Analisis Pengaruh Variasi Pitch Ratio dan Sudut Pitch Tube terhadap Kinerja Oil Cooler di PLTA Tulungagung

Nugroho, Muhammad Nabil Adi (2025) Analisis Pengaruh Variasi Pitch Ratio dan Sudut Pitch Tube terhadap Kinerja Oil Cooler di PLTA Tulungagung. Other thesis, Institut Teknologi Sepuluh Nopember.

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Abstract

Bearing merupakan komponen penting dalam sistem pembangkit listrik tenaga air, yang berperan dalam menopang putaran poros turbin. Pada Unit 1 di PLTA Tulungagung menggunakan oil cooler tipe shell and tube dalam menjaga temperatur oli pelumas untuk lower guide bearing dan thrust bearing. Sistem ini beroperasi tanpa menggunakan pompa, dimana sirkulasi oli mengandalkan gaya sentrifugal dari putaran poros, sementara aliran air pendingin bergantung pada gaya gravitasi atau tekanan alami dari head tank. Kondisi eksisting menunjukkan peningkatan temperatur oli dibandingkan data historis, yang mengindikasikan terjadinya penurunan efektivitas oil cooler. Oleh karena itu, penelitian ini bertujuan untuk mengevaluasi kinerja oil cooler berdasarkan data historis dan kondisi eksisting, serta menganalisis pengaruh variasi konfigurasi tube berupa pitch ratio (1.25; 1.33; 1.5) dan sudut pitch (30° dan 45°) terhadap koefisien perpindahan panas dan pressure drop. Simulasi dilakukan menggunakan software HTRI dan dibandingkan dengan contoh perhitungan manual untuk melihat kesesuaian hasil dari kedua metode. Hasil penelitian ini juga membandingkan kinerja oil cooler berdasarkan performa eksisting dengan berbagai variasi konfigurasi tube yang diterapkan. Hasil analisis menunjukkan terjadinya penurunan efektivitas oil cooler sebesar 12.2% dibandingkan data historis (Ɛhistoris = 0.41; Ɛeksisting = 0.36). Sementara itu, hasil variasi konfigurasi tube menunjukkan bahwa konfigurasi dengan pitch ratio 1.33 dan sudut pitch 45° menghasilkan koefisien perpindahan panas menyeluruh (U) tertinggi. Hal ini disebabkan oleh nilai koefisien konveksi sisi tube (hi) dan sisi shell (ho) yang relatif lebih tinggi dibandingkan konfigurasi lainnya. Di sisi lain, konfigurasi dengan pitch ratio 1.5 dan sudut pitch 45° menghasilkan pressure drop sisi tube (∆PT) tertinggi. Jumlah tube yang lebih sedikit pada konfigurasi ini menyebabkan peningkatan kecepatan aliran fluida di dalam tube dan berdampak pada tingginya nilai pressure drop. Secara umum, hasil penelitian menunjukkan bahwa seluruh variasi konfigurasi tube yang diterapkan mampu meningkatkan efektivitas perpindahan panas sistem dibandingkan dengan performa desain eksisting.
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Bearings are critical components in power generation systems, serving to support the rotation of shafts. The Tulungagung Hydroelectric Power Plant (PLTA) uses a shell and tube type oil cooler in Unit 1 to maintain the temperature of the lubricating oil for the lower guide bearing and thrust bearing. This system operates without a pump; oil circulation relies on the centrifugal force generated by shaft rotation, while coolant water flow depends on gravity or natural pressure from the head tank. The existing condition shows an increase in oil temperature compared to historical data, indicating a decline in the cooling system's effectiveness. This study aims to evaluate the oil cooler’s performance based on historical and current data and to analyze the influence of tube configuration variations specifically pitch ratio (1.25; 1.33; 1.5) and pitch angle (30° and 45°) on the heat transfer coefficient and pressure drop. Simulations were conducted using HTRI software and validated against manual calculations to assess the consistency of both methods. The results compare the oil cooler’s performance under existing conditions with various tube configurations.The analysis reveals a 12.2% decrease in oil cooler effectiveness compared to historical performance (Ɛhistorical = 0.41; Ɛexsisting = 0.36. Among the configuration variations, a pitch ratio of 1.33 with a 45° pitch angle produced the highest overall heat transfer coefficient (U), attributed to relatively higher tube-side (hi) and shell-side (ho) convection coefficients. Conversely, the configuration with a 1.5 pitch ratio and 45° angle generated the highest tubeside pressure drop (∆PT), due to a reduced number of tubes increasing fluid velocity. In general, all tube configuration variations implemented were able to enhance heat transfer effectiveness compared to the existing design.

Item Type:	Thesis (Other)
Uncontrolled Keywords:	Oil Cooler, Pressure Drop, Thrust Bearing
Subjects:	T Technology > TJ Mechanical engineering and machinery > TJ263 Heat exchangers
Divisions:	Faculty of Industrial Technology > Mechanical Engineering > 21201-(S1) Undergraduate Thesis
Depositing User:	Muhammad Nabil Adi Nugroho
Date Deposited:	31 Jul 2025 04:31
Last Modified:	31 Jul 2025 04:31
URI:	http://repository.its.ac.id/id/eprint/123980

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