Athin-walled cylindrical pressure vessel of inner radius 20 mm, wall thickness 2mm and closed ends is subjected to an internal pressure of 8 mpa. a twisting moment (torque) t is now applied to the ends of the vessel. find the value of t at which compressive stresses will start to appear in the vessel wall.

For the closed feedwater heater below, feedwater enters state 3 at a pressure of 2000 psia and temperature of 420 °f at a rate of ix10 ibhr. the feedwat extracted steam enters state 1 at a pressure of 1000 psia and enthalpy of 1500 btu/lbm. the extracted er leaves at an enthalpy of 528.7 btu/lbm steam leaves as a saturated liquid. (16) a) determine the mass flow rate of the extraction steam used to heat the feedwater (10) b) determine the terminal temperature difference of the closed feedwater heater