plant the tailwater elevation is at 500 m. What is the head water elevation if the net head is 30 m and the head loss is 5% of the gross head? A. 785.25 m B. 582.57 m C. 528.57 m D. 758.25 m

A twin cylinder ammonia compressor with volume displacement of 14,726 cm3 operates at 300 rpm. Condenser and evaporator pressure are 1200 kPa and 227 kPa respectively. Specific volume of refrigerant at the entrance of compressor is 528.26 L/kg. Compression process is polytropic with n = 1.20 and clearance factor of compressor is 2 percent. Determine the horsepower required. A. 60 hp B. 70 hp C. 80 hp D. 90 hp

A 35% solution leaves the absorber and 30% solution enters the absorber. The heat removed from the absorber by cooling water is 547.6 Btu and ammonia is superheated by 10°. Find the pound per pound of ammonia gas from the evaporating coils. A. 11 B. 12 C. 13 D. 14

Steam at 2 MPa and 250°C in a rigid cylinder is cooled until the quality is 30%. Find the heat rejected from the cylinder. @ 2 Mpa and 250°C: υ = 0.11144 m3/kg u = 2679.6 kJ/kg @ 2 Mpa, (saturated): υf = 0.0011767 m3/kg υg = 0.09963 m3/kg uf = 906.44kJ/kg ug = 1693.8 kJ/kg A. -423.23 kJ/kg B. -926.26 kJ/kg C. -1265.02 kJ/kg D. 1082.34 kJ/kg

Compute the specific volume of an air-vapor mixture in cubic meter per kg of dry air when the following conditions prevail: t = 40°C, w = 0.015 kg/kg, and Pt = 90 kPa. A. 0.99 m3/kg B. 0.89 m3/kg C. 0.79 m3/kg D. 0.69 m3/kg

A Carnot cycle uses nitrogen (k = 1.399) as the working substance. The heat supplied is 54 kJ and the adiabatic expansion ratio is 10. Determine the heat rejected. A. 10 kJ B. 32.4 kJ C. 21.6 kJ D. 54 kJ

A heat engine receives heat from a source at 1200 K at a rate of 500 kJ/s and rejects the wasted heat to a sink at 300 K. If the power output of the engine is 200 kW, the second law efficiency of this heat engine is? A. 35% B. 40% C. 53% D. 75%

A wall with an area of 10 m2 is made of a 2 cm thickness of white pine (k = 0.133 W/m- °C) followed by a 10 cm of brick (k = 0.649 W/m- °C). The pine is on the inside where the temperature is 30°C while the outside temperature is 10°C. Assuming equilibrium conditions exist, what is the temperature at the interface between the two metals? A. 15.65 °C B. 17.64 °C C. 18.21 °C D. 19.31 °C

A two-stage, double acting compressor is to deliver 90 lb/min of air from 14.3 psia to 90°F to a final pressure of 185 psia. The normal barometer is 29.8 in-Hg and the temperature is 80°F. The pressure drop in the intercooler is 3 psi and the speed is 210 rpm and pV1.34 = C during compression and expansion. The clearance is 5% for both cylinders. Find the volume of free air if the temperature of the cooling water increased by 18°F. A. 1282 CFM B. 1230 CFM C. 1320 CFM D. 1822 CFM

A single-stage ammonia compressor is producing 10 tons of refrigeration and the power consumed is 15 Hp. Suction pressure is 25 psi, condensing pressure is 180 psi. Brine temperature is 20°F off brine cooler. Determine the actual coefficient of performance. A. 10.14 B. 11.14 C. 12.14 D. 13.14

A single acting compressor has a volumetric efficiency of 89%, operates at 500 rpm. It takes in air at 100 kPa and 30°C and discharges it at 600 kPa. The air handled is 8 m3/min measured at discharged condition. If compression is isentropic, find the effective mean pressure in kPa. A. 233.34 B. 973.17 C. 198.34 D. 204.82

A turbine has a mechanical efficiency of 93%, volumetric efficiency of 95% and total efficiency of 82%. If the effective head is 40 m, find the total head. A. 48.72 m B. 40.72 m C. 36.22 m D. 34.72 m

