
Xi'an Jiaotong University, China


fmos
Open Access
Article
Article ID: 4043
by Sreenesh Valiyandi, Gireeshkumaran Thampi
Energy Storage and Conversion, Vol.4, No.1, 2026;
Diffusion absorption refrigeration (DAR) is a promising cycle concerning renewable energy utilization, as the cycle can operate using only thermal energy input. However, to realize the benefits of the DAR cycle, there is a need to develop an improved understanding of how design parameters influence its performance. The cycle’s performance was particularly sensitive to several factors: the rate of heat added and the temperature of the generator, the effectiveness of the gas and solution heat exchangers, the mass flow rate of the refrigerant, and the type of working fluid. The aim of this research work is to conduct numerical simulations of the diffusion absorption refrigeration (DAR) cycle to study the thermodynamic performances. The working fluids utilized in this system are isobutane (R600a) (C4H10) as a refrigerant, dimethylformamide (CH3)2NC(O)H, as absorbent and helium as the inert gas. The cycle operation characteristics are investigated through numerical analysis, in terms of the coefficient of performance (COP) and minimum temperature by using the effect of generator temperature, absorber temperature, evaporator temperature and the solution concentrations. The performance of the system is examined by computer simulation using MATLAB software. The mathematical model will provide a reasonable estimation of the maximum COP, cooling capacity, mass flow rate, and exergy analysis. The refrigeration cycle experiments were conducted under the ambient condition of 30 ℃. Based on a mathematical model, performance evaluation and exergy analysis of the system are performed. The experiment set included a 0.04 m3 volume of commercial absorption diffusion refrigerator working with the dimethylformamide (CH3)2NC(O)H solution. Furthermore, the results obtained in the proposed system compare with the previous studies.
Open Access
Article
Article ID: 4099
by Victor J. Law, James F. Lalor, Jenny. Magnes, Denis P. Dowling
Energy Storage and Conversion, Vol.4, No.1, 2026;
This paper investigates the proof of principle of small-scale off-grid solar thermal batch recovery of candle wax on the island of Crete in astronomical winter season, where the Sun’s irradiance is in the range of 820–940 W×m−2. The investigation was carried out based on the recovery of unconsumed mixed petroleum-based paraffin and plant-based soy and palm-wax (250 g each) candle fragments and their re-casting into new 50–60 g blended-wax candles. Based on a converted family size (27 L) solar box cooker the investigation is conducted during the spring equinox of March 2025 and the winter solstice in December 2025. The solar box cooker conversion extends its functionality from simple food cooking and culinary leaf dehydration to the circular economy of mixed-wax fragments recovery and reuse thereby increasing the cost-benefits of the cooker. Sensible heat measurements and latent heat of fusion calculations for the solar wax recovery process are explored; in terms of solar box cooker energy conversion to applied power (W, or J.s−1) into the wax phase-change process, wax energy budget (J), and wax energy density (J.g−1). The challenge in sourcing pre-used temporary and permanent molds is explored along with solar heated water used for releasing of the blended wax From a circular economy perspective, the off-grid solar box cooker design allows future scaling-out to a possible 1 kg of mixed-wax recovery, when solar processing is performed at, or around, the time of the summer solstice where solar irradiance is strongest (typically, 1,020 W×m−2) and increased available daylight hours allow a third, and possibly a fourth 250 g of mixed-wax to be recovered and re-cast.
