Usage:
The two stage aftercooler is located in the center of the engine vee. The two stage aftercooler assembly is significantly taller and heavier than the single stage aftercooler. The two stage aftercooler assembly has one long housing, one core assembly and one cover unlike the two sets of housing, cover and core assembly which make up the single stage aftercooler.
The major difference between the two stage aftercooler and the single stage aftercooler is the two stage aftercooler uses two coolant circuits to cool the charge air from the turbocharger. The air side is one single pass similar to the single stage aftercooler. The two stage aftercooler also has removable end tanks to allow for mechanical cleaning.
The use of two coolant circuits (or stages) provides various advantages such as heat recovery with the high temperature stage, improved detonation margin, and cooling system optimization. There are eight different cooling system configurations recommended for use with a two stage aftercooler engine.
Configuration 1
This configuration cools the first stage of the aftercooler in parallel with the engine water jacket. This allows for 45-50 percent of the aftercooler heat load to be rejected to the high temperature jacket water circuit. The second stage of the aftercooler is cooled in parallel with the engine oil cooler, similar to a single stage aftercooler. The overall radiator sizing for this configuration will be significantly reduced compared to the single stage aftercooler, as the low temperature portion of the heat load (from second stage aftercooler) is reduced by half from the single stage aftercooler configuration.
Configuration 2
This configuration is similar to the standard cooling system on G3612 and G3616 engines, with an additional circuit for the first stage of the two stage aftercooler. This additional stage requires a customer supplied pump. As much as 82 percent of the aftercooler heat load can be recovered from the first stage with this configuration. The inlet temperature and pressure limits for the first stage aftercooler are shown on the schematic.
Configuration 3
This configuration uses a two stage aftercooler connected in series for better cooling capability. The overall effectiveness of the aftercooler is increased significantly which helps in providing more detonation margin and lowering the deration factor for all applications. This is also recommended for applications where raw water is used for cooling the aftercooler directly and where mechanically cleanable aftercoolers are required.
Configuration 4
This configuration uses a two stage aftercooler connected in series for better cooling capability while allowing a higher temperature cooling of the oil cooler. The oil cooler needs a customer supplied pump for circulation. The overall effectiveness of the aftercooler is increased significantly which helps in providing more detonation margin and lowering the deration factor for all applications. This is also recommended for applications where raw water is used for cooling the aftercooler directly and where aftercooler cleaning is required.
Configuration 5
This configuration uses four different circuits to make optimum use of the heat recovery capabilities of each of the cooling system components on the engine with a two stage aftercooler. The oil cooler and first stage of aftercooler require a customer supplied pump for water circulation. The various components can also be connected in series to make one single heat recovery loop (i.e. oil cooler to first stage, first stage to jacket water heat exchanger, etc) to achieve a targeted total efficiency of the engine installation.
Configuration 6
This configuration uses three circuits with the oil cooler connected in series with the first stage of the aftercooler. The oil cooler-first stage circuit requires a customer supplied pump to circulate water. This oil cooler-first stage circuit can also be connected in series with other components to make one single heat recovery loop (i.e. first stage to jacket water heat exchanger) to achieve a targeted total efficiency of the engine installation.
Configuration 7
This configuration uses three circuits with the oil cooler and first stage of aftercooler cooled in parallel. The second stage of the aftercooler requires a customer supplied pump for circulation. The oil cooler-first stage aftercooler circuit can obtain up to 73 percent of the total aftercooler heat load in addition to the oil cooler heat load at an inlet temperature of 54°C (130°F) while maintaining a 32°C (90°F) engine rating with the help of the second stage aftercooler.
Configuration 8
This configuration provides two external circuits with a combined jacket water and oil cooler-first stage aftercooler circuit. The second stage of the aftercooler needs a customer supplied pump for circulation. The combined circuit can obtain the jacket water heat load, oil cooler heat load and up to 73 percent of total aftercooler heat load at an inlet temperature of 54°C (130°F) while maintaining engine rating with the help of the second stage aftercooler.