.
Industrial Plant Engineering
REMEDIAL EXAMINATION Department of Mechanical and Manufacturing Engineering, University of S an Carlos Name:_________________
Score:______________
Schedule:______________
Date:_______________
I.
Multiple Choice (100 items)
Instructions: Encircle the l etter of the best answer directly on the questionnaire. Erasure and unnecessary markings means wrong. No pencil allowed. Use blue or black pen. No borrowing of anything. Anybody caught caught using cellular phone for whatever whatever reason needs to retake the test.
9. 1.
A chimney constructed of metal with a minimum thickness of n ot less than one hundred and twenty-seven one hundredths (0.127) inch. a. Factory built chimney c. Masonry Chimney b. Metal Chimney d. Wood Chimney Answer: Metal Metal Chimney Chimney Reference-PME Code Code 2012 page page 18
2.
An automatic closing metal assembly consisting of one or more louvers, blades, slats or vanes that closes upon detection of heat so as to restrict the passage of flame. a. Fire Damper c. Smoke Damper b. Water Damper d. Volume Damper Answer: Fire Damper Reference-PME Code 2012 page 19
3.
4.
5.
A vented appliance category that operates with a positive vent static pressure with a vent gas temperature that avoids excessive condensate production in vent. a. Category I c. Category II b. Category III d. Category IV Answer: Category Category III Reference-PME Code 2012 page 26 What is the minimum condensate pipe diameter in mm for an equipment capacity of 91-125 Tons of Refrigeration (320.03-439.6) kW a. 20 mm c. 32 mm b. 25 mm d. 40 mm Answer: 40 mm Reference-PME Code 2012 page 32 What is the minimum exhaust rate for a Barber shop per square meter? a. 2.5 L/s c. 3.5 L/s b. 4.5 L/s d. 7.5 Ls Answer: 2.5 L/s Reference-PME Code 2012 page 65
6.
What is the maximum spacing of supports for ducts 8 inches (203mm) in diameter? a. 8 feet c. 10 feet b. 12 feet d. 15 feet Answer: 12 feet Reference-PME Code 2012 page 77
7.
What is the minimum conveying velocity for vapors, gases, smoke and fumes? a. 2000 fpm c. 2500 fpm b. 3000 fpm d. Any Answer: Any Reference-PME Code 2012 page 101
8.
Duct systems used with blower type equipment that are portions of a heating, cooling, absorption, evaporative cooling, or outdoor air ventilation system shall be sized in accordance with the following except : a. ASHRAE c. ACCA b. SMACNA d. ASME Answer: ASME ASME Reference-PME Code 2012 page 115
A flammable and toxic gas which is colorless and has an odor resembling rotten eggs. Continued exposure will paralyze the olfactory nerves. a. Natural Gas c. Hydrogen Sulfide b. Carbon Monoxide d. Carbon Dioxide Answer: Hydrogen Sulfide Reference-PME Code 2012 page 726
10. A possible source of ignition and its accumulation is generally greatest in an atmosphere of low humidity. a. Static Electricity c. Dynamic Electricity b. Stray Currents d. None of the Above Answer: Static Electricity Reference-PME Code 2012 page 723 11. Air temperature for Gypsum products which are exposed in ducts or plenums shall be restricted to a range of a. 40°F to 60°F c. 20°F to 90°F b. 50°F to 125°F d. 60°F to 125°F Answer: 50°F to 125°F Reference-PME Code 2012 page 115 12. A Steam boiler operated at a pressure exceeding 15 psi. a. Power Boiler c. Low pressure Boiler b. Miniature Boiler d. High pressure Boiler Answer: Power Power Boiler Reference-PME Code 2012 page 497 13. The term in plumbing for unwanted flow of water in the reverse direction and poses a serious health risk for the contamination of potable water supplies with foul water. a. Reverse flow c. Back flow b. Converse flow d. Rear flow Answer: Back Back flow Reference-PME Code 2012 page 400 14. An inspection of all visible external surfaces and appurtenance of an installed boiler or fired pressure vessel. Where practicable this inspection shall be made with the boiler in operation to permit the inspector inspector to witness the the operation of the controls. a. Field inspection c. External inspection b. Internal inspection d. Plant inspection Answer: External inspection Reference-PME Code 2012 page 495 15. An elevator classification having a source of mechanical power, such as shafting, in common with other machinery. a. Electric elevator c. Carriage type elevator b. Gravity elevator d. Auxiliary power elevator Answer: Auxiliary Auxiliary power elevator elevator Reference-PME Code 2012 page 543 16. A system providing 2 ½ inch (64mm) hose connections to supply water for use by fire departments and those trained in handling heavy fire streams. a. Class I system c. Class II system b. Class III system d. Class IV system Answer: Class Class I Reference-PME Code 2012 page 380
17. A membrane, either vertical or horizontal, such as a wall, floor, or ceiling assembly that is designed and constructed to restrict the movement of smoke. a. Smoke Guard c. Smoke detector b. Smoke Barrier d. Smoke shield Answer: Smoke Smoke Barrier Barrier Reference-PME Code 2012 page 173 18. R-13B1 is known as? a. Chlorodifluoromethane c. Bromotrifluoromethane b. Chlorotrifluoromethane d. Trichlorofluoromethane Answer: Bromotrifluoromethane Reference-PME Code 2012 page 213 19. The time period that the penetration firestop system limits the spread of fire through the penetration, when tested in accordance with ASTM E 814. a. T Rating c. F Rating b. U Rating d. Z Rating Answer: F Rating Reference-PME Code 2012 page 179 20. What is the factor of safety for chains o perated at 350 fpm? a. 9.6 c. 5.2 b. 4.5 d. 8.8 Answer: 8.8 Reference-PME Code 2012 page 640 21. A type of brazing that uses acetylene, propane, or other fuel gas, burned with oxygen or air. a. Furnace Brazing c. Torch Brazing b. Induction Brazing d. Dip Brazing Answer: Torch Brazing Reference-Mark’s Reference-Mark’s handbook 11th ed. page 13-34 22. The difference between suction pressure and vapor pressure, at the pump suction nozzle, when the pump is run ning. a. NPSH c. NIP b. NPIP d. All of the Above Answer: All of the Above Reference-Mark’s Reference-Mark’s handbook 11th ed. Page 14-2 23. A device which reduces the pressure pulsation created, in a suction or discharge pipe, by the interaction of a pump and a system. a. Return Spring c. Relief Valve b. Pulsation dampener d. Plunger Answer: Pulsation dampener Reference Reference-Mark’s Reference-Mark’s handbook 11th ed. Page 14-14 24. A fan classification wherein the air passes through the blading twice, entering more or less tangentially through the tip, passing across the impeller impeller and out the other other side. a. Mixed-Flow impeller c. Cross-Flow impeller b. Radial Flow impeller d. Axial-Flow impeller Answer: Cross-Flow impeller Reference Reference-Mark’s Reference- Mark’s handbook 11th ed. Page 14-47 25. The ratio of the fan total pressure that would be developed with an incompressible fluid to the fan total pressure that is developed with a compressible fluid. a. Fan Static Efficiency c. Pressure Efficiency b. Fan Total Efficiency d. Compressibility Factor Answer: Compressibility Factor Reference-Mark’s Reference- Mark’s handbook th 11 ed. Page 14-48 26. Which of the following carries the maximum heat loss in a boiler? a. Dry Flue gases c. Moisture present in Fuel b. Unburnt Carbon d. Radiation
Answer: Dry Flue Gases Engineering page 351
Reference-A textbook of Thermal
