Experimental study of heat transfer from in-line tube bundles to upward foam flow

The heat transfer from the in-line tube bundle to the vertically upward directed laminar aqueous foam flow was investigated by means of experimental set up, consisting of the foam generator, experimental channel, in-line tube bundle, measurement instrumentation and auxiliary equipment. Two in-line tube bundles with different geometries were used for the experiments. One bundle consisted of three rows with six tubes in each. Spacing between centres of the tubes across the experimental channel was s(1)=0.06 m and spacing along the channel was s(2)=0.03 m. The second in-line tube bundle consisted of five vertical rows with six tubes in each. Spacing between centres of the tubes was s(1)=s(2)=0.03 m. All tubes had an external diameter of 0.02 m. Statically stable foam was used for experiments. It was noticed that structure of foam varied while it passed the bundle: bubbles changed their size, liquid-drainage from the foam appeared. Dependence of heat transfer intensity on flow velocity, volumetric void fraction of foam and liquid drainage was determined and described by empirical relationships. Moreover, density and the pattern of tubes location were estimated in experiments and the development of the heat transfer computation method.