Optimization of Flow Parameters for Waste Lubricating Oil Combustion

The global energy demand has continued to skyrocket, exacerbating the already severe energy problem and environmental pollution, prompting researchers to look for alternative energy sources. Exploration of waste lubricating oil (WLO) as an alternative source of fuel has gained prominence among researchers due to its availability at low cost and the potential to generate energy while providing a safer means of disposal. The main challenge with WLO combustion is proper regulation of fuel and oxidizer during combustion to realize a near stoichiometric result. Additionally, WLO has high viscosity, hence preheating of the oil is necessary to lower the viscosity and enhance atomization, for a more efficient combustion process. This paper presents the optimization of flow parameters for combustion of WLO in a burner system by use of response surface methodology (RSM). The effects of air flow rate, injection pressure and fuel flow rate on combustion performance of a WLO burner were investigated. The highest flame temperature recorded was 1200°C at an air flow rate of 1 m3/min, fuel flow rate of 0.08 m3/hr and injection pressure of 20 bar. Tests on physical and chemical properties of WLO were conducted and characterized according to ASTM standard to ascertain its potential as an alternative fuel. The calorific values of WLO from petrol and diesel engines were found to be 41.23 MJ/kg and 42.65 MJ/kg respectively. Therefore, recycling of WLO by utilizing it as a fuel for burners has double benefits of mitigating environmental pollution and harnessing energy for process heating and power generation.

Performance of Water in Glass Evacuated Tube Solar Water Heater under Kenya Climatic Condition

Solar water heaters which provide a cost-effective and environmental friendly approach to hot water generation are in widespread application. Evacuated tube solar water heaters perform better than flat plate solar water heaters as a result of their greater surface area exposed for sunlight absorption. Water-in-glass evacuated tube solar water heaters are widely used as compared to heat-pipe solar water heaters due to their short payback periods. In this study, the performance of water-in-glass evacuated tube solar water heater is investigated through experiments under the climatic conditions in Kenya. The results revealed a daily efficiency range of 0.58 - 0.65 and a daily final outlet temperature greater than 55°C given an initial temperature of 25°C.

Effect of Exhaust Gas Recirculation on Performance and Emission Characteristics of a Diesel-Piloted Biogas Engine

In this research, a Direct Injection Compression Ignition (DICI) engine was modified into a dual-fuel engine that used biogas as the primary fuel and diesel as pilot fuel, with the focus on reduction of harmful exhaust emissions while maintaining high thermal efficiency. The effect of exhaust gas recirculation (EGR) on engine performance and emission characteristics was studied. The EGR system was developed and tested with different EGR percentages, i.e. 0%, 10%, 20% and 30%. The effect of EGR on exhaust gas temperature and performance parameters like brake specific fuel consumption, brake power and brake thermal efficiency was studied. The performance and emission characteristics of the modified engine were compared with those of the conventional diesel engine. The results showed that EGR led to a decrease in specific fuel consumption and an increase in brake thermal efficiency. With increase in percent (%) of EGR, the percentage increase in brake thermal efficiency was up to 10.3% at quarter load and up to 14.5% at full load for single fuel operation while for dual-fuel operation an increase up to 9.5% at quarter load and up to 11.2% at full load was observed. The results also showed that EGR caused a decrease in exhaust gas temperature;hence it’s potential to reduce NOX emission. However, emissions of HC and CO increased slightly with EGR.

Influence of Car Park Proximity on Air Pollutant Concentrations at a Level 5 Hospital Outpatient Ward

Air quality is a critical factor in maintaining health and well-being, influencing both current conditions and future outcomes. Hospitals are one of the sensitive areas of our society, for they are built as sanctuaries for treatment and recovery, making the quality of paramount importance. This study investigates the impact of traffic-related emissions on indoor air quality within a Level 5 Hospital outpatient ward. Measurements were taken over five consecutive days, revealing that while CO2 levels generally remained within safe limits, there were instances where concentrations exceeded 3000 ppm, categorizing them as “Hazardous.” Notably, particulate matter (PM2.5 and PM10) levels fluctuated significantly, with peak concentrations observed during working hours correlating with increased vehicle activity. The data indicated that PM2.5 levels reached as high as 75 µg/m3, with 91.68% of recorded values exceeding the World Health Organization’s (WHO) and Environmental Protection Agency 24-hour mean threshold of 25 µg/m3. Similarly, PM10 concentrations peaked at 120 µg/m3, with 61.19% of values surpassing the WHO threshold of 50 µg/m3, both of which pose serious health risks, particularly to vulnerable populations such as pregnant women, infants, and the elderly. Additionally, the study highlighted the critical role of wind direction in pollutant dispersion, with specific patterns contributing to elevated indoor concentrations. These findings underscore the urgent need for targeted interventions and proactive air quality management strategies in healthcare facilities, including the strategic design of hospital wards away from primary emission sources and the promotion of electric vehicle use to mitigate traffic-related emissions.

Experimental study of four-step thermal swing adsorption cycle to upgrade biogas obtained from anaerobic digestion

Biogas is a renewable source of energy that when upgraded can be adopted as a reliable and sustainable alternative.This study evaluates the performance of thermal swing adsorption technology applying resistive heating,in upgrading biogas obtained from anaerobic digestion to biomethane.Commercial coconut shell-based activated carbon was used as an adsorbent in the four-step cycle process to capture carbon dioxide,using a fabricated adsorption model.The influence of minor gas constituents of biogas in carbon dioxide breakthrough curves was analyzed.Dynamic adsorption tests were carried out to evaluate the system performance in carbon dioxide capture.The maximum regeneration temperature of 60℃was found to have peak carbon dioxide concentration of 39%in the waste gas,maximum energy requirements of 0.1538 kWh per cycle,and an energy efficiency of 87%.This is a good trade-off between adsorbent recovery and system energy efficiency.The adoption of thermal swing adsorption technology in biogas upgrading systems is a viable alternative for water-deficient regions.

Experimental investigation and optimization of the gasification parameters of macadamia nutshells in a batch-fed bubbling fluidized bed gasifier with air preheating

Gasification of biomass waste has a significant potential to reduce environmental impact and promote sustainability by producing syngas,which is considered as renewable energy.This work investigated the gasification of macadamia nutshells in air-preheated,batch-fed fluidized bed gasifier.The study conducted a parametric analysis to assess the effect of equivalence ratio(ER)and air temperature on the gasifier temperature profile and its performance based on gas composition,higher heating value(HHV),and gas yield.The research was conducted within the range of 0.15-0.35 for the ER and 25-825℃ for the air temperature.Multi-objective numerical optimization was conducted using response surface methodology(RSM).From the parametric study,a distinct temperature profile was observed along the gasifier height,with the peak temperature near the top of the fluidized bed section and the lowest temperature at the top of the gasifier.Air preheating mostly favored gasification temperature at the lower part of the gasifier and showed rare significance at the top.No improvement in gasifier performance was observed beyond an air temperature of 620℃,which was identified as the ideal air-preheating temperature.Analysis of variance(ANOVA)revealed that the ER was the most influential parameter in the production of combustible gasses,syngas HHV and gas yield.Air preheating did not have a significant effect on methane production and gas yield.The most optimal values for ER and air temperature were obtained as 0.195℃ and 620℃,respectively,producing optimal values of 9.54,14.65%,2.03,4.02 MJ⋅Nm^(-3),and 1.82 Nm^(3)⋅kg^(-1) for hydrogen,carbon monoxide,methane,HHV,and gas yield,respectively.