Ahollow sphere is constructed of pure aluminum with an inner diameter of 4 cm and an outer diameter of 8 cm. the sphere is covered with a 1-cm layer of insulating material having k = 50 w/m · k and the outside of the insulation exposed to h = 20 w/m2.k and t = 10c. the inside temperature of the sphere is maintained at 100c. (a) sketch the thermal resistance network and (b) determine the heat loss to the ambient.

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