Man L23/30DF, Project Manual

Page: 254 / 392

Charge air preheating – via LT (low temperature)
cut-out is used in the partial load range from 0 % to
40 % of engine load, to achieve the higher charge
air temperature. Thereby an improved combustion
is ensured and thus - conditionally reduced exhaust
smoke. In contrast to the charge air preheating via
CHATCO control valve, there is no time delay in this
case.
Control of the charge air temperature (CHATCO)
▪
CHATCO
▪
To prevent water condensation in charge air.
▪
Controlled charging air temperature by LT cool-
ing water by-pass valve.
▪
Increases charge air temperature above the
dew point.
The charge air temperature control CHATCO
reduces the amount of condensed water that accu-
mulates during engine operation under tropical con-
ditions. In this case, the charge air temperature is
controlled depending on the relative humidity meas-
ured directly in the charge air receiver, so that the
temperature in the charge air pipe does not drop
below the condensation temperature. The CHATCO
functionality includes integrated charge air preheat-
ing on low load by passing the low temperature air
cooler stage (LT).
Device for accelerating the turbocharger (jet
assist)
This equipment is used where special demands
exist for rapid acceleration and/or load application.
In such cases, the compressed air from the starting
air cylinders is reduced to 4 bars (relative), directed
to the compressor casing of the turbocharger and
blown to the compressor wheel. In this way, addi-
tional air is supplied to the compressor which, in
turn, is accelerated, thus increasing the charge air
pressure. Operation of the accelerating system is
activated by the control system, during start-up and
load steps.
Releasing the exhaust gas (Waste gate)
▪
Exhaust gas waste gate used for:
▪
Control of max. pressure at Part Load Opti-
mised operation.
▪
Control of exhaust gas temperature for SCR
operation.
By blowing-off exhaust gas before the turbine, and
its return to the exhaust pipe behind the turbine,
exhaust gas pressure reduction at the turbocharger
takes place, or there is a turbine speed reduction at
full load. This measure is necessary when the turbo-
charger is designed for an optimised partial-load
operation.
MAN Diesel & Turbo
B1600 0
Equipment to optimize performance
3700546-9.0
Page 2 (3)
V28/32S, L28/32S, L28/32H, L27/38S, L27/38, L23/30S, L23/30H, L21/31S,
L21/31, L16/24S, L16/24