The purification of hydrogen gas is possible by diffusion through a thin palladium sheet. calculate the number of kilograms of hydrogen that pass per hour page 2 of 3 through a 6 mm thick sheet of palladium having an area of 0.25 m2 at 600°c. assume a diffusion coefficient of 1.7 × 10-8 m2 /s, that the concentrations at the high and low pressure sides of the plates are 2.0 and 0.4 kg/m3 of hydrogen per cubic meter of palladium, and that steady state conditions have been attained.

If the thermal strain developed in polyimide film during deposition is given as 0.0044. assume room temperature is kept at 17.3 c, and thermal coefficient of expansion for the film and the substrate are 54 x 10^-6c^-1 and 3.3 x 10^-6c^-1respectively. calculate the deposition temperature.

Air is to be cooled in the evaporator section of a refrigerator by passing it over a bank of 0.8-cm-outer-diameter and 0.4-m-long tubes inside which the refrigerant is evaporating at -20°c. air approaches the tube bank in the normal direction at 0°c and 1 atm with a mean velocity of 4 m/s. the tubes are arranged in-line with longitudinal and transverse pitches of sl- st 1.5 cm. there are 30 rows in the flow direction with 15 tubes in each row. determine (a) the refrigeration capacity of this system and (b) pressure drop across the tube bank. evaluate the air properties at an assumed mean temperature of -5°c and 1 atm. is this a good assumption?

Thermal stresses are developed in a metal when its a) initial temperature is changed b) final temperature is changed c) density is changed d) thermal deformation is prevented e) expansion is prevented f) contraction is prevented