VOL. 12, NO. 14, JULY 2017 ISSN 1819-6608 ARPN Journal of Engineering and Applied Sciences ©2006-2017 Asian Research Publishing Network (ARPN). All rights reserved. www.arpnjournals.com 4255 EMISSION CHARACTERISTICS OF HYDROGEN ENRICHMENT IN LIGHT DUTY SINGLE CYLINDER DIESEL ENGINE Mohammad Nazry Bin Rosley 1,2 , N. Tamaldin 1,2 , M. F. B. Abdollah 1,2 , Z. M. Zulfattah 1,2 and A. K. Mat Yamin 1,2 1 Faculty of Mechanical Engineering, Universiti Teknikal Malaysia Melaka, Malaysia 2 Centre for Advanced Research on Energy, Universiti Teknikal Malaysia Melaka, Hang Tuah Jaya, Durian Tunggal, Melaka, Malaysia E-Mail: noreffendy@utem.edu.my ABSTRACT The aim of this paper is to investigate the emission of a single cylinder diesel engine when being injected with hydrogen gas. The hydrogen gas was produced by alkaline electrolyser, which has multiple separators to separates hydrogen and oxygen gas produced. The input hydrogen gas injected into the single cylinder diesel engine was altered by changing the alkaline electrolyser input voltage. The effects of the hydrogen gas injected into the diesel engine was observed by measuring the emission characteristics. The engine emission was measured in terms of carbon monoxide (CO) and also nitrogen monoxide (NO) in parts per millionth (ppm). The results shows that, as more hydrogen gas was injected, the emission of carbon monoxide (CO) decreases while Oxides of Nitrogen (NOx) increases. Keywords: hydrogen gas, diesel engine, emission characteristics. 1. INTRODUCTION Diesel engine has been prime movers of industries such as agriculture, transportation and also heavy machineries for centuries. The advantages of diesel engines compared to other internal combustion engines, are lower fuel consumptions, lower unburned hydrocarbons produced and also have better energy release compared to the other type of engines [1]. Although there are many advantages regarding the diesel engine, scientists and engineers cannot neglect the effects of pollutant emits from the burning of fossil fuels by the engine. Therefore, there are many efforts and researches conducted all over the world to produce an efficient engine that has less pollutant emitted [2]. One of the methods is by using alternative fuel such as hydrogen. Hydrogen potential are being reviewed by many researchers shows promising future as alternative fuel due to its favorable fuel like characteristics. Hydrogen itself as an element is the most lightest, abundant and renewable source in the planet [3]. Hydrogen technology is not new and was being studied as alternative energy for the past decades. Hydrogen when injected into the diesel engine has proven to reduce the overall fuel consumption of the engine ([4], [5], [6], [7], [8], [9] and [10]). Other than that was also proven that by enriching the diesel engine with hydrogen, the efficiency of the engine also exhibits increment in performance ([5], [6], [7], [9], [10], [11], and [12]). However due to combustion by compression principle of the diesel engine, Hydrogen is not suitable to be used solely as a fuel. This is due to its higher self- ignition temperature and lower octane number compared to diesel fuel which requires an ignition source for combustion to occur. Therefore Hydrogen is feasible to be used as secondary fuel in duel fuel operation method, where diesel fuel acted as the pilot fuel to start engine combustion before hydrogen can be injected into the engine [4], [5], [8], [12] and [13]). Past studies show that when hydrogen gas is injected in a diesel engine as secondary fuel, the engine emission shows reduction in pollutant emission ([4], [5], [9], [10], [11], and [12]). An investigation was conducted to observe the performance of diesel engine direct injection with pure Hydrogen [12]. They found out that both the Oxides of Nitrogen (NOx) and Carbon Monoxide (CO) emitted by the engine decreases as more hydrogen was injected into the engine. The same decrement trend of NOx also can be found in [11] when they are investigating the effects of injecting pure hydrogen gas into a diesel engine at the intake port. In review paper [5] also has stated the same behavior of emission decrement of the engine when enriched by hydrogen gas. The dangerous gaseous emission produced from the normal diesel engine is the concern of this research. Hydrogen is expected to be a safer and cleaner fuel that can be utilize as an alternative fuel. Thus the objective of this study is to investigate the effects of hydrogen enrichment in the single cylinder diesel engine by observing the changes of the diesel engine’s emission characteristics. The emission will be taken from the engine exhaust pipe in terms of NOx and CO when the engine is in normal condition and compared with when the engine is enriched by hydrogen gas. 2. METHODOLOGY The Hydrogen source for this experiment was produced from an alkaline electrolyser system. The alkaline electrolyser consists of multiples electrodes mounted together and sandwiched between special membranes. The membranes will isolate the hydrogen and oxygen gas produced from the cell so that a nearly pure quality of hydrogen gas can be used throughout the experiment. The electrolyser solution pH was kept constant and the output hydrogen gas produced from the system was altered by altering the system’s input voltage [14]. The hydrogen gas produced was injected into the single cylinder diesel engine through the air intake port of the engine. The single cylinder diesel engine used has the following specifications as stated in Table-1.