IOSR Journal of Mechanical and Civil Engineering (IOSR-JMCE) e-ISSN: 2278-1684,p-ISSN: 2320-334X, Volume 13, Issue 2 Ver. III (Mar- Apr. 2016), PP 74-80 www.iosrjournals.org DOI: 10.9790/1684-1302037480 www.iosrjournals.org 74 | Page Effect of HHO gas on fuel consumption and brake thermal efficiency of four stroke spark ignition engine with variable compression ratio Budhesh K. Jambukiya 1 , Prof. Krunal B.Patel 2 ,Prof. GauravP.Rathod 3 , Dr. Tushar M. Patel 4 1 (ME – Scholar, L.D.R.P-ITR- Gandhinagar) 2 (Associate professor, L.D.R.P-ITR, Gandhinagar) 3 (Assistant Professor, L.D.R.P-ITR, Gandhinagar) 4 (Associate professor, L.D.R.P-ITR, Gandhinagar) Abstract: In this study, HHO gas was produced by the process of water electrolysis. Electrolytes such that KOH is used as an electrolyte which reacts with electrode and produce the hydrogen. HHO gas was used as a supplementary fuel in a single cylinder, four strokes, spark ignition (SI) engine without any modification. In this experiment the HHO gas was supplied with intake air. The control valve was used for control the supply of HHO gas. The range of amount of HHO gas was placed between 2.57% to 2.74% with intake air. Also compression ratio was arranged at 7, 8 and 9 turn by turn. At this condition load was set at different condition at 1kg, 3kg, 5kg, 7kg and 9kg. After completing this experiment, an analysis was done. The fuel consumption was decreased when compression ratio and % of HHO gas was increased. Also the brake thermal efficiency was increased when compression ratio and % of HHO gas was increased. Key words: Brake thermal efficiency,Compression ratio, Electrolyte,Engine performance, Four Stroke SI engine, Fuel consumption, HHO gas. I. Introduction The reserve of petroleum over the world is limited. Decreasing supplies of fossil fuels and steadily rising concentrations of atmospheric carbon dioxide concentrations and levels of atmospheric pollutants are some of major challenges to the modern society. The scientific community is addressing these problems by an attempt to replace fossil fuels with cleaner and renewable sources of energy [4]. Hydrogen gas is an example of a renewable energy source that can be used to partially supplement petrol fuel by enriching supply air. Advantages of introducing hydrogen gas include higher net heating value and diffusivity of hydrogen in air when compared to fossil fuels [5]. In addition, better diffusivity produces a much faster flame velocity that can lead to a better acceleration and torque output from the engine. II. HHO Generation HHO gas is a combinationofdaiatomic hydrogen and monatomic oxygen.. HHO gas is produced by a similar design of the electrolyzer that will split water into its various components [5]. Brown’s gas has a plethora of unusual characteristics that seem to defy current chemistry [5]. The goal is to confirm claims of the Brown’s gas and to help solidify the current theory of Brown’s gas [5]. Electrolysis Process: This isthe simplest methodofhydrogenproduction.Electrolyzers make hydrogen by passing an electric current through water containing an electrolyte as shown in Fig 1 [5]. The figure represents a schematic view of the HHO gas electrolyzer. The electromagnetic field changes the atomic structure of the hydrogen (H2) and oxygen (0) found in water from diatomic to monatomic [5]. In addition, the neutron bond holding H & 0 together releases [5]. As H & 0 separate, H is drawn to the positive and 0 to the negative terminal of the electrolyzer [5]. This is called disassociation. As the process continues, volume increases, and the H & 0 gas bubbles which stick to the fins of the electrolyzer become dislodged and float to the top [5]. As the monatomic hydrogen and oxygen gas bubbles break the surface of the water they recombine in the air space in the top of the electrolyzer as Brown's gas [5].