Spray Cooling Comparative Analysis: Inert Particles Vs. Evaporating Droplets Using DPM

Description

Comparative Analysis of Spray Cooling Methods Using Different DPM Models in ANSYS Fluent

Description

In this comprehensive study, three distinct cases were investigated to analyze the effectiveness of spray cooling approaches utilizing ANSYS Fluent software. This project study on 3 cases.

Case 1 served as the baseline scenario, featuring only air flow without any water injection (Stream case).

Case 2 employed water injection using DPM with an inert particle model, where water droplets were treated as inert particles interacting with the air flow domain.

Case 3 utilized water injection through DPM with a droplet model, incorporating comprehensive particle-fluid interactions and advanced phase change phenomena. .

The simulation setup began with the creation of detailed geometry using SpaceClaim, followed by the generation of a high-quality quadrilateral mesh in ANSYS Meshing.

Methodology

This All simulations were performed using the SIMPLE (Semi-Implicit Method for Pressure Linked Equations) algorithm in ANSYS Fluent to ensure robust pressure-velocity coupling and solution convergence

meticulous approach to mesh generation ensured accurate results and proper resolution of flow features. The simulation parameters were carefully selected, implementing the standard k-ε turbulence model, with steel used for the solid domain and air as the primary fluid medium. Water was introduced as the cooling spray medium in Cases 2 and 3 through DPM injection. A two-way coupling approach was employed in the DPM configurations to capture the complete interaction between the discrete phase and the continuous flow field.

Results

The results demonstrated significant variations in cooling effectiveness across the three cases. In the baseline stream case (Case 1), with only air flow and without any water spray cooling mechanism, the solid zone maintained a high temperature of 1033 K, while the fluid zone showed a temperature of 618 K. In Case 2, where water was injected using the Inert DPM model, notable temperature reductions were observed, with the solid zone temperature decreasing to 844 K and the fluid zone dropping to 551 K. This represented an 18.3% and 10.8% reduction in temperature for the solid and fluid zones, respectively, compared to the baseline case.

The most remarkable results were observed with Case 3 using the droplet DPM model, which achieved the most substantial cooling effect. In this case, the solid zone temperature decreased dramatically to 546 K, representing a 47.1% reduction from the baseline case. Similarly, the fluid zone temperature dropped to 524 K, showing a 15.2% reduction. This superior performance can be attributed to the comprehensive physical modelling incorporated in the droplet DPM approach.

The enhanced cooling efficiency of the droplet model can be explained by its implementation of multiple physical laws governing particle behavior. While the inert model in Case 2 only considers Laws 1 and 6 (inert heating/cooling), the droplet model in Case 3 incorporates additional mechanisms, including Law 2 (droplet vaporisation) and Law 3 (droplet boiling). This more complete physical representation allows for better simulation of real-world spray cooling phenomena, resulting in more effective heat transfer predictions.

The visual results, as shown in the accompanying figures, provide additional insight into the simulation outcomes. The geometry and mesh illustrations demonstrate the careful attention paid to the model setup. The streamline visualisation helps in understanding the flow patterns, while the temperature contours clearly show the thermal distributions across the domain for different cases.

In conclusion, this study effectively demonstrates the superiority of the droplet DPM model for spray cooling applications. The comprehensive inclusion of various physical mechanisms in the droplet model leads to more accurate and effective cooling predictions compared to simpler approaches. These findings have significant implications for industrial applications where spray cooling is utilised, suggesting that the droplet DPM model should be preferred when accurate thermal management predictions are required.

One application of this study was used in the enhancement of electronic engine cooling using a water spray cooling system.

This research contributes valuable insights into the selection of appropriate modeling approaches for spray cooling simulations, highlighting the importance of considering comprehensive physical models for accurate results. Future work could explore additional parameters or alternative cooling configurations to further optimise the cooling performance in various industrial applications.