Spring 10 Makeup Exam 1 Key

Spring 10 Makeup Exam 1 Key - MEEN 315—Spring 2010 Makeup...

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Unformatted text preview: MEEN 315—Spring 2010, Makeup Exam 1 Name 3 0 /U "1’ 0 U 3 Section Number 1. Put name on w page. 2. RELAX, this is only an exam. Read over the whole exam, then decide which problem to work first. 3. Exam is closed book and notes. Tables provided by instructor. No collaboration with others! 4. Include a sketch, and clearly state assumptions and equations used on problems requiring detailed analysis. 5. If you get stuck on a problem, go to the next one. 6. Problems must be worked in the unit system in which they are specified. Failure to do so will result in a lower score. 7 Assure that you have 13 different pages, including the formula sheet as the last page. AN AGGIE DOES NOT LIE, CHEAT, OR STEAL OR TOLERATE THOSE WHO DO Your Score: Multiple-Choice: Problem 1 Problem 2 Problem 3 Problem 4 Total: MEEN 315—Spring 2010, Makeup Exam 1 Name Section Number Multiple choice problems worth 2 pts each. Circle the answer that is the most appropriate or closest (numerically) to your answer. 1. Which of the following best describes the critical point? A. the location where all three phases co-exist. C. the location where the ideal gas relation is valid e location where the liquid and vapor D. the location where sublimation occurs saturation lines meet 2. Consider a system which consists of an electrical motor driving a pump. Which of the following ratios best expresses the efficiency of the entire system? A. electrical energy divided by the fluid energy C. mechanical shaft energy divided by the fluid energy uid energy divided by the electrical energy B. mechanical shaft energy divided by the fluid energy 3. Consider a closed system that is adiabatic, has a work input, a change of internal energy, and a change of kinetic energy. Which of the following is true? 4. Wa A. the heat transfer equals the change of internal energy he heat transfer is zero C. the heat transfer is negligible D. the heat transfer equals the work ter at 10°C and 150 kPa is compressed liquid B. a saturated liquid C. a superheated vapor D. a mixture of vapor and liquid MEEN 315—Spring 2010, Makeup Exam 1 Name Section Number 5. If references are given in a paper only by consecutive numbers, starting with "1”, then in the reference section they must be in what order? A. Alphabetical (according to the first author’s last name) B. Alphabetical (according to the last author’s last name) C. Reverse alphabetical (according to the first author’s last name) Numerical (according to the numbers in the paper) 6. What is the correct EES syntax used to get the pressure thermodynamic property data for water at a temperature of 100°C and specific volume of 1.9 m3/kg? P = Pressure('Water", T = 100, v = 1.9) P = Ca|lFunction('FindPressure’,Substance=’Water’, T = 100, v = 1.9, Units = ’Sl') C. P = 0.4615*(100+273.15)/1.9 D. P = LookUp(’TableA-6’, T = 100+273.15, v = 1.9) 7. Select the extensive property from the list below: A. P in psig C. Tin Rankine in Btu D. u in Btu/lbrn 8. In two-phase mixture, the portion that is saturated vapor A. is not in equilibrium with the saturated liquid portion. is in equilibrium with the saturated liquid portion. C. has a different temperature but the same pressure as the saturated liquid portion. D. has a different pressure but the same temperature as the saturated liquid portion 9. A pressure gage reading in "kPa" reads zero when exposed to standard atmospheric pressure. It is installed on an air tank. What is the pressure in "psig" in the tank when the gage reads 900 kPa? (‘1.7 ' W):/31P¢‘j A. 160 psig @132 psig 9 017 R B‘WC m m); 1 B. 147 psig D. 0 psig MEEN 315—Spring 2010, Makeup Exam 1 Name Section Number 10. A piston cylinder arrangement contains one kilogram of air that undergoes a constant pressure (200 kPa) process from an initial volume of 0.1 m3 to a final volume of 0.05 m3. How much work is transferred during the process? 