Very Very Important PIPE

609 kJ/kg

Find the work possess for a helium gas at 20°C.

Ethane

Two kilograms of gas is confined in a m³ tank at 200 kPa and 88°C. What type of gas is in the tank?

333.42 kJ/kg

Find the enthalpy of Helium if its internal energy is 200 kJ/kg.

9.47 kg

Compute the mass of a 2 m³ propane at 280 kPa and 40°C.

200 ft³/min

Compute the air flow in ft3/min of mechanical ventilation required to exhaust an accumulation of refrigerant due to leaks of the system capable of revolving air from the machinery for a mass of 4 lbs refrigerant.

0.414 m²

Compute the free aperture cross section in m3 for the ventilation of a machinery room if the mass of refrigerant is 9 kg.

110.71 kg/hr

A 29.53” x 39.37” pressure vessel contains ammonia with f = 0.041. Compute the minimum required discharge capacity of the relief device in kg/hr.

0.286 ft

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.

30%

A thermal power plant has the heat rate of 11,363 Btu/kW-hr. Find the thermal efficiency of the plant.

0.00714 miles

What is the hydraulic gradient of a 1 mile, 17 inches inside diameter pipe when 3300 gal/min of water flow with f = 0.03?

2.55 m

Find the loss of head in the pipe entrance if speed of flow is 10 m/s.

3543.75 kg/hr

Wet material, containing 220% moisture (dry basis), is to be dried at a rate of 1.5 kg/s in a continuous dryer to give a product containing 10% (dry basis). Find the moisture removed in kg/hr.

2.258 lbs

Copra enters a dryer containing 70% moisture and leaves 7% moisture. Find the moisture removed on each pound of solid in the final product.

106.33 × 10⁶ dynes

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.

1793.96 kPag

Find the pressure at the 100 fathom depth of water in kPa.

1 furlong

Find the depth in furlong of the ocean (SG = 1.03) if the pressure at the sea bed is 2,032.56 kPa.

9.46 kg

Find the mass of 10 quartz of water.

1.24 lbs

Find the mass of carbon dioxide having a pressure of 20 psia at 200°F with 10 ft3 volume.

1647.29 kJ/kg

Find the heat needed to raise the temperature of water from 30°C to 100°C with 60% quality. Consider an atmospheric pressure of 101.325 kPa. Use the approximate enthalpy formula of liquid.

471 BTU/lb

Find the enthalpy of water at 212°F and 14.7 psi if the dryness factor is 30%. Use the approximate enthalpy formula of liquid.

85%

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 compressor is 34 kW, find the mechanical efficiency of the compressor.

49.15 TR

A refrigeration system consumed 28,800 kW-hr per month of energy. There is 20% of energy lost due to the cooling system of the compressor and the motor efficiency is 90%. If the COP of the system is 6, find the mechanical efficiency of the compressor.

14.42

A 23 ton refrigeration system has a heat rejected of 100 kW. Find the energy efficiency ratio of the system.

37.50 kW

A 200 mm x 250 mm, 8-cylinder, 4-stroke diesel engine has a brake power of 150 kW. The mechanical efficiency is 80%. If two of the cylinders were accidentally cut off, what will be the new friction power?

3.69

If the energy efficiency ratio of the refrigeration system is 12.6, what is the COP of the system?

40 kW

An air compressor has a power of 40 kW at 4% clearance. If the clearance will increase to 7%, what is the new power?

115.55°C

What is the approximate value of temperature of water having enthalpy of 208 Btu/lb?

416.33 K

Convert 750°R to K.

18.38

An Otto cycle has a compression ratio of 8. Find the pressure during compression.

11.11%

A diesel cycle has a cut off ratio of 2.5 and expansion ratio of 4. Find the clearance of the cycle.

3365.50°C

A dual cycle has an initial temperature of 30°C. The compression ratio is 6 and the heat addition at constant volume process is 600 kJ/kg. If the cut-off ratio is 2.5, find the maximum temperature of the cycle.

215.44 kPa

A 3-stage air compressor compresses air from 100 kPa to 1000 kPa. Find the intercooler pressure between the 1st and 2nd stage.

123.11 kPa

A 10-stage air compressor compresses air from 100 kPa to 800 kPa. Find the intercooler pressure between the 1st and 2nd stage.

