Air quality monitoring is a critical component of environmental management, especially in developing countries where pollution levels are a growing concern. This review systematically analyzes recent advances in Internet-of-Things (IoT)-based air quality monitoring systems and highlights the impact of artificial intelligence (AI) technologies. A comprehensive selection process was used to identify 220 relevant studies using databases such as Google Scholar, Scopus, and ResearchRabbit. Following a selection process based on specific eligibility criteria, a total of 147 studies were chosen for a detailed analysis. These studies present notable advances in the application of artificial intelligence to improve data accuracy, predictive capabilities, and real-time analysis in air quality monitoring systems. A key contribution of this review is the proposal of a classification framework for AI techniques in air quality monitoring, organized into five main application areas: data imputation, sensor calibration, anomaly detection, air quality index (AQI) estimation, and short-term forecasting. The review takes an in-depth look at the different uses of these technologies in both urban and industrial settings, presenting successful case studies that showcase their effectiveness in addressing pressing air quality issues. Additionally, the paper identifies research gaps in the literature, particularly related to data quality, system scalability, and integration challenges in AI-driven IoT systems. The insights provided aim to guide researchers and practitioners in selecting appropriate AI techniques and system architectures, inform the design of more reliable and scalable air quality monitoring frameworks, and support future efforts to mitigate air pollution through data-driven decision-making.

In recent years, phase change materials (PCMs) have been presented as a suitable alternative for thermal energy storage (TES) systems for solar water heater (SWH) applications. However, PCMs’ low thermal conductivity and the high dependence on external conditions are the main challenges during the design of TES systems with PCMs. Design actions to improve the performance of the TES systems are crucial to achieve the necessary stored/released thermal energy and guarantee the all-day operation of SWHs under specific system requirements. In this study, a TES with PCM in the configuration of a heat exchanger was redesigned, focused on achieving two main targets: an outlet water temperature over 43 °C during discharging time (15 h) and efficiency over 60% to supply the hot water demand of two families (400 L). A four-step redesign methodology was proposed and implemented through numerical simulations to address this aim. It was concluded that the type, encapsulation shape, and amount of PCM slightly impacted the system’s performance; however, selecting a suitable sensible heat storage material had the highest impact on meeting the system’s targets. The redesigned TES reached 15 operating hours with a minimum outlet water temperature of 45.30 °C and efficiency of 76.08%.

The utilization of phase change materials (PCMs) in solar water heating systems (SWHS) has undergone notable advancements, driven by a rising demand for systems delivering superior performance and efficiency. Extensive research suggests that enhancing heat transfer (HTE) in storage systems is crucial for achieving these improvements. This review employs a bibliometric analysis to track the evolution of HTE methods within this field. While current literature underscores the necessity for further exploration into hot water generation applications, several methodologies exhibit significant promise. Particularly, strategies such as fins, encapsulation, and porous media emerge as prominent HTE techniques, alongside nanofluids, which hold the potential for augmenting solar water heating systems. This review also identifies numerous unexplored techniques awaiting investigation, aiming to pave new paths in research and application within the field of hot water generation. It highlights methods that could be used independently or alongside predominantly used techniques.

This study presents a numerical investigation of a solar dryer prototype integrated with microencapsulated phase change material (MPCM) for rice drying under tropical climatic conditions. The thermal and drying behavior of the system was evaluated under the following four configurations: a baseline solar dryer, a dryer with MPCM only, a dryer with an auxiliary heater, and a combined system using both MPCM and auxiliary heating. The prototype was also tested with rice layers of 25 mm and 45 mm to assess the influence of layer thickness on drying performance. The results showed that the use of MPCM reduced temperature fluctuations from about $\Delta T\approx 70$ °C in the baseline case to stabilized values near 33–34 °C (MPCM only) and 35–38 °C (MPCM + heater), contributing to a more stable thermal environment. In thinner layers (25 mm), MPCM helped prevent localized overheating, while in thicker layers (45 mm), it promoted more uniform moisture reduction. However, the overall improvement in drying performance was marginal, as efficiency remained strongly dependent on heater support. The study points out the need for improved integration of PCM within dryer design. Enhanced thermal contact and strategic preheating of MPCM could improve heat discharge during non-solar periods. Future work will focus on experimental validation, design optimization, and the development of preheating strategies to maximize the benefits of PCM-assisted solar drying systems.

En este artículo se presenta el desarrollo de un trabajo de investigación teórico-experimental de caracterización, modelado y análisis de factibilidad técnica de los sistemas de acondicionamiento de aire por adsorción con fuente de energía solar, utilizando el sistema instalado en el Centro de Innovación Eléctrica, Mecánica y de la Industria (CINEMI) de la Universidad Tecnológica de Panamá. El estudio parte del análisis del sistema de adsorción, su caracterización y modelado matemático, el cual permitió la obtención de expresiones útiles para evaluar parámetros tales como el COP, SCP y la eficiencia térmica del mismo. Utilizando data experimental recabada, se obtuvieron curvas de interés las cuales fueron comparadas con curvas obtenidas mediante simulación numérica. Se concluye que los sistemas de adsorción pueden ser técnicamente viables bajo ciertas condiciones de operación e instalación controlables y ha de tomarse en cuenta las perspectivas para el futuro de esta tecnología y actuales aplicaciones exitosas a nivel mundial.