The main purpose of Low temperature cooling (LT) system of a diesel engine is to control charge air temperature. Main engine cooled by HT water system. Lt cooling water system also used to cool other heat exchangers. In diesel engine power plant Lt cooling system works in a close loop while in ship the cooling system is open cycle (cooled by sea water).
Components of LT Cooling Water System of Diesel Engine:
- LT Water Pump
- PID controlled 3-way valve
- Radiator or Cooling Tower
- Engine Components-Charge Air Cooler
- Other Components-Lube oil cooler, LFO cooler(Booster module), Nozzle cooling water cooler, Alternator bearing oil cooler etc.
- Expansion Tank
- Maintenance Water Tank
LT Water Cooling System Flow Diagram:
Description of LT Water Cooling System :
LT water pump generally engine driven pump, also separate electric motor driven used. Lt water pump draw water from the radiator outlet and pumped to the second stage of charge air cooler. Charge air cooler first stage cooled by Ht water. In first stage temperature reduced around 100 degree Celsius and second stage by Lt reduced around 50 degree Celsius.. Charge air Lt cooling water temperature is controlled by CHATCO valve.
Lt water from the pump delivery and from CAC outlet used to cool down other heat exchangers such as Lube oil cooler, LFO (diesel) cooler in booster module, Nozzle cooling water cooler (MAN B&W Engine), Alternator bearing oil cooler (Geomont alternator) if the system exists.
The mixing of lt pump outlet and cooler outlet water controlled by PID controlled 3-way valve. After cooling all the Lt related system/heat exchangers It passes through CHATCO valve. CHATCO valve also pid controlled 3-way valve, it allows or restrict water flow to the radiator to get required Lt water temperature. CHATCO valve operate automatically depending upon ambient temperature and relative humidity.