Calculate steady-state cooling load, thermal runaway propagation zoning, and HVAC sizing for utility-scale BESS installations.
Presets
Project Parameters
Environmental Design
Battery Chemistry
Cooling Configuration
▸ Results appear here after calculation
Outputs: heat load · chiller sizing · NFPA 855 firebreak · HVAC selection · gas detection zones
Rack-to-System Breakdown
NFPA 855 Clearances
Gas Detection Zones (UL 9540A)
Annual Energy Balance
Steady-State Cooling Load Methodology
Heat dissipation is derived from I²R losses during charge/discharge cycling. The power loss is computed as P_loss = P_cycle × (1 − η_RT) / η_RT, where η_RT is the round-trip efficiency. A 20% safety factor is applied to account for cell-to-cell variation and transient peaks. The chiller is then sized at 1.2× the calculated heat load.
Thermal Runaway Propagation Methodology
Propagation distance is estimated using a simplified point-source heat flux model: q" = E / (2πr²t). The critical heat flux threshold of 10 kW/m² is derived from NFPA 855 and UL 9540A requirements for LFP systems. Minimum separation distances follow NFPA 855 Table 6.5.1.2: 3 m for LFP, 10 m for NMC. NFPA 68 deflagration vent area uses A_v = 0.26 × A_v0 × √V × (C_gap/√T), where V is the enclosure volume and C_gap is the gap factor.
HVAC Sizing Methodology
Forced air cooling uses mass flow balance: ṁ = Q / (c_p × ΔT), with fan power estimated at 0.5 W/m³/s of airflow. Liquid cooling uses Q = ṁ × c_p × ΔT, with pump head at 150 kPa typical for rack-level coolant loops. Annual parasitic energy is computed at 60–70% average duty cycle. RTE derate is the percentage of nominal BESS capacity consumed by cooling parasitic load annually.