Rational design of a heat recovery system for cooling the scavenge air of the main ship diesel engine considering the seasonal climate conditions

Abstract

There has been analyzed the efficiency of cooling the scavenge air of a ship low speed diesel engine in two- and three stage air coolers in the heat recovery cooling system based on an ejector chiller utilizing the air heat. The three stage air coolers consist of the following stages: at the first stage, high potential heat is extracted from the scavenge air after the turbo-charger (the so called utilizing or cogenerative stage); at the second convention stage, sea water is used as a cooling medium; and at the third stage, the cold from the ejector chiller is used to utilize the heat of scavenge air extracted at the first stage. The heat loads the high-temperature (utilizing and cogenerative) and low temperature (cooling) sections of the heat recovery cooling system; the corresponding scavenge air temperature is calculated. It is shown that the goal of calculating the rational parameters of three stage air coolers is to determine the air temperature at the output of heat recovery high temperature cooler stage that provides the cooler depth and its aerodynamic resistance commeasurable with two stage coolers of cogenerative type.