27. Fires in cooking oils and greases such as animal fats and vegetables a. Class A c. Class H b. Class K d. Class D Answer: Class Class K Reference-PME Code 2012 page 392 28. A wall or partition designed to inhibit or prevent the spread of fire. a. Fire Barrier c. Water Wall b. Fire Guard d. Fire Shield Answer: Fire Fire Barrier Barrier Reference-PME Code 2012 page 397 29. What is the maximum temperature of the air to be conveyed in ducts? a. 100°C c. 130°C b. 122°C d. 140°C Answer: 122°C Reference-PME Code 2012 page 117 30. Electrically charges the ash particles in the products of combustion to collect and remove them. a. Electrostatic Precipitator c. Fabric Filter b. Collecting electrode d. Discharge electrode Answer: Electrostatic Precipitator Reference- Mark’s handbook 11th ed. Page 9-50 31. Occurs in tall buildings when the outdoor temperature is lower than the temperature of the spaces inside. a. Reverse Stack Effect c. Cross-ventilation effect b. Density effect d. Stack Effect Answer: Stack effect Reference- Mark’s handbook 11th ed. Page 4.1 32. What is the typical range of air temperature for a hotel natatorium? a. 28-29 °C c. 24-29 °C b. 27-29 °C d. 29-32 °C Answer: 28-29°C Reference-2011 ASHRAE handbook – handbook – HVAC HVAC Applications (SI) Page 5.6 33. The acceptable method of scavenging the combustion chamber, boiler passes, and breeching to remove all combustible gases. a. Preheating c. Recycling b. Purging d. Cleansing Answer: Purging Reference-PME Code 2012 page 192 34. A boiler in which water is heated for the purpose of supplying heat at pressures not exceeding 160 psi(1,102 kPa) and temperatures not 250°F (121°C). a. High Temperature Boiler c. Low Pressure Hot water heating boiler b. Power Boiler d. Miniature Boiler Answer: Low Pressure Hot water heating boiler Reference-PME Code 2012 page 192 35. A boiler operated at pressures not exceeding 15 psi (103 kPa) for steam a. Power Boiler c. Steam Heating boiler b. Miniature Boiler d. High Temp. Water Boiler Answer: Steam heating boiler Reference-PME Code 2012 page 192
36. What is the Fire protection system maintenance standard for portable fire extinguisher? extinguisher? a. NFPA 12 c. NFPA 17A b. NFPA 17 d. NFPA 10 Answer: NFPA 10 Reference-PME Code 2012 page 377
46. A reliable conductor to ensure the required electrical electrical conductivity between metal metal parts required to be electrically electrically connected. connected. a. Grounding electrode c. Static conductor b. Electrical connector d. Bonding Jumper Answer: Bonding Bonding Jumper Reference-PME Code 2012 page 18
37. An alarm caused by mechanical failure, malfunction, improper installation, or lack of proper maintenance, or an alarm activated by a cause that cannot be determined. a. Smoke alarm c. Nuisance alarm b. Fire alarm d. False alarm Answer: Nuisance alarm Reference-PME Code 2012 page 380
47. The following should appear in the nameplate of any fuel burn ing heating equipment except? a. Manufacturer’s Manufacturer’s name c. Model and serial number b. Approved fuel input rating d. Date of manufacture Answer: Date Date of manufacture manufacture Reference-PME Code 2012 page 31
38. A pipe failure mode which exhibits material deformation in the area of the break. a. Ductile failure c. Stress rupture b. Brittle failure d. Creep Answer: Ductile Ductile Failure Reference-PME Code 2012 page 447
48. What is the minimum number of hoisting rope for traction elevators? a. 1 c. 2 b. 3 d. 4 Answer: 3 Reference-PME Code 2012 page 50
39. A substance which when taken in small quantities or low concentrations by mouth, inhaled, or absorbed through the skin rapidly jeopardizes life by other than mechanical or physical action. a. Psycho-active drugs c. Hazard b. Downer substance d. Poison Answer: Poison Reference-PME Code 2012 page 448
49. What is the minimum number of hoisting rope for drum type elevators? a. 1 c. 2 b. 2 d. 4 Answer: 2 Reference-PME Code 2012 page 50
40. A smooth metal panel extending below the car sill which eliminates the opening below the platform when the elevator is above the landing and in the leveling zone. a. Plunger c. Platform Guard b. Freight Platform hoist d. Hatchway Answer: Platform Platform Guard Reference-PME Code 2012 page 552
41. Are brown to black in color and have a bed moisture content of 30 to 45 percent with a resulting lower heating value than higher rank coals. a. Lignites c. Bituminous b. Subbituminuous d. Anthracite Answer: Lignites Reference-Mark’s Reference-Mark’s handbook 11th ed. page 7-5 42. The part of the system designed to liquefy refrigerant vapor by the removal of heat. a. Evaporator c. Condenser b. Compressor d. Expansion valve Answer: Condenser Condenser Reference-PME Code 2012 page 19 43. The total amount of air provided to the space that contains fuel burning equipment. Includes air for fuel combustion, draft hood dilution, and ventilation of the equipment enclosure. a. Combustion air c. Natural draft b. Forced draft d. Excess air Answer: Combustion Combustion air Reference-PME Code 2012 page 19 44. An area in building accessible by crawling, having a clearance less than human height, for access to plumbing or wiring, storage, etc. a. Small space c. Clearance b. Crawl space d. Confined space Answer: Crawl Crawl space Reference-PME Code 2012 page 19 45. A metal connector for medium and high heat appliances. a. Piping c. Heating line b. Breeching d. Hot line Answer: Breeching Breeching Reference-PME Code 2012 page 18
50. In apartments or residential condominiums of five (5) storeys or more, how many passenger elevator shall be kept on twentyfour hour constant service? a. 1 c. 2 b. 3 d. 4 Answer: 1 Reference-PME Code 2012 page 50 51. What is the maximum angle of inclination from the horizontal of an escalator? a. 25° c. 35° b. 30° d. 40° Answer: 30° Reference-PME Code 2012 page 51 52. What is the maximum allowable rated speed of an escalator measured along the angle of inclination? a. 25 m/min c. 32 m/min b. 38 m/min d. 45 m/min Answer: 38 m/min Reference-PME Code 2012 page 51 53. No part of the the boiler shall shall be closer closer than ___ meter meter from any wall and shall have at least ___ separate exits. a. 1, 2 c. 2, 3 b. 2, 1 d. 3, 2 Answer: 1, 2 Reference-PME Code 2012 page 51 54. In case the main building is n ot made up of fire resistive materials, boilers shall be located outside the building at a distance of not less than ___ meters from the outside wall of the main building. a. 1 c. 3 b. 2 d. 4 Answer: 3 Reference-PME Code 2012 page 51 55. A smokestack, whether self-supporting or guyed, shall b e able to withstand a wind load of ___ kilometers per hour. a. 150 c. 200 b. 175 d. 250 Answer: 3.5 L/s Reference-PME Code 2012 page 51
56. At what height shall a smokestack rise above the eaves of any building within a radius of 50.00 meters? a. 5 m c. 8 m b. 10 m d. 15 m Answer: 5 m Reference-PME Code 2012 page 51 57. How many feeding water shall be provided for boilers of more than 46.00 sq. meters of heating surface? a. 1 c. 3 b. 2 d. 4 Answer: 2 Reference-PME Code 2012 page 51 58. What is the effective temperature range of air to be used for comfortable cooling? a. 10-15° C c. 20-24° C b. 16-20° C d. 25-30° C Answer: 20-24° C Reference-PME Code 2012 page 53 59. What is the required range of air movement within a living zone? a. 1.5-2.5 m/min c. 3.7-4.5 m/min b. 2.6-3.6 m/min d. 4.6-7.6 m/min Answer: 4.6-7.6 m/min Reference-PME Code 2012 page 53 60. What is effective relative humidity of air to be used for comfortable cooling? a. 20-30 % c. 40-50 % b. 30-40 % d. 50-60 % Answer: 50-60 % Reference-PME Code 2012 page 53 61. What is the minimum ventilation rate per person in a lecture classroom? a. 2.5 cfm c. 3.5 cfm b. 4.5 cfm d. 7.5 cfm Answer: 7.5 cfm Reference-PME Code 2012 page 62 62. A relative value in minutes or hours assigned to materials or assemblies that have withstood a fire exposure. a. Fire resistance rating c. Fire endurance rating b. Fire tolerance rating d. Fire limit rating Answer: Fire resistance rating Reference-PME Code 2012 page 72 63. An object placed in or near an appliance to change the direction or retard the flow of air, air fuel mixtures or flue gases. a. Damper c. Baffle plate b. Breeching d. Appurtenance Answer: Baffle plate Reference-PME Code 2012 page 71 64. A substance capable of dissolving or dispersing another substance; a chemical compound designed and used to convert solidified grease into a liquid o r semi-liquid state in order to facilitate a cleaning operation. a. Solute c. Base b. Solvent d. Acid Answer: Solvent Reference-PME Code 2012 page 74
