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1. Which of the following dimensionless numbers would best be described as the ratio of buoyant forces to Viscous forces in the case of natural convection? Nu None of the above F190;”? re m 2. Which of the following dimensionless numbers would best be described as the ratio of the momentum diffusivity to the mass diffusivity? A. Re B. Sc C. Nu D. Sh E. None of the above 3. Which of the following dimensionless numbers would best be described as the ratio of the convective heat transfer to conductive heat transfer to a surface in a fluid? A. Re B. Sc C. Nu D. Sh E. None of the above 4. Which of the following dimensionless numbers would best be described as the ratio of the inertial forces to viscous forces in a flow situation? A. Re B. Sc C. Nu D. Sh E. None of the above 5. The following equation shows a simplified version of the mechanical energy balance: 2 3 p L+gzz+fi = V—;—+g2,+'-L] 2 1’1 - Pi Which of the following IS NOT an assumpti energy balance? ‘ A. The system being analyze daries. B bT‘h‘exfe is no heat exchange across the system boundary. C. There is no shaft work done on or bythi‘seystem. D. Viscous dissipation of energy is negligi . E. None of the above. on that must be made in deriving this form of the d only contains one entrance and one exit for flow across its Mir For problems 7-10. you are given the pump curve and system curve Sit0\\l‘t on the next pages in Figure l for the pumping system shown schematically in the figure below. The air and lake rcivnperature are 25_ ‘fC and pump sits with its intake submerged at the surface of the lake and With no_suction piping. droning water directly into the pump. The discharge linc from the pump climbs up a hill where it empties its water into the open air which subsequently falls into another holding pond. The dark solid grcy cunt: shows what the head loss in the piping S\ stem is as a function of flowralc. ‘ 6. From the data given on the ' . ‘ pump curve and system curve, how far in elevation above the lak whe/r: [:13ng sits is the discharge point from the piping system? C . eet B. 200 feet C. 300 feet D. 350 feet E. None of the above 7 101 “19111010" POWex line depicted as the dashed 11115 "131'de A 0 l the €113ng l “hat 0101 power does this 1 ne represent ’ A. 300 horsepower B. 310 horsepower C. 450 horsepower D. 700 horsepower E. None of the above 8, If wailing: [1:15:51 for the pumv operates at 2000 rpm, What flow rate ofwater will be Pumped 2400 gpm 2550 gpm 2800 gpm 3050 gpm 3300 gpm noon? Name: ,7 7/ 7777 't/ d _ , - . ~ we Going back to Problem #9, in the case where the inlet velocuy t0 the pump ‘5 10:1 151:; loss 10' assume that flow into the suction inlet to the pump is turbulent, what is the actu - caused by the water entering the suction port on the pump rounded to the nearest foot? A. 0 it B. 1 it C, 28 h D. 55 it E. None of the above 5/18 ii 11. You are processing solid aluminum spheres in which you are czooling them in an oil bat: it the convective heat transfer coefficient in the oil bath is 20 lW/in K] and the thermal con :c lVl y of aluminum is 200 [W/m K]. how large must the diameter of the altiminum spsc: '83:; before you can no longer treat it using the lumped temperature assumption in whic t e in temperature is assumed to be uniform. A. 1 m B. 3 m C. 6 m D. 10 m E. None of the above two flat plates of the same surface area as shown in h other centered with one another and suspended o be black bodies at a temperature off) K. be considered to be black bodies and are insulated on all Sides ' u from the insulated except their front faces that View each other so that no heat transfer occ rs sides One black body plate is heated electrically to a temperature Ti. In the other chamber. ' t ’ ' urev body \\iih an one plate is heated electrically to a temperature T3 and the other pla e is a g ‘ emissivity e, If T1 = T; at steady-state which of the following would be true about the temperature of the plates that are not electrically heated? A. T2 B. T; = T4 C. T; > T4 . D. Can not be deterinined 12. You have two different chambers in which the diagrams face each other. They face eac inside an enclosures whose surfaces can be assumed t In one chamber, both plates can Qelectricrty Qelectricitv Fool x .305 = mun 30"“ 0'3- N s ' . m x 25.4 = Minimum .. z ._ cm x .227 . cum mm 2-00 1050 “In“ E 2 GPM x 3.735 = UNIS/MIN“. Y: E HP x .146 a Kw SINGLE VOLUTE MOUNTING CONFIG; cc. VM. F. VF. EM, vc 5n. 1|.5 M) 6FT. (1.8 Ml 698. FT. (2.! M) 11 Pr. (3.4 M) . :72 ' 7t 8 E 2 ul 3: 9 2 < z > 1009 2‘ '5 ._ 8 n 2 § Head Loss in Piping System (FEET) § é iv o 500 1000 i500 2000 2500 3000 3500 4000 CAPAC|TY us. GALLONS PER MINUTE 1‘” 200 30° 400 500 000 700 800 900 CUBlC METERS FER HOUR Cornell Pump Company - Portland. Oregon 6NHT819 - VARIOUS RPM VAS ISLHNQ W3 7/!" I For pmblems 13 a 15, you are working in a plant and need to analyze the pressure drop in a pipe flow application. One of the plant operators has measured the pressure drop in the pipe at several different flow velocities and at several points down the length of the pipe. You don‘t have access to your engineering books and need to do a quick back of the envelope calculation to determine how correlate this pressure drop data with the pipe length and the flow velocity. The variables involved in the problem are the pressure drop across the length of pipe (AP), the velocity of the flowmg liquid in the pipe (v), the length of the pipe (L). the diameter of the pipe (0). the dénSiIY 0f the fluid (p), and the viscosity of the fluid Lu). Recall that the units of viscosity are [Mass/(Length Time)]. Answer the following questions: 13. How/\mzlmy different dimensionless groups can be formed in this analysis? B. 2 C. 3 D. 4 E. None of the above 14. If you want to correlate the data on pressure dro ‘ ' ' ‘ _ ‘ . p in the pipe With pipe length and flow velocuyz which of the variables should you choose as “core variables" that appear in all of the dimensionless groups? Pt [1’ D AP, L, v 4P4» #1 AP, D, v None of the above none? 15. If you were to form a dimensionless group involving AP ,pt [1, D, which of the following could be that dimensionless group? “ A. LB" F B. L?” it 02 C. M p [1 APDZ D. ," E. None ofthe above gym Name: fi/ .777 sissfi.‘ 16. which of the following statements is true about overall heat transfer coeffictents for 3. ca exchanger? A. The overall heat transfer coefficient based on the outside tube surface area is always smaller than the overall heat transfer coefficient based on the inside tube surfa.ce area. B. The overall heat transfer coefficient can simply be complucd as the average 01 the convective heat transfer coefficients for the fluid inside the tubes and for the fluid outside the tubes. . C. If the thermal Conductivity of the tube decreases, the overall heat transfer coeffictents will increase. D. The overall heat transfer coefficients can be larger than one of the convective heat transfer coefficients for heat transfer inside or outside of the tubes. E. None of the above. 17. For a shell and tube heat exchanger which has tubes with an inside diameter of 20 mm and an outside diameter of 22 mm. The fluid on both the shell and tube side is water such that the convective heat transfer coefficients on the inside of the tubes and the outside of the tubes are equal and have a value of 50 [W/m2 K]. If the resistance to heat transfer through the wall is negligible, which of the following overall heat transfer coefficient values would be used with the outside tribe surface area to calculate the amount of heat exchanged between the two streams? A. 50.0 [W/m2 K] B. 25.0 [W/mZ K] c. 23.8 [wmn2 K] D. Can not be determined without knowing the length of the tubes E. None of the above 18. You are analyzing heat transfer through a flat thick wall of insulation. The air temperature outside the wall is 90 ”F and the wall surface temperature on the side exposed to the 90 °F air is 80 ”F at steady-state. The air temperature inside the wall is 72 ”F and the wall surface temperature on the inside exposed to the 72 °F air is 75 °F at steady-state. Which of the following statements is TRUE? A- houtsldl = hillside 3- hoursme > hinsme C- houtslde < hmnde . D. No relationship between the two convective heat transfer coefficients can be determined from the information given 19. You have a packed bed in which the superficial velocity is 10 m/s and the void volume under these flow conditions is 0.4. Which of the following is the average interstitial flow velocity for fluid between the particles in the bed? 4 m/s 10 m/s 20 m/s 25 m/s None of the above P1909“? 9/13 Name: _I/ T T W W 30, You have a large sand filter bed that is operated as a fluidized bed. When there is no flow through the bed. the total depth of the sand in the bed is 10 ft and the bed has a Void “2‘9“0“ 0‘ 0.4. The void fraction of the bed at minimum tluidization has been determined to be 0.45. How deep will the sand in the bed be (rounded to the nearest 0.1 ft) when the bed 15 at minimum fluidization conditions? A. 8.9 ft B. 10ft C. 10.9 ft D. 40.0 n E. None ofthe above 22. You have a heat exchanger in which 20 gpm of cold water enters at 20 6C and exits at 40 °C. The hot stream flows at a rate of 40 gpm and enters at 90 “C. The overall heat transfer coefficient is 30 [W/ m2 K] for these conditions. The heat capacity of water is 4.2 [J g °C]. What is the exit temperature of the hot stream? 50 °C 60 °C 70 °C 80 °C None of the above neon? 'oiimN

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