365.88 kPa

A 3-stage air compressor compresses air from 100 kPa to 700 kPa. Find the intercooler pressure between the 2nd and 3rd stage.

111.44 kW

Carnot cycle A, B and C are connected in series so that the heat rejected from A will be the heat added to B. and heat rejected from B will be added to C. Each cycle operates between 30°C and 400°C. If heat added to A is 1000 kW, find the work output of C.

0

Air compressed adiabatically from 30°C to 100°C. If the mass of air being compressed is 5 kg, find the change of entropy.

0

Two kilogram of air in a rigid tank changes its temperature from 32°C to 150°C. Find the work done during the process.

97.41 kPa

Determine the atmospheric pressure at a location where barometric reading is 740 mm Hg and gravitational acceleration is g = 9.7 m/s2. Assume the temperature of mercury to be 10°C, at which the density is 13,570 kg/m3.

1289.00 m

The barometer of a mountain hiker reads 930 mbars at the beginning of a hiking trip and 780 mbars at the end. Neglecting the effect of altitude on local gravitational acceleration, determine the vertical distance climbed. Assume g = 9.7 m/s2.

90.74 kPa

The lower half of a 10 m high cylindrical container is filled with water and the upper half with oil that has SG = 0.85. Determine the pressure difference between the top and bottom if the cylinder.

0.0122 moles

An ideal gas at 0.80 atmospheres and 87°C occupies 0.450 liter. How many moles are in the sample? (R = 0.0821 liter-atm/mole-K).

314.2 K

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?

97°F

A perfect gas has a value of R = 58.8 ft-lb/lb-°R and k = 1.26. If 20 Btu are added to 10 lbs of this gas at constant volume when initial temperature is 90°F, find the final temperature.

667 kJ

Ammonia weighing 22 kg is confirmed inside a cylinder equipped with a piston has an initial pressure of 413 kPa at 38°C. If 3200 kJ of heat is added to the ammonia until its final pressure and temperature is 413 kPa and 100°C, respectively. What is the amount of work done by the fluid in kJ?

-6232.09 BTU

A tank contains 90 ft3 of air at a pressure of 350 psig; if the air is cooled until its pressure and temperature decreases at 200 psig and 70°F respectively, what is the decrease in internal energy?

78.57%

A large mining company was provided with a 3 m3 of compressed air tank. Air pressure in the tank drops from 700 kPa to 150 kPa while the temperature remains constant at 28°C. What percentage has the mass of air in the tank been reduced?

34.59 liters

A 4 m3/hr pump delivers water to a pressure tank. At the start, the gage read 138 kPa until it reads 276 kPa and then the pump was shut off. The volume of the tank is 180 liters. At 276 kPa, the water occupied 2/3 of the tank volume. Determine the volume of the water that can be taken out until the gage reads 138 kPa.

37,500 lb/hr

A refrigeration plant is rated at 15 tons capacity. How many pounds of air per hour will it cool from 70°F to 90°F at constant temperature?

1582 kJ/kg

An air standard engine has a compression ratio of 18 and a cut-off ratio of 4. If the intake air pressure and temperature are 100 kPa and 27°C, find the work in kJ per kg.

62.11%

Determine the air-standard efficiency of an engine operating on the diesel cycle with a clearance of 6% when the suction pressure is 99.7 kPa and the fuel is injected for 7% of the stroke. Assume k = 1.4.

-1265.02 kJ/kg

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):

u_f = 0.0011767 m³/kg

u_f = 906.44 kJ/kg

u_g = 0.09963 m³/kg

u_g = 1693.8 kJ/kg

1162.40 kJ/kg

At 1.3 MPa, a mixture of steam and water has an entropy of 3 kJ/kg-K, Find the enthalpy of the mixture.

@ 1.3 MPa:

sf = 2.2515 kJ/kg-K

hf = 814.93 kJ/kg

sg = 6.4952 kJ/kg-K

hfg = 1972.7 kJ/kg

745.92 kJ

A mixture with 70% quality at 500 kPa is heated isothermally until its pressure is 300 kPa. Find the heat added during the process.

@ 600 kPa: sf = 1.8607 kJ/kg-K sfg = 4.9606 kJ/kg-K

@ 300 kPa and 151.86°C: s = 7.0888 kJ/kg-K

785.92 kJ/kg

A tank contains exactly one kilogram of water consisting of liquid and vapor in equilibrium at 1 MPa. If the liquid contains one-third and the remaining is vapor of the volume of the tank, what is the enthalpy of the contents of the tank?

