An experimental study on waste cooking oil and its emulsions as diesel engine fuel

Performance characteristics of a WCO (Waste cooking oil) based compression ignition engine was investigated. A single cylinder water-cooled, direct injection diesel engine was used. Base data was generated with diesel and neat WCO as fuels. Subsequently, WCO oil was converted into its emulsions and tested in the diesel engine. Results showed increased specific energy consumption, higher smoke, hydrocarbon and carbon monoxide emissions with neat WCO in the engine as compared to neat diesel. The specific energy consumption was found as 20200 kJ/kW.hr with neat WCO and 15380 kJ/kW.hr with diesel at the maximum power output of 4.4 BMEP. It was improved to 19190 kJ/kW.hr with WCO emulsions at the maximum power output. Smoke emission was reduced from 4.4 BSU with neat WCO to 2.6 BSU with WCO emulsion in the unmodified diesel engine at the maximum power output. WCO resulted in reduced the NO emission at all power outputs as compared to neat WCO due to inferior combustion. NO emission was reduced further with WCO emulsions at all power outputs. Peak pressure was found lower neat WCO at all power outputs. However it was increased with WCO emulsions due to improvement in combustion. Ignition delay was observed as higher with neat WCO. It was further increased with the WCO emulsions. It is concluded that neat WCO can be used as fuel in diesel engine with slightly inferior performance. WCO emulsions can result in superior performance and reduced emissions mainly at peak power outputs.