67. What is the minimum opening for makeup air provided in the door for a closet designed for a clothes dryer installation? a. 70 in2 c. 90 in2 2 b. 80 in d. 100 in2 2 Answer: 100 in Reference-PME Code 2012 page 75 68. What is the maximum temperature rating for a fire actuated damper installed in an exhaust outlet of a system? a. 190 °C c. 200 °C b. 220°C d. 150 °C Answer: 190 °C Reference-PME Code 2012 page 96 69. What is the minimum conveying velocities for heavy dusts such as metal tumings, and lead dusts? a. 2500 fpm c. 3500 fpm b. 3000 fpm d. 4000 fpm Answer: 4000 fpm Reference-PME Code 2012 page 101 70. The property of materials which commends them to the mass production techniques of pressure-forming desired shapes. a. Elasticity c. Brittleness b. Plasticity d. Malleability Answer: Plasticity Reference-Mark’s handbook 11th ed page 1310 71. Attempts to describe how much heat the body will lose under certain conditions of wind and temperature. a. Cooling factor c. Heat release factor b. Wind-chill index d. Chill-wind index Answer: Wind-chill index Reference-Mark’s handbook 11th ed. Page 12-50 72. Heat gains that are based on the total electrical wattage of the operating lights, including ballasts, converted to Btu/h. a. Lighting gains c. Equipment gains b. People gains d. Internal gains Answer: Lighting gains Reference- Mark’s handbook 11th ed. page 12-61 73. What is the minimum service clearance for pumps? a. 350 mm c. 500 mm b. 450 mm d. 600 mm Answer: 600 mm Reference-PME Code 2012 page 217 74. What is the maximum distance between manholes? a. 150 ft. c. 300 ft. b. 250 ft. d. 350 ft. Answer: 300 ft. Reference-PME Code 2012 page 289 75. What is the fire protection system maintenance standard for portable fire extinguisher. a. NFPA 10 c. NFPA 12A b. NFPA 12 d. NFPA 17 Answer: NFPA 10 Reference-PME Code 2012 page 377
65. A device or method that minimizes the passage of airborne sparks and embers into a plenum, duct, and flue. a. Charge trap c. Spark trap b. Spark terminator d. Spark arrester Answer: Spark arrester Reference-PME Code 2012 page 74
76. What is the assigned color coding s ystem for potable water supply in all buildings? a. Green c. Yellow b. Blue d. Orange Answer: Green Reference-PME Code 2012 page 247
66. What is the minimum diameter of moisture exhaust for a compartment or space for domestic clothes dryer? a. 1 inch c. 3 inches b. 2 inches d. 4 inches Answer: 4 inches Reference-PME Code 2012 page 75
77. What is the minimum jet of water that should be constantly available for potable drinking water? a. 1 inch c. 2 inches b. 1.5 inches d. 2.5 inches Answer: 2 inches Reference-PME Code 2012 page 247
78. An environment in which the quantity and location of smoke is limited or otherwise restricted to allow for ready evacuation through the space. a. Smoke zone c. Tenable environment b. Safe environment d. Smoke room Answer: Tenable environment Reference-PME Code 2012 page 174
87. A unit containing one or more indicator lamps, alphanumeric displays, or other equivalent means in which each indication provides status information about a circuit, condition or location. a. Annunciator c. Deluge system b. Control box d. Status display Answer: Annunciator Reference-PME Code 2012 page 379
79. A device that senses a limit or off limit condition or improper sequence of events and shuts down the offending or related piece of equipment or prevents pro ceeding in an improper sequence in order to prevent a hazardous condition from developing. a. Interlock c. Emergency button b. Reset alarm d. Dampers Answer: Interlock Reference-PME Code 2012 page 192
88. A fuel oil tank located inside a structure that provides fuel to the engine. a. Enclosed tank c. Day tank b. Integral tank d. Supply tank Answer: Day tank Reference-PME Code 2012 page 227
80. Any joint obtained by joining of metal parts with alloys that melt at temperatures higher than 449 °C but lower than the melting temperature of the parts being joined. a. Compression c. Brazed b. Flanged d. Flared Answer: Brazed Reference-PME Code 2012 page 22 81. A joint made by the joining of metal parts with metallic mixtures or alloys that melt at a temperature up to and including 449°C. a. Soldered c. Brazed b. Flanged d. Flared Answer: Soldered Reference-PME Code 2012 page 22 82. The highest stress level that the component can tolerate without rupture. a. Ultimate strain c. Ultimate pressure b. Ultimate tension d. Ultimate strength Answer: Ultimate strength Reference-PME Code 2012 page 25 83. A blend comprising multiple components of different volatiles that when used in refrigeration cycles change volumetric composition and saturation temperatures as they evaporate or condensate at constant p ressure. a. Zeolites c. Isotope b. Zeotrope d. Azeotrope Answer: Zeotrope Reference-PME Code 2012 page 27 84. A type of central furnace designed with airflow essentially in a vertical path, discharging air at or near the top of the furn ace. a. Horizontal c. Up-flow b. Down-flow d. Enclosed Answer: Up-flow Reference-PME Code 2012 page 21 85. A change in composition of a blend by preferential evaporation of the more volatile component or condensation of the less volatile component. a. Fractionation c. Crystallization b. Distillation d. Condensation Answer: Fractionation Reference-PME Code 2012 page 21 86. A standard instrument for measuring duct velocity. a. Anemometer c. Pitot tube b. Laser Doppler velocimeter d. Solid tracer Answer: Pitot tube Reference-ASHRAE 1997 HVAC fundamentals page 14.15
89. What is the maximum capacity of an integral tank for an engine? a. 80 L c. 95 L b. 90 L d. 100 L Answer: 95 L Reference-PME Code 2012 page 231 90. What is known as the Mechanical Engineering Act of 1998? a. R.A 8495 c. R.A 9019 b. R.A 8140 d. R.A 8540 Answer: R.A 8495 Reference-PME Code 2012 page 11 91. What is the color field assigned to fire quenching materials? a. Blue c. Yellow b. Orange d. Red Answer: Red Reference-PME Code 2012 page 740 92. What is the color field assigned to radioactive materials, explosives, toxic, etc.? a. Blue c. Yellow b. Orange d. Red Answer: Yellow Reference-PME Code 2012 page 740 93. What is the color field assigned to liquid or liquid admixture of inherently low hazardous? a. Green c. Yellow b. Orange d. Red Answer: Green/Orange Reference-PME Code 2012 page 740 94. What is the color of the pi pe that conveys Gasoline? a. Green c. Yellow b. Orange d. Red Answer: Orange Reference-PME Code 2012 page 741 95. What is the color of the pipe that conveys Ammonia? a. Green c. Yellow b. Orange d. Red Answer: Yellow Reference-PME Code 2012 page 741 96. What is the color of the pipe that conveys high pressure steam? a. Green c. Yellow b. Orange d. Red Answer: Yellow Reference-PME Code 2012 page 65 97. The standard handbook for equipment and materials for climatic conditions application. a. ANSI c. NFPA b. ASHRAE d. ASME Answer: ASHRAE Reference-PME Code 2012 page 748 98. What is the flash point range of kerosene? a. 100-162 °F c. 164-190 °F b. 50-92 °F d. 195- 240 °F Answer: 100-162 °F Reference-PME Code 2012 page 729
99. A desalination process in which a membrane permits fresh water to be forced through it but holds back dissolved solids. a. Purification c. Reverse osmosis b. Osmosis d. Distillation Answer: Reverse osmosis Reference-Mark’s handbook 11th ed. Page 6-177
100. The following are ions found in seawater except? a. Chloride c. Magnesium b. Calcium d. Barium Answer: Barium Reference-Mark’s handbook 11th ed. Page 6176
Test II – Problem Solving Instructions: Use black or blue pen, no pencils allowed. Use yellow pad for your solutions. Write only your solutions on the front page of your solution sheet. Anybody caught using cellular phone for whatever reason means cheating. You are not allowed to leave the room unless you are done. Raise your hand if you have questions and clarifications. Submit your solution sheet together with the q uestionnaire.
