Optimizing the effect of micro-surface on the thermal hydraulic performance of plate heat exchanger

This research used electrochemical etching as a new method for generating micro surfaces in an effort to improve the thermal-hydraulic performance of a plate heat exchanger (PHE). This technique has significant advantages in terms of producing evenly structured surfaces and enabling exact size control compared to other techniques such as sandblasting and electroplating. Thus, it has great potential to be a pioneer in the industrial implementation of micro surface on heat exchangers. This work is the first to examine the impact of optimum roughness on both the Nusselt number (Nu) and the Performance of Evaluation Criterion (PEC) of PHE using a multi-objective genetic algorithm. In order to do this, several microstructure surfaces were generated on the PHEs, with average roughness values ranging from 0.65 to 1.51 mu m. The impact of these microstructure surfaces on heat transfer and pressure drop was experimentally investigated through heat transfer experiments conducted at Reynolds numbers (Re) ranging from 3,000 to 12,500. The findings reveal that the introduction of microstructure surfaces leads to a noteworthy enhancement of 10 % to 18 % in the overall heat transfer coefficient (OHTC) across all experimental scenarios. Conversely, the friction factor experienced an increase of 28 % to 53 % compared to a smooth surface. PEC values ranged from 1.05 to 1.21, showing a superior heat transfer performance over a marginal pressure drop increase. Furthermore, the microstructure surfaces demonstrated significantly improved values of 0.23 to 0.32 for the Number of Transfer Units (NTU) and 0.18 to 0.26 for effectiveness, in comparison to the smooth surface. This corresponds to an enhancement of 9.7 % to 18.5 % and 7.2 % to 16.4 %, respectively. In addition, a multi-objective genetic algorithm determined that an optimal roughness value of Ra = 1.1 mu m achieves a balance between maximizing Nu and PEC.