A certain gas at 101.325 kPa and 10°C whose volume is 2.83 m3 capacity. Before admission, the storage vessel contained gas at a pressure and temperature of 137.8 kPa and 26°C; after admission, the pressure increased to 1171.8 kPa. What should be the final temperature of the gas in the vessel in Kelvin? A. 298.0 B. 319.8 C. 180.0 D. 314.2

A vapor compression refrigeration system is designed to have a capacity of 150 tons of refrigeration. It produces chilled water from 22°C to 2°C. Its actual coefficient of performance is 5.86 and 35% of the power supplied to the compressor is lost in the form of friction and cylinder cooling losses. Determine the condenser cooling water required for a temperature rise of 10°C. A. 14.75 kg/s B. 15.65 kg/s C. 18.65 kg/s D. 13.75 kg/s

A diesel engine consumed 945 liters of fuel per day at 35°C. If the fuel was purchased at 15.6°C and 30°API at P29.00/li. Determine the cost of fuel to operate the engine per day. A. P5,677.50 B. P4,677.50 C. P48,088.90 D. P27,127.76

To what height will a barometer column rise if the atmospheric conditions are 13.9 psia and 68°F and barometer fluid is ethyl alcohol? Note: @ 68°F; Pv =138.5 lbf/ft3 and specific gravity of 0.79 for ethyl alcohol: A. 79.37 in B. 37.79 in C. 353.54 in D. 453.53 in

A plate-type solar energy collector with an absorbing surface covered by a glass plate is to receive an incident radiation of 800 W/m2. The glass plate has a reflectivity of 0.12 and a transmissivity of 0.85. The absorbing surface has an absorptivity of 0.90. The area of the collector is 5 m2. How much solar energy in watts is absorbed by the collector? A. 2500 B. 2880 C. 3510 D. 3060

The gain of entropy during isothermal nonflow process of 5 lb of air at 60°F is 0.462 Btu/°R. Find the V1/V2. A. 3.85 B. 0.259 C. 1.0 D. 0.296

A 300 mm diameter pipe discharges water at a rate of 200 li/s. Point 1 on the pipe has a pressure of 260 kPa and 3.4 m below point 1 is point 2 with a pressure of 300 kPa. Compute the head loss between points 1 and 2. A. 4.29 m B. 2.59 m C. 6.32 m D. 1.87 m

A 50 kg block of iron casting at 500 K is thrown into a large lake that is at a temperature of 285 K. The iron block eventually reaches thermal equilibrium with the lake water. Assuming average specific heat of 0.45 kJ/kg-K for the iron, determine the entropy generated during this process. A. -12.65 kJ/K B. 16.97 kJ/K C. 4.32 kJ/K D. 6.32 kJ/K

Compute the maximum length of the discharge pipe installed on an outlet of a pressure-relief device in feet for internal pipe diameter of 0.5 inch and rated discharge capacity is 8 lb/min of air. The rated pressure of relief valve is 10 psig. A. 0.286 ft B. 0.386 ft C. 0.486 ft D. 0.586 ft

A water cooler uses 50 lb/hr of melting ice to cool running water from 80°F to 42°F. Based on the inside coil area, Ui = 110 Btu/hr-ft2- °F. Find the gpm of water cooled. A. 0.10 GPM B. 0.21 GPM C. 0.38 GPM D. 0.45 GPM

Water substance at 70 bar and 65°C enters a boiler tube of constant inside diameter of 35 mm. The water leaves the boiler tube at 50 bar and 700 K at velocity of 150 m/s. Calculate the inlet volume flow (liters/s). From steam tables: @ 70 bar (7Mpa) and 65°C: υ1 = 0.001017 m3/kg @ 50 bar (5Mpa) and 700 K (427°C): υ2 = 0.06081 m3/kg A. 0.821 B. 1.261 C. 0.344 D. 1.609

Determine the temperature for which a thermometer with degrees Fahrenheit is numerically twice the reading of the temperature in degrees Celsius. A. -24.6 B. 320 C. 160 D. -12.3

A Francis turbine is to be operated at a speed of 600 rpm and with discharge of 4 m3/s. If r1 = 0.6 m, β = 110°, and the blade height B is 10 cm, what should be the guide vane angle α1 for non-separating flow condition at the runner entrance? A. 14.4° B. 15.4° C. 16.4° D. 17.4°