1. A pump delivers 490 gpm of water against a total head of 220 ft. and operating at 1650 rpm. Changes have increased the total head to 380 ft. At what rpm should the pump be operated to achieve the new head at the same efficiency? Source: Power and Industrial Plant engineering reviewer 2nd edition by JAS TORDILLO
= 220380 =1650 =
2. A pump operating at 1850 rpm delivers 520 gal/min against a total head o f 155 ft. Changes in the piping system have increased the total head to 365 ft. At what rpm should the pump be operated to achieve this new head at the same efficiency? Source: Power and Industrial Plant engineering reviewer 2nd edition by JAS TORDILLO
= 155365 =1850 =
3. It is desired to deliver 6 m 3/s at a head of 643 m in a single stage pump having specific speed not to exceed 45. If the speed is not to exceed 1360 rpm, how many stages are required? Source: Power and Industrial Plant engineering reviewer 2nd edition by JAS TORDILLO Let n = no. of stages h = head per stage =
= ℎ 6 45= 1360√ 643 =
4. A centrifugal pump delivers 85 liters per second of water on test. Suction gauge reads 12 mmHg and 1.5 meters below pump centerline. Power input is 75 kw. Find the total dynamic head in meters. Source: Power and Industrial Plant engineering reviewer 2nd edition by JAS TORDILLO
= 1 =85 1000 =0.085 / = = 75 0.7475=9.810.085 =
Since no pump efficiency is given, use the usual pump efficiency used which is 74%
5. A pump discharges 160 L/s per second of water to a height of 80 meters. If the efficiency is 74%, and the speed of the pump is 1900 rpm, what is the torque in N-m to which the drive shaft is subjected? Source: Power and Industrial Plant engineering reviewer 2nd edition by JAS TORDILLO
= =0.1609.8180=125.6 = = 125.0.746 =169.73 =2 169,726=2190060 =
6. A fuel pump is delivering 15 gpm of oil with with a specific gravity of 0.85. The total head is 10 meters, find how much energy does the pump consumes in kJ per hour. Source: Power and Industrial Plant engineering reviewer 2nd edition by JAS TORDILLO
= 60 3. 7 854 =15 ℎ 10000.85 9.81 10 = /
7. A pump receives 10 kg/s of water at 230 kPa and 112°C and discharges it at 1120 kPa. C ompute for the power required in kilowatts. Source: Power and Industrial Plant engineering reviewer 2nd edition by JAS TORDILLO
= =10 1000 1120230 =.
8. A pump lifts water at a rate of 290 L/s from a lake and force it into a tank 10 meters above the level of the water at a pressure of 140 kPa. What is the power required in kW? Source: Power and Industrial Plant engineering reviewer 2nd edition by JAS TORDILLO
= ℎ=+ =10+ 9.14081 =23.97 = = 0.2909.8123.97 =
9. A 6-stage centrifugal pump discharges 1300 gpm of water at 1510 rpm with pressure drop of 580 psi. Find the specific speed. Source: Power and Industrial Plant engineering reviewer 2nd edition by JAS TORDILLO
= 580144 62.4 =1338.46 . = 1338.6 46 =223.08 . = / 1 300 √ = 1510 223.08/ =
10. A 6-stage centrifugal pump discharges 1550 gpm of water at 1850 rpm with pressure drop of 720 psi. Find the specific speed. Source: Power and Industrial Plant engineering reviewer 2nd edition by JAS TORDILLO
ℎ= ℎ= 720144 62.4 =1661.54 . 1661.6 54 =276.92 . = 1550 = = 1850√ 276.92 =
11. Find the percent slip of a reciprocating pump if the volumetric efficiency is 97% Source: Power and Industrial Plant engineering reviewer 2nd edition by JAS TORDILLO
=1 =10.97=0.03 =%
12. Find the percent slip of a reciprocating pump if the volumetric efficiency is 94% Source: Power and Industrial Plant engineering reviewer 2nd edition by JAS TORDILLO
=1 =10.94=0.06 =%
13. A pump driven by an electric motor moves 27 gal/min of water from reservoir A to reservoir B, lifting the water to a total of 250 feet. The efficiency of the pump and motor are 65% and 85%, respectively. What size of motor (HP) is required? Source: Power and Industrial Plant engineering reviewer 2nd edition by JAS TORDILLO
27 =0.0602 / = 7.48160 = = 0.060262.550 4250 =1.706 ℎ = 1.0.76065 =2.63 ℎ
14. Water is pumped at 1.5 m3/s to an elevation of 7 m through a flexible hose using a 100% efficient pump rated at 120 kW. Using the same length of the hose, what size motor is needed to pump 1.5 m3/s of water to a tank with no elevation gain? In both cases both ends of hose are at atmospheric pressure. Neglect kinetic energy. Source: Power and Industrial Plant engineering reviewer 2nd edition by JAS TORDILLO
= 120=9.811.5 =8.15 ℎ :ℎ=8.157=1.15 = 9.811.51.15 =
15. A pump discharges 55 ton of water per hour to a height of 10 m. The overall efficiency of the pumping system is being 70%. Calculate the energy consumed by the pump in 3 hours, expressed in MJ. Source: Power and Industrial Plant engineering revi ewer 2nd edition by JAS TORDILLO
1000 1 =55 ℎ 1000 =55 ℎ = = 9.81 550.70ℎ 10 3 ℎ=23,123.57 =.
16. Water flow through a pipe at 20 L/s. The inlet diameter of pipe is 13 cm and its exit diameter is 17cm. If water is to be pumped from a reservoir located 9 m below and heat losses amounts to 3 kW, determine the power input to the pump. Source: Power and Industrial Plant engineering reviewer 2nd edition by JAS TORDILLO
=20 =0.020 / = = 40..01203 =1.51 ; = = 40..17020 =0.88 0. 8 8 1. 5 1 =9+ =8. 9 2 29. 8 1 = +=9.810.0208.92+3 =.
17. A single-acting reciprocating pump has a diameter of 0.15 meter and a stroke of 0.30 meter. Compute the theoretical discharge if the pump delivers water at 100 rpm. Source: Power and Industrial Plant engineering reviewer 2nd edition by JAS TORDILLO
= 4 = 4 0.150.3100 =. /
18. A single-acting reciprocating pump, with a diameter of 0.20 meter and stroke of 0.25 meter, delivers water at a rate of 0.20 m3/min. What is the percentage slip if it delivers at 50 revolutions per minute? Source: Power and Industrial Plant engineering reviewer 2nd edition by JAS TORDILLO
= 4 = 4 0.200.2550=0.39 / =0.20 / 2 0 = = 0.390. 0.39 =0.4871 =.%
19. A pump operating at 1900 rpm delivers 650 gpm against a total head of 210 ft. Changes in the piping system have increased the total head to 250 ft. At what rpm should the pump be operated to achieve this new head at the same efficiency? Source: Power and Industrial Plant engineering reviewer 2nd edition by JAS TORDILLO
ℎℎ = 210250 =1900 =
20. A centrifugal pump has a constant speed of 1400 rpm and has a head of 80 m. What is the effect on the head of the pump if the impeller diameter is reduced from 275 mm to 220 mm? Source: Power and Industrial Plant engineering reviewer 2nd edition by JAS TORDILLO
ℎℎ = 80ℎ =275220 =.
21. If the available head of the hydrostation is 290 m and available water flow is 1500 m3/s, determine the hydrostation water power. Source: Power and Industrial Plant engineering reviewer 2nd edition by JAS TORDILLO
= =9.811500290 =.