13.2010 MEEN 315—Spring 2010, Makeup Exam 1 Name Section Number 1) An oil pump is drawing 35 kW of electric power while pumping oil with p = 800 kg/m3 at a rate of 0.1 m3/s. The inlet and outlet diameters of the pipe are 8 cm and 12 cm, respectively. The pressure rise of oil in the pump is 400 kPa and the motor efficiency is 95 percent. You may neglect changes in potential energy. A. Determine the inlet and outlet oil velocity (m/s) of the pump (6 pts) B. Determine the increase of the mechanical energy of the fluid (kW). (8 pts) C. Determine the mechanical efficiency (%) of the pump (6 pts) . . 3 ma A) 0V: in V -W 4 I ’4/ #D/Z 77%),05’ 4/ : ,. m > °r/, — / 9- 9 /5 '1 t '7" r/ v V __ 0" 5 3 —' : ‘ z ‘ 2 1 Av VDZ 7T(O:IZm)/(/ C7. mle lag>£9wléfflw3 +[s>,r</:/7.q‘-11 Met/r58 C.) QM: 7W? Odie} :flpflf) 3ffiur = 33,.arficf 27.3 42w MI... guy/4w“ ll MEEN 315—Spring 2010, Makeup Exam 1 Name Section Number 2. Consider the manometer system pictured. The diameter of the manometer tube is 1.2 cm. The atmospheric pressure is 95 kPa. The specific weights of the two fluids are: fluid A, 10.0 kN/m3 and fluid B, 8.0 kN/m3. A. Determine the absolute pressure (kPa) in the tank. (16 pts) B. If fluid A is replaced with fluid B, what is the new absolute pressure (kPa). All dimensions remain the same. (4 pts) A) ,fmjk= Pahfl“ (63);!“ +638»: LB €¥0,/,1,rlum abpu‘l'n’tlS 'thllé: KI“ “f h} L” Ilmc. 'Pflfih: 951+ [00%; (O'Ob’m‘) + 810% (0)’5’7\\ MEEN 315—Spring 2010, Makeup Exam 1 Name Section Number 3. A 1|bm saturated mixture of R-134a is initially at 20 °F and a quality of 30%. The substance is then subjected to a process where its temperature is increased to 60 °F at constant quality. A What is the mass in lbrn of liquid R-134a in the mixture initially? (4 pts) What is the pressure in psia of the R—134a initially? (4 pts) What is the pressure in psia finally? (4 pts) What is the volume in in3 of liquid R—134a finally? (4 pts) Sketch the process on a P—v diagram, showing the process, the vapor dome and the two isotherms in all three regions. (4 pts) "10007 7- M‘Mfil => mt, M‘ ‘r: 60": 33."? T :QOOF‘ V ‘2, = V; ~l~ K: > Loni-4'34. (3)011 osq—, Olaf-D ' 0-‘i3 9 V3: , 01970 + [. 3X6619:.,0/m) Va. 5' 0. 30 8 MEEN 315—Spring 2010, Name Section Number 4. A linear spring-loaded piston cylinder device contains 4.0 kg of air (fluid) as the system. The air is heated from 100 kPa and 20°C to 400 kPa and 1000°C. Use tabulated data. A. Determine initial specific volumes (m3/kg). (2 pts) B. Show the process on a p-v diagram. The process path must be correct. (2 pts) C. Determine the net work output (kJ) done by the air. (6 pts) D. Determine the change of the energy (kl) of the air. (5 pts) E. Determine thenet heat input to air (kJ). (5 pts) rm RT 2?3I< a. ’YV‘ 'U' 7 WV Av: 0,0752%? m/ - I" J” a) “who 0hr ; m 79,“; 0v: (V 1%){250 {awe/2% ) : 72.53%?“ 6E: U2-U/ :rm (“Z’a’) fir a2: [kg/g (11/: 2020( Ae= {9%V 9925120400”? :> [Md/ff“) @rw—Ag : 707vf+3/5é’ =>le 3230 (Ml ...
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Spring 10 Makeup Exam 1 Key - MEEN 315—Spring 2010 Makeup...

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