Effects of Viscosity and Heat Transfer on Developed Marine Fuel Preheating System Utilizing Diesel Engine Exhaust
Diesel engines in maritime applications exert heat energy from combustion gases. The main engines are the prime movers of ships and vessels; used marine fuel oil serves as working substance while the auxiliary diesel engine provides mechanical energy to the electric generator through the combustion of diesel fuel. The marine fuel oil preheating system is a contributor for energy consumption and diesel fuel consumption of auxiliary engines. Research on waste heat recovery from exhaust gases led to an alternative source of heat which may be applied to marine fuel oil as it enters the electrical operated pre-heater and purifier. The purpose of this study is to determine the heat transfer equations for fluid heat exchanger, heat transfer conduction and convection through pipe. The mathematical equation derivation resulted specifications, size and dimensions of a serpentine coil, conveying pipe and baffle plate of the heat exchanger assembly. This was done by fabricating a serpentine copper coil tube due to the higher thermal conductivity of copper compared to other tubing materials. The conveying pipe and baffles were made from 1.2 mm steel sheet because of its durability and availability in the market. Results of the conducted test and simulation have shown that 92% heat was gained from the aimed temperature. Heat transfer units were also enough to heat marine fuel oil. A highly viscous fluid ranges from 150 to 190 centistokes at normal temperature reduced its viscosity to 119 centistokes at 57°C. This is the target temperature to feed the fluid through a purifier.