Bogumił Bieniasz

Forced convection mass/heat transfer coefficient at the surface of the rotor of the sucking and forcing regenerative exchanger

Abstract Experimental investigations of mean mass/heat transfer coefficients at the surface of two different curved short ducts of rotors of the sucking and forcing regenerative heat exchanger were made for forced laminar flow in static conditions. An electrolytic technique was employed. The results for two types of ducts are presented finally by correlations for jM Chilton-Colburn coefficient vs Reynolds number. The results for one of the ducts are consistent with the previous results of the author for the inner surface and developed flow in a straight annular duct with similar L/Dh.

Effect of positioning the axis of a lamellar rotor model of a sucking and forcing regenerative exchanger on the intensity of convective mass/heat transfer

Abstract Mean values of the convective mass/heat transfer coefficients for two porous structures—differing in bc th profile and the value of Dh—of the rotor of a heat regenerator were measured for horizontal and vertical positions of the axis. The flow in short curved ducts of the immovable model was forced by the pump. The results of electrolytic measurements were independent of the positioning of the axis. Final correlations of the jM-factor or Sh vs Re are almost identical for both duct geometries for the common range of Re. An example of the use of the results for simple heat transfer calculations illustrates a problem. The results are valid for a constant-potential/temperature boundary condition.

Short ducts consisting of cylindrical segments and their convective mass/heat transfer, pressure drop and performance analysis

Abstract The effect of turbulence stimulation caused by dividing a short duct into seven cylindrical segments and setting them in three different arrays at one value of displacement ratio was studied by the use of the electrolytic technique. The inlet of the duct was connected to the plenum with a diffuser causing a non-developed flow in the duct. One value of contraction ratio between the plenum and the tested duct was in use. Schmidt number was 1590. Mean values of the mass/heat transfer coefficient for each segment and the friction losses for the whole ducts were measured for Reynolds numbers spanning the range 7600–44200. Correlations on the mean Chilton-Colburn coefficient were stated for the whole duct of three types. Performance analysis of the ducts was done at equal surface area for two common cases of equal flowrate and pumping power. The results might be used, e.g. in the design of turbine blade cooling channels and of some highly effective shell-and-tube heat exchangers.