Open Access
Article
Article ID: 4036
by Ayman Abdul Karim Alhijazi, Samer diab, Adil adam
Energy Storage and Conversion, Vol.4, No.1, 2026;
Accurate estimation of solar radiation and optimal tilt angles is essential for maximizing the efficiency and power output of photovoltaic (PV) systems. This study investigates the optimal tilt angles and expected power generation of PV systems across major Syrian cities using climatic and geographical data. Both isotropic and anisotropic solar radiation models were evaluated, with the anisotropic model yielding approximately 5% higher energy estimates than the isotropic model. Monthly and annual optimal tilt angles were calculated using global horizontal irradiance (GHI) and ambient temperature data. The estimated total solar radiation across the studied cities reaches peak values of 8.45–8.92 kWh/m2/day in June. Using a 2.76 kWp monocrystalline silicon PV system, the predicted peak PV power output ranges from 0.92–0.96 kW during the summer months, while winter outputs decrease to approximately 0.45–0.50 kW due to reduced solar radiation and shorter daylight hours. The findings indicate that the predicted optimal tilt angle for the year is quite close to the towns' latitudes. By adjusting the photovoltaic module monthly rather than annually, it is possible to achieve a 3.8% increase in power output at ambient temperature for the investigated cities. The paper also uses geographic and meteorological data, such as monthly averages of GHI and ambient temperatures, to determine optimal tilt angles on a monthly and yearly basis. These findings highlight the significant solar energy potential across Syrian regions and provide practical guidelines for optimizing PV system installation and performance. The results can assist engineers and energy planners in improving solar energy utilization and supporting sustainable energy development in Syria.
Open Access
Article
Article ID: 4058
by Souleymane Kientega, Mohammed Ferfra , Youssef El Baqqal
Energy Storage and Conversion, Vol.4, No.1, 2026;
This study looks at the resilience and cross-region fidelity of a HRES (Hybrid Renewable Energy Systems) across multiple climates in Africa. The study modelled the systems with a PSO (Particle Swarm Optimization) algorithm in MATLAB (Matrix Laboratory). “Large-scale transferability” refers to the system’s capacity maintained against tight acceptance criteria. Normalized load curves were used to derive the climate impacts and case studies were in Laâyoune–Sakia El Hamra, Morocco and Ouagadougou, Burkina Faso. They display high adaptability of the systems; a complementarity of winds and solar see a LCOE (Levelized Cost of Energy) of 0.0954 USD/kWh and an annual system cost of $100,039 in Laâyoune–Sakia El Hamra, in Ouagadougou dominates mostly solar, with additional storage requirements, remained very competitive, with LCOE at 0.1014 USD/kWh (+6.3% variance). Both sites achieved similar levels of reliability (Loss of Load Probability, LLP ≈ 0.01) and reduced CO2 emissions significantly (275.29 tCO2/yr and 283.13 tCO2/yr, respectively). LCOE variation was less than 6.5% and LLP variation is less than 0.002, regardless of climate change. These results demonstrate that the flexibility of the methodology employed ensures the maintenance of techno-economic advantages, even in the face of a 45% decrease in wind power potential. Thus, the present paper contributes to the further evolution of HRES design—from an ad hoc narrow-site-specific optimization regime to a scalable, context-sensitive design framework. It also proposes a proven path toward sustainable and affordable renewable energy growth in developing countries.
Open Access
Article
Article ID: 4098
by Victor J. Law, James F. Lalor, Jenny Magnes, Denis Pius Dowling
Energy Storage and Conversion, Vol.4, No.1, 2026;
Open solar dehydration has been used traditionally to remove moisture from culinary leaves in order to preserve their medicinal and nutritional qualities. This paper investigates the performance of a converted family-size (27 L) solar box cooker for solar dehydration of culinary leaves (Bay, Sweet, and Greek Basil and Common Sage). The investigation was carried out over the three month period from May to July 2025, on the island of Crete. The chosen leaves vary in their in vivo water content and leaf-blade morphology. The leaves are vertically triple-stacked within the dehydrator, and a green agricultural shadow-mesh cover is used to prevent direct solar irradiance damage. By performing solar dehydration during the day, leaf dehydration stress characteristics are identified. Solar dehydration parameters reported are: air temperature, relative humidity as a function of process time, leaf mass pre- and post-dehydration, and leaf water stress outcome in terms of visually observed leaf morphological changes (leaf rolling score and leaf shrinkage). For the top frame within the unloaded dehydrator, the relative humidity baseline follows a 4th-order polynomial time series 0D-model, with a extreme end behavior equilibrating to 8% relative humidity. Leaf-loaded studies reveal leaf water moisture is injected into the dehydrator, thereby linearizing the unloaded dehydration curve. Over a 3 to 7.5 h period of sunlight exposure, the top frame leave average a weight loss of 4.0 to 4.5 g per hour. For the partially sun blocked leaves on the middle and bottom frames, a supervised endpoint model is used, required adding approximately 1 hour to account for the longer drying time.