Design of an innovative system for hydrogen production by electrolysis using waste heat recovery technology in natural gas engines.

This research proposes designing and implementing a system to produce hydrogen, utilizing the thermal energy from the exhaust gases in a natural gas engine. For the construction of the system, a thermoelectric generator was used to convert the thermal energy from the exhaust gases into electrical power and an electrolyzer bank to produce hydrogen. The system was evaluated using a natural gas engine, which operated at a constant speed (2400 rpm) and six load conditions (20 %, 40 %, 60 %, 80 %, and 100 %). The effect of hydrogen on the engine was evaluated with fuel mixtures (NG + 10 % HEF and NG + 15 % HEF). The results demonstrate that the NG + 10 % HEF and NG + 15 % HEF mixtures allow for a decrease of 1.84 % and 2.33 % in BSFC and an increase of 1.88 % and 2.38 % in BTE. Through the NG + 15 % HEF mixture, the engine achieved an energy efficiency of 34.15 % and an exergetic efficiency of 32.84 %. Additionally, the NG + 15 % HEF mixture reduces annual CO, CO2, and HC emissions by 9.52 %, 15.48 %, and 13.39 %, respectively. The addition of hydrogen positively impacts the engine's economic cost, allowing for a decrease of 1.56 % in the cost of useful work and a reduction of 3.32 % in the cost of exergy loss. In general, the proposed system for hydrogen production represents an alternative for utilizing the residual energy from exhaust gases, resulting in better performance parameters, reduced annual pollutant emissions, and lower economic costs.

Experimental evaluation of low-displacement compression ignited engines operating with hydroxy gas as a supplementary gaseous fuel.

A large proportion of annual production of worldwide greenhouses gases results from the use of internal combustion engines. This experimental work evaluates the influence of dual-fuel operation on the overall emissions of a low-displacement compression-ignition engine based on operational conditions such as torque, rotational speed, and load. Hydroxy gas is used as a supplementary gaseous fuel while using pure diespel or palm oil biodiesel as baseline fuels. The CO, CO2, NOx, and HC emissions levels were carefully characterized through experimental measurements and statistical analysis. The influence of hydroxy enrichment was also examined on the engine's fuel consumption. The study incorporates an in-house hydroxy generator to store and supply the gas in the intake air system using an electrolyzer. The results demonstrated that the ANOVA analysis provides accurate predictions compared to experimental measurements with less than 5% relative error. The use of hydroxy reduces the SFC by up to 25%, which represents an economic advantage of dual-fuel operation, additionally it decreases CO, HC, and CO2 emissions. However, with hydroxy enrichment, NOx emissions levels escalate at medium and high loads. Overall, hydroxy enrichment demonstrates to be a robust alternative from an environmental and economic perspective. Future research will be focused on evaluating the biodiesel - hydroxy dual operation, broadening the spectrum of biodiesel concentration percentages, and selecting different raw materials for biofuel production.