A thermosyphon consists of a closed container that absorbs heat along its boiling section and rejects heat along its condensation section. Consider a thermosyphon made from a thin-walled mechanically polished stainless steel cylinder of diameter D. Heat supplied to the thermosyphon boils saturated water at atmospheric pressure on the surfaces of the lower boiling section of length Lb and is then rejected by condensing vapor into a thin film, which falls by gravity along the wall of the condensation section of length Lc back into the boiling section. The two sections are separated by an insulated section of length Li. The top surface of the condensation section may be treated as being insulated. The thermosyphon dimensions are D = 20 mm, Lb = 20 mm, Lc = 40 mm, and Li = 40 mm.

(a) Find the mean surface temperature, Ts,b, of the boiling surface if the nucleate boiling heat flux is to be maintained at 30% of the critical heat flux.

(b) Find the total condensation flow rate, m, and the mean surface temperature of the condensation section. Ts.c.

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A.C 4. Condensation Saturated section steam Condensation film L, Insulation Saturated. Boiling section water Electric -D heater