Dolfred Vijay Fernandes

This study examines the cooling performance of lithium‐ion (Li‐ion) batteries in electric vehicles, emphasizing the importance of maintaining temperatures below 35°C to ensure efficiency and safety. A simulation‐based approach is used to study battery pack cooling using a liquid coolant (deionized water) within a cold plate system, focusing on a 16‐cell battery pack connected in series‐parallel. A novel stereoscopic‐serpentine cold plate design is implemented. The thermal response of the battery pack is evaluated under constant and worldwide harmonized light vehicles test cycle (WLTC Class 3 drive) discharge rates. The inlet temperature and inlet flow velocities of the liquid coolant are varied. The simulation results for the stereoscopic‐serpentine cold plate design are compared with those for the traditional serpentine bottom cold plate design. The new design improved coolant flow and effectively reduced temperature differences in the battery pack. The findings highlight that lowering the coolant temperature is significantly more effective for reducing the battery temperature than increasing the coolant flow speed, with a 1% decrease in coolant temperature leading to a 7.1% reduction in the maximum battery temperature, compared with a mere 0.21% reduction from a 1% increase in coolant flow speed.

Bubble formation during mixing of the base elastomer and the curing agent for polydimethylsiloxane (PDMS) preparation presents a significant challenge, traditionally addressed through vacuum degassing or centrifugation. This study introduces a novel alternative for bubble removal in PDMS mixtures: a churning motion inspired by industrial dairy separation processes. A low-cost, manually operated, do-it-yourself (DIY) churning device has been developed for this purpose. We investigate the effectiveness of churning in eliminating bubbles across three different churning speeds and two PDMS mixtures with differing viscosities. The efficacy of this method is quantitatively assessed through the analysis of images captured during the churning process. The results demonstrate that bubble removal is notably more efficient in the PDMS mixture with a higher viscosity due to enhanced bubble coalescence. Among the tested speeds, fast churning emerges as the most effective, achieving bubble removal in less than 100 s & horbar;significantly outperforming the traditional vacuum degassing method, which requires over 3000 s. These findings highlight churning motion as a rapid, efficient, and cost-effective alternative for bubble removal in PDMS processing, promising significant advancements in material preparation techniques.

Heat exchangers of high effectiveness are generally sought by the thermal industry for the efficient utilization of heat energy. The present study focuses on the enhancement of the effectiveness of a single-tube heat exchanger by attaching equilateral triangular-prism roughness elements on the peripheral heat transfer surface. The forced convection in a circular tube is analyzed using ANSYS-fluent considering air as the working fluid in the Reynolds number (Re) range of 10,000 to 18,000. The geometric parameters (the cross-section and the roughness element height) are fixed. The effects of longitudinal pitch, angular pitch and the orientation of triangular-prism roughness elements on the heat transfer and the frictional energy loss are studied. The presence of roughness elements on the heat transfer surface is found to increase turbulence and fluid mixing. Up to a 23% increase in heat transfer performance is seen in the Nusselt number values of the roughened tube over the smooth tube. The presence of roughness elements on the tube surface also increases the frictional losses; however, this increase is found to be gradual with the reduction in both longitudinal and angular pitch.

Enhancement of heat transfer in solar air heater systems using corrugations has the dual benefit of enhanced heat transfer area and enhanced flow turbulence. This work presents two-dimensional computational fluid dynamics (CFD) analysis to evaluate the effect of discrete triangle wave corrugations on the absorber plate for different flow Reynolds numbers of 6000–24000. The geometric parameters of corrugation such as the non-dimensional amplitude (A = 0.025, 0.05 and 0.1) and non-dimensional wavelength (W_L = 0.113, 0.226 and 0.453) are varied to establish the thermo-hydraulic performance. The CFD results reveal that the presence of discrete triangle wave corrugations significantly affect the flow structure near the absorber surface and exhibit enhanced fluid turbulence levels. The highest increase in the Nusselt number is found to be about 2.082 times higher than that of the smooth duct for A = 0.1 and W_L = 0.453 at Re = 6000. The maximum rise in friction factor is about 2.568 times that of the smooth duct at Re = 6000 for the configuration of W_L = 0.113 and A = 0.1. The configuration having A = 0.1 and W_L = 0.453 can be particularly useful for lower flow rate requirements and exhibits the highest thermal enhancement factor (TEF) of about 1.612 at Re = 6000 among all the configurations considered in the present study. However, the configuration having A = 0.05 and W_L = 0.453 provides a relatively steady TEF performance for a wider range of flow rates with a maximum TEF of 1.473 at Re = 12,000.

This article presents the heat transfer and friction factor characteristics of circular tube fitted with an array of novel semi-elliptical vortex generator inserts using air as working fluid. The study makes use of computational fluid dynamics methodology and the influence of varying aspect ratio (AR = 1, 2, 4 and 6), flow attack angle (45°, 60°, 75° and 90°) and longitudinal pitch (P = 30 mm, 60 mm and 90 mm) of vortex generator is investigated for the turbulent flow Reynolds number regime of 8000–26000. The numerical results reveal that the presence of semi-elliptical vortex generator has significant influence on both Nusselt number and friction factor characteristics of circular tube. The vortex generators produce strong longitudinal vortices which intensifies fluid mixing near the tube wall region thereby augmenting the heat transfer to the flowing air stream. In addition, the presence of flow impingement effect on the upstream side and flow reattachment zones on the downstream side of vortex generator is found to contribute to enhanced heat transfer. The influence of aspect ratio on heat transfer is found to be more significant than that of flow attack angle. However, both parameters affect the friction factor significantly. On the other hand, the pitch distance of insert significantly affects both heat transfer and friction factor. The maximum rise in Nusselt number and friction factor is about 2.1 times and 6.34 times higher than plain tube, respectively, for P = 30 mm. The thermal enhancement factor (TEF) is found to decrease with increasing flow attack angle and aspect ratio for all flow rates considered in the study. However, the TEF increases with decreasing pitch distance of inserts and the overall TEF is found to be in the range of 0.86–1.19.

Electrohydrodynamic flow of a dielectric liquid around a wire electrode sandwiched between two parallel flat-plate electrodes is studied both numerically and experimentally. The Poisson-Nernst-Planck equations for the ion transport and the Navier-Stokes equations for the fluid flow are solved numerically by using a commercial code. Charge generation in a dielectric liquid (dodecane + 0.5% wt Span 80) due to Onsager effect is considered in the ion transport equations. Numerical results well predict the experimental ones both qualitatively and quantitatively. At high electric field the numerical approach slightly over-predicts the flow velocity measured from the experiment, but the level of discrepancy can be further lowered by using a truncated series for the Onsager function.