Surface heat transfer and pressure drop in forced flow helium II

his thesis investigates the surface heat transfer and pressure drop in forced flow He II. The pressure drop is measured across smooth tubes and corrugated bellows at flow rates of up to 70 g/s. The surface heat transfer measurements are carried out with two different length test sections at mass flow rates of up to 50 g/s and at heat fluxes as high as 10kW/m;The results of the experiments show that surface heat transfer into forced flow He II is independent of flow rate and any effects due to thermal entry length are less than 20%. Pressure drop through smooth tubes and bellows as well as pump performance is observed to be the same as for classical fluids. Standard heat exchanger design techniques can not be used with He II heat exchangers. The experiments further indicate that He II flowing at Re...