RESUMEN
Decentralized power generation using renewable gaseous biofuels faces challenges due to their inconsistent quality and availability. Mixing producer gas (PG) with diesel as a secondary fuel is a promising option, but the non-stable calorific value (CV) of PG from different biomasses poses a serious problem for the efficient operation of a dual-fuel engine. This study aims to examine how the CV of PG from various biomasses affects a 3.75-kW dual-fuel IC engine's performance. The experimental facility, which has a dual-fuel engine and a 115-kW thermal gasifier, tested the blends of diesel and PG from different biomasses. We chose biomass based on its availability and PG's CV of 3.4, 4.4, 5.2, and 6.3 MJ/Nm3. For this range of CV, the efficiency, energy consumption, and fuel replacement of a dual-fuel engine vary between 20.9 and 26.6%, 17.3 and 13.5 MJ/kWh, and 10.8 and 76.9%, respectively. Furthermore, the blend with the maximum CV of PG had a 69.64% lower specific diesel consumption and an 86% higher diesel replacement rate than the blend with the lowest CV of PG. In terms of emission characteristics, the comparison showed a 2.02-7.06% reduction in NOx and a 4.05-55.6% increase in hydrocarbons (HCs) for the tested conditions. The overall observations demonstrated that a significant enhancement in a dual-fuel engine's performance is possible with a higher CV of PG. However, the emissions trade-offs demand additional optimization studies, as well as case-based research, in order to integrate renewable energy and emission management in smaller-scale applications across more geographies.
RESUMEN
The need to address global warming issues and international policies has placed a greater emphasis on the development of solar energy utilization systems. Intensive study is necessary to expand solar energy applications, as solar energy potential varies widely. This study investigates the thermal and thermohydraulic performance of a modified flat plate solar air heater (FSAH) to assess the effects of using corrugated aluminium duct and sand heat storage elements (HSE) in various combinations. The different arrangements selected for the experimental investigation are the FSAH, FSAH with corrugated aluminium duct (FSAH-C), FSAH with a sand heat storage element (FSAH-S), and FSAH with a combined use of corrugated aluminium duct and a sand heat storage element (FSAH-CS). The materials used for fabrication are low-cost and readily available in the study area. The results indicate that the sand bed enhanced the thermal performance by acting as the thermal heat storage medium, which could also supply heat for a short duration after non-sunny hours, and the corrugated aluminium duct enhanced the surface area and allowed the air to pass twice inside the SAH. We observed that the SAHs with sensible heat storage had a higher top loss compared to the FSAH-S configuration. The average thermal efficiency of the FSAH-CS configuration was 59.17%, which is 8.81%, 5.72%, and 10.95% higher than FSAH-S, FSAH-C, and FSAH, respectively. Furthermore, this configuration achieved an exit temperature of 64.5 °C. The proposed system has a thermohydraulic efficiency of 59.14%, which is not significantly different from the average thermal efficiency. Therefore, the suggested system verifies its ability to function without requiring substantial external power.
RESUMEN
Climate change is an important environmental issue that is causing global temperatures to rise. The primary environmental targets are to reduce carbon emissions and mitigate the impacts of climate change. The refrigeration system is a major emitter of greenhouse gases because it uses refrigerants with a high global warming potential. Due to its excellent thermophysical properties, the R134a is the most commonly used refrigerant in refrigeration systems; however, its high GWP will need to be disposed of earlier. To achieve global environmental objectives, conventional refrigerants need to be replaced with environmentally friendly and energy-efficient refrigerants. In the present work, a mathematical simulation has been carried out to check the performance of low-GWP refrigerant mixtures as environmentally friendly alternatives for R134a in a low-temperature system. In this study, a 190-L domestic refrigerator has been considered a low-temperature system. This simulation was performed using the MATLAB software, and the REFPROP database was used to obtain thermophysical properties of the refrigerants. The results showed that the COP of HFO mixtures decreased by 4-20% compared to R134a. The exergy efficiency of the R1234ze/R134a mixture improves by 4 to 16% as compared to the other mixtures and its performance is very similar to the R134a. Due to the environmentally friendly properties and flammability aspects, R1234ze/R134a (90/10) could be a good substitute for R134a in lower temperature applications and to satisfy the Montreal and Kyoto Protocol expectations.