Modeling photovoltaic modules using the single-diode model presents an adequate balance between complexity and accuracy; however, the current–voltage characteristic has to be calculated every time the operating condition changes. In turn, IEC-60891 provides procedures for direct translation from one operating condition to another, allowing a more straightforward application, provided that specific parameters are known. That international standard describes a procedure to quantify such parameters; however, their calculation requires complex equipment or extensive experimental tests. This article presents an alternative and simplified method to compute the parameters of IEC-60891, specifically the second procedure presented in the standard. It requires a reduced amount of measurements to be used as references. The validation of the method has been carried out taking extensive experimental data as reference, considering thousands of measurements taken for 16 months. The application of the proposed method to translate the reference curves presented mean absolute error and root-mean-square error below 3%, considering two different photovoltaic modules.

Models based on energy balance and that consider the main heat transfer processes that may be present in PV modules have already proved to be a good alternative for temperature prediction, however, the resolution of these models may not be trivial due to the large number of variables involved and the implicit solutions they generate, especially when transitory regime conditions are considered. Therefore, this study aims to obtain a model to estimate the temperature of photovoltaic modules from an energy balance under steady state conditions. Initially, the developed model was applied to five different photovoltaic modules for irradiance, air temperature and wind speed values corresponding to the NOCT condition and validated based on the operating temperature given by the manufacturers in the same condition. Experimental data from the Laboratory UMR CNRS 6134 SPE-University of Corsica, France, referring to meteorological measurements and thermal and electrical measurements of four PV modules, were applied to the developed temperature model. An evaluation of the consistency of experimental and simulated data was carried out using the statistical parameters MAE, RMSE and MAPE. The results concluded that the developed predictive model provides a consistent reference for the temperature of the different photovoltaic modules studied, mainly for incident irradiance levels within the range of 800 W/m² and 1200 W/m² and wind speed values between 2 m/s if 8 m/s, and that it is possible to keep the mean absolute errors below 8.5% in the estimate of Tmod. Resumo. Modelagens baseadas em balanço energético e que consideram os principais processos de transferência de calor que podem estar presentes nos módulos fotovoltaicos (FV) já se mostraram uma boa alternativa para predição de temperatura, porém, a resolução desses modelos pode não ser trivial em razão da grande quantidade de variáveis envolvidas e das soluções implícitas que elas geram, principalmente quando são consideradas as condições de regime transitório. Diante disso, esse estudo tem como objetivo obter um modelo para estimar a temperatura de módulos FV (Tmod) a partir de um balanço de energia em condição de regime estacionário. Inicialmente, o modelo desenvolvido foi aplicado em cinco diferentes módulos FV para valores de irradiância, temperatura do ar e velocidade do vento correspondentes à condição NOCT e validado com base na temperatura operacional dada pelos fabricantes nessa mesma condição. Dados experimentais do Laboratório UMR CNRS 6134 SPE, Université de Corse, na França, referentes a medições meteorológicas, térmicas e elétricas de quatro módulos FV foram aplicados ao modelo de temperatura desenvolvido. Foi realizada uma avaliação do ajuste dos dados experimentais aos simulados utilizando os parâmetros estatísticos MAE, RMSE e MAPE. Os resultados concluíram que o modelo preditivo desenvolvido fornece uma referência consistente para a temperatura dos diferentes módulos FV estudados, principalmente para níveis de irradiância incidente dentro da faixa de 800 W/m² e 1200 W/m² e valores de velocidade do vento entre 2 m/s e 8 m/s, e que é possível manter os erros médios absolutos abaixo de 8,5% na estimativa de Tmod.

This study applies the Constructal Design method to the geometric optimization of a branched symmetric concentration divider for calibrating ultrasound devices used to monitor tumor response with dynamic contrast. Accurate calibration ensures image quality and diagnostic reliability. The geometry consists of a three-dimensional, tree-shaped flow network with two inlets and three outlets, where inlet 1 carries water containing contrast particles, while inlet 2 carries only water. Laminar flow simulations are performed using Computational Fluid Dynamics (CFD) with Ansys Fluent, assuming no-slip wall conditions and zero-pressure outlets. The analysis investigates the effects of the inlet velocity ratio, the diameter ratio, and the vertical positions of the central outlet and inlet tubes, while keeping the total volume and inlet diameter constant. Additionally, velocity, pressure, particle distributions, flow partition ratio, and hydraulic resistance are evaluated. Results show nearly linear concentration responses among the outlets (100%, 50%, and 0%) when the device approaches geometric symmetry with equal inlet velocities, demonstrating efficient control of flow splitting. Although the diameter ratio imposes a trade-off with hydraulic resistance, geometric symmetry combined with Constructal Design promotes improved flow uniformity and enhanced performance, with potential applications in microfluidic mixers that require precise intermediate concentrations.