Thermo-Economic Optimization Of A Biogas-Diesel Dual Fuel Engine As Remote Power Generating Unit Using Response Surface Methodology

The present study proposes a techno-economic assessment of a biogas run diesel engine under dual-fuel (DF) mode using response surface methodology (RSM). Initially, engine experiments are conducted based on an experimental matrix designed with design of experiments (DoE) to investigate the effects of load, compression ratio (CR), and injection timing (IT). The quadratic models developed based on the experimental results are used to predict the output variable responses such as brake thermal efficiency (BTE), biogas flow rate (BFR), oxides of nitrogen (NOx), hydrocarbon (HC), carbon monoxide (CO) and carbon dioxide (CO2). Optimization of independent variables with desirability approach gave the optimum running condition for the engine i.e. 71% engine load, CR of 17.5, and IT of 28.5 degrees BTDC with an overall desirability index of 0.96. Experimental verification of the optimized results gave a very close agreement with least error levels. Further, a financial evaluation of the optimized DF system as a remote power-generating unit is carried out. The results indicated a levelized unit cost of electricity (LUCE) of 0.36 USD/kWh with a payback period of 7.5 years. However, with the increase in capacity of the system, the LUCE is bought down significantly to 0.183 USD/kWh and tariff charges to 0.125 USD/ kWh after a payback period of 6.8 years.