Abstract:Solar energy represents the best alternative for traditional energy sources used in many thermal energy systems. Among solar thermal systems, Flat Plate Solar Collectors (FPSCs) are the most utilized type implemented in low and medium-level thermal domestic applications. Recently, the usage of nanofluids (NFs) to enhance FPSCs is one of the newest technologies that has drawn the attention of researchers to improve the overall thermal efficiency of solar systems. This paper briefly reviews the recent studies ca… Show more
“…Nevertheless, several limitations are reported, such as long-term degradation and optimal nano concentration to fulfil the desired properties, homogeneity issues/concerns, and cost consideration [99]. Preparation of PPCM-NPs is usually done using the same methods used to prepare nanofluids, such as sonication, magnetic stirrer, and so on [100,101]. However, stable PPCM-NPs is still one of the most challenging tasks, even in recent literature studies [102].…”
Section: Enhancement Techniques For Ppcm Poor Thermal Conductivitymentioning
In recent years, phase change materials (PCMs) have increasingly received attention in different thermal energy storage and management fields. In the building sector, paraffin as a phase change material (PPCM) has been introduced as an efficient PCM incorporated in a building envelope, which showed remarkable results. However, the poor thermal conductivity of PPCM is still the topmost drawback in experimental and numerical investigations. In this paper, a general assessment of paraffins, their common uses and applications, have been presented with a particular focus on their potential in building envelope applications. Moreover, the general and desired properties of PPCM are highlighted and evaluated. The primary practical limitation of PPCM of poor thermal conductivity and their effect on PPCM performance is presented and discussed. Correspondingly, the popular techniques applied to improve the poor thermal conductivity are presented and discussed in four categories: the dispersion of nanoparticles, expanded graphite, metallic foam, and extended surfaces technique (fins). All in all, the analysed research works indicated that PPCM based building envelope applications could remarkably improve the thermal performance of buildings in terms of thermal load reduction, energy-saving and thermal comfort. Furthermore, the adoption of enhancement techniques is essential to improve the thermal performance of PPCM in building applications for better utilisation. This review provides a clear vision for the newcomers and interested parties about the main application aspects of PPCM in the building sector for further investigations towards technology commercialisation.
“…Nevertheless, several limitations are reported, such as long-term degradation and optimal nano concentration to fulfil the desired properties, homogeneity issues/concerns, and cost consideration [99]. Preparation of PPCM-NPs is usually done using the same methods used to prepare nanofluids, such as sonication, magnetic stirrer, and so on [100,101]. However, stable PPCM-NPs is still one of the most challenging tasks, even in recent literature studies [102].…”
Section: Enhancement Techniques For Ppcm Poor Thermal Conductivitymentioning
In recent years, phase change materials (PCMs) have increasingly received attention in different thermal energy storage and management fields. In the building sector, paraffin as a phase change material (PPCM) has been introduced as an efficient PCM incorporated in a building envelope, which showed remarkable results. However, the poor thermal conductivity of PPCM is still the topmost drawback in experimental and numerical investigations. In this paper, a general assessment of paraffins, their common uses and applications, have been presented with a particular focus on their potential in building envelope applications. Moreover, the general and desired properties of PPCM are highlighted and evaluated. The primary practical limitation of PPCM of poor thermal conductivity and their effect on PPCM performance is presented and discussed. Correspondingly, the popular techniques applied to improve the poor thermal conductivity are presented and discussed in four categories: the dispersion of nanoparticles, expanded graphite, metallic foam, and extended surfaces technique (fins). All in all, the analysed research works indicated that PPCM based building envelope applications could remarkably improve the thermal performance of buildings in terms of thermal load reduction, energy-saving and thermal comfort. Furthermore, the adoption of enhancement techniques is essential to improve the thermal performance of PPCM in building applications for better utilisation. This review provides a clear vision for the newcomers and interested parties about the main application aspects of PPCM in the building sector for further investigations towards technology commercialisation.
“…Con el nanofluido TiO ଶ /H ଶ O, el estudio realizado por Said, Z., la fracción de volumen de las nanopartículas fue de 0.1% y 0.3% respectivamente, mientras que los caudales másicos del nanofluido variaron de 0.5 a 1.5 kg/min, por lo que calculando un promedio de caudal másico de 1 kg/min, es lo mismo que 01ݔ99.3 ି ݉ ଷ ݏ/ [10].…”
En este estudio se llevó a cabo la investigación para determinar el potencial de los nanofluidos como fluidos caloportadores no convencionales en colectores solares en un país con tanto potencial térmico como Panamá. Luego de hacer la investigación preliminar sobre cuatro posibles fluidos caloportadores, encontramos que los nanofluidos de CuO, Al2O3, SiO2 y TiO2 con agua como fluido base poseen propiedades térmicas de gran interés. Después se realizó la simulación de un sistema de colector solar simple a través del software TRNSYS y se utilizaron las condiciones climáticas de Panamá. Se utilizó un intercambiador de calor de contraflujo para suministrar el agua caliente sanitaria a una residencia estándar de cuatro personas, donde cada una consume 50 litros diarios. Se logró comprobar que los nanofluidos son fluidos caloportadores más eficientes que el fluido convencional (agua), siendo el SiO2 el mejor nanofluido a la hora de escoger el intercambiador de calor que vaya a utilizarse, por lo que estos fluidos caloportadores no convencionales podrían ser posibles sustitutos para nuevos colectores en un futuro.
“…To offset the negative impact of anthropogenic activities associated with the extraction and burning of fossil fuels, alternative energy sources need to be exploited [5][6][7][8][9][10]. Solar energy is one of the cleanest and cheapest sources of energy [11][12][13][14][15]. Solar energy is much more predictable than its rival, i.e., wind energy [16][17][18].…”
An enhanced design for a solar still desalination system which has been proposed in the previously conducted study of the research team is considered here, and the experimental data obtained during a year are employed to develop ANN models for that. Different types of artificial neural network (ANN), as one of the most popular machine learning approaches, are developed and compared together to find the best of them to predict the hourly produced distillate and water temperature in the basin, which are two key performance criteria of the system. Feedforward (FF), backpropagation (BP), and radial basis function (RBF) types of ANN are examined. According to the results, by having the coefficients of determination of 0.963111 and 0.977057, FF and RBF types are the best ANN structures for estimation of the hourly water production and water temperature in the basin, respectively. In addition, the annual error analysis done for the data not used to develop ANN models demonstrates that the average error in prediction of the hourly distillate production and water temperature in the basin varies from 9.03 and 5.13% in January (the highest values) to 4.06 and 2.07% in July (the lowest values), respectively. Moreover, the error for prediction of the daily water production is in the range of 2.41 to 5.84% in the year.
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