22. A pump lifts water at a rate of 550 L/s from a source and forced it into a tank 15 meters above the level of the water at a pressure of 200 kPa. What is the power required in Hp? Source: Power and Industrial Plant engineering reviewer 2nd edition by JAS TORDILLO
= 9.20081 +15=35.39 ==9.810.55035.39=190.93 =
23. A plant has installed a single-suction centrifugal pump with a capacity of 320 gpm under 210 ft. at 1300 rpm. It is proposed to install another pump with double suction but of the same type to operate at 90 ft. head and delivers 410 gpm. Determine the speed of the proposed pump. Source: Power and Industrial Plant engineering reviewer 2nd edition by JAS TORDILLO
/ = / ;= 4102 =205 1300210√ /320 = 90√ /205 =
24. A pressure rise of 550 kPa is needed across a pump in a pipe transporting 0.2 m 3/s of water. If the pump is 80% efficient, the power needed in kW would be: Source: Power and Industrial Plant engineering reviewer 2nd edition by JAS TORDILLO
2 = = 5500. 0.80 =
25. Water is to be raised to a height of 50 meters at a rate of 15 kg/s. Heat losses due to friction is 3 kW. Determine the motor power required to drive this pump. Source: Power and Industrial Plant engineering reviewer 2nd edition by JAS TORDILLO
.
=15 = 0.015 / = + = 9.810.01550 +3 =.
26. A certain fan delivers 7 m3/s of air at 30°C and 105.3 kPa is operating at 550 rpm and requires 3 kW of power. If the air temperature is increased to 80°C and the speed of the fan remains the same, calculate the new power in kW. Source: Power and Industrial Plant engineering reviewer 2nd edition by JAS TORDILLO
= 2 = 30+273 80+273 =.
27. What is the static air power in watts of a fan designed to deliver 1200 m3/hr of air with a static pressure of 12 cm of water column on full delivery? Source: Power and Industrial Plant engineering reviewer 2nd edition by JAS TORDILLO
ℎ = ℎ = 0.121000 =100 1000 1. 2 = =1.2 9.8112001003600 =
28. A certain ventilating fan delivers 520 m3/min of air against a back pressure of 13 cm water when the fan is operating at 530 rpm. The plant wishes to increase the air flow to 650 m3/min. Determine the air power produced by the fan. Source: Power and Industrial Plant engineering reviewer 2nd edition by JAS TORDILLO
= =ℎ =1000 9.81 0.13520 min=663,156 60 =11,052.6 =.
29. In problem No. 28, what is the new speed to obtain the increased air flow? Source: Power and Industrial Plant engineering reviewer 2nd edition by JAS TORDILLO
= 530 = 520650 =.
30. In problem No. 28, what is the new back pressure? Source: Power and Industrial Plant engineering reviewer 2nd edition by JAS TORDILLO
= 13 =662.5305 =.
31. In problem No. 28, find the new power at the increased flow rate. Source: Power and Industrial Plant engineering reviewer 2nd edition by JAS TORDILLO
= 11.05 =662.5305 =.
32. A blower is driven by a belt and pulley so that its speed can be changed by changing the pulley diameter. The fan is rated at 300 m3/min and 16cm static pressure for 1950 rpm and 20°C air. Determine the static air horsepower. Source: Power and Industrial Plant engineering reviewer 2nd edition by JAS TORDILLO
18°, ℎ ℎ:
=300 =5 = 0.746 1 6 = 9.0.87150. 46 /ℎ =.
33. A fan used for ventilation discharges 7.5 m3/s of air through a duct 100 cm in diameter against a static pressure of 25 mmWG. Barometric pressure is 740 mmHg, the temperature of the air is 27°C and the gage fluid density is 995 kg/m3. If the power input to the fan is 4 kW, determine the static efficiency of the fan. Source: Power and Industrial Plant engineering reviewer 2nd edition by JAS TORDILLO
= − 995 9. 8 110 7. 5 0. 0 25 = 4 =. %
34. A large forced draft fan is handling atmospheric air, 45 °C under a total head of 285 mm water gage at 43°C. The power input to the fan is 220 kW and the fan is 80% efficient. Compute the air pressure. Assume local gravity of acceleration of 9.87 m/s2. At 45°C, density = 990.2 kg/m3. Source: Power and Industrial Plant engineering reviewer 2nd edition by JAS TORDILLO
= =220 0.80=176 9. 8 7 / =990.2 / 1000 =9. 77 =ℎ = 0.2859.77 =.
35. From Problem number 34, compute the volume of air handled each minute. Source: Power and Industrial Plant engineering reviewer 2nd edition by JAS TORDILLO
= 176=9.770.285 =. . /
36. A forced draft fan is used to provide combustion air requirements for a power b oiler that burns coal at the rate of 10 metric tons per hr. The air requirements are: 130,000 m3/hr, air being provided under 190 mm water gauge by a fan which has a mechanical efficiency of 75%. Assume fan to deliver at a total pressure of 190mm water gauge. Determine the air power of fan. Source: Power and Industrial Plant engineering reviewer 2nd edition by JAS TORDILLO
= 190 9. 8 1 / 1.8639 ℎ= ℎ= 1000 = =130,000 ℎ =36.11 = 33.33 1.8639 =.
37. Find the air power of a blower needed to provide the forced-draft service to a boiler that burns coal at the rate of 12 metric tons per hour. The air requirements are 130,000 m3/hr, air being provided under 155 mm water gage by the blower which has a mechanical efficiency of 70%. Assume the blower to deliver a total pressure of 165 mm water gage. Source: Power and Industrial Plant engineering reviewer 2nd edition by JAS TORDILLO
= =130,000 ℎ =36.11 ℎ=ℎ=155 =0.155 = 9.8136.110.155 =.
38. A certain power boiler requires 1650 m3/min of air at a pressure of 25 cm of water for the combustion process. The fan has a mechanical efficiency of 65% at a given conditions. How large of a motor, in kW, is required to power this fan? Source: Power and Industrial Plant engineering reviewer 2nd edition by JAS TORDILLO
= ℎ=1000 9.81 0.25 =2452.5 = =2452.5 1650 min60 =67,443.75 =67.44
= = 67.0.6454 =.
39. What horsepower is supplied to air movie at 25 fpm through a 3 x 4 ft. duct under a pressure of 4 in. water gage? Source: Prime’s Industrial Plant Engineering Reviewer
= 20 == 3 4 60=4 4 62. 4 ℎ 12 ℎ= = = 20. 8 1 =4 20.8=83.2 550 =.
40. A ventilating fan discharges 4.5 m3 of air per second through a duct 90 cm in diameter against a static pressure of 25 mm water gauge. Barometric pressure is 725 mm Hg, the temperature of air is 30.44°C and the gauge fluid density is 995 kg/m3. If the power input is 2.85 kW, determine the static efficiency. Source: Prime’s Industrial Plant Engineering Reviewer
= = 2.ℎ85 5 0. 0 25 = (9.810.995)4. 2.85 =. . %
41. The mechanical efficiency and static pressure of a fan are 50% and 25 m of air respectively. What is the static efficiency if the total pressure created by the fan i s 30 m of air? Source: Prime’s Industrial Plant Engineering Reviewer
= 25ℎℎ =. 5030 =. . %
42. The forced draft fans in parallel with a capacity of 75.5 m3 per second each supplying combustion air to a steam generator. Air inlet is at 45.33°C, a static pressure of 255 mm water gage is developed and the fan speed is 1300 rpm. The fan input is 260 kW each. Calculate the capacity of the fan for a speed increase of 25%. Source: Prime’s Industrial Plant Engineering Reviewer
=1.25 =1.2575.5 =.
43. What is the set efficiency of a fan if the fan efficiency is 43% and motor efficiency is 87%? Source: Prime’s Industrial Plant Engineering Reviewer
= =0.430.87 =. . %
44. A 15 hp motor is used to drive a fan that has a total head of 25 m. If the fan efficiency is 75%, what is the maximum capacity in m3/s? Source: Prime’s Industrial Plant Engineering Reviewer
=0.7515 =11.25 8.39 =ℎ 8.39=1.2 0.0098125 =.
45. A fan develops a brake power of 160 kW at 1.2 kg/m3 air density. What is the new brake power of the fan if it operates at 105 kPa and 32°C at the same speed? Source: Prime’s Industrial Plant Engineering Reviewer
= 105 =1.19 = 0.28732+273 160 = 1.1.129 =.
