At approximately what temperature (in Kelvin) would a specimen of an alloy have to be carburized for 1.2 h to produce the same diffusion result as at 750°C for 13 h? Assume that values for D0 and Qd are 3.4 × 10-5 m2/s and 156 kJ/mol, respectively.

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?

The filament of an incandescent lamp has a temperature of 2000k. calculate the fraction of radiation emitted in the visible light band if the filament is approximated as blackbody

What is the heat treatment of metals? what is the benefit of it? why and how it's useful? answer in details, do not write by hand.