Охолодження Наддувного Повітря Головного Суднового Двигуна Ежекторною Холодильною Машиною В Екваторіальних Широтах

Abstract

The efficiency of cooling the scavenge air of the main low-speed engine of the transport vessel during operation in the equatorial tropical latitudes is analyzed. The peculiarity of the tropical climate is the high relative humidity of the air at the same time its high temperatures and temperatures of seawater. The cooling of the s scavenge air with a refrigerant ejector chiller was investigated by transforming the scavenge air heat into the cold. With this, the potentially possible minimum temperature of the cooled air was determined considering the boiling temperature of the refrigerant and the temperature differences in the heat exchangers of the intermediate water cooling circuit. Refrigerant ejector chiller is used as the most simple and reliable in design. However, the efficiency of converting the heat to cold by ejector chillers is low: their coefficients of performance are approximately 0.3. Circuit-design solution of three-stage cooling system of scavenging air of ship's main engine - in high-temperature (cogeneration) stage using the extracted heat of scavenging air to get cold with ejector chiller and traditional stage for cooling scavenge air by seawater and low-temperature cooling stage by ejector chiller. The effect of deeper cooling of the scavenge air was determined in comparison with the cooling of the scavenge air with seawater, taking into account the changing climatic conditions during the route of the vessel. It is shown that because of the insufficiently high efficiency of transformation of the scavenge air heat by the ejector chiller (low coefficients of performance) the obtained cooling capacity is not sufficient to cool the scavenge air to a potentially possible minimum temperature of 22 °C when operating the ship engine in tropical climates. However, the heat deficit is relatively small and can be covered by the use of additional exhaust gas heat.