An auditorium seating 1500 people is to be maintained at 80°F dry bulb and 60°F wet bulb temperature when outdoor air is at 91°F dry bulb and 75°F wet bulb. Solar heat load is 110,000 Btu/hr and supply air is at 60°F, determine the amount of supply air. A. 93,229.17 lb/hr B. 83,229.17 lb/hr C. 73,229.17 lb/hr D. 63,229.17 lb/hr

Two liters of an ideal gas at a temperature of T1 = 25°C and a pressure of P1 = 0.101 MPa, are in a 10 cm diameter cylinder with a piston at one end. The piston is depressed so that the cylinder is shortened by 10 centimeters. The temperature increases by 2°C. What is the change in pressure? A. 0.156 MPa B. 0.167 MPa C. 0.251 MPa D. 0.327 MPa

A gaseous fuel mixture has a molal analysis: H2 = 14% CH4 = 3% CO = 27% O2 = 0.6% CO2 = 4.5% N2 = 50.9% Determine the air-fuel ratio for complete combustion on molal basis. A. 2.130 B. 3.230 C. 1.233 D. 1.130

A mixing tank mixes two inlet streams containing salt. The salt concentration in stream 1 is 5% by weight, at stream 2 it is 15% by weight. Stream 1 flows at 25 kg/s, and stream 2 flows at 10 kg/s. There is only one exit stream. Find the salt concentration in the exit stream. A. 5% B. 8% C. 11% D. 13%

Which of the following is not a unit of pressure? A. Pa B. bars C. kg/m-s2 D. kg/m2

A double purpose tank 18 ft wide, 24 ft long and 4 ft depth is filled with water. What is the weight of water in the tank in long tons? A. 49 tons B. 48 tons C. 54 tons D. 50 tons

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 m3/hr with air at 60°F (15.6°F) and 14.7 psia (101.325 kPa) the coal is burned with 30% excess air. Boiler efficiency is 70% and factor of evaporation of 1.10. A. 212,861.04 m3/hr C. 218,261.04 m3/hr B. 221,861.04 m3/hr D. 281,261.04 m3/hr

Steam enters a turbine stage with an enthalpy of 3700 kJ/kg and a velocity of 80 m/s and leaves with an enthalpy of 2864 kJ/kg with a velocity of 12.8 m/s. If the rate of a steam flow through the turbine is 0.44 kg/s, what is the work done in kW? A. 365 kW B. 365.64 kW C. 366.0 kW D. 366.50 kW

An air compressor takes in 9 kg/min of air at 98 kPa; v1 = 0.125 m3/kg and discharges it at 680 kPa; v2 = 0.03 m3/kg. The increase of internal energy is 93 kJ/kg and the work done on air is 163 kJ/kg; the change in potential and kinetic energy are neglected. How much heat is transferred per kg of air? A. 264.15 kJ/kg B. 61.85 kJ/kg C. 288.65 kJ/kg D. 78.15 kJ/kg

Pressure difference of 400 Pa is available to force 20°C air through a circular sheet-metal duct 450 mm in diameter and 25 m long. At 20°C, ρ = 1.204 kg/m3 and take friction factor, f = 0.016. Determine the velocity. A. 27.34 ft/s B. 43.72ft/s C. 89.68 ft/s D. 86.98 ft/s

A 1 m x 1.5 m cylindrical tank is full of oil with SG = 0.92. Find the force acting at the bottom of the tank in dynes. A. 106.33 x 103 dynes B. 106.33 x 104 dynes C. 106.33 x 105 dynes D. 106.33 x 106 dynes

An insulated rigid tank initially contains 1.5 lb of helium at 80°F and 50 psia. A paddle wheel with power rating of 0.02 hp is operated within the tank for 30 min. Determine the final temperature. A. 159.22°F B. 169.22°F C. 179.22°F D. 189.22°F

An adiabatic tank containing air is used to power an air turbine during times of peak power demand. The tank has a volume of 500 m3 and contains air at 1000 kPa and 500 K. Determine the mass remaining when the pressure reaches 100 kPa. A. 273.37 kg B. 672.73 kg C. 772.73 kg D. 227.73 kg

A house that was heated by electric resistance heaters consumed 1200 kWh of electric energy in a winter month. If this house were heated instead by a heat pump that has an average performance factor, PF of 2.4, determine how much money the homeowner would be saved that month. Assume a price of 0.085 $/kWh for electricity. A. $42.5 B. $59.50 C. $102 D. $97.75

A turbine receives 150 lbm/s of air at 63 psia and 2450°R and expands it polytropically to 14.7 psia. The exponent n is equal to 1.45 for the process. Determine the power. A. 52,343.16 BTU/s B. 52,343.16 kW C. 53.343.16 HP D. 53,343.16 ft-lb/s

In a gas unit, air enters the combustion chamber at 550 kPa, 227°C and 43 m/s. The products of combustion leave the combustor at 511 kPa, 1004°C and 180 m/s. Liquid fuel enters with a heating value of 43,000 kJ/kg. For fuel-air ratio of 0.0229, what is the combustor efficiency in percent? A. 70.38% B. 79.38% C. 75.38% D. 82.38%

During the working stroke of an engine the heat transferred out of the system was 150 kJ/kg of working substance. The internal energy also decreased by 400 kJ/kg of working substance. Determine the work done. A. 250 kJ/kg B. 550 kJ/kg C. 600 kJ/kg D. 350 kJ/kg

Predict the pressure of nitrogen gas at T = 200 K and υ = 0.00385 L/g and b = 0.00141 L/g; a = 0.178 L2-kPa/g2. Use Van der Waals equation. A. 15,331 kPa B. 14,331 kPa C. 13,331 kPa D. 12,331 kPa

Consider 1 kg of air at 32°C that expanded by a reversible polytropic process with n = 1.25 until the pressure is halved. Determine the heat transfer. Specific heat at constant volume for air is 0.1786 kJ/kg-K. A. 17.02 kJ heat rejected C. 17.02 kJ heat added B. 7.05 kJ heat rejected D. 7.05 kJ heat added

A two-stage air compressor at 90 kPa and 20°C discharges at 700 kPa. Find the polytropic exponent n if the intercooler intake temperature is 100°C. A. 1.29 B. 1.33 C. 1.4 D. 1.25

In an open feedwater heater for a steam plant, saturated steam at 7 bar is mixed with subcooled liquid at 7 bar and 25°C. Just enough steam is supplied to ensure that the mixed steam leaving the heater will be saturated liquid at 7 bar when heater efficiency is 95%. Calculate the mass flow rate of the subcooled liquid if steam flow rate is 0.865 kg/s. Steam properties: @ 7 bar, saturated vapor: hg = 2763.5 kJ/kg @ 7 bar and 25°C: hf = 105.5 kJ/kg @ 7 bar, saturated liquid: hf = 697.22 kJ/kg A. 2.725 kg/s B. 3.356 kg/s C. 2.869 kg/s D. 3.948 kg/s

Find the thrust and efficiency of two 2-m diameter propellers through which flows a total of 600 m3/s of air to 11.3 N/m3. The propellers are attached to an airplane moving at 250 kph through still air. Neglect eddy losses. A. 36,077 N, 73% B. 77,630 N, 37% C. 66,033 N, 33% D. 77,330 N, 77%

The following coal has the following ultimate analysis by weight: C = 70.5% H2 = 4.5% O2 = 6.0% N2 = 1.0% S = 3.0% Ash = 11% Moisture = 4% A stocker fired boiler of 195,000 kg/hr steaming capacity uses this coal as fuel. Calculate volume of air in m3/hr with air at 60°F and 14.7 air pressure if the boiler efficiency is 70% and FE = 1.10. A. 234,019 m3/hr B. 215,830 m3/hr C. 213,830 m3/hr D. 264,830 m3/hr

A liquid dominated geothermal plant with a single flash separator receives water at 204°C. The separator pressure is 1.04 MPa. A direct contact condenser operates at 0.034 MPa. The turbine has a polytropic efficiency of 0.75. For cycle output of 60 MW, what is the mass flow rate of the well water in kg/s? @ 204°C: hf = 870.51 kJ/kg @ 1.04 MPa: hf = 770.38 kJ/kg hfg = 2009.2 kJ/kg hg = 2779.6 kJ/kg sg = 6.5729 kJ/kg-K @ 0.034 MPa: hf = 301.40 kJ/kg hfg = 2328.8 kJ/kg sf = 0.09793 kJ/kg-K sfg = 6.7463 kJ/kg-K A. 2,933 B. 2,100 C. 1,860 D. 2,444

Air passes thru a nozzle with efficiency of 90%. The velocity of air at the exit is 600 m/s. Find the actual velocity at the exit. A. 382 m/s B. 540 m/s C. 458 m/s D. 568 m/s

Hot gases at 280°C flow on one side of the metal plate 10 mm thickness and air at 35°C flows on the other side. The heat transfer coefficient of the gases is 31.5 W/m2-K and that of the air is 32 W/m2-K. Calculate the over-all heat transfer coefficient. A. 15.82 W/m2-K B. 16.82 W/m2-K C. 14.82 W/m2-K D. 17.82 W/m2-K

A windmill with a 12 m diameter rotor is to be installed at a location where the wind is blowing at an average velocity of 10 m/s. Using standard condition of air (1 atm, 25°C), determine the maximum power that can be generated by the windmill. A. 68 kW B. 70 kW C. 72 kW D. 74 kW

Consider 4800 lb of steam per hour flowing through a pipe at 100 psia pressure. Assume a velocity of 5280 ft/min. What size of pipe is required? Specific volume of steam at 100 psia v = 4.432 ft3/lb. A. 3 in B. 5 in C. 4 in D. 6 in

A small pump serving as model, when tested in laboratory using water at 3600 rpm, delivered 30 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 to develop the same head as model pump and the model pump has a scale ratio of 1:10. Assume the efficiency of the prototype pump is 90%. A. 50.6 hp B. 4730 hp C. 3740 hp D. 60.5 hp

A rigid tank contains 2 kmol of N2 and 6 kmol of CO2 gases at 300 K and 115 MPa. Find the tank volume using the ideal gas equation. A. 7.33 m3 B. 5.33 m3 C. 3.33 m3 D. 1.33 m3

A heat engine receives heat from a source at 1200 K at a rate of 500 kJ/s and rejects the waste heat to a medium at 300 K. The power output of the engine is 180 kW. Determine the irreversibility rate for this process. A. 190 kW B. 195 kW C. 200 kW D. 205 kW

The fuel oil has the ff. analysis: C = 89% N2 = 2% H2 = 8% S = 1% With 3% excess air, what is the actual amount of air needed to burn the fuel oil? A. 13.17 kgair/kgfuel C. 14.47 kgair/kgfuel B. 13.47 kgair/kgfuel D. 14.17 kgair/kgfuel

A 650 BHP diesel engine uses fuel oil of 28°API gravity, fuel consumption is 0.65 lb/BHP-hr. Cost of fuel is P7.95 per liter. For continuous operation determine the minimum volume of cubical day tank in cm3, ambient temperature is 45° C. A. 4,372,890 cm3 B. 5,987,909 cm3 C. 5,291,880 cm3 D. 7,352,789 cm3

A 5 cm diameter spherical ball whose surface is maintained at a temperature of 70°C is suspended in the middle of a room at 20°C. If the convection heat transfer coefficient is 15 W/m2- °C and the emissivity of the surface is 0.8, determine the total heat transfer from the ball. A. 23.56 watts B. 32.77 watts C. 9.22 watts D. 43.45 watts

A centrifugal pump (efficiency 88%) lifts water through a total height of 40 m from a reservoir to discharge. Pumping is through 300 m of 75 mm diameter pipe at the rate of 20 liter/s. If pipe friction, f = 0.025, what horsepower is required? A. 28.4 kW B. 32.2 kW C. 25kW D. 9kW

Carbon dioxide flows through a nozzle with speed of 380 m/s. The entrance condition of nozzle is 250°C and 1200 kPa. Find the stagnation pressure. A. 2,136.34 kPa B. 2,146.34 kPa C. 2,156.34 kPa D. 2,166.34 kPa

What is the pressure 7000 ft below the water surface of the ocean? Neglect compressibility. A. 512,000 psf B. 324,500 psf C. 447,000 psf D. 213,000 psf