Performance Optimization of Step-Like Divergence Plenum Air-Cooled Li-Ion Battery Thermal Management System Using Variable-Step-Height Configuration

Several studies on air-cooled battery thermal management systems (BTMSs) have shown that improvement can be achieved through redesign of the BTMSs. Recent studies have achieved improvements in managing the temperature in the system, but mostly with an increase in pressure drop. It is therefore imperative to carry out an extended study or redesign of the existing designs to overcome these challenges. In this work, a standard Z-type BTMS, which has a flat divergence plenum, was redesigned to have a step-like divergence plenum of variable step height. Computational Fluid Dynamics (CFD) approach was adopted to investigate the thermal and airflow performance of the BTMSs. The CFD methodology was validated by comparing its results with experimental data in the literature. Various step height configurations were considered for 3-step and 4-step models. Findings from the result revealed that the variable step height design enhances the cooling performance of the battery pack. For instance, a 3-step model with step heights of 3, 6, and 6 mm offered the least pressure drop and maximum temperature difference, and when compared with the model with a constant step height of 5, 5, and 5 mm, it yielded reductions of 3.4% and 21.6%, respectively. By increasing the inlet airflow velocity, the 4-step cases generally improved. The best cooling improvement was seen in case 26 at velocities over 3.7 m/s for maximum temperature and velocities over 4.8 m/s for maximum temperature difference. Doi: 10.28991/ESJ-2024-08-03-01 Full Text: PD

Thermal radiation analysis of an oil well gas flare

Paper presented at the 7th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Turkey, 19-21 July, 2010.Gas flaring, a long-established but unacceptable practice in the Nigerian Petroleum industry, has deleterious effects on the environment. Generally, empirical formulae are employed to estimate thermal radiation fluxes around a gas flare. Thermal radiation field data on Nigerian oil field associated gas flares are rare to come by, thus restricting information on such fields to what can be obtained from existing empirical formulae which are based on data from foreign oil fields. Even then such methods are unable to provide local information on a point-by­ point basis. In this work, the governing equations have been solved numerically yielding local information on the thermal radiation field. The gas flare was considered as a three dimensional turbulent jet issuing into a continuous cross flow of air. The momentum and scalar fluxes were approximated by the k-E turbulence model and the resultant conservation equations were solved using the finite volume technique. The laminar flamelet concept was used to characterize the local thermochemical state of the combusting mixture, while the discrete transfer method was used to compute the radiative heat flux. A model for an accurate prediction of the heat flux at any point in the thermal radiation field around a gas flare was developed. This model has superior prediction capabilities to existing empirical formulae. Safe distances could be deduced from the heat flux field around the flare for both humans and habitat using the model.ej201

Design optimization of Air-Cooled Li-ion battery thermal management system with Step-like divergence plenum for electric vehicles

Air-cooled Battery Thermal Management System (BTMS) technology has been proven and is frequently employed to regulate the distribution of temperature in a battery pack of an electric vehicle. In this study, a step-like divergence plenum was introduced to a standard Z-type BTMS to alter its airflow distribution pattern and thus improve its cooling effectiveness. The impacts of the number and length of steps in the divergence plenum on the cooling responses of the BTMS were investigated using a validated Computational Fluid Dynamics (CFD) method. Analysis of 1-step, 3-step, 4-step, and 7-step BTMS models were conducted and findings showed that the step quantity has a significant impact on the battery pack's ability to dissipate heat. For a step length of 30 mm, a 7-step case model offered the best system’s maximum temperature of 324.9 K and cell temperature difference of 1 K which were both 3.94 K and 5.93 K, respectively lower than that of the standard Z-type model. Furthermore, the step case models were optimized by observing the impacts of their step length on system's thermal performance. The outcomes showed that there was a substantial impact of the step length on cooling performance for all case models. For instance, a 4-step case model with a 45 mm step length offered a reduction in maximum temperature of 3.61 K and maximum temperature difference of 6.01 K when compared to the standard Z-type model. Finally, the behaviour of each case model was examined under increasing inlet air velocity and it shows that at higher airflow velocity, the 7-step case model performed substantially well than other investigated cases