Enhancing Energy Efficiency of Ship Diesel Engine with Gas Ecological Recirculation

Abstract

During the operation of ships, millions of tons of nitrogen oxides NOx, sulfur oxides SOx, soot, heavy metal compounds, and water vapor are emitted into the atmosphere every year. The exhaust gas recirculation (EGR) technology reuses engine exhaust gases during combustion to reduce the amount of oxygen at the engine cylinder’s inlet and reduce the amount of NOx rejected. The exhaust gas recirculation temperature is an important factor in allowing a higher percentage of the exhaust gas recirculation. Caused by higher loads, higher exhaust gas temperatures limit the higher exhaust gas recirculation coefficients. The application of the EGR system of the ship’s diesel engine using the heat of the gases by the ejector and absorption chillers for cooling the engine inlet air is proposed to cool the air entering the 6G50ME-C9.6 marine engine. A circuit design solution was proposed using the heat of recirculation gas (RG) by an ejector chiller (ECh) and absorption chiller (ACh) in the EGR system. The analysis has been made of using the heat of RG to cool the air entering the engine. The effect has been analyzed, considering changes in climatic conditions on the Odessa-Shanghai route for a dry cargo vessel. It has been found that the use of an exhaust gas recirculation system using heat RG for cooling engine intake air by ECh and ACh reduces the temperature of the air entering the engine. The temperature drops by 5–15 °C, which in turn reduces the specific fuel consumption (SFC) by 0.6–1.8 g/(kW \(\cdot\) h). Also, the amount of harmful substances formed during engine operation decreases SOx by 10–14%; NOx by 25–35%.