Air at 10°C and I atm flows over a flat plate (30 cm x100 cm) at 20 m/s. The plate is maintained at 70°C. (a) calculate the boundary layer thikness at distances of 30 cm and 100 cm, (b) calculate the heat transfer from first 30 cm and from whole the plate.
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The following weather reactions are taking place at 0.7L PFR: The reaction temperature is 520oC, the pressure is 1 atmosphere pressure, and the initial reaction is composed only of acetone. The results of measuring the conversion rate when changing the mass flow rate of acetone are shown in the table below. When the response is secondary, calculate the response rate constant. The molecular weight of acetone is 58.
CH3COCH3 (acetone) CH3=C=O + CH4
Run No. | 1 | 2 | 3 |
Mass Flow Rate (g/hr) | 50 | 21 | 10.8 |
XA (%) | 13 | 24 | 35 |
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In the process of methanol production, a gas stream flowing at a molar flow rate of 100 mol / min containing 32 mol% CO, 64 mol% Hz. and 4 mol% of N2 is led to the reactor. The product from the reactor is condensed where liquid methanol is separated. Unreacted gases are recycled in a ratio of 5: 1 mol of recycle to moles of fresh feed. Parts of the recycled gases are purged. The reaction equation is CO + 2H2 - CH2OH. A- Calculate purge, recycle, and product flow rates and compositions. B - Check the reactor material balance.
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The service life of a battery used in a cardiac pacemaker is assumed to be normally distributed. A sample of twelve batteries is subjected to an accelerated life test by running them continuously at an elevated temperature until failure, and the following lifetimes (in hours) are obtained: 26.7, 26.8, 25.8, 24.7, 24.6, 27.4, 25.5, 27.2, 27.5, 24.9, 26.9, and 25.5. Test the hypothesis that the mean battery life exceeds 25 hours.
A.) State the null and alternative hypothesis.
B.) Compute the test statistics.
C.) Compute the P-value.
D.) State a conclusion
E.) Construct a 95% two-sided confidence interval on mean life in the accelerated test.
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The data given below are for the adsorption of nitrogen on alumina at 77.3 K. Show that they fit in a BET isotherm in the range of adsorption and find Vmono and hence surface area of alumina (m2 g-1). At 77.3 K, saturation pressure, P* = 733.59 torr. The volumes are corrected to STP and refer to 1 g of alumina. The area occupied by a nitrogen molecule at -195 °C estimated to be 16.2
x 10-20 m2.
P/ (torr) |
37.67 |
74.20 |
114.54 |
142.0 |
185.34 |
V (cm3 g-1: STP) |
23.14 |
28.1 |
33.1 |
36.35 |
41.49 |
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Steam at 400°C and 40 bar flows steadily through an adiabatic
turbine at a volumetric
flowrate of 5,000 m3/h. The steam leaving the turbine at 1 bar is
then cooled at constant
pressure in a condenser to 25°C. The rate of transfer from the
condenser is 50 MW.
Calculate the power output generated by the turbine (MW). Clearly
state assumptions (if
any) and reference state.
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The ammonia gas (mw = 17 kg/kgmol) at 40 oC and 3 atm was transported at flowrate of 5 kg/h by an insulated pipeline having the total thickness of 2.0×10-3 m. The pressure and temperature of the ammonia gas suddenly drop to ambient temperature and pressure of 25 oC and 1 atm. A thorough investigation showed that the ammonia gas leaked to surrounding atmosphere through a pipeline wall cracking hole having an equivalent diameter of 3 mm.
a) State all the assumptions. Determine the mass rate of ammonia gas lost to surrounding atmosphere as well as the mass contamination rate of ammonia gas in the insulated pipeline by air (mw = 28.97 kg/kgmol).
b) Determine the mole fraction air in the pipeline. If repairing the pipeline required 5 hours, how much ammonia gas was lost from the incident.
Given: Ammonia-air diffusivity, DAB at 298.0 K is 2.8×10-5 m2 /s. The ammonia gas and air at those conditions could be assumed obeyed an ideal gas law. The universal gas constant, R is 8.205×10-2 m3 atm/kmol.K.
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Q3)
Briefly write the biomass potential in Malaysia. Describe the efficient thermodynamic cycles that could be used to convert biomass energy for industrial applications.
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By using an appropriate example and diagram, explain the steady state diffusion of component A through non-diffusing component B for molecular diffusion of gases.
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All normally ductile polymers can also craze even in the absence of solvents, given the right circumstances. The crazing stress of each polymer is slightly sensitive to temperature but insensitive to strain rate. Ductile to brittle transition temperature (Tb) are often found at low temperatures for such polymers; explain why Tb shifts to higher temperatures at increasing strain rates. (Hint: the easiest way to explain this is to use diagrams. If you do, be sure the label the curves and explain briefly what they mean.)
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Explain how electricity is produced using a hydrogen fuel cell.
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