The inner and outer surfaces of a 25-cm-thick wall in summer are at 27 °c and 44 °c, respectively. the outer surface of the wall exchanges heat by radiation with surrounding surfaces at 40 °c, and convection with ambient air also at 40 °c with a convection heat transfer coefficient of 8 w/m2°c. solar radiation is incident on the surface at a rate of 150 w/m2. if both the emissivity and the solar absorptivity of the outer surface are 0.8, determine the effective thermal conductivity of the wall.

An electrical motor raises a 50kg load at a construct velencity .calculate the power of the motor, if it takes 40sec to raise the load through a height of 24m(take g =9.8n/g)

During a steady flow process, the change of energy with respect to time is zero. a)- true b)- false

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