Stationärer Stoff- und Wärmeübergang an stationär quer angeströmten Zylindern

Abstract

The steady forced convection mass and heat transfer from circular cylinders has been investigated. The full mass transport differential equation has been integrated numerically.The employed velocity distributions are known [ 1]. The most important result is reproduced in a correlation for the mass transfer, which regards the turbulence intensity in the flow of the cylinders. This mass transfer law is proofed theoretically and experimentally in the range of Schmidt numbers from Se = 0.73 up to Sc = 3.3 • 104 ; however it is valid for 0 <-Sc goo. It can be used for all values of ReSc greater than ReSc = 7.3 • I0 -s and for all values of the Reynolds number less than the critical value, Rex r 9 The critical Reynolds number, Re k r , is a known function of the turbulence intensity [ I]. For values of Re Sc less than Re Sc = 7.3 • mass transfer can be predicted by an analytical equation that based on Oseen type linearization of the differential equation. The conditions are illustrated, which allow to calculate the quantities for heat transfer by means of the correlations for the mass transfer.

Impact of agglomeration on the quantitative assessment of Bacillus stearothermophilus heat inactivation

“…At time t = 0 the capillary is immersed in the heating medium. Temperature of the suspension at time t = 0 is 0°C, and Thermal conductivity and specific heat from the suspension as soon as kinematic viscosity and Prandl number (dimensionless number approximating the ratio of kinematic viscosity and thermal diffusivity; Sucker & Brauer, 1976;VDI, 1994) from the heating medium are dependent of temperature, all other physical properties are independent of temperature.…”

“…Agglomeration size distribution q 0 (i) of a B. stearothermophilus spore suspension with different geometrical assumptions for the agglomerates and an inset, which shows occurrences between 10 2 and 10 5 spores per agglomerate. Prandl number (according to Sucker & Brauer, 1976) of 39.89 for the heating medium silicon oil. The biggest differences exist during the initial phase between zero and one second treatment time.…”

“…Because of axis symmetry just a quarter of the glass capillary geometry is necessary. According to Sucker and Brauer (1976) the outer heat transfer coefficient can be calculated. All necessary properties of the heating medium and water are given (VDI, 1994).…”

Unsteady conjugate heat/mass transfer from a circular cylinder in laminar crossflow at low Reynolds numbers

“…Forced convection heat/mass transfer from a circular cylinder in laminar crossflow (we restricted the literature citation to articles similar to the present work) have been studied by Dennis et al [2], Sucker and Brauer [3], Jain and Goel [4], Karniadakis [5], Chen and Weng [6], Yang et al [7], Kurdyumov and Fernandez [8] and Lange et al [1]. In the articles mentioned previously, the temperature/concentration of the cylinder is considered constant.…”

Effects of turbulence on heat and mass transfer in stagnation flows

“…[16 -181 for the stagnation line and by Sucker and Brauer [47] for the integral heat transfer on circular cylinders. Then, three regions can be distinguished.…”