RESUMO
Photovoltaic technology has been widely recognized as a means to advance green energy solutions in the sub-Saharan region. In the real-time operation of solar modules, temperature plays a crucial role, making it necessary to evaluate the thermal impact on the performance of the solar devices, especially in high-insolation environments. Hence, this paper investigates the effect of operating temperature on the performance of two types of organometallic halide perovskites (OHP) - formamidinium tin iodide (FASnI3) and methylammonium lead iodide (MAPbI3). The solar cells were evaluated under a typical Nigerian climate in two different cities before and after graphene passivation. Using a one-dimensional solar capacitance simulation software (SCAPS-1D) program, the simulation results show that graphene passivation improved the conversion efficiency of the solar cells by 0.51 % (FASnI3 device) and 3.11 % (MAPbI3 device). The presence of graphene played a vital role in resisting charge recombination and metal diffusion, which are responsible for the losses in OHP. Thermal analysis revealed that the MAPbI3 device exhibited an increased fill factor (FF) in the temperature range of 20-64 °C, increasing the power conversion efficiency (PCE). This ensured that the MAPbI3 solar cell performed better in the city and the season with harsher thermal conditions (Kaduna, dry season). Thus, MAPbI3 solar cells can thrive excellently in environments where the operating temperature is below 65 °C. Overall, this study shows that the application of OHP devices in sub-Saharan climatic conditions is empirically possible with the right material modification.
RESUMO
A work on the design and construction of an integrated tetrafluoroethane (R134a) refrigerator-waste heat recovery dryer suitable for use in tropical regions is presented. The system comprises of a refrigerator with its condenser unit retrofitted to serve as the heat recovery mechanism and a drying chamber. The refrigerator had a vapour compression cycle driven by environmentally friendly R134a working fluid (refrigerant). The dryer component was powered by heat dissipated by the condenser piping from the exit of the compressor (superheat region) to the entrance of the sub-cooled region. The maximum drying temperature attained during pre-loading test was 49 °C while the evaporator provided cooling at a temperature of 5 °C. The specific moisture extraction rate of the dryer varied over 0.19-0.22 kg/kW.hr while 150W of cooling was produced at the evaporator in all cases. The energy utilization ratio obtained was 0.92, indicating that 92% of the waste heat recovered was actually utilized. The system coefficient of performance was estimated to be 10.09 thus indicating that the energy derived from IRWHRD was 10 times the energy it consumed. Application potentials therefore exist for use of this dual purpose system for simultaneous production of refrigeration and heating. Storage of food and drying of fabrics make the IRWHRD an option for use in both agricultural development and entrepreneurship development in laundry business.