46. A small blower handles 45.33 m3 of air per minute whose density is 1.159 kg/m3. The static and velocity heads are 17.38 and 1.20 cm water gage (at 15.7°C) respectively. Local gravity acceleration is 9.75 m/s2. Find the power input to the air from the blower. Source: Prime’s Industrial Plant Engineering Reviewer
=ℎ ℎ=17.38+1.20=18.85 =0.1858 =45.33 =0.76 =9.750.760.1858 =.
47. The fan has a total head of 200 m and a static pressure of 21 cm WG. If the air density is 1.2 kg/m 3, what is the velocity of air flowing? Source: Prime’s Industrial Plant Engineering Reviewer
ℎ = 2 200=0.2110001.2+ℎ ℎ =25 25= 29.81 =.
48. A 50 in. diameter fan rated at 180,000 cfm standard air at 15 in. static pressure is operating at 12 50 rpm. Solve for the specific speed. Source: Prime’s Industrial Plant Engineering Reviewer
= ℎ/ = 125015 √ 180,1 0/00 12 =, .
49. A boiler requires 80,000 m3/hr of standard air. What is the motor power if the fan can deliver a total pressure of 150 mm of water gage? The mechanical efficiency of the fan is 65%. Source: Prime’s Industrial Plant Engineering Reviewer
= =ℎ =9.8180000 3600 0.150=32.7 = 32.0.765 =.
50. The motor power needed to drive the fan is 80 kW and the volume flow of air delivered by fan is 25 m3/s and 21 cm water gage. The density of air is 1.225 kg/m3. What is the fan efficiency? Source: Prime’s Industrial Plant Engineering Reviewer
= =9.81250.21 =51.5 = 51.805 =. . %
51. Heat is transferred from hot water to an oil in a double pipe counter flow heat exchanger. Water enters the outlet pipe at 110°C and exits 60°C while the oil enters the inner pipe at 35°C and exits at 50°C. Calculate the log mean temperature difference. Source: Power and Industrial Plant engineering reviewer 2nd edition by JAS TORDILLO
= ∆ln∆ ∆∆ ∆∆=11050=60° =6035=25° = 6025 ln 6025 =. °
Water, tx=110°C
Oil, t1=35°C
Oil, t2=50°C
Water, ty=60°C
52. A fuel oil heater designed for counter flow heat transfer is used to heat fuel oil from 26°C to 100°C while the heating fluid enters at 145°C and leaves at 110°C. The fuel oil has a specific gravity of 25°API, a specific heat of 0.65 kcal/kg-C and enters the heater at the rate of 2700 liters per hour. Determine the true log mean temperature difference. Source: Power and Industrial Plant engineering reviewer 2nd edition by JAS TORDILLO
= ∆ln∆ ∆∆ = 11026145100 11026 ln 145100 =. ℃
Heating fluid, tx=145°C Fuel Oil, t1=26°C
t2=100°C
ty=110°C
53. Brine enters a circulating brine cooler at the rate of 7.7 m3/hr at -10°C and leaves at -16°C. The specific heat of brine is 0.26 kcal/kg-C and the specific gravity is 1.20. The refrigerant evaporates at -25°C. What is the refrigerating load in TOR? Source: Power and Industrial Plant engineering reviewer 2nd edition by JAS TORDILLO
=∆ =1. 210007.7=9240 ℎ =92400.26(10 16) =14,414.4 ℎ 0.25260mi1ℎn200/ =.
54. It is desired to heat cold water at a pressure 510 kPa from 6°C to 55°C at a rate of 1.5 kg/s in a thin-walled copper tube by condensing waste process steam at 310 kPag on the outside of the tube. At 400 kPa abs, Tsat=143°C. Determine the log mean temperature difference. Source: Power and Industrial Plant engineering reviewer 2nd edition by JAS TORDILLO
∆∆ =1436=137℃ =14355=88℃ 13788 = ∆ln∆ = ∆∆ ln 13788 =℃
Steam, tx=143°C Water t1=6°C t2=55°C
t y=143°C
55. Calculate the logarithmic mean temperature difference for a condenser if the temperature difference between condensing steam and water inlet is 800°C and that steam inlet and water is 110°C. Source: Power and Industrial Plant engineering reviewer 2nd edition by JAS TORDILLO
= ∆ln∆ ∆∆ 800110 ln 800110 =℃
56. An oil heater heats 160 kg of oil per minute from 32°C to 125°C in a cou nter flow heat exchanger. The average specific heat if the oil is 3.5 kJ per kg per °C. Exhaust gases used for heating enter the heater with an average specific heat of 1.005 kJ per kg per °C, a mass flow rate of 300 kg/min and an initial temperature of 225°C. The overall heat transfer coefficient is 85 watts per m2 per C. Determine the temperature of the gas leaving the heater in °C. Source: Power and Industrial Plant engineering reviewer 2nd edition by JAS TORDILLO
∆ =∆ 1603.512532 =3001.005(225) =.℃
57. From problem 56, determine the amount of heat transferred in kW. Source: Power and Industrial Plant engineering reviewer 2nd edition by JAS TORDILLO
=∆ =1603.512532 =52080 /min 601 =
58. From problem 56, determine the heating surface area in m2. Source: Power and Industrial Plant engineering reviewer 2nd edition by JAS TORDILLO
52. 3 32 225125 = ∆ln∆ = ∆∆ ln 20.1003 =49.98 ° = 8681000 =8549.98 =.
59. In a hot water system, water is heated to 9 6°C and then pumped at the rate of 4 L/min through a radiator where it is cooled to 30°C. If the water arrives at the radiator at 30°C, how much heat does a radiator release per hour? Source: Industrial plant Engineering Practice Problems for Heat exchanger IPE class of 2015-2016
1 =∆=4 10001000 4. 1 87 9630 =1105.37 160 = .
60. A brine enters a cooler at the rate of 55 m3/hr at 17°C and leaves at 3°C. Specific heat and specific gravity of brine are 1.1 kJ/kgK and 1.2 respectively. Calculate the heat transfer in kW. Source: Industrial plant Engineering Practice Problems for Heat exchanger IPE class of 2015-2016
=∆ ℎ 1000 1.2 1.1 173 =55 ℎ 1 3600 .
61. In a hot air heating system, the furnace heats the air from 65°F to 165°F. If the air is then circulated at the rate of 340 ft3/min by the blower, how much thermal energy is transferred per hour. The specific heat of air at constant pressure is 0.255 Btu/lb°F, the density of air is 0.0808 lb/ft3 at atmospheric pressure. Source: Industrial plant Engineering Practice Problems for Heat exchanger IPE class of 2015-2016
=∆ =340 0.0808 0.255 ℉ 16565℉ =700.5 60 1ℎ =,.
62. An air-cooled condenser is to reject 75 kW of heat from a condensing refrigerant to air. The condenser has an air-side area of 215 m2 and a U value based on this area is 0.040 kW/m2K; it is supplied with 6.8 m 3/s of air which has a density of 1.19 kg/m3. If the condensing temperature is to be limited to 60°C, what is the maximum allowable temperature of the inlet air? C p of air = 1.006 kJ/kgK Source: Industrial plant Engineering Practice Problems for Heat exchanger IPE class of 2015-2016
==6. 81.1 9 =8. 09 =∆
75 =8.091.006 60 =.℃
63. An oil heater heats 105 kg/min of oil from 36°C to 110°C in a counter flow heat exchanger. The average specific heat of the oil is 2.5 kJ/kg°C. Exhaust gases used for heating enter the heater with an average specific heat of 1 kJ/kg°C, a mass flow rate of 245 kg/min and an initial temperature of 210°C. The over-all heat transfer coefficient is 75 W/m2°C. Determine the heating surface in m2. Source: Industrial plant Engineering Practice Problems for Heat exchanger IPE class of 2015-2016
= (∆) =(∆) 105 2.5 ℃ 11036 =245 1 ℃ 210℃ =130.7 ° 210110 130. 7 36 = ∆ln∆ = =97. 3 3 ℃ ∆∆ 100 ln 94.7 1 1000 11036 1052. 5 60 1 = = 75 ℃ 97.33 =.
