Mitigasi Thermal Runaway pada Sistem Pendingin Hybrid Rangkaian Baterai LiFePO4 Kapal Selam dengan Simulasi CFD 3D

Narotama, Fajri (2026) Mitigasi Thermal Runaway pada Sistem Pendingin Hybrid Rangkaian Baterai LiFePO4 Kapal Selam dengan Simulasi CFD 3D. Masters thesis, Institut Teknologi Sepuluh Nopember.

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Abstract

Kapal selam diesel-elektrik bergantung pada baterai untuk menyuplai propulsi dan peralatan bantu selama operasi bawah air. Pengoperasian baterai LiFePO₄ berarus tinggi di ruang yang terbatas tetap menimbulkan risiko akumulasi panas. Konfigurasi acuan numerik menggunakan bottom liquid cooling dengan kecepatan air suling 1,5 m/s tanpa pendinginan udara aktif. Konfigurasi tersebut menjaga temperatur maksimum di bawah cutoff pada skenario 0,2C dan 1C, tetapi mencapai cutoff sekitar 2.436 s pada skenario 1,4C. Nilai kondisi batas digunakan untuk pemodelan dan bukan spesifikasi operasional aktual kapal selam tertentu. Hasil ini menjadi dasar penambahan sirkulasi udara tertutup dan peningkatan kecepatan air suling. Penelitian ini menganalisis efektivitas sistem pendingin hybrid dalam mempertahankan temperatur maksimum rangkaian baterai LiFePO₄ di bawah batas cutoff 50°C. Simulasi Computational Fluid Dynamics tiga dimensi transien dilakukan dengan pendekatan Conjugate Heat Transfer pada Ansys Fluent 2024 R2 dan model turbulensi SST k-ω. Modul baterai direpresentasikan sebagai padatan homogen ortotropik dengan konduktivitas termal 0,91 W/m·K pada arah ketebalan dan 25 W/m·K pada dua arah bidang. Pembangkitan panas diterapkan melalui User-Defined Function berbasis Equivalent Circuit Model. Resistansi efektif dihitung dari resistansi ohmik R₀ dan resistansi polarisasi R₁ menggunakan hubungan Reff = R₀ + 0,3R₁; kedua resistansi diperbarui berdasarkan state of charge, temperatur lokal, dan C-rate. Validasi model sumber panas pada sel LiFePO₄ prismatik 100 Ah menghasilkan RMSE 0,40°C, MAE 0,31°C, dan deviasi relatif 0,86%. Simulasi menggunakan tiga skenario asumsi tingkat pengosongan, yaitu 0,2C, 1C, dan 1,4C, yang merepresentasikan operasi berdaya rendah, manuver kecepatan tinggi, serta manuver berdaya puncak disertai penggunaan countermeasure. Nilai tersebut bukan profil beban aktual kapal selam tertentu. Sembilan variasi dibentuk dari No Active Cooling, Hybrid Standard, dan Hybrid Maximum. Hybrid Standard menggunakan kecepatan udara 9,65 m/s dan air suling 1,5 m/s, sedangkan Hybrid Maximum menggunakan 16 m/s dan 2,5 m/s. Pada skenario 0,2C, temperatur maksimum akhir V1–V3 masing-masing 36,62°C, 28,63°C, dan 28,20°C. Pada skenario 1C, temperatur maksimum akhir V4–V6 masing-masing 48,25°C, 45,25°C, dan 44,90°C. Seluruh variasi pada kedua skenario tersebut tidak mencapai cutoff. Kondisi paling kritis terjadi pada skenario 1,4C. V7 mencapai cutoff pada 2.142 s dan menghasilkan temperatur maksimum akhir 51,89°C. V8 mencapai cutoff pada 2.403 s dengan temperatur maksimum akhir 50,69°C, sehingga memperpanjang decision window sebesar 261 s dibandingkan V7. V9 menghasilkan temperatur maksimum akhir 49,82°C dan tidak mencapai cutoff hingga akhir durasi 2.571 s. Dalam ruang parameter yang diuji, Hybrid Maximum memberikan manfaat termal tertinggi pada skenario 1,4C. Hasil tersebut menunjukkan bahwa waktu menuju cutoff dapat digunakan sebagai informasi decision window untuk mendukung pengurangan beban atau tindakan pengamanan sebelum proteksi termal bekerja.
