Analytical solution and experimental measurements for temperature distribution prediction of three-phase direct-contact condenser

摘要

An experimental ana analytical investigation ror tne temperature distribution prediction ot a tnree-pnase bubble-type direct-contact condenser conducted, using a short Perspex column with 4 cm internal diameter and 70 cm height as a direct contact condenser. Vapour pentane and water were exploited as dispersed phase and continuous phase respectively. The effect of mass flow rate ratio (43.69%, 22.97%, 12.23%, 8.61% and 6.46%) and initial dispersed phase temperature (37.6 ℃, 38.4 ℃ and 41.7 ℃) on the direct contact condenser output were studied. Linear temperature distributions along direct contact condensers were found experimentally, except at mass flow rate ratio 43.69% and with less magnitude at 22.97%, for different initial vapour temperatures, while theoretically this behaviour is purely linear. The results showed that the mass flow rate ratio and the hold up have a dominant effect on the direct contact condenser output. On the other hand, the initial vapour temperature had a slight effect on the direct contact condenser output temperature which indicates that the latent heat is controlled in the exchange process. The analytical model is based on the one-dimensional mass and energy equations. New expressions for average heat transfer coefficient and two-phase bubbles relative velocity are derived implicitly. Furthermore, the model correlated very well against experimental data obtained.