64. A parallel flow economizer receives hot gas (C p=0.27 Btu/lb°R) and water in the ration of 2 lb gas/lb water. The gas enters at 860 °F and leaves at 360°F; the water enters at 120°F. Find the exit temperature of the water. Source: Industrial plant Engineering Practice Problems for Heat exchanger IPE class of 2015-2016
∆ =∆ (∆) = ∆ 1 ° ,120=1.50.27850360 , =.℉
65. The sun generates 2 kW/m2 when used as a source for solar collectors. A collector with an area of 1.5 m2 heat water. The flow rate is 4 L/min. What is the temperature rise in the water? The specific heat of water is 4200 J/kg°C. Source: Power and Industrial Plant engineering revi ewer 2nd edition by JAS TORDILLO
=2 1.5 =3 =3000 1 =4 10001000 160=0.067 =∆ 3000=0.0674200∆ ∆=.℃
66. At an average temperature of 100°C, hot air flows through a 3.5 m lon g tube with an inside diameter of 55mm. The temperature of the tube is 25°C along its entire length. Convective film coefficient is 20.2 W/m2-K. Determine the convective heat transfer from air to the tube. Source: Power and Industrial Plant engineering revie wer 2nd edition by JAS TORDILLO
=ℎ = =0.0553.5 =0.6047 =ℎ =20.20.604710025 =.
67. What is the heat transfer in the glass surface area of 1 m 2 having an inside temperature (room) of 30°C and 15°C outside temperature (surrounding). The thickness o f glass surface is 0.005 m. The glass thermal conductivity is 2 W per m per K. Source: Power and Industrial Plant engineering reviewer 2nd edition by JAS TORDILLO
= ∆ = 213015 0.005 =
68. Compute the amount of condensate formed during 15 minutes warm-up of 200 m pipe that conveys the saturated steam with enthalpy of vaporization hfg = 1947.8 kJ/kg. The minimum external of pipe is 5°C, the final temperature of the pipe is 100°C. The specific heat of the pipe material is 0.6 kJ/kg-°C. The specific weight is 28 kg/m. Source: Power and Industrial Plant engineering reviewer 2nd edition by JAS TORDILLO
=ℎ 20060 1 0.6 ℃ 1005℃= 1947.8 30 15 =.
69. At P4.50 per kw-hr, how much will it cost to maintain a temperature of 100°F for 48 hours in a box 2.5 ft2 on each side if the outside temperature is 75°F and the overall heat transfer coefficient for the box is 0.1 Btu/hr-ft2°F. Source: Power and Industrial Plant engineering reviewer 2nd edition by JAS TORDILLO
=∆ =2.5 2.5 6=37.5 =0.1 ℎ ℉37.510075℉ 1ℎ 48 ℎ=1.319 ℎ =93.75 ℎ 1.055 3600 4.50 =1.319 ℎ ℎ = .
70. A tank containing liquid nitrogen at -115°C is suspended in a vacuum shell by three stainless steel rods 1 cm in diameter and 4 meters long with a thermal conductivity of 18.3 W/m-°C. If the ambient air outside the vacuum shell is 30°C, calculate the magnitude of the cond uctive heat flow in watts along the support rods. Source: Power and Industrial Plant engineering reviewer 2nd edition by JAS TORDILLO
=ℎ∆ =18.34 0.01(30115) =.
71. What is the rate of heat flow through a brick wall that is constructed 35 cm thick and 5m x 6m in area. The temperature on one side is 190°C and 55°C on the other side. The average coefficient of thermal conductivity is equal to 0.85 W/m-k. Source: Power and Industrial Plant engineering reviewer 2nd edition by JAS TORDILLO
∆ = 19055℃ 0. 8 0 56 = 0.35 =. .
72. The mass flow rate of a Freon refrigerant through a heat exchanger is 15 kg/min. The enthalpy of entry of Freon is 255 kJ/kg, and the enthalpy of exit Freon is 70 kJ/kg. Water coolant is allowed to rise 10°C. Determine the water flow rate in kg/s. Source: Power and Industrial Plant engineering reviewer 2nd edition by JAS TORDILLO
∆=ℎ ℎ 4.187 10=15 25570 =66.28 160 =.
73. A quantity of 75 m3 of water passes through a heat exchanger and absorbs 3000 MJ. The exit temperature is 100°C. Find the entrance water temperature in °C. Source: Power and Industrial Plant engineering reviewer 2nd edition by JAS TORDILLO
=∆= 3,000,000 =75 1000 4.187 100 =. ℃
74. The heat loss per hour through 5 m3 of furnace wall that is 80 cm thick is 1300 W. The inside wall temperature is 1000°C, and its average thermal conductivity is 0.65 W/m-C. Find the outside surface temperature of the wall in °C. Source: Power and Industrial Plant engineering reviewer 2nd edition by JAS TORDILLO
0. 6 5 5 1000 ° =1300 = = 0.80 = ℃
75. What is the critical radius in cm for an insulated pipe (k=0.40 W/m-K) if the external heat transfer coefficient is 15 W/m2K. Source: Power and Industrial Plant engineering reviewer 2nd edition by JAS TORDILLO
= ℎ 0. 4 0 = 15 =0.027 =.
76. A boiler evaporates 4.6 kg of water per kg of coal into dry saturated steam at 11 bar. The temperature of feed water is 32°C. Find the equivalent evaporation “from and at 100°C”. Source: A Textbook of Thermal Engineering by J.K. Gupta and R.S. Khurmi
=4.6 ;=11 ; =32℃ 100℃: , 32℃, ℎ =134. 1 5 / ℎ=ℎ=2781. 7 / 11 , 62781.7134.15 = (ℎℎ)=4.2257 =. 7134.15 = 2781.2257 =. 77. From problem number 76, determine the factor of evaporation. Source: A Textbook of Thermal Engineering by J.K. Gupta and R.S. Khurmi
78. The following observations were made in a boiler trial: Coal used 260 kg of calorific value 30 800 kJ/kg, water evaporated 2500 kg, steam pressure 12 bar, dryness fraction of steam 0.97 and feed water temperature 35°C. Calculate the equivalent evaporation “from and at 100°C per kg of coal. Source: A Textbook of Thermal Engineering by J.K. Gupta and R.S. Khurmi
100℃: , 35℃, ℎ =146. 6 8 / ℎ =798. 65 12 , ;ℎ =1986. 2 ℎ=ℎ +ℎ =798.65+0.97 1986.2 =2685.54 /
= : 2500 = =9. 6 2 260 ) 9. 6 22685. 5 4146. 6 8 = (ℎℎ = 2257 2257 =.
79. From problem number 78, determine the efficiency of the boiler. Source: A Textbook of Thermal Engineering by J.K. Gupta and R.S. Khurmi
= (ℎℎ ) 6 8 = 9.622685.30,584146. 00 =. . %
80. A Lancashire boiler generates 2500 kg of dry steam per hour at a pressure of 12 bar. The grate area is 4 m2 and 100 kg of coal is burnt per m 2 of grate area per hour. The calorific value of the coal is 33 580 kJ/kg and the temperature of feed water is 19°C. Determine actual evaporation per kg of coal. Source: A Textbook of Thermal Engineering by J.K. Gupta and R.S. Khurmi Mass of coal burnt per hour:
Actual evaporation per kg of coal:
=100 4=400 /ℎ = 2500 =. 400
81. From problem number 80, determine the Equivalent evaporation “from and at 100°C” Source: A Textbook of Thermal Engineering by J.K. Gupta and R.S. Khurmi
,ℎ =79. 77 19℃, / ℎ=ℎ 12 , =2784.8 ) 6. 2 52784. 8 79. 7 7 = (ℎℎ = 2257 2257 =. /
82. From problem number 80, determine the efficiency of the boiler. Source: A Textbook of Thermal Engineering by J.K. Gupta and R.S. Khurmi
= (ℎℎ ) = 6.252784.33580879.77 =. . %
83. A coal fired boiler plant consumes 450 kg of coal per hour. The boiler evaporates 3400 kg of water at 45°C into superheated steam at a pressure of 12 bar and 275°C. If the calorific value of fuel is 33760 kJ/kg of coal, determine the equivalent evaporation “from and at 100°C”. Source: A Textbook of Thermal Engineering by J.K. Gupta and R.S. Khurmi
= = 3400 450 =7.56 ,ℎ =188. 4 45℃, 5 12 , ℎ =2784.8 =188° ℎ =ℎ +( )=2784.8+ 2.1 275188=2967.5 ℎ ) = 7.562967.22575188.45 = (ℎ2257 =.
