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The prevalent numerical models for simulating axially finned heat exchangers with phase change materials (PCMs) and water as the heat transfer fluid rely on computational fluid dynamics (CFD) techniques, with a primary focus on phase change modeling. However, the computational demands of these models, incorporating phase change effects and resolving PCM movement in the liquid state, are substantial. From experiments suggesting that conduction in the solidified PCM around the finned tube dominates heat transfer during the heat discharge process, this article introduces a simplified CFD‐based model in which convective flow of the PCM is neglected. The model is experimentally validated using a 1‐m‐long axially finned heat exchanger prototype with four fins, recording temperatures under different water flow rates and orientations (horizontal and vertical). Results show that the proposed model predicts outlet water temperature satisfactorily, with absolute errors below 1.0°C and 2.2°C for the horizontal and vertical orientations, respectively. Additionally, the model can capture the temperature trend inside the PCM for the horizontal orientation. [ABSTRACT FROM AUTHOR]

The aim of this work is to present an experimental procedure at laboratory scale that was developed to validate a new CFD-based methodology for the estimation of water evaporation rate in indoor swimming pools, under a wide range of convective flow conditions (36 experiments) and focussing on the most common operation conditions of these facilities: low air mean velocities (0.08–0.24 m/s), and water and air temperatures in the ranges 24-28 °C and 26-30 °C, respectively. One of the main hypotheses of the simulation methodology set a free slip wall condition (no shear stress) at the air-water interface, based on the fact that the dynamic boundary layer depth will be smaller than the thickness of the thermal and humidity boundary layers in this kind of flows. The comparison between simulated and experimental results show that the modelling strategy proposed is a promising tool, with average relative errors of 9% for the typical mixed convection flows in indoor swimming pools. [ABSTRACT FROM AUTHOR]

This paper presents a new methodology in which a computational fluid dynamics model is applied to estimate water evaporation rate in indoor swimming pools. This rate is needed to achieve a suitable energy performance of ventilation and dehumidification systems. The main hypotheses of the model set the following boundary conditions at the air-water interface: air temperature equal to water temperature, water vapour concentration equal to saturation humidity of air at water temperature and free slip wall condition (no shear stress). This last condition can be justified by the fact that Prandtl and Schmidt turbulent numbers are usually less than one in this kind of flows. Consequently, the dynamic boundary layer depth will be smaller than the thickness of the thermal and humidity boundary layers. The model was experimentally validated by using data from three different test chambers and from a real swimming-pool. A total of 233 different flow conditions were simulated. The results were quite satisfactory, with a relative error of only 3% in the simulations of the real swimming-pool and a total average relative error smaller than 9%. [ABSTRACT FROM AUTHOR]