@ 1MPa:

υf = 0.0011273 m3/kg υfg = 0.19444 m3/kg

hf = 762.81 kJ/kg hfg = 2015.3 kJ/kg

2.51 m/s

Water substance at 70 bar and 65°C enters a boiler tube of constant inside diameter of 25 mm. The water leaves the boiler tube at 50 bar and 700 K at velocity of 150 m/s. Calculate the inlet velocity (m/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

1.609 L/s

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

3.08%

Steam leaves an industrial boiler at 827.4 kPa and 171.6°C. A portion of the steam is passed through a throttling calorimeter and is exhausted to the atmosphere when the calorimeter pressure is 101.4 kPa. How much moisture is leaving the boiler container if the temperature of the steam at the calorimeter is 115.6°C?

@ 827.4 kPa and 171.6°C: hf = 727.25 kJ/kg hfg = 2043.2 kJ/kg

@ 101.4 kPa and 115.6°C: h2 = 2707.6 kJ/kg

6.2 kJ/kg-K

A throttling calorimeter is connected to a desuperheated steam line supplying steam to the auxiliary feed pump on a ship. The line pressure measures 2.5 MPa. The calorimeter pressure is 110 kPa at 150°C. Determine the entropy of the steam line.

@ 110 kPa and 150°C: h2 = 2775.6 kJ/kg

@ 2.5 MPa: hf = 962.11 kJ/kg hfg = 1841 kJ/kg

sf = 2.5547 kJ/kg-K sfg = 3.7028 kJ/kg-K

449.42°F

Atmospheric pressure boils at 212°F. At the vacuum pressure at 24 in Hg, the temperature is 142°F. Find the boiling temperature when the pressure is increased by 40 psia from atmospheric.

3.5%

A certain coal has the following ultimate analysis:

C = 69% N2 = 5% H = 2.5% S =7%

Determine the amount of oxygen if the heating value of fuel is 26,961.45 kJ/kg.

P27,127.76

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.

17.53 days

A cylindrical tank 4 m long and 3 m diameter is used for oil storage. How many days can the tank supply the engine having 27°API with fuel consumption of 60 kg/hr?

28.00%

A logging firm in Isabella operates a Diesel Electric Plant to supply its electric energy requirements. During a 2 hour period, the plant consumed 250 gallons of fuel at 80°F and produced 2900 kW-hrs. Industrial fuel is used at 30°API and was purchased at P30/li at 60°F. Determine the overall thermal efficiency of the plant.

1.055

The dry exhaust gas from the oil engine has the following gravimetric analysis:

CO2 = 21.6% O2 = 4.2% N = 74.2%

Specific heats at constant pressure for each component of the exhaust gas in kCal/kg-°C are:

CO2 = 0.203 O2 = 0.219 N = 0.248

Calculate the specific gravity if the molecular weight of air is 28.97 kg/kg-mol.

7.526 lb/lb_coal

A bituminous coal has the following composition:

C = 71.5% H = 5.0% O = 7.0% N = 1.3% S = 3% Ash = 7.6%

W = 3.4%

Determine the theoretical weight of Nitrogen in lb/lb of coal.

1.233 mol_air/mol_fuel

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.

17.55%

A volumetric analysis of a gas mixture is a follows:

CO2: 12% O2: 4% N2: 80% CO: 4%

What percentage of CO2 on a mass basis?

234,019 m³/hr

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.

80.67%

23.5 kg of steam per second at 5 MPa and 400°C is produced by a steam generator. The feedwater enters the economizer at 145°C and leaves at 205°C. The steam leaves the boiler drum with a quality of 98%. The unit consumes 3 kg of coal per second as received having value of 25,102 kJ/kg. What would be the overall efficiency of the unit in percent?

Steam properties:

@ 5 MPa and 400°C: h = 3195.7 kJ/kg

@ 5 MPa: hf = 1154.23 kJ/kg hfg = 1640.1 kJ/kg

@ 205°C: hf = 875.04 kJ/kg

@ At 145°C: hf = 610.63 kJ/kg

25.55%

In a Rankine cycle steam enters the turbine at 2.5 MPa (enthalpies & entropies given) and condenser of 50 kPa (properties given), what is the thermal efficiency of the cycle?

