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To enhance the effective surface, and hence the chemical reaction rate, catalytic surfaces often take the form of porous solids. One such solid may be visualized as consisting of a large number of cylindrical pores, each of diameter D and length L.
Consider conditions involving a gaseous mixture of A and B for which species A is chemically consumed at the catalytic surface. The reaction is known to be first order, and the rate at which it occurs per unit area of the surface may be expressed as
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Fundamentals of Heat and Mass Transfer
- Your team has invented a compound for use in refrigeration processes, R−X. You have asked your technician to characterize the pure component vapor-liquid equilibrium of the fluid at 300 K, and he has faxed you the results below. Unfortunately, the quality of the fax is low so that you are unable to distinguish if the properties correspond to those of the liquid or vapor phase. Using only the provided data, determine which properties correspond to the liquid and vapor phase. Also be sure to explain how you came up with your answer. T = 300 K P = 7.0282 bar V = 0.83357cm3/g V = 29.246cm3/g U = 392.71 kJ/kg U = 236.60 kJ/kgarrow_forwardA substance has a melting point of 20°C and a heat of fusion of 2.4 × 10 to power of ((4)) J/kg. The boiling point is 150°C and the heat of vaporization is 4.8 × 10 to power of ((4)) J/kg at a pressure of 1.0 atm. The specific heats for the solid, liquid, and gaseous phases are 600 J/(kg • K), 1000 J/(kg • K), and 400 J/(kg • K), respectively. The quantity of heat required to raise the temperature of 3.00 kg of the substance from 9°C to 98°C, at a pressure of 1.0 atm, is closest toarrow_forwardShown to the right is the solid-liquid phase behavior for mixtures of component A and component B at 1 atm. Use the phase diagram to answer the following questions. a) Specify the melting point of substance B at 1 atm b) What is the maximum composition (mole fraction) of component B that is possible for the mixture to exist in phase S2? At what temperature does this occur? c) 20mol of component A and 180mol of component B are mixed at 350°C and 1 atm. The mixture is cooled at constant pressure to 200°C. i) What phases are present at the final state? ii) What is the composition of each phase at the final state? iii) What is the number of moles of each phase at the final state?arrow_forward
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- A mechanism for hardening steel is called carburization. To achieve this process, the piece of steel is exposed to an atmosphere rich in hydrocarbon such as methane (CH4). Consider a steel with a carbide concentration of 0.25wt%, which must be treated at 950˚C. If the carbon concentration at the surface is suddenly increased to 1.20wt%, how long does it take for a penetration of 0.5mm from the surface to reach a concentration of 0.80wt%? . The diffusion coefficient for carbon in iron at this temperature is 1.6 x 10-11 m2s-1. Assume that the piece of steel is semi-finite. Use the table below.arrow_forwardA large piece of biological tissue has to be kept at a temperature as low as possible without freezing (ice formation). The water in the tissue has several solutes dissolved in it and the effective molecular weight of the dissolved solutes is 50. The weight of all dissolved solutes combined is 10% of the weight of water. The latent heat of fusion of water is 335 kJ/kg and the molecular weight of water is 18. What is the lowest temperature that this tissue can be stored at, without ice formation?arrow_forwardA plate of iron is exposed to a carburizing atmosphere on one side and a decarburizing atmosphere on the other side at 850 oC. If a condition of steady state is achieved, calculate the diffusion flux of carbon through the plate if the concentrations of carbon at positions of 5 and 10 mm beneath the carburizing surface are 1.4 and 0.8 kg/m3, respectively. Assume a diffusion coefficient of 3 x 10 -11 m2/s at this temperature.arrow_forward
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