Pengaruh Radius Belokan T-Junction Minichannel Horisontal Terhadap Karakteristik Aliran Gas-Cair di Daerah Downstream

Leila Hanjani Hananto, Prof. Dr. Ir. Indarto, DEA., IPM., ASEAN Eng.

2023 | Tesis | S2 Teknik Mesin

Aplikasi sistem transportasi fluida semakin berkembang pada saluran berdiameter kecil untuk mengalirkan aliran dua fase. Distribusi fase yang tidak merata ketika aliran dua fase melewati sebuah T- Junction dapat menyebabkan permasalahan pada performa di daerah downstream. Salah satu permasalahan yang diakibatkan penggunaan T-Junction adalah kemunculan slug. Ukuran panjang dan frekuensi pola aliran slug dapat mengakibatkan fluktuasi penurunan tekanan yang akan mempengaruhi kinerja sistem transportasi fluida.

Pengamatan visual dilakukan terhadap pola aliran yang muncul dan karakteristik pola aliran slug menggunakan high speed video camera yang kemudian diolah dengan metode image processing pada software Matlab R2020a. Seksi uji merupakan T-Junction MInichannel dengan penampang persegi panjang berukuran 1,25 x 2,25 mm dengan diameter hidraulik sebesar 1,6 mm yang dilewati oleh fluida kerja air dan udara. Variasi radius yang diaplikasikan pada belokan pertemuan cabang di T-Junction sebesar 0; 0,48; dan 0,80 mm.

Pola aliran yang terbentuk dari eksperimen ini adalah bubbly, slug, churn, dan pola aliran transisi churn to elongated slug. Kecepatan superfisial air dan udara mempunyai pengaruh pada karakteristik slug. Radius T-Junction tidak memberi pengaruh signifikan pada panjang rata-rata slug yang diamati di daerah downstream. Peningkatan radius T-Junction tidak memiliki tren yang linear apabila dibandingkan dengan kecepatan slug yang terjadi di daerah downstream. Frekuensi slug meningkat secara polinomial pada peningkatan kecepatan superfisial air dan udara. 

The development of fluid transportation systems is increasingly advancing in small-diameter channels for conveying two-phase flows. Uneven phase distribution when a two-phase flow passes through a T-Junction can lead to performance issues in the downstream area. One of the problems caused by using a T-Junction is the emergence of slugs. The length and frequency of slug flow patterns can result in fluctuations in pressure drop, which will affect the performance of the fluid transportation system. 

Visual observations were carried out on the flow patterns that emerged, and the characteristics of slug flow patterns were analysed using a high-speed video camera. The recorded videos were then processed using image processing methods within the Matlab R2020a software. The test section consisted of a T-Junction Minichannel with a 1.25 x 2.25 mm rectangular cross-section and a hydraulic diameter of 1.6 mm, through which flows a mixture of air and water as the working fluid. Variations in radii were applied at the branching bend of the T-Junction, specifically 0 mm, 0.48 mm, and 0.80 mm.

The flow patterns formed from this experiment include bubbly, slug, churn, and the transitional flow pattern churn to elongated slug. The superficial velocities of water and air have an impact on slug characteristics. The radius of the T-Junction does not significantly influence the average length of the observed slugs in the downstream region. Increasing the T-Junction radius does not exhibit a linear trend when compared to the slug velocity occurring in the downstream area. The slug frequency increases with polynomial correlation as the superficial velocities of both water and air increases. 

Kata Kunci : radius belokan, T-Junction, karakteristik pola aliran slug, downstream.