Experimental Investigation of Hydrogen Addition in the Intake Air of Compressed Engines Running on Biodiesel Blend Hendrick Maxil Z´ arate Rocha, Ricardo da Silva Pereira, Manoel Fernandes Martins Nogueira, Carlos R. Pereira Belchior, Maria Emilia de Lima Tostes Abstract—This study investigates experimentally the effects of hydrogen addition in the intake manifold of a diesel generator operating with a 7% biodiesel-diesel oil blend (B7). An experimental apparatus setup was used to conduct performance and emissions tests in a single cylinder, air cooled diesel engine. This setup consisted of a generator set connected to a wirewound resistor load bank that was used to vary engine load. In addition, a flowmeter was used to determine hydrogen volumetric flowrate and a digital anemometer coupled with an air box to measure air flowrate. Furthermore, a digital precision electronic scale was used to measure engine fuel consumption and a gas analyzer was used to determine exhaust gas composition and exhaust gas temperature. A thermopar was installed near the exhaust collection to measure cylinder temperature. In-cylinder pressure was measured using an AVL Indumicro data acquisition system with a piezoelectric pressure sensor. An AVL optical encoder was installed in the crankshaft and synchronized with in-cylinder pressure in real time. The experimental procedure consisted of injecting hydrogen into the engine intake manifold at different mass concentrations of 2,6,8 and 10% of total fuel mass (B7 + hydrogen), which represented energy fractions of 5,15, 20 and 24% of total fuel energy respectively. Due to hydrogen addition, the total amount of fuel energy introduced increased and the generators fuel injection governor prevented any increases of engine speed. Several conclusions can be stated from the test results. A reduction in specific fuel consumption as a function of hydrogen concentration increase was noted. Likewise, carbon dioxide emissions (CO2), carbon monoxide (CO) and unburned hydrocarbons (HC) decreased as hydrogen concentration increased. On the other hand, nitrogen oxides emissions (NOx) increased due to average temperatures inside the cylinder being higher. There was also an increase in peak cylinder pressure and heat release rate inside the cylinder, since the fuel ignition delay was smaller due to hydrogen content increase. All this indicates that hydrogen promotes faster combustion and higher heat release rates and can be an important additive to all kind of fuels used in diesel generators. Keywords—Diesel engine, hydrogen, dual fuel, combustion analysis, performance, emissions. Hendrick Maxil Z´ arate Rocha is with the Department of Mechanical Engineering, Federal University of Rio de Janeiro, Cidade Universit´ aria, 21941-970 Rio de Janeiro, Brazil. Ricardo da Silva Pereira and Maria Emilia de Lima Tostes are with the Department of Electrical Engineering, Federal University of Par´ a, 66075-110 Bel´ em, Par´ a, Brazil. Manoel Fernandes Martins Nogueira is with the Department of Mechanical Engineering, Federal University of Par´ a, 66075-110 Bel´ em, Par´ a, Brazil. Carlos R. Pereira Belchior is with the Department of Mechanical Engineering, Federal University of Rio de Janeiro, Cidade Universit´ aria, 21941-970 Rio de Janeiro, Brazil (e-mail: belchior@oceanica.ufrj.br). I. I NTRODUCTION A S the world’s energy demand increases to propel economic and technical growth, so does the environmental impact associated with this demand. Fossil fuels, in particular, are responsible for the majority of noxious gas emissions, greenhouse gas emissions and due to its key strategic value, also play an important role in geopolitical interactions between countries and increase energy security concerns worldwide. In this context, there has been an increased interest in finding alternative and renewable energy sources of energy that can replace or at least mitigate those concerns [1]. Some of these alternative fuels include renewable biofuels such as ethanol, biodiesel and vegetable oils [2]-[4]. Sandalci et al. successfully conducted experimental tests on unmodified diesel engines operating with ethanol-diesel mixtures and found that increased ethanol percentage by volume in the mixture results in an increase specific fuel consumption, while also reducing thermal efficiency, CO 2 and NO x emissions [5]. As it pertains to Brazil, commercial diesel consists of a blend of diesel oil and 7% in volume of biodiesel, which is usually made up of a transesterified mixture of mono-alkyl esters of long chain fatty acids from either vegetable oils or animal fats [6]. Due to having similar properties to diesel oil, this fuel can be used in most diesel engines without requiring significant changes to the machine [7], [8] and presents benefits in comparison to pure diesel, such as reduced particulate matter (PM), hydrocarbons (HC) and carbon monoxide (CO) emissions [7]-[12]. Furthermore, due to its viscosity, biodiesel can improve an engine’s lubricity and consequently extend its useful life [8], [13]. On the other hand, biodiesel has a smaller lower heating value, as well as higher viscosity and smaller cetane number when compared to diesel. The latter results in increased ignition delays, which in turn causes the engine’s efficiency to decrease and results in higher fuel consumption [7]. However, additives can be blended with biodiesel in order to mitigate or even solve this problem by improving the engine’s combustion. One of the methods employed to mitigate the downsides of biodiesel use in internal combustion engines is hydrogen addition. Hydrogen is a renewable, odorless, non-toxic fuel and can improve combustion speed while also reducing carbon emissions due to the absence of carbon in its composition. However, it is also a secondary energy source, meaning it World Academy of Science, Engineering and Technology International Journal of Aerospace and Mechanical Engineering Vol:11, No:9, 2017 1604 International Scholarly and Scientific Research & Innovation 11(9) 2017 ISNI:0000000091950263 Open Science Index, Aerospace and Mechanical Engineering Vol:11, No:9, 2017 publications.waset.org/10008016/pdf