Browsing by Author "Buhr, Heinrich Otto"
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- ItemOpen AccessHeat transfer to liquid metals, with observations on the effect of super-imposed free convection in turbulent flow(1967) Buhr, Heinrich Otto; Carr, A DEvaluation of the different theories of heat transfer to liquid metals requires values of the ratio of eddy diffusivities of heat and momentum, which may be obtained from temperature and velocity profiles measured in the flowing liquid metal. Temperature profiles have been reported by a number of workers, but these results are in poor agreement and this investigation was undertaken to measure further profiles and thus obtain reliable eddy diffusivities. Chapter 1 introduces the background to liquid metal heat transfer theory, and Chapter 2 contains a discussion of the experimental apparatus that was constructed for the purposes of this investigation. A description of this equipment he-s been published (Ref. 64) and the material is included here with the permission of the candidate's supervisor. Chapter 3 discusses the unsuccessful attempts to measure velocity profiles, and then goes on to consider appropriate values of the eddy diffusivity of momentum, based on the universal velocity profile. The data of Nikuradse are recommended after a careful study of all the available data and the author believes that this is a conclusion which will be useful to other workers in the field, who usually make an essentially random choice of eddy diffusivities.
- ItemOpen AccessMass transfer in bubble column contractors(1974) Rudolph, Victor; Buhr, Heinrich Otto; De Kock, J WGas holdup and overall volumetric mass transfer coefficients in bubble column contactors have been investigated for water and aqueous electrolyte solutions. Two methods were used to obtain experimental data on volumetric mass transfer coefficients: the steady state oxidation technique and a transient method. The former technique was found to be unsuitable for absorption measurements because chemical enhancement of mass transfer, due to simultaneous absorption and fast reaction, caused erroneously high mass transfer coefficients to be evaluated. In the transient experiments the effect of superficial gas velocity, concentration of electrolytes in solution, bubble column diameter and gas inlet orifice diameter on the gas holdup and the mass transfer rate, were investigated. The experimental data for gas holdup and overall mass transfer coefficients obtained both in this study and from the literature have been correlated by dimensionless equations.
- ItemOpen AccessVelocity and temperature distributions for mercury in turbulent flow(1971) Louw, Robert Alexander; Carr, A D; Buhr, Heinrich OttoVelocity and temperature profiles in mercury are reported for vertical flow in a pipe at Reynolds numbers of approximately 3.3 x 10⁴ and 5.4 x 10⁴ with variation in heat flux. At a Reynolds number ≈ 3.3 x 10⁴ profiles are reported for thermal calming lengths of approximately 17, 36, 61 and 84. The velocity profiles, temperature profiles and Nusselt numbers are shown to be strongly influenced by free convection effects. Correlations are presented whereby the amount of distortion of the velocity profile from the isothermal profile under given conditions may be estimated, and the value of the Nusselt number under given conditions may be predicted.