The one-dimensional slab below has constant properties and no internal heat generation. the slab is initially at a uniform temperature ti. an electrical heater at the bottom surface is energized for t> 0, providing a uniform heat flux at the surface x=0. all boundaries are perfectly insulated. a) simplify the heat conduction equation and provide the necessary boundary conditions and initial condition. b) on t-x coordinates, sketch the temperature distributions for the initial condition and for three times after the heater is energized. will a steady-state temperature distribution ever be reached? c) sketch the flux versus time for planes x=0, x=l/2, and x=l.

Amass of m 1.5 kg of steam is contained in a closed rigid container. initially the pressure and temperature of the steam are: p 1.5 mpa and t 240°c (superheated state), respectively. then the temperature drops to t2= 100°c as the result of heat transfer to the surroundings. determine: a) quality of the steam at the end of the process, b) heat transfer with the surroundings. for: p1.5 mpa and t 240°c: enthalpy of superheated vapour is 2900 kj/kg, specific volume of superheated vapour is 0. 1483 m/kg, while for t 100°c: enthalpy of saturated liquid water is 419kj/kg, specific volume of saturated liquid water is 0.001043m/kg, enthalpy of saturated vapour is 2676 kj/kg, specific volume of saturated vapour is 1.672 m/kg and pressure is 0.1 mpa.

Different types of steels contain different elements that alter the characteristics of the steel. for each of the following elements, explain what the element does when alloyed with steel.

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