RESEARCH OF THE EFFICIENCY OF MARINE DIESEL FUEL COOLING SYSTEM ON THE BASIS OF NEW REFRIGERANTS

The requirements of the International Maritime Organization, government environmental agencies and other non-governmental groups are aimed at reducing emissions of harmful substances into the environment during the operation of diesel engines. Among these substances, the most dangerous are sulfur oxide (SOx), nitrogen oxide (NOx) and particulate matter (PM). In accordance with the specified requirements, there is an active transition to fuels with ultra-low sulfur content. The use of these fuels in marine diesel engines is associated with a number of difficulties, because these engines are usually designed for operation on fuels with high viscosity and lubricity. The viscosity values for ultra-low sulfur fuels are close to the permitted minimums for diesel engines at normal engine room temperature. The greatest difficulties occur when the viscosity values fall below the specific range when the fuel temperature before the engine increases. For reliable operation of the engine, the fuel temperature must be constantly maintained at a range in which the fuel viscosity will have the required values. For this purpose the engine design provides presence of fuel cooling system with a water cooler and a chiller for heat removal from water. In this paper the efficiency of chiller refrigeration plant was investigated using new perspective refrigerant mixtures R125/R290 and R134a/R290 as working fluids in comparison with basic R134a and R22. The values of composition for both mixtures are chosen such that they are closest to the azeotrope. It is possible for azeotrope mixtures to minimize the temperature difference between heat exchanging medias in condenser and evaporator of refrigeration plant. During the investigation it was revealed that the values of refrigeration coefficient of refrigerating plant when using mixtures as working fluids were somewhat lower when operating on R134a and R22. But the values of volumetric refrigeration capacity with mixtures as working fluids are significantly higher.