Question

Problem 1. Steam at 120°C is transported in a long 8" outer diameter pipe. Its outer surface is covered with a 1" thick fiberglass (thermal conductivity, 0.05 W/(mK)) insulation. When the outer temperature is 0°C, the rate of condensation of steam is measured to equal 0.06 g per meter of the pipe length. Estimate the heat transfer coefficient. The heat of vaporization of the steam is 2600 J/g. The resistance to the heat transfer through the pipe wall may be assumed to be negligible. New environmental regulations and energy saving considerations require that the heat lost be reduced by 50 per cent. Your boss suggests that you can meet the requirement by increasing the insulation thickness. Determine the heat lost as a function of the insulation thickness on an EXCEL spreadsheet. What must be the thickness to meet the new requirement? Prepare a chart showing the percent energy saved as a function of the insulation thickness to impress your boss. You also want to be conservative in your recommendation so that you carry out additional calculations allowing for the possibility that the heat transfer coefficient may be twice the measured value on some days. What will be your recommended insulation thickness?

Answer 1

The given question is related to Heat loss from an Insulated steam pipe.

ニ 2-600T, conduuahea of steam m = 0.067/m per mehe pipe pipe,lingh Then Heat trans for coelfsi steam PiPE as e ne have hea-lost-frm, steam a thre AT-temp difference betwe en inh do audouhid R. Feremce T,--な lost n S Here 2.

0-1 =0.363. 0.314 Convec penm 120 c to oo lost 26 2.4 lost- 393-273 But SiosR 0 369 1 120 24-0-369 23:43 071b h = 0.06

dation, e have ть. critial .~aaius 8 insulatio", we have D-86 ivey 2 - 0830 203 t = 0.627 m e) t = 24.6 iuches.