Heat Transfer and Friction Characteristics of Wavy Fin with Hydrophilic Coating under Dehumidifying Conditions

An experimental study on the airside heat transfer and friction characteristics of seven hydrophilic-coated wavy finned tube heat exchangers is performed under dehumidifying conditions. The effects of fin pitch, number of tube rows and inlet air relative humidity on the airside characteristics are investigated. The airside heat transfer and friction characteristics are presented in the form of Colburn factor and friction factor, respectively. The test results indicate that the Colburn factor and friction factor increase with decreasing fin pitch. The Colburn factor of 2 tube row heat exchanger is higher than that of 3 row heat exchanger, while their friction factors are nearly equal. As the inlet relative humidity increases, the Colburn factor increases and the friction factor is almost unchanged. The airside heat transfer and friction correlations are proposed for the hydrophilic-coated wavy fin with mean deviations of 6.5% and 9.1%, respectively. They can be used to design or evaluate hydrophilic-coated wavy fin-and-tube heat exchangers.

Experimental Study of the Airside Performance for Interrupted Fin-and-tube Heat Exchanger with Hydrophilic Coating under Dehumidifying Conditions

The airside heat transfer and friction characteristics of seven interrupted fin-and-tube heat exchangers with hydrophilic coating under dehumidifying conditions are experimented.The effects of number of tube rows,fin pitch and inlet relative humidity on airside performance are analyzed.The test results show that the influence of fin pitch on the friction characteristic under dehumidifying conditions is similar to that under dry surface,and the friction factors decrease slightly with the increase of number of tube rows.The heat transfer performance decreases as fin pitch and number of tube rows increases.The heat transfer performance and the friction characteristic are independent of inlet relative humidity.Based on the test results,heat transfer and friction correlations in terms of the Colburn j factor and Fanning f factor,are proposed to describe the airside performance of the interrupted fin geometry with hydrophilic coating under dehumidifying conditions.The correlation of the Colburn j factor gives a mean deviation of 9.7%,while the correlation of the Fanning f factor shows a mean deviation of 7.3%.

Topological prime

This paper describes a general method, called topological prime, to stitch functional groups to a substrate of entropic polymer network. The precursor of a topological primer contains polymers, crosslinkers, and coupling agents. When the precursor is applied on the surface of the substrate, the crosslinkers link the primer polymers into a primer network, in topological entanglement with the substrate network, while the coupling agents link the primer network to the functional groups. The use of topological prime is demonstrated by priming a hydrophobic elastomer of an arbitrary shape for hydrophilic coating. We describe an approach that fulfills two fundamental requirements: wetting and adhesion. The coated elastomer maintains hydrophilicity and lubricity after stretch, scratch, swell, and slide. As a further demonstration, a hydrogel substrate is primed for hydrophobic coating. Topological prime opens an enormous space for applications in engineering and biomedicine.

Preface on “Biomaterial Foundations of Therapeutic Delivery”

Driven by the enormous clinical need,drug delivery systems（DDS）have become a prime research focus in the field of biomaterials.They offer opportunities for developing new therapeutic approaches to prevent and treat debilitating and life-threatening diseases.Smart biomaterials,whether synthetic or naturally-derived,