Performance of plastic-derived liquid fuel in a compression ignition engine

Abstract

Fossil fuels are the major sources of energy for running engines, powering industries, and for supporting domestic activities. However, as energy-intensive activities increase, there is a need for diverse sources of energy other than petroleum-based sources. This has led to the production of alternative liquid fuels from industrial waste, residential waste, agricultural waste, and plastics. Such fuels have been characterized and compared to petroleum fuels. However, additional testing of these fuels in engines reveals more data regarding the quality of these fuels in relation to the power of the engine. This study was designed to produce fuel from two types of plastics, High-Density Polyethylene (HDPE) and Polypropylene (PP) plastics through thermal pyrolysis, characterize the obtained liquid fuels, and evaluate their performance in a diesel engine in relation to standard diesel. The density of the fuel samples were measured to be 0.830 ± 0.001, 0.790 ± 0.003 and 0.788 ± 0.001 g cm-3, ash content was 0.02 ± 0.01, 0.03 ± 0.01and0.02 ± 0.00 % (m/m), cetane index was 53, 65 and 66, copper strip corrosion was class 1 a, class 3a, and class la, kinematic viscosity of 2.71±0.04, 2.00 ± 0.04 and 2.04 ± 0.02 cSt, and calorific value was 47.59 ± 0.49, 48.65 ± 0.13 and 48.52 ± 0.00 MJ/kg for standard diesel, High-Density Polyethylene Liquid Fuel (HDPELF) and Polypropylene Liquid Fuel (PPLF) respectively. The engine tests revealed that liquid fuel from HDPE and PP plastics had 12.8 % and 10.7 % higher Brake Specific Fuel Consumption, and a lower Brake Power of 1.3 % and 2.3 % respectively than that of standard diesel. The Brake Thermal Efficiency of HDPELF and PPLF were found to be 15.2 % and 13.1 % lower than when using standard diesel. These results suggest that the liquid fuel obtained from HDPE and PP plastic can be used as fuels in diesel engines with a minimum drop in brake power.