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Lithium ion batteries are increasingly used in electrical energy storage systems despite their thermal and chemical hazards on failure. These hazards are magnified when multiple cells are combined together in a pack because of the risk of cascading failure. An experimental setup was utilized to investigate the dynamics, gaseous emissions, and energetics associated with thermal failure of cylindrical 18650 form factor, 2600 mAh, lithium cobalt oxide cathode cell arrays in an inert atmosphere. Cell state of charge (SOC) and arrangement were altered to investigate mitigation strategies and provide recommendations for safer battery pack design, transportation, and storage. Complete failure propagation was not prevented in any test, but decreasing to 50% SOC did result in propagation speeds 8.5 times slower than at 100% SOC. Introducing a 5 mm gap between cell rows also slowed propagation somewhat, but to a lesser degree than lowering SOC. Maximum temperatures, hazardous gas yields, and chemical heat generation were all reduced for cells at 50% SOC compared with 100% SOC, but introducing 5 mm gaps had little impact on these quantities. Limiting cells to 50% SOC was by far the most effective mitigation strategy tested, but no strategy was able to eliminate the failure propagation risk. Installing battery packs in inert environments, limiting SOC, and instituting gaps between certain cells can all be effective strategies to lessen the severity of cascading failure, but none of these strategies are individually sufficient for safe transportation and storage of battery packs.

A novel combustion technology which combines colorless distributed combustion (CDC) and oxygen enriched combustion (OEC) air is examined to achieve optimum benefits of both technologies and to foster novel technologies for cleaner environment. The influence of oxygen enriched air–methane flames under nonpremixed and premixed fuel-lean combustion conditions is examined with focus on emission of NO and CO, combustor exit temperature (Texit), and distribution of reaction zone in the combustor using OH* chemiluminescence intensity distribution. A cylindrical combustor was used at combustion intensity of 36 MW/m3·atm and heat load of 6.25 kW. Results are also reported with normal air (21% oxygen). Oxygen enrichment provided stable combustion operation at lower equivalence ratios than normal air and also reduced CO emission. Increase in oxygen concentration from 21% to 25% or 30% increased the NO and decreased CO emissions at all the equivalence ratios examined. Using 30% O2 enriched air in premixed case showed NO emissions of 11.4 ppm and 4.6 ppm at equivalence ratios of 0.5 and 0.4, respectively. Oxygen enrichment also reduced CO emission to 38 ppm at equivalence ratio of 0.5. Operating the combustor with normal air at these equivalence ratios resulted in unstable combustion. OH* chemiluminescence revealed increased intensity with the reaction zone to shift upstream at increased oxygen concentration. The exhaust temperature of the combustor increased with oxygen enrichment leading to lower CO concentration and increased combustion efficiency. The oxidizer injected at higher velocities moved the reaction zone to upstream location with simultaneous reduction of both NO and CO, specifically under nonpremixed combustion.