In a gas-fired boiler, water is boiled at 150°C by hot gases flowing through 25-m-long, 5-...

In a gas-fired boiler, water is boiled at 150°C by hot gases flowing through 25-m-long, 5-cm-outer-diameter mechanically polished stainless-steel pipes submerged in water. If the outer surface temperature of the pipes is 160°C, determine (a) the rate of heat transfer from the hot gases to water. (b) the rate of evaporation, (c) the ratio of the critical heat flux to the present heat flux, and (d) the surface temperature of the pipe at which critical heat flux occurs.

Answers: (a) 1609 kW,-(b) 0.761 kg/s. (c) 4.52 (d) 166.5°C

FIGURE P10 – 38