(1.22) an overhead 25-m-long, uninsulated industrial steam pipe of 100- mm diameter is routed through a building whose walls and air are at 25°c. pressurized steam maintains a pipe surface temperature of 150°c, and the coefficient associated with natural convection is h = 10 w/m 2 · k. the surface emissivity is ε = 0.8. (a) what is the rate of heat loss from the steam line? (b) if the steam is generated in a gas-fired boiler operating at an efficiency of ηf = 0.90 and natural gas is priced at cg = $0.02 per mj, what is the annual cost of heat loss from the line?

The filament of an incandescent lamp has a temperature of 2000k. calculate the fraction of radiation emitted in the visible light band if the filament is approximated as blackbody

Agas contained within a piston-cylinder assembly e end nation about same energy states, 1 and 2, where pi 10 bar, v undergoes two processes, a and b, between the sam 0.1 m3, ui-400 kj and p2 1 bar, v2 1.0 m2, u2 200 kj: process a: process from 1 to 2 during which the pressure- volume relation is pv constant process b: constant-volume process from state 1 to a pressure of 2 bar, followed by a linear pressure-volume process to +20 0 state 2 kinetic and potential energy effects can be ignored. for each of the processes a and b, (a) sketch the process on p-v coordinates, (b) evaluate the work, in kj, and (c) evaluate process the heat transfer, in kj

Air (c-1.006 kj/kg.k, r-0.287 kj/kg.k) enters a nozzle steadily at 280 kpa and 77°c with a velocity of 50 m/s and exits at 85 kpa and 320 m/s. the heat losses from the nozzle to the surrounding medium at 20°c are estimated to be 3.2 kj/kg. determine (a) the exit temperature and (b) the total entropy change for this process. solve this problem using constant specific heats.