Perancangan dan Unjuk Kerja Empat Evaporator dengan Fluida Kerja (R123, n-pentane, n-butane, dan R245fa) untuk Siklus Rankine Organik

MUHAMAD SAIFUDIN, Ir. Joko Waluyo, M.T., Ph.D., IPM,. ASEAN Eng., APEC Eng.

2025 | Skripsi | TEKNIK MESIN

Tugas akhir ini membahas perancangan dan unjuk kerja empat evaporator tipe shell and tube heat exchanger (STHE) menggunakan fluida kerja, yaitu R123, n-Pentane, n-Butane, dan R245fa untuk aplikasi Siklus Rankine Organik (Organic Rankine Cycle/ORC). Tujuan utama dari tugas akhir ini adalah untuk mengevaluasi kinerja termal dan implikasi mekanikal desain evaporator terhadap variasi fluida kerja yang digunakan. Metodologi penelitian mencakup dua tahapan utama, yaitu perancangan termal berdasarkan data properti fluida dan analisis mekanikal mengacu pada standar ASME VIII Div.1 dan TEMA. Parameter yang dianalisis meliputi laju perpindahan panas, luas perpindahan panas, koefisien perpindahan panas keseluruhan (U), pressure drop, serta ketebalan shell, head, tubesheet, baffle, dan berat total alat. Hasil perancangan menunjukkan bahwa setiap fluida menghasilkan konfigurasi dimensi yang berbeda. n-Pentane menggunakan 156 tube dengan panjang tube 6 meter dan diameter dalam shell 406 mm. n-Butane hanya memerlukan 49 tube dan diameter shell yang sama (406 mm), sehingga menjadi desain paling ringkas. R123 memiliki jumlah tube terbanyak (364 buah) dan diameter shell terbesar (660 mm), menyebabkan berat total alat mencapai 2965,9 kg. Sementara itu, R245fa menggunakan 53 tube dan shell berdiameter 432 mm, dengan total berat 1450,9 kg. Seluruh desain memenuhi batasan mekanikal berdasarkan standar ASME VIII Div.1 dan TEMA. Secara kuantitatif, R123 menunjukkan laju perpindahan kalor tertinggi (663,30 kW) namun memerlukan luas perpindahan kalor terbesar (130,20 m²) dan memiliki pressure drop tertinggi (6817,84 Pa pada sisi shell). n-Butane memiliki laju kalor terendah (372,19 kW), tetapi area dan pressure drop terendah (17,36 m² dan 5426,81 Pa). R245fa menunjukkan koefisien perpindahan kalor keseluruhan tertinggi di sisi tube (U = 860 W/m²°C) dengan pressure drop 5580,74 Pa, sedangkan n-Pentane memberikan hasil paling seimbang antara laju kalor (474,56 kW), luas area (27,81 m²), dan performa mekanikal. Hasil perbandingan menunjukkan bahwa pemilihan fluida kerja sangat mempengaruhi dimensi dan unjuk kerja evaporator dalam sistem ORC.

This final project discusses the design and performance of shell and tube heat exchanger (STHE) four evaporator using different working fluids: R123, n-Pentane, n-Butane, and R245fa, for application in an Organic Rankine Cycle (ORC). The main objective is to evaluate the thermal performance and mechanical design implications of the evaporator when using different working fluids. The research methodology consists of two main stages: thermal design based on fluid property data, and mechanical analysis referring to ASME Section VIII Division 1 and TEMA standards. The analyzed parameters include heat transfer rate, heat transfer area, overall heat transfer coefficient (U), pressure drop, as well as the thickness of the shell, head, tubesheet, baffle, and the total weight of the unit. The design results show that each fluid produces a different dimensional configuration. n-Pentane uses 156 tubes with a tube length of 6 meters and an internal shell diameter of 406 mm. n-Butane requires only 49 tubes and the same shell diameter (406 mm), making it the most compact design. R123 has the highest number of tubes (364) and the largest shell diameter (660 mm), resulting in the heaviest unit (2965.9 kg). Meanwhile, R245fa uses 53 tubes and a shell diameter of 432 mm, with a total weight of 1450.9 kg. All designs meet mechanical requirements according to ASME VIII Div.1 and TEMA standards. Quantitatively, R123 achieves the highest heat transfer rate (663.30 kW) but requires the largest heat transfer area (130.20 m²) and experiences the highest pressure drop (6817.84 Pa on the shell side). n-Butane records the lowest heat transfer rate (372.19 kW) but has the smallest area and pressure drop (17.36 m² and 5426.81 Pa). R245fa shows the highest tube-side overall heat transfer coefficient (U = 860 W/m²°C) with a pressure drop of 5580.74 Pa, while n-Pentane provides the most balanced performance in terms of heat transfer rate (474.56 kW), surface area (27.81 m²), and mechanical design. The comparison results indicate that the choice of working fluid significantly affects both the dimensional and performance aspects of the evaporator in an ORC system.

Kata Kunci : Evaporator, Shell and Tube, Organic Rankine Cycle, n-Pentane, n-Butane, R123, R245fa