@ 2.5 MPa: hg = 2803.1 kJ/kg sg = 6.2575 kJ/kg-K

@ 50 kPa: sf = 1.0910 kJ/kg-K sfg = 6.5029 kJ/kg-K

hf = 340.49 kJ/kg hfg = 2305.4 kJ/kg

υf = 0.00103 m3/kg

300 kW

A thermal power plant generates 5 MW and the heat generated by fuel is 13,000 kJ/s. If the thermal efficiency is 36.15%, find the power needed for the auxiliaries.

25.32 kJ/kg

A superheat steam Rankine cycle has turbine inlet conditions of 17.5 MPa and 530°C expands in a turbine to 0.007 MPa. The turbine and pump polytropic efficiencies are 0.85 and 0.75 respectively. Pressure losses between the pump and turbine inlet are 1.5 MPa. What should be the pump work in kJ/kg?

2.869 kg/s

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%.

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

567 kg/s

A steam condenser receives 10 kg/s of steam with an enthalpy of 2770 kJ/kg. Steam condenses and leaves with an enthalpy of 160 kJ/kg. Cooling water passes through the condenser with temperature increases from 13°C to 24°C. Calculate the water flow rate in kg/s.

79.46%

Steam expands adiabatically in a turbine from 2000 kPa, 400°C to 400 kPa, 250°C. What is the effectiveness of the process in percent assuming an atmospheric pressure of 18°C? Neglect changes in kinetic and potential energy.

Steam properties:

@ 2000 kPa and 400°C: h = 3247.6 kJ/kg s = 7.1271kJ/kg-K

@ 400 kPa and 250°C: h = 2964.2 kJ/kg s = 7.3789 kJ/kg-K

44.86°C

A heat exchanger was installed purposely to cool 0.50 kg of gas per second. Molecular weight is 32 and k = 1.32. The gas is cooled from 150°C to 80°C. Water is available at the rate of 0.30 kg/s and at a temperature of 15°C. Calculate the exit temperature of the water in °C.

15.25%

A 350 mm x 450 mm steam engine running at 280 rpm has a clearance steam condition of 2 MPa and 230°C and exits at 0.1 MPa. The steam consumption is 2000 kg/hr and mechanical efficiency is 85%. If indicated mean effective pressure is 600 kPa, determine brake thermal efficiency.

@ 2 MPa and 230°C: h1 = 2849.6 kJ/kg s1 = 6.4423 kJ/kg-K

@ 0.1 MPa: sf = 1.3026 kJ/kg-K hf = 417.46kJ/kg sfg = 6.0568 kJ/kg-K

hfg = 2258 kJ/kg hf2 = 417.46 kJ/kg

1373.60 kW

A steam turbine receives 5,000 kg/hr of steam at 5 MPa and 400°C and velocity of 30 m/s. It leaves the turbine at 0.006 MPa and 85% quality and velocity of 15 m/s. Radiation loss is 10,000 kJ/hr. Find the kW developed.

@5 MPa and 400°C: h1 = 3195.7 kJ/kg s1 = 6.6459 kJ/kg-K

@ 0.006 Mpa: hf = 151.53 kJ/kg hfg = 2415.9 kJ/kg

1,054.95 kJ/kg

A steam turbine with 85% stage efficiency receives steam at 7 MPa and 550°C and exhausts at 20 kPa. Determine the turbine work.

@ 7 MPa and 550°C: h1 = 3530.9 kJ/kg s1 = 6.9486 kJ/kg-K

@ 20 kPa (0.020 MPa): sf = 0.8320 kJ/kg-K hf = 251.40 kJ/kg

sfg = 7.0766 kJ/kg-K hfg = 2358.3 kJ/kg

96.96%

A steam turbine with 80% stage efficiency receives steam at 7 MPa and 550°C and exhausts at 20 kPa. Determine the quality at exhaust.

@ 7 MPa and 550°C: h1 = 3530.9 kJ/kg s1 = 6.9486 kJ/kg-K

@ 20 kPa (0.020 MPa): sf = 0.8320 kJ/kg-K hf = 251.40 kJ/kg

sfg = 7.0766 kJ/kg-K hfg = 2358.3 kJ/kg

2 wells

An 18,000 kW geothermal plant has a generator efficiency of 90% and 80% respectively. If the quality after throttling is 20% and each well discharges 400,000 kg/hr, determine the number of wells required to produce if the change of enthalpy at entrance and exit of turbine is 500 kJ/kg.

