International Journal of Renewable Energy and Electrical Power Systems

Energy Loss Analysis and Reduction Techniques in Single-phase Induction Motors for Household Applications

Fri, 22 May 2026 00:00:00 +0000

This work investigates the performance and energy efficiency of single-phase induction motors (SPIMs), which are extensively used in household appliances such as ceiling fans, refrigerators, and washing machines due to their simplicity and low cost. Although these motors are widely adopted, they exhibit relatively low efficiency compared to three-phase machines because of inherent design limitations and multiple forms of energy loss, which reduce overall performance. In this study, the total losses in SPIMs are systematically categorized into copper losses, core losses, mechanical losses, and stray losses, and each type is analyzed in detail. Copper losses increase significantly with load because of higher current flow in the windings, whereas core losses remain nearly constant, as they primarily depend on supply voltage and frequency. Mechanical losses, which arise from friction and windage, and stray losses, which occur due to leakage flux and other minor factors, also contribute to the total energy dissipation, although their impact is comparatively smaller. An experimental as well as analytical methodology is employed to evaluate motor performance under varying load conditions, and the results clearly indicate that copper losses dominate at higher loads, while other losses exhibit less variation. Although the efficiency decreases under heavy loading, it can be improved if appropriate measures are taken. The implementation of improved magnetic materials, optimized winding design, and effective control strategies can enhance efficiency by approximately 8–12%, and these improvements are both practical and cost-effective. Therefore, the findings provide valuable guidelines that can be applied to enhance the energy efficiency of household motor-driven systems.

Design of a Protected Stand-Alone Photovoltaic System for Uninterrupted Power Supply in Nigerian Hospitals

K. E. Orie , S. A. Ike, T. A. Aika — Fri, 22 May 2026 00:00:00 +0000

Healthcare delivery service is very crucial and depends to a large extent on reliable, clean and adequate power supply. However, in Nigeria, grid-connected electricity supply has never been reliable, as most Nigerian hospitals depend on alternative gasoline or diesel-powered generating sets, thereby skyrocketing the operating cost of hospitals, causing an increase in patients’ medical bills and an increase in death rates as a result of power outages in essential departments/units with life support gadgets/machines that require uninterrupted power to save lives. This study, therefore, aims to develop a protected and cost-effective stand-alone PV system for uninterrupted power supply in Nigerian hospitals. Solar irradiation and ambient temperature form input data, used for analysis and investigation, which were assessed from the NASA database, while the energy audit data for essential loads of the hospital were obtained using a clamp meter across the 3-phase supply at the various departments. Electrical Transient Analyzer Program (ETAP), version 19.0.1, was used to model and simulate the existing power supply to the hospital and design two networks for essential loads. Placement of capacitor banks on designed networks was carried out to provide reactive power support for a more efficient, stable and reliable network. Thereafter, governing equations were formulated to characterize the study case for improved power supply and size the PV components for both networks. An overcurrent protection scheme was carried out on the networks with a fault inserted at the modular unit (with a lump load of 4.88kVA) and radiology unit (with a lump load of 71.33kVA). Finally, the value engineering approach was adopted for cost savings using the utility bill for the year 2024. The result showed a 138kW of essential loads in RSUTH across fourteen departments, recommending a 180kW(220kVA) capacity protected and cost-effective photovoltaic system with 3 days of autonomy to provide an uninterrupted power supply to essential loads in RSUTH. Capacitor banks of (1 × 45 kVAR) and (1 × 50 kVAR) were adequately sized and placed on the networks, thereby improving the voltage at the buses.

A Review of Solar Absorption Refrigeration: A Sustainable and Energy-Efficient Alternative to Conventional Mechanical Cooling

Samhar Saeed Shukir — Mon, 06 Jul 2026 00:00:00 +0000

This paper presents a technical assessment of solar absorption refrigeration (SAR) as a sustainable alternative to conventional, electricity-driven vapour compression cooling systems. It examines the performance of two primary working fluid pairs—ammonia-water (NH₃-H₂O) and lithium bromide-water (LiBr-H₂O)—with a focus on their efficiency under high ambient temperatures. A key outcome is the development of a comparative framework that highlights how peak solar availability aligns with periods of highest cooling demand, making SAR particularly suitable for off-grid cooling in arid climates. The review covers recent innovations, including hydrogen-assisted pressure control and the integration of Phase Change Materials (PCM) to stabilize system operation during fluctuations in solar input. Additionally, the study assesses the scalability of SAR systems, noting their potential for industrial applications with capacities extending into the thousands of kilowatts. The results outline a viable pathway to lower greenhouse gas emissions and reduce operating expenses by utilizing low-temperature waste heat, contributing to broader efforts toward decarbonizing the cooling industry.

Measuring What Matters: Field Data on E-Rickshaw Chargers in Greater Dhaka Expose a Measurement-Basis Gap and Bound Potential Energy Savings

Thu, 22 Oct 2026 00:00:00 +0000

Battery-powered auto-rickshaws are one of the fastest-growing vehicle segments in South Asian cities, yet studies of their charging load generally assume the efficiency of the chargers rather than measure it. This study reports a preliminary field survey of 55 battery–charger units (45 of the 48 V class and 10 of the 60 V class, all with iron-core chargers) in 10 garages in greater Dhaka, Bangladesh, in which voltage, current, temperature, and charging duration were recorded during normal garage operation. The recorded output-to-input power ratio averaged 31.3% (SD 0.9 percentage points; garage means 30.9–31.9%), with the 48 V and 60 V classes at 31.4% and 31.0%. This ratio cannot be read as a charger efficiency: output power was computed from the terminal voltage of a single battery rather than the four-battery pack, and input power was estimated as the product of voltage, current, and an assumed power factor of 0.82–0.97. On a pack basis, the same readings give 120–132% for all 55 units, which is physically impossible, so the survey identifies a measurement-basis problem in the recorded data rather than a charger efficiency problem. Because the true baseline efficiency is unknown, a bounding techno-economic model was run over baselines of 31.3–70%, three annual consumption baselines (two from cited inputs, one derived; 1.70–7.30 TWh/year on a 365-day basis), and retrofit efficiencies of 60–90%. Taking 31.3% at face value gives up to 47.8–65.2% lower grid draw, worth up to Tk 1,050–6,147 crore/year (about US$86–500 million at Tk 122.6/US$) at the BPDB-estimated average generation cost of Tk 12.91/kWh and up to 335–457 MW of avoided evening peak; the savings fall to 0–33% if the true baseline efficiency is 60%. A reduced-scale 15–30 V DC–DC push–pull stage measured about 92% ± 4 percentage points at 3–13.5 W, which is transformer-stage evidence only. Re-measurement of pack voltage and true input power over whole charging sessions, and rated-power testing of a complete charger are required.