Publication Date

Fall 2024

Degree Type

Thesis

Degree Name

Master of Science (MS)

Department

Mechanical Engineering

Advisor

Vimal Viswanathan; Farzan Kazemifar; Syed Zaidi

Abstract

The growing demand for electric vehicles (EVs) necessitates efficient thermal management of lithium-ion batteries (LIBs), especially NMC 523 cells. This thesis investigates thermal runaway (TR) mechanisms and evaluates cooling strategies to mitigate overheating risks. Using ANSYS Fluent, the TR of four cells in series was simulated and validated with Jun Wu et al.'s experimental data, achieving an error margin below 10%. Peak temperatures reached 1,126°C in the first cell, with delayed propagation in adjacent cells. Sensitivity analysis of voltage, current, and state of charge (SOC) under varying C-rates was performed using a multi-scale multi-domain (MSMD) battery model. A logarithmic voltage drop during TR showed a strong correlation (R² = 0.9228), and internal resistance aligned with manufacturer data within 5%. Cooling strategies for a 13S2P battery pack were evaluated, including Phase Change Materials (PCMs), Heat Pipes (HPs), and air cooling. Nonadecane, PW-48, and PW-58 PCMs at 7.5 mm and 12 mm thicknesses were studied, with the 12 mm PW-48 layer reducing temperatures to 127.65°C. Combining PCM and HPs further lowered temperatures, with PW-48 reaching 55.8°C. Hybrid cooling (PCM, HPs, and air) achieved 29.3°C, supported by turbulent airflow (Re ≈ 17,881). This study demonstrates the effectiveness of integrated cooling strategies for next-generation Battery Thermal Management Systems (BTMS) in EVs

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