Fixed flat-plate solar collectors suffer from low energy efficiency during mornings and evenings due to suboptimal solar incidence angles, reducing thermal output. While tracking systems improve efficiency by following the sun’s path, their high initial costs, mechanical complexity, and need for advanced control systems limit widespread adoption. These drawbacks demonstrate the importance of cost-effective, efficient alternatives that balance performance and simplicity in solar thermal applications. Thus, a triple-sided solar dryer (TSSD) integrated with intelligent airflow gating was developed to overcome these issues. This study evaluates the performance of a TSSD for drying tilapia strips at three thicknesses (4, 8, and 12 mm) using computational fluid dynamics (CFD), energy-exergy analysis, and sustainability indicators. According to the CFD simulations, they were employed to analyze airflow patterns, temperature distribution, and velocity profiles inside the TSSC and drying room (DR) during a day from 8 a.m. to 5 p.m. Additionally, the CFD was used to estimate the highest air temperature inside the drying to choose the appropriate speed of the air exhaust fan. The simulation analysis indicated that the highest air temperatures were 188.67, 124.4, and 96.51 °C, at three corresponding air velocities of the exhaust fan (1.0, 1.5, and 2.0 m/s), respectively, under a solar intensity of 872 W/m². Where the best velocity of the air exhaust fan was 2 m/s, it provided a uniform drying temperature of 96.51 °C, at solar noon (less than 100 °C). On the other hand, the energy-exergy analysis and sustainable indicators were estimated over two consecutive drying days (8 a.m.–5 p.m.) to assess the thermal behavior of the TSSC and TSSD. The energy analysis showed that the TSSC attained a maximum input energy of 1752.72 W and a useful energy of 810.31 W. Its energy efficiencies ranged from 40.79% to 57.21%. Meanwhile, the maximum drying efficiency was 8.19%, 8.51%, and 8.46% for tilapia strip thicknesses of 4, 8, and 12 mm, respectively. Furthermore, the exergy efficiency ranged from 7.28% to 32.83% (TSSC) and from 66.5% to 87.19% (DR). Additionally, sustainability indicators, such as improvement potential (IP) ranging from 1.19 to 7.22 W, waste exergy ratio (WER) between 0.67 and 0.93, and sustainability index (SI) from 1.08 to 1.49, showed that the system is both environmentally friendly and effective in its operations. The results show that the TSSD is an effective, eco-friendly, and affordable option compared to traditional solar drying systems, providing the best heat performance, better energy-exergy efficiency, and less harm to the environment for drying tilapia.

Analyzing the influence of rifled tube and magnesium oxide (MgO) nanoparticle on the performance of flat-plate solar collector under natural circulation

Thermo-hydraulic performance assessment of mono and hybrid ceramic nanofluids in flat plate solar collectors: a CFD-based study

This study investigates the effect of rotation step size on the performance of flat-plate solar collectors (FPSC) equipped with single-axis tracking. Numerical simulations were carried out in EnergyPlus, coupled with a custom Python interface enabling dynamic control of collector orientation. The analysis was carried out for the city of Kragujevac in Serbia, located in a temperate continental climate zone, based on five representative summer days (3 July–29 September) to account for seasonal variability. Three collector types with different efficiency parameters were considered, and inlet water temperatures of 20 °C, 30 °C, and 40 °C were applied to represent typical operating conditions. The results show that single-axis tracking increased the incident irradiance by up to 28% and the useful seasonal heat gain by up to 25% compared to the fixed configuration. Continuous tracking (ψ = 1°) achieved the highest energy yield but required 181 daily movements, which makes it mechanically demanding. Stepwise tracking with ψ = 10–15° retained more than 90–95% of the energy benefit of continuous tracking while reducing the number of daily movements to 13–19. For larger steps (ψ = 45–90°), the advantage of tracking decreased sharply, with thermal output only 5–10% higher than the fixed case. Increasing the inlet temperature from 20 °C to 40 °C reduced seasonal heat gain by approximately 30% across all scenarios. Overall, the findings indicate that relative single-axis tracking with ψ between 10° and 15° provides the most practical balance between energy efficiency, reliability, and economic viability, making it well-suited for residential-scale solar thermal systems. This is the first study to quantify how discrete rotation steps in single-axis tracking affect both thermal and economic performance of flat-plate collectors. The proposed EnergyPlus–Python model demonstrates that a 10–15° step offers 90–95% of the continuous-tracking energy gain while reducing actuator motion by ~85%. The results provide practical guidance for optimizing low-cost solar-thermal tracking in continental climates.

Temperature switching strategies analysis of large flat plate solar collector coupled with dual-source heat pump system

Techno-economic simulation of solar flat plate collector systems for building hot water demand supply

A new conceptual design of flat-plate solar collector based on two-phased closed thermosyphon: CFD-based exergetic optimization

Numerical Study on the Improvement of Flat-Plate Solar Collector Performance Using a Finned Storage Tank Containing Phase Change Materials.