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Diesel-electric submarines rely on batteries to supply propulsion and auxiliary equipment during submerged operations. High-current LiFePO₄ battery operation inside a confined compartment may still cause heat accumulation. A reference numerical configuration employs bottom liquid cooling with a distilled-water velocity of 1.5 m/s without active air cooling. It maintained the maximum temperature below the cutoff under the 0.2C and 1C scenarios but reached the cutoff at approximately 2,436 s under the 1.4C scenario. The boundary-condition values are used for numerical modelling and do not represent the actual operational specifications of any particular submarine. This result provided the basis for introducing closed-loop air circulation and increasing the distilled-water velocity. This study evaluated a hybrid cooling system for maintaining the maximum temperature of a submarine LiFePO₄ battery string below the 50°C cutoff limit. Three-dimensional transient Computational Fluid Dynamics simulations were performed using a Conjugate Heat Transfer approach in Ansys Fluent 2024 R2 with the SST k-ω turbulence model. The battery modules were represented as homogeneous orthotropic solids with a thermal conductivity of 0.91 W/m·K in the through-thickness direction and 25 W/m·K in each of the two in-plane directions. Heat generation was implemented through an Equivalent Circuit Model-based User-Defined Function. The effective resistance was calculated from the ohmic resistance R₀ and polarization resistance R₁ using Reff = R₀ + 0.3R₁, with both resistances updated according to state of charge, local temperature, and C-rate. Cell-level validation against a 100 Ah prismatic LiFePO₄ experiment resulted in an RMSE of 0.40°C, an MAE of 0.31°C, and a relative deviation of 0.86%. Simulations employed three assumed discharge scenarios of 0.2C, 1C, and 1.4C, representing low-power operation, high-speed manoeuvring, and peak-power manoeuvring accompanied by countermeasure deployment. These values do not represent the actual load profile of any particular submarine. Nine variations were formed from No Active Cooling, Hybrid Standard, and Hybrid Maximum. Hybrid Standard employed air and distilled-water velocities of 9.65 m/s and 1.5 m/s, whereas Hybrid Maximum used 16 m/s and 2.5 m/s. Under the 0.2C scenario, the final maximum temperatures of V1–V3 were 36.62°C, 28.63°C, and 28.20°C. Under the 1C scenario, the final maximum temperatures of V4–V6 were 48.25°C, 45.25°C, and 44.90°C. None of these variations reached the cutoff limit. The most critical condition occurred under the assumed 1.4C scenario. V7 reached the cutoff at 2,142 s and produced a final maximum temperature of 51.89°C. V8 reached the cutoff at 2,403 s with a final maximum temperature of 50.69°C, extending the decision window by 261 s relative to V7. V9 produced a final maximum temperature of 49.82°C and did not reach the cutoff by the end of the 2,571 s operating period. Within the investigated parameter range, Hybrid Maximum provided the greatest thermal benefit under the 1.4C load. The time to cutoff can therefore be used as an operator decision window for load reduction or other safety actions before thermal protection is activated.

Item Type: Thesis (Masters)
Uncontrolled Keywords: LiFePO₄, Kapal Selam, Sistem Pendingin Hybrid, CFD Tiga Dimensi Transien, ECM-UDF, Temperatur Maksimum Baterai, Cutoff, Decision Window
Subjects: T Technology > TJ Mechanical engineering and machinery
T Technology > TJ Mechanical engineering and machinery > TJ263 Heat exchangers
U Military Science > U Military Science (General) > UG Military Engineering
V Naval Science > VM Naval architecture. Shipbuilding. Marine engineering > VM471 Ships--Electric equipment
Divisions: Faculty of Industrial Technology > Mechanical Engineering > 21101-(S2) Master Thesis
Depositing User: Fajri Narotama
Date Deposited: 31 Jul 2026 06:13
Last Modified: 31 Jul 2026 06:13
URI: http://repository.its.ac.id/id/eprint/140692

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