Question

Nyple an phoicuitomerid=400178 is alleilal Y Yahoo! Google Maps Wkipedia Nous 0 2 of 3 A spherical, thin walled metallic container is used to store liquid nitrogen at 80K. The container has a diameter covered with an evacuated, reflective insulation composed of silica powder. The insulation is 25mm thic and is alertas exposed to ambient air at 300K. The thermal conductivity of the silicon powder is 0.0018W/mK The convectivo estrand coefficient of the outer surface is 25W/m2K. The latent heat of vaporization and density of liquid nogen an 2:15. Sands kg/m.. Determine the rate of heat transfer to the liquid nitrogen and the mass rate of nitrogen boil of de

Answer 1

aluhion, Solution - Given data: Diameter di =0.5m, thicknen 8) = 225 mm To,l = ook and Too,2 = 300k latent heat of vapa piration = 2x105 They density of liquid nitrogen = 204 kg/m3 Thermal conductivity of silicos Paudep = 0.0018 W/mk connective heat tranybe coefficient of outer Sabace = 25 W/m2K (a) rate of heat transfer to the Hiquid nitrogen Thermal Circuit: Too, 2 1 ,2- * ) * -* ') -Wnew " , un Pet,cond = arrel to tow ; tecay = For = 0.250 g +30.245m the page Too,2 - Tool (ark) [ta-te] +(1/4man) 300- 80 (146.001a) (car ents) + (0.985)*(es) 220 = 13.65 W 16.076+ 0.04209 19= 13.65W any

(b) The rate of liquid boid-off Energy balance for a cantaol peabace Šn - Sat 20 An= q and Far = minta - q- mihing =0 13.65 ma 2x105 = 6.825x105 kg leee = 5.823 kg/day cor) on volume bayir þ= mle V = 5.823 kg/day 304 kg /m2 = 7.242x10* m? I day = 7.242 litree /day