P. J. Erens

Bio: P. J. Erens is an academic researcher from Stellenbosch University. The author has contributed to research in topics: Heat exchanger & Micro heat exchanger. The author has an hindex of 2, co-authored 2 publications receiving 36 citations.

Analysis of spray-cooled finned-tube heat exchangers

Abstract: A mathematical model has been developed for the analysis of spray-cooled finned-tube heat exchangers. An experimental study was conducted on a four-pass, finned-tube heat exchanger in a vertical air/water mist flow to validate the model, and the results compared well with the predicted performance. Significant performance enhancement (up to 3.5 times the dry performance) was found by spraying relatively small amounts of water onto the heat exchanger. The two-phase pressure drop across the heat exchanger was also measured, and the spray water mass flow rate was found to have a significant effect on the pressure drop across the tube bundle. This study helped to identify certain factors, such as the geometry of the finned tubes and the optimum air/spray water ratios, which have to be taken into consideration when designing spray-cooled heat exchangers.

Comparison of Some Design Choices for Evaporative Cooler Cores

Abstract: Three different design options for closed-circuit evaporative cooler cores are compared by way of numerical examples obtained with the use of computer programs written for the three cases. It is concluded that bare-tube cooler performance can be considerably enhanced by the judicious use of fill material without resorting to the use of fins to increase the mass transfer area.

A comprehensive design and rating study of evaporative coolers and condensers. Part I. Performance evaluation

Abstract: The mathematical models of evaporative fluid coolers and evaporative condensers are studied in detail to perform a comprehensive design and rating analysis. The mathematical models are validated using experimental as well as numerical data reported in the literature. These models are integrated with the fouling model presented in an earlier paper, using the experimental data on tube fouling. In this paper, we use the fouling model to investigate the risk based thermal performance of these evaporative heat exchangers. It is demonstrated that thermal effectiveness of the evaporative heat exchangers degrades significantly with time indicating that, for a low risk level ( p =0.01), there is about 66.7% decrease in effectiveness for the given fouling model. Furthermore, it is noted that there is about 4.7% increase in outlet process fluid temperature of the evaporative fluid cooler. Also, a parametric study is performed to evaluate the effect of elevation and mass flow rate ratio on typical performance parameters such as effectiveness for rating calculations while surface area for design calculations.

Review of nature-inspired heat exchanger technology

Abstract: The enormous heat and mass transfer phenomena in nature have led engineers to seek solutions for heat transfer enhancement problems from nature. In a current study, a comprehensive review of nature-inspired heat exchanger technology is presented, with focuses on fractal geometries, heat exchanger surface wettability control and evaporative cooling. Fractal geometry, widely found in respiratory systems and vascular systems of plants and animals, has been introduced into heat transfer area because of its intrinsic advantage of minimized flow resistance and strong heat transfer capability. Plant leaves with different surface wettability inspire heat exchanger surface treatment for condensation and frosting application. Evaporation of perspiration to regulate human temperature enlightened the application of evaporative condensers. Based on a review, an outline for applying biomimicry to heat exchanger design has been developed. Promising natural phenomena for future design are discussed. This review is expected to motivate future research on nature-inspired heat transfer devices.