Efficiency of intensification of heat removement of a closedcircuit marine power plant cooling systems

The paper considers a method for increasing the efficiency of closedloop cooling systems of ship power plants that exclude the consumption of seawater. It is noted that currently widespread openloop cooling systems that provide