Evaluating the impact of recycled ceramic-PCM compound and absorber tube positioning on the efficiency of flat-plate solar collector

Solar-energy-driven membrane distillation provides a sustainable pathway to mitigate freshwater scarcity by utilizing an abundant renewable heat source. This study develops a two-dimensional axisymmetric computational fluid dynamics (CFD) model to simulate the transient performance of a hollow fiber water gap membrane distillation (HF-WGMD) module integrated with flat-plate solar collectors (FPCs). A lumped-parameter transient FPC model is coupled with the CFD framework to predict feed water temperature under time-varying solar irradiation, evaluated across four representative days in a Mediterranean city. The model is validated against experimental data, showing strong agreement. A comprehensive parametric analysis reveals that increasing the collector area from 10 to 50 m2 enhances the average water flux by a factor of 6.4, reaching 10.9 kg/(m2h), while other parameters such as collector width, tube number and working fluid flow rate exert comparatively minor effects. The module flux strongly correlates with solar intensity, achieving a maximum instantaneous value of 18.4 kg/(m2h) with 35 m2 collectors. Multistage HF-WGMD configurations are further investigated, demonstrating substantial reductions in solar energy demand due to internal thermal recovery by the cooling stream. A 40-stage system operating with only 10 m2 of solar collectors achieves an average specific thermal energy consumption of 424 kWh/m3, while the overall solar desalination efficiency improves dramatically from 2.6% for a single-stage system with 50 m2 collectors to 57.5% for the multistage configuration. The proposed system achieves a maximum freshwater productivity of 51.5 kg/day, highlighting the viability and optimization potential of solar-driven HF-WGMD desalination.

Investigation of melting and energy storage performance of PCM in a flat plate solar collector considering novel dendritic fin design and GO+MXene hybrid nanoparticles

The rising demand for sustainable energy sources has driven further study and development in solar energy systems. Capturing solar energy for many applications, such as space heating, water heating, and power generation, flat plate solar collectors (FPSCs) are very necessary. This work is to provide a comprehensive overview of present development and strategies used to increase the efficiency of the solar collector as well as fundamental ideas guiding the operation of (FPSC). Among the many methods examined, the use of modern materials and nanotechnology especially the inclusion of nanoparticles and nanostructured coatings has been shown to greatly improve thermal performance, therefore attaining the most increase in efficiency. The overview of these significant findings in the assessment points to topics of future investigation direction. It emphasizes the need for all-encompassing strategies that take environmental issues into account along with technical advancement to enhance performance and general use(FPSC). Academics, engineers, and legislators working toward the sustainable development of technologies will find great value in this work.

Abstract This study investigates the design, operation, and thermal performance of a solar-assisted heat pump dryer (SAHPD), conceptualized as a low-temperature hybrid thermal reactor for efficient drying of agricultural biomass. Focused on post-harvest processing of cardamom, the system integrates a vapor compression heat pump with a flat-plate solar collector, aiming to enhance energy recovery and improve moisture removal efficiency under tropical climatic conditions. Experiments were conducted in Karnataka, India, using a 10 kg batch of fresh cardamom subjected to drying over an 8-h period. The system was tested in three configurations: solar drying (SD), heat pump drying (HPD), and the integrated SAHPD mode. Key environmental parameters, including ambient temperature, relative humidity, and solar radiation (with peaks up to 870 W/m2), were recorded in real-time. Drying kinetics, energy efficiency, and total moisture loss were evaluated for each mode. The integrated SAHPD system demonstrated superior reactor performance, achieving approximately 80 % moisture removal (about 6 kg), while maintaining product quality and significantly reducing drying time. Compared to standalone modes, the SAHPD showed improved thermal utilization and operational stability under fluctuating weather conditions. The experimental results position the SAHPD as a promising thermal reactor configuration for sustainable, energy-efficient drying of moisture-laden biomass. This study contributes to the growing body of work on thermal reactor engineering for agricultural processes, supporting the development of environmentally responsible and process-intensified technologies in biomass conversion and post-harvest systems.

Estimation of Solar energy incident on solar flat-plate collectors and determination of the optimum tilt angle at Bharatpur, Northern-West Region (NWR) of India

Thermal performance of a flat plate solar collector in Ugandan climatic conditions

Performance improvement of flat plate solar collector employing phase change material bags and hybrid nanofluid

Magnetohydrodynamic enhancement of solar collector efficiency using Al2O3–Cu hybrid nanofluids with variable thermal conductivity

Multi-walled carbon nanotube nanofluids in solar flat plate collectors for advanced heat transfer solution

In many developing African countries, milk safety is often managed through traditional methods such as fermentation or boiling over firewood. While these approaches reduce some microbial risks, they present critical limitations. Firewood dependency contributes to deforestation, depletion of agricultural residues, and loss of soil fertility, which, in turn, compromise environmental health and food security. Solar pasteurization provides a reliable and sustainable method for thermally inactivating pathogenic microorganisms in milk and other perishable foods at sub-boiling temperatures, preserving its nutritional quality. This study aimed to evaluate the thermal and microbial performance of a low-cost solar milk pasteurization system, hypothesized to effectively reduce microbial contaminants and retain milk quality under natural sunlight. The system was constructed using locally available materials and tailored to the climatic conditions of the Savanna ecological zone in West Africa. A flat-plate glass solar collector was integrated with a 0.15 cm thick stainless steel cylindrical milk vat, featuring a 2.2 cm hot water jacket and 0.5 cm thick aluminum foil insulation. The system was tested in Navrongo, Ghana, under ambient temperatures ranging from 30 °C to 43 °C. The pasteurizer successfully processed up to 8 L of milk per batch, achieving a maximum milk temperature of 74 °C by 14:00 GMT. Microbial analysis revealed a significant reduction in bacterial load, from 6.6 × 106 CFU/mL to 1.0 × 102 CFU/mL, with complete elimination of coliforms. These results confirmed the device’s effectiveness in achieving safe pasteurization levels. The findings demonstrate that this locally built solar pasteurization system is a viable and cost-effective solution for improving milk safety in arid, electricity-limited regions. Its potential scalability also opens avenues for rural entrepreneurship in solar-powered food and water treatment technologies.

Thermo-economic modelling of fouling in flat plate solar collector networks in batch operation