Ventilation

The heat generation area, where heat release machines (e.g., Diesel-generator, air-conditioning and air compressors, boilers, etc.) are located, needs fresh air for cooling and ventilation. In ISO 8861, the temperature of these spaces is specified as 35°C. Fresh air supply and exhaust fans working together create a balanced air flow in the engine rooms, providing both combustion air for diesel engines and forced air exchange for engine rooms with the light pressure they create. Sufficient combustion and engine room cooling can be realized by good ventilation. Amount of ventilation required can be found in the ISO 8861 regarding engine room ventilation in diesel-engine ships. Supply fans take care of the air intake. The airflow is calculated using the following equation.

Air flow for combustion= (P_dg x M_ad)/ρ

P_dg: Maximum power output [kw]

M_ad: Air required according to manufacturer. If Mad is not available, then 0.0023 kg/kW.s for 2-stroke engines and, 0.0020 kg/kW. s for 4-stroke engines

ρ: Air density (1.13 kg/m³).

Ventilation is done with the control panel (Fig.2), locally or remotely, manually or automatically, by means of Exhaust Fans (Fig.3), Fresh Air Fans (Fig.4) or Circulation Fans (Fig.5). Circulation fans are designed to be used with air filter, without adding vitality to the indoor air, when the outdoor air quality is worse than the indoor air quality. Circulation fans can also be designed to be used as exhaust fans with the addition of an exhaust line. The fact that the exhaust fans cause a small decrease in the ambient pressure during suction also prevents the engine room air from escaping to other spaces. The polluted air expelled by the exhaust fans is replaced by fresh air fed by the fresh air fans. Whether used for ventilation only or air conditioning purposes, exhaust, fresh air and supply ducts are equipped with dampers, fire alarm and extinguishing systems to provide fire tightness at the passages of ship-compartments.

Figure.2 Ventilation fan control panel

Figure.3 Exhaust fan

Figure.4 Fresh air supply fan

Figure.5 Circulation fan

Volumes, requiring variable ventilation, are provided with aspirators and ventilators installed in Air Handling Units (Figure.6). which also either operated automatically or manually by means of a control panel.

Figure.6 Aspirator and supply fans application in air handling unit