84. From problem number 83, determine the efficiency of the boiler. Source: A Textbook of Thermal Engineering by J.K. Gupta and R.S. Khurmi
= (ℎ ℎ) = 7.562967.337605188.45 =. . %
85. The following observations were made on a boiler plant during one hour test: Steam pressure = 22 bar; Steam temperature = 270°C; steam generated = 38 500kg; Temperature of water entering the economizer = 17°C; temperature of water leaving the economizer = 95°C; Fuel used = 4500 kg; Energy of combustion of fuel = 31 500 kJ/kg. Calculate the equivalent evaporation per kg of fuel. Source: A Textbook of Thermal Engineering by J.K. Gupta and R.S. Khurmi
= = 38500 =8. 5 6 4500 ,ℎ@15℃=63 / 22 ;ℎ =2801.3 / =217.29° ℎ =ℎ +( )=2807.3+2.1270217.29 =2917.99 9 963 ℎ) = 8.562917. = (ℎ2257 2257 =.
86. From problem number 85, determine the thermal efficiency of the plant. Source: A Textbook of Thermal Engineering by J.K. Gupta and R.S. Khurmi
= (ℎ ℎ) 9 963 = 8.562917. 31500 =. . %
87. From problem number 85, determine the heat energy of the fuel utilized by the economizer. Source: A Textbook of Thermal Engineering by J.K. Gupta and R.S. Khurmi
ℎ , ℎ 90℃ =397.96 ℎ ℎ : =(ℎ ℎ)=8. 56397.9663=2867.26 ℎ ℎ : 2 6 = 2867. 31500 =0.0910 . %
88. A boiler produces 4 kg of steam per kg of coal from feed water at 45°C. The steam pressure is 10 bar. If the dryness fraction of steam is 0.98, determine the equivalent evaporation from and at 100°C. Source: A Textbook of Thermal Engineering by J.K. Gupta and R.S. Khurmi
) = (ℎℎ 2257 ℎ@45℃=188.45 ℎ=ℎ+ℎ @10 ,ℎ =762.81 ℎ =2015.3 ℎ=762.81+ 0.982015.3 =2737.8 = 42737.22578188.45 =.
89. A boiler raises 3.7 kg of water per kg of coal from feed water at 54.5°C, to steam at the pressure 34 bar and temperature of 370°C. Assuming specific heat of superheated steam as 2.6, calculate equivalent evaporation/kg coal. Source: A Textbook of Thermal Engineering by J.K. Gupta and R.S. Khurmi
ℎ@54.5℃=228. 1 35 ℎ@34 =2803.7 =240.94℃ ℎ =ℎ+( )=2803.7+2.6370240.94 =3138.56 56228.135 ℎ) = 3.73138.2257 = (ℎ2257 =.
90. In a boiler trial, the following observations were recorded: Boiler pressure = 10 bar; Dryness fraction of steam=0.95; Coal consumption = 500 kg/h; Calorific value of coal = 30,500 kJ/kg; feed water temperature=50°C; feed water supplied=4 tonnes/h. Find the evaporation factor. Source: A Textbook of Thermal Engineering by J.K. Gupta and R.S. Khurmi
=4 ℎ 1000 =4000 ℎ = = 4000 =8 500 ℎ@50℃=209.33 @10 1:ℎ =762.81 ℎ =2015.3 ℎ=762.81+0.952015.2677. 3=2677. 3 5 = 322575209.33 =.
91. From problem number 91, determine the equivalent evaporation from and at 100°C. Source: A Textbook of Thermal Engineering by J.K. Gupta and R.S. Khurmi
) 82677. 35209. = 33(ℎℎ 2257 = 2257 =.
92. A boiler produces 9000 kg of steam while 1 tonne of coal is burnt. The steam is produced at 10 ba r from water at 15°C. The dryness fraction of steam is 0.9. Determine the equivalent evaporation from and at 100°C. Source: A Textbook of Thermal Engineering by J.K. Gupta and R.S. Khurmi
= = 9000 =9 1000 ℎ@15℃=62.99 @10 :ℎ =2015.3 ℎ =762.81 ℎ=ℎ +ℎ =762.81+0.92015.3 =2576.58
) 92576. 5 862. 9 9 = (ℎℎ = 2257 2257 =.
93. From problem number 92, determine the efficiency of the boiler when the calorific value of the coal is 32,000 kJ/kg. Source: A Textbook of Thermal Engineering by J.K. Gupta and R.S. Khurmi
= (ℎℎ ) 9 9 = 92576.32,50862. 00 =. . %
94. In a laboratory experiment, a sample of wet steam is allowed to pass through a separating calorimeter. At some instant, the water collected in the chamber was 0.15 kg whereas the condensed steam was found to be 1.35. Determine the dryness fraction of steam entering the calorimeter. Source: Formation and Properties of steam PDF
= 1.35+0. 1.35 15 ℎ , = + =. %
For a separating calorimeter,
95. In a throttling calorimeter, the steam is admitted at a pressure of 11 bars. If it is discharged at atmospheric pressure and 115°C after throttling, determine the dryness fraction of steam. Assume specific heat of steam as 2.1 kJ/kgK Source: Formation and Properties of steam PDF
ℎ +ℎ =ℎ +( ) ,ℎ@ 11 =781.34 ℎ =2000.4 1.013 , ℎ =2676 =100℃ 781.34+2000.4=2676+2.1115100 =. . %
For a throttling calorimeter:
96. An investment of P300 000 can be made in a project that will produce a uniform annual revenue of P195,40 0 for 5 years and then have a salvage value of 12% of the investment. Out-of-pocket costs for operation and maintenance will be P85 000 per year. Taxes and insurance will be 5% of the first cost per year. The company expects capital to earn not less than 27% before income taxes. Is this a desirable investment? Use Rate of return method. Source: Engineering Economy 3rd edition by Hipolito B. Sta. Maria
ℎ ℎ: =195 400 264 000 = 300 00036000 = =30 939. 6 9 1. 2 7 1 , 2 7%, 5 0. 2 7 =85 000 = 0. 0 5 300 000 =15 000 =130 939. 6 9 = =64 460. 3 1 64 460. 3 1 = 300 000 =0.2148 . % ℎ %,ℎ . :
97. Repeat Problem 88 using the annual worth method. Source: Engineering Economy 3rd edition by Hipolito B. Sta. Maria
=195 400 264 000 = 300 00036000 = =30 939. 6 9 1. 2 7 1 , 2 7%, 5 0. 2 7 =85 000 = 0. 0 5 300 000 =15 000 =211 =0.27300 000=81 000 939. 6 9 = . ℎ ℎ ℎ ℎ. ℎ , 16539.69, :
98. Repeat problem 88 using the Present worth method. Source: Engineering Economy 3rd edition by Hipolito B. Sta. Maria
,27%,5+36 000 ,27%,5 ℎ 11.=195 400 − 2 7 =195 400 0.27 +36 0001.27− = .
=85 000+300 0000.05=100 000 ,27%,5 ℎ =300 000+100 000 − 11. 2 7 =300 000+100 000 0.27 = . >; . 99. Repeat problem 88 using the future worth method. Source: Engineering Economy 3rd edition by Hipolito B. Sta. Maria
,27%,5 ℎ =36 000+195 400 1. 2 7 =36 000+195 400 0.271 =1 703 295.33 ,27%,5+300 000 ,27%,5 ℎ =100 000 1. 2 7 =100 000 0.271+300 0001.25 =1 768 800.29 >; . 100. An engineer is considering building a 25-unit apartment in a place near a progressive commercial center. He felt that because of the location of the apartment it will be occupied at all time. He desires a rate of return of 22%. Other pertinent data are the following: Source: Engineering Economy 3rd edition by Hipolito B. Sta. Maria
=5 500 000 =7 300 000 =20 20 =20 150 000 20 =2 100 000 ℎ=8 000 =800 =1. 3 % =0.55% Is this a good investment? By ROR method:
: = 800012250.90 =2 160 000
