Annealing is a process by which steel is reheated andthen cooled to make it less brittle. consider the reheatstage for a 100-mm-thick steel plate (7830 kg/m3,c550 j/kgk, k48 w/mk), which is initially at auniform temperature of ti200c and is to be heatedto a minimum temperature of 550c. heating iseffected in a gas-fired furnace, where products of com-bustion at t800c maintain a convection coeffi-cient of h250 w/m2k on both surfaces of the plate. how long should the plate be left in the furnace?

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

Carbon dioxide gas expands isotherm a turbine from 1 mpa, 500 k at 200 kpa. assuming the ideal gas model and neglecting the kinetic and potential energies, determine the change in entropy, heat transfer and work for each kilogram of co2.

Along 8-cm diameter steam pipe whose external surface temperature is 900c connects two buildings. the pipe is exposed to ambient air at 70c with a wind speed of 50 km/hr blowing across the pipe. determine the heat loss from the pipe per unit length. (b) air at 500c enters a section of a rectangular duct (15 cm x 20 cm) at an average velocity of 7 m/s. if the walls of the duct are maintained at 100c. a) the length of the tube for an exit temperature of the air to be 40 0c. b)the rate of heat transfer from the air. c) the fan power needed to overcome the pressure drop in this section of the duct.