1. The role of fresh air
Cooling requirement: Diesel generators generate a large amount of heat during operation, especially high-power units (such as 1250kVA). Fresh air (outdoor air) is used to cool the generator room or machine room to prevent equipment from overheating.
Combustion assistance: Diesel engines require sufficient oxygen for combustion, and fresh air provides the necessary oxygen to support efficient combustion.
Emission control: Fresh air helps dilute exhaust gases (such as carbon monoxide and nitrogen oxides) and improve the air quality inside the computer room.
2. Calculation of fresh air volume
Cummins usually recommends designing fresh air according to the following principles:
Cooling and ventilation:
Fresh air volume ≈ Generator heat dissipation (kW) ÷ (Δ T × 1.1) (m ³/s) Fresh air volume ≈ (Δ T × 1.1) Generator heat dissipation (kW) (m ³/s)
Among them, Δ T is the allowable temperature rise (usually ≤ 10 ° C), and the heat dissipation of a 1250kVA generator requires approximately 2000-3000 CFM (about 0.9-1.4 m ³/s) per unit.
Combustion air:
Diesel engines require approximately 25-30 m ³/min for combustion per unit (refer to Cummins technical manual for details).
Total demand for 3 units:
Cooling and combustion may require 75-90 m ³/min of fresh air (adjusted according to the layout of the machine room and local climate).
Diesel engines require approximately 25-30 m ³/min for combustion per unit (refer to Cummins technical manual for details).
3. Design considerations
Air inlet/exhaust duct: It is necessary to independently set up air inlet and exhaust outlet to avoid airflow short circuit. The air inlet should be close to the inlet end of the generator, and the exhaust outlet should be close to the radiator.
Dustproof and rainproof: The air inlet needs to be equipped with a filter screen and rainproof louvers to prevent debris from entering.
Silencing measures: If the computer room is close to a sensitive area, a silencer needs to be installed in the fresh air duct.
Negative pressure control: Ensure a slight negative pressure in the computer room to prevent exhaust gas leakage.
4. Cummins official suggestion
Cummins technical manuals (such as the datasheet for Diesel Generators) explicitly require:
Adequate ventilation must be provided to maintain ambient temperature below 40°C and supply combustion air. "
5. Consequences of no fresh air
The temperature in the computer room skyrockets, triggering a high temperature alarm or shutdown.
Insufficient combustion leads to a decrease in power and an increase in carbon deposition.
Accumulation of harmful gases poses a threat to personnel safety.
It is necessary to design a fresh air system for three 1250kVA Cummins generators and ensure that the air volume meets the cooling and combustion requirements. Specific parameters need to be calculated in detail based on the size of the computer room, ambient temperature, and technical data provided by Cummins (such as TSL-0259 Ventilation Guide). Suggest consulting Cummins engineers or professional ventilation design teams.
Post time: Apr-07-2025