Characteristics of Flow Pattern, Void Fraction, and Pressure Drop in A Horizontal Minichannel (Case Study Using Air-Mixture of Distilled Water and Butanol)

ELI KUMOLOSARI, Prof. Dr. Ir. Indarto, DEA.; Dr. Deendarlianto, S.T., M.Eng.

2017 | Tesis | S2 Teknik Mesin

Parameter aliran dua fasa penting untuk menentukan nilai koefisien konveksi (h) pada perpindahan panas dan penurunan tekanan (��P), nilai properti aliran dua fasa, kurva karakteristik sistem perpipaan. Penelitian ini meneliti pola aliran dua fasa, fraksi hampa, dan penurunan tekanan pada saluran mini horisontal transparan dengan diameter dalam 1,6 mm. Fluida kerja adalah campuran udara dari akuades dan butanol. Kecepatan superfisial gas dan cairan divariasikan pada rentang 0,066 - 66 m/s dan 0,033 - 4,935 m/s. Pola aliran yang teramati adalah plug, bubbly, slug-annular, annular, dan churn. Penelitian ini juga menghasilkan peta pola aliran. Hasil penelitian menunjukkan bahwa peta pola aliran penelitian ini hanya memiliki kesesuaian yang baik dengan penelitian Triplett et al. (1999a) kecuali untuk garis transisi plug dan bubbly ke churn. Hasil fraksi hampa menunjukkan bahwa pada JL konstan, peningkatan JG menyebabkan gas plug semakin panjang, sementara pada JG konstan, saat JL meningkat, gas plug semakin pendek; persentase butanol sebanding dengan nilai fraksi hampa. Hasil penurunan tekanan menunjukkan bahwa secara umum, seiring persentase butanol meningkat, nilai penurunan tekanan semakin tinggi; penurunan tekanan adalah kuadratik terhadap JG dan JL.

Two-phase flow parameter is important to determine the value of convection coefficient (h) on heat transfer and pressure drop (��P), property values of two-phase flow, characteristics curve of the piping system. The present study investigated the two-phase flow pattern, void fraction, and pressure drop in a transparent horizontal minichannel with inner diameter of 1.6 mm. The working fluids were air-mixture of distilled water and butanol. Superficial velocities of gas and liquid were varied in the range of 0.066 - 66 m/s and 0.033 - 4.935 m/s, respectively. The flow patterns observed were plug, bubbly, slug-annular, annular, and churn. The study also yielded flow pattern map. The results showed that flow pattern map of this study only agreed well with that by Triplett et al. (1999a) except for the transition line of plug and bubbly to churn. Void fraction results show that at constant JL, as JG increased, gas plug was getting longer, while at constant JG, as JL increased, gas plug was getting shorter; butanol percentage was proportional to void fraction values. Pressure drop results show that generally, as butanol percentage increased, pressure drop values were getting higher; pressure drop was quadratic to JG and JL.

Kata Kunci : Two-Phase Flow, Minichannel, Flow Pattern, Void Fraction, Pressure Drop