Case Studies in Thermal Engineering (May 2023)
Investigating the thermal performance of air-cooling system integrated with TEC modules: Transient numerical simulation
Abstract
The current study represents a developed 3-D numerical transient model to a complete indirect non-evaporative cooling system integrated with an assisted TEC unit using OpenFOAM V.9 source code. The TEC model was developed using a hand-written code as a source added to the energy equation. The primary air temperature was a criterion to compare between three cases of environment's temperature: low mode (299 K), medium mode (309 K), and high mode (319 K). A new dimensionless factor called by Heat Flux Ratio (HFR) is derived to evaluate the thermal performance. In addition, wall heat flux and temperature difference along the vertical air channel were the parameters used for comparison. The complete system was constructed and validated according to number of experimental and theoretical studies from literature. Furthermore, all cases were tested under five different air inlet velocities: 0.75 m/s, 1 m/s, 1.25 m/s, 1.5 m/s, and 1.75 m/s. Results show that HFR values increase as time increases. In addition, it was found that HFR increases with the reduction in the velocity. Moreover, it was found that higher temperature difference can be reached at the lowest velocity (0.75 m/s) while the minimum difference would be at the highest velocity (1.75 m/s) with the error between modes doesn't pass (2.5%). On the other hand, the highest wall heat flux approached at the highest velocity (1.75 m/s) and vice versa where the error doesn't exceed (2.85%) between the modes. Finally, the validation shows good and acceptable agreement in COP values of the system with both experimental and theoretical works form literature where the error is ranged between (20.3% and 3.64%).
