Pengembunan campuran uap dan gas dalam kondensor tegak

• Main Author: SARTO, SARTO
• Format: Theses and Dissertations NonPeerReviewed
• Published: Universitas Gadjah Mada 2001
• Subjects: Fluid Physics
• Online Access: https://repository.ugm.ac.id/171830/; http://etd.repository.ugm.ac.id/index.php?mod=penelitian_detail&sub=PenelitianDetail&act=view&typ=html&buku_id=111
• Institution: Universitas Gadjah Mada

Condensation of vapor-gas mixtures is a simultaneous heat and mass transfer process. The existence of gases in condensation does not only affect the heat transfer rate, but also the mass transfer rate. In the multi-component condensation, its mathematical model become more complicated because of the existence of the diffisional interaction between vapors. Theoretical studies on condensation of vapor and gas mixtures have been done extensively, but have not given satisfactory results yet. The objective of the research is to determine semi-empirical equations, which are simple and accurate enough, to be used to estimate the heat and mass transfer coefficients for designing vapor-gas mixture condensers. The experiment was conducted in a vertical double pipe condenser of 1.7 m length. The inner and outer pipe sizes were, respectively, 1" and 2". The mixture of vapors and gas was flowing in the annulus from the top of the condenser and cooling water was counter-currently flowing inside the tube. There were 7 sample points to take samples of vapors and gas mixtures. The distance between two sample points were 0.25 m. The mixture systems were chosen based on the variation of boiling points and diffisivity coefficients of the components. The chosen systems were ethanol-benzene, ethanol-toluene, methanol-propanol, and methanol-water. While air was used as an inert or gas. The measurements of process variables were done when the process had been steady. The experimental data consisted of flow-rates and temperatures of the colling water, compositions and temperatures of the vaporgas, flow-rates and temperatures of condensate, air flow-rates, and pressures of the system. The gas mole fractions used were between 1% and 10 % and the Reynolds number were between 2000 and 28000 The results of the experiment showed that the mixture of methanol-water-gas behaved differently from the other three mixtures. At some distance from the inlet, methanol behaved as a gas while water condensed since it was entering the condenser. The other three mixtures, on€ythe air behaved as a gas in all part of the condenser. Heat and mass transfer coefficients were evaluated based on the experimental data using simple mathematical models, that were developed from heat and mass balances. The relationship of the Nusselt number with the Reynolds number, Prandtl number, and gas mole @actionsis shown by the following equation ~rl' Nu = 19,7811 (l-y,,)3~~g'Reo~8112 ~ with standard deviations between 27,23% and 30,80%. Where as fimctional relationship between Sherwood number with Reynolds number, Schmidt number, and gas mole fiaction were stated by equation Sh=5,6266( l-yn)2s8839Reo*8'64 Sc'" with standard deviations between 27,82% and 30,76 %. Both equations can be used for all systems studied, but the methanol-water-air system.