Experimental study on the heat transfer in small cyclones

Abstract

Paper presented at the 9th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Malta, 16-18 July, 2012.

Cyclone separators are widely used in automotive applications, for the cleaning of hot oil mist. Most of the available studies are dealing with the cyclone collection efficiency, and the corresponding pressure drop. The aim of this experimental study is to investigate the gas-to-wall heat transfer, for a flow in a constant wall temperature cyclone configuration, to derive an average Nusselt number correlation. The cyclone is placed in a cold jacket, where the temperature is imposed by external circulation of a coolant. The simultaneous measurements of mass flow rate and characteristic temperatures (cyclone inlet, cold wall and cyclone outlet temperatures) permit the determination of the average wall heat transfer coefficient, through an enthalpy balance. Static pressure measurements at the inlet and outlet of the cyclone are used to evaluate the pressure drop in the cyclone, and a comparison between these results and those obtained by application of the currently available models. The inlet Reynolds number and geometry of the cyclone are varied. An average Nusselt number correlation is proposed for heat transfer in a cyclone under constant wall temperature conditions, as a function of the inlet Reynolds number Rei (400 Rei 20 000), and for different values of the dimensionless geometrical parameters L* (0.75 L* 2.5).