ANALYZING THE EFFECTS OF CHANGING THE COM-PRESSION RATIO ON THE PERFORMANCE AND EMISSIONS OF HYDROGEN-PROPANE DUAL FUEL CI ENGINES

Abstract: Growing worries about the depletion of fossil fuels and harsh emission rules have pushed the hunt for sustainable and low carbon fuels for internal combustion engines. Hydrogen and propane are among the viable alternatives and are attracting much interest because of their excellent combustion properties and potential reduction of greenhouse gas emissions. This work presents extensive numerical research to investigate the effect of compression ratio (CR) on the performance, combustion characteristics and emission behavior of a hydrogen–propane dual fuel compression ignition (CI) engine. The study was conducted using AVL Workspace software on four-cylinder direct injection engine running at full load circumstances and constant engine speed of 2500 rpm. Five CRs (13:1, 14:1, 15:1, 16:1 and 17:1) were considered in the study. The effect of CR on brake thermal efficiency (BTE), brake specific fuel consumption (BSFC), effective torque, effective power, nitrogen oxides (NOx), carbon dioxide (CO2), unburned hydrocarbons (UHC), smoke opacity, ignition delay (ID), peak fire temperature (PFT), and peak fire pressure (PFP) was studied. The findings indicated that the increase of CR greatly improved the engine performance, which resulted in increased BTE, effective torque and effective power as well as lower BSFC. Moreover, higher CRs led to reduced NOx and CO2 emissions, lower smoke opacity and a shorter ignition delay, suggesting better combustion efficiency and cleaner engine running. On the other hand, UHC emissions rose with CR, whereas PFT and PFP increased due to enhanced combustion process and higher thermodynamic conditions in the cylinder.