... reductions in q and m are achieved with r2 = 0 .26 -3 m With increasing r2, q and m decrease from values of 17 02 W and 8×10 kg/s at r2 = 0 .25 m to 0. 627 W and 2. 9×10-6 kg/s at r2 = 0.30 m COMMENTS: ... surface of the insulation, it follows that q′ cond = q′ conv + q′ rad Ts,1 − Ts ,2 ln ( r2 r1 ) 2 k ( = Ts ,2 − T∞ + Ts ,2 − Tsur ( 2 r2 h ) ( 2 r2 h r ) where h r = εσ Ts ,2 + Tsur 2 ) (Ts ,2 + Tsur ... r1 ) − (1 r2 )] , and, from Eq 2 ) (Ts ,2 + Tsur ) With t = 10 mm (r2 = 26 0 mm), ε = 0 .2 and T∞ = Tsur = 29 8 K, an iterative solution of the energy balance equation yields Ts ,2 ≈ 29 7.7 K, where...