EML 3015C Thermal Fluids I Fall 2002Lab Assignment # 4 (Oct. 2, 2002)1. The figure shows a T-v Diagram for water where a 3 MPa, constant pressure line is also shown. (a) What is the specific volume of saturated vapor atthis pressure; what is the correspondingtemperature? Indicate these on the graph.(b) If 10 kg of saturated vapor at 2 MPa condensesto saturated liquid at the same pressure, what isthe change in temperature during this process?What is the change in the total volume?(c) Consider a constant volume process wheresaturated vapor at 3 MPa condenses to 2 MPa.Indicate this process on the T-v diagram.(d) What is the mass of the vapor at 2 MPa, if thetotal mass of the mixture is 10kg ?(e) What is the change in total enthalpy of thesystem for this process (in part c)?(f) At 3 MPa, estimate the temperature above whichwater vapor can be treated as an ideal gas, withan error less than 1%. Justify your answer.2. A very thin computer chip generates heat at the rate of 10 W and is being cooled by an air stream at T=20C, as shown. A piece of metal with a conductivity, kmetal =100 W/(m C) and a thickness of 0.1 m is placed above the chip. The manufacturer specifies that the computer cannot be operated at a temperature above 100C. (a) What is the surface temperature (TS) of the metal plate if this condition (TC=100 C) is satisfied?(b) What is the convective heat transfer coefficient for this condition?(c) If the thermal conductivity of air, kair = 0.03 W/(m C?), what is the temperature gradient, dT/dy, in the air at the surface of the metal.(d) What will be the new surface temperature, TS, and the chip temperature, TC , if the heat transfer coefficient were halved of the value calculated for part b.(e) Suggest two practical ways in which the temperatures are lowered for computer processors.Assume that heat transfer to the sides of the plate is negligible and the heat transfer is one-dimensional and only in the vertical direction.EML 3015C Thermal Fluids I Fall 2002Lab Assignment # 4 (Oct. 2, 2002)1InsulatorMetal blockk =100 W/(m C)Area 0.001 m2Thickness 0.1 mAir stream at T=20CSurface temperature, TS= ?Computer chip,10 W of power, Chip Temperature, TC=100C0.1 mTemperature Distribution in airTemp gradientdT/dy = ?yxTvP = 3 MPa3. A very large pressurized tank contains waterand is connected to a U-tube mercurymanometer, which is open to atmosphere onone side, as shown. The tank has a 0.1 m2hole at the bottom, which is plugged with astopper. All other pertinent information isalso given in the figure. a. Determine the gage pressure in the airinside the tank at the surface of water.b. Find the force needed to hold the stopperin place.c. If the stopper is removed, calculate themass flow rate with which the waterbegins to drain. For this part you mayassume that the pressure at the watersurface = 65 kPa, gage.d. If the tank has a diameter of 3m find therate at which the water level begins todrop when the plug is removed.e. If a 20m long., 0.36m diameter, smoothhorizontal pipe is attached to the end ofthe hole at the bottom of the tank and astopper is placed at the exit of the pipe. Calculate the mass flow rate when the stopper is removed. Compare this value to part c, doe is make sense ?2Mercury, = 13600 kg/m3Open to atmosphereAir, = 1 kg/m3Water = 1000 kg/m3Stopper Area = 0.1 m20.5 m5 m0.25 m0.25
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