2,933 kg/s

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

25,714 kW

An engine-generator rated 9000 kVA at 80% power factor, 3 phase, 4160 V has an efficiency of 90%. If the overall plant efficiency is 28%, what is the heat generated by the fuel?

45%

The indicated thermal efficiency of a two stroke diesel engine is 60%. If friction power is 15% of heat generated, determine the brake thermal efficiency of the engine.

14.64%

A 305 mm x 457 mm four stroke single acting diesel engine is rated at 150 kW at 260 rpm. Fuel consumption at rated load is 0.56 kg/kW-hr with a heating value of 43,912 kJ/kg. Calculate the break thermal efficiency.

1.81 kg/s

A waste heat recovery boiler produces 4.8 MPa (dry saturated) steam from 104°C feedwater. The boiler receives energy from 7 kg/s of 954°C dry air. After passing through a waste heat boiler, the temperature of the air has been reduced to 343°C. How much steam in kg is produced per second? Note: @ 4.80 MPa dry saturated, h = 2796 kJ/kg.

P6.87/kW-hr

A diesel electric power plant supplies energy for Meralco. During a 24-hour period, the plant consumed 240 gallons of fuel at 28°C and produced 3930 kW-hr. Industrial fuel used is 28°API and was purchased at P30 per liter at 15.6°C. What is the cost of fuel to produce one kW-hr?

75.38%

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?

835.57 kW

The specific speed of turbine is 85 rpm and running at 450 rpm. If the head is 20 m and generator efficiency is 90%, what is the maximum power delivered by the generator?

3.0 m

In Francis turbine, the pressure gage leading to the turbine casing reads 380 kPa. The velocity of water entering the turbine is 8 m/s. If net head of the turbine is 45 m, find the distance from the center of the spiral casing to the tailrace.

36.22 m

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.

1,355.73 mm

A Pelton type turbine has 25 m head friction loss of 4.5 m. The coefficient of friction head loss (Morse) is 0.00093 and penstock length of 80 m. What is the penstock diameter?

80,080 kW-hrs

In a 9,000 kW hydro-electric plant, the overall efficiency is 88% and the actual power received by the costumer is 110,000 kW-hrs for that day. What is the secondary power that this plant could deliver during the entire day?

34,452 kW

A Pelton type turbine was installed 30 m below the head gate of the penstock. The head loss due to friction is 12 percent of the given elevation. The length of the penstock is 100 m and the coefficient of friction is 0.00093. Determine the power output in kW. (Use Morse equation).

0.0307

Water flows steadily with a velocity of 3.05 m/s in a horizontal pipe having a diameter of 25.24 cm. At one section of the pipe, the temperature and pressure of the water are 21°C and 689.3 kPa respectively. At a distance of 304.8 m downstream, the pressure is 516.9 kPa. What is the friction factor?

2.20 m

A hydro-electric plant having 30 sq. km reservoir area and 100 m head is used to generate power. The energy utilized by the consumers whose load is connected to the power plant during a five-hour period is 13.5x106 kWh. The overall generation efficiency is 75%. Find the fall in the height of water in the reservoir after the 5-hour period.

0.25 kPa

The gas density of chimney is 0.75 kg /m3 and air density of 1.15 kg /m3. Find the driving pressure if the height of the chimney is 63.71 m.

98 kPa

The actual velocity of gas entering in a chimney is 8 m/s. The gas temperature is 25°C with a gas constant of 0.287 kJ/kg-K. Determine the gas pressure for a mass of a gas is 50,000 kg/hr and chimney diameter of 1.39 m.

651.10 m

A steam generator with economizer and air heater has an overall draft loss of 25.78 cm of water. If the stack gases are at 177°C and if the atmosphere is at 101.3 kPa and 26°C, what theoretical height of stack in meters is needed when no draft fan is used? Assume that the gas constant for the flue gases is the same as that for air.

598 sacks

A foundation measures 12 ft x 14 ft x 16 ft. Find the number of sacks of cement needed for a 1:2:4 mixture.