SINOPSIS

The heat and mass transfer performances of falling liquid films subjected to evaporative heating and sensible heating inside two converging-diverging tubes were studied and compared to a built-in spring coil tube and a smooth tube. By studying the relationship between heat transfer coefficient and falling film flow rate, we found the converging-diverging tubes were appropriate for falling liquid films subjected to evaporative heating and sensible heating with larger Reynolds number. When the Reynolds number was larger, the converging-diverging tubes had a better heat transfer coefficient than the other two tubes. Within the converging-diverging tubes or the built-in spring coil tube, the evaporation heat transfer coefficient was larger than the sensible heating heat transfer coefficient, but the two coefficients in all these cases increased with the rise of falling film flow rate. According to the experimental data, the heat transfer correlations of falling films subjected to evaporative heating and sensible heating were obtained, which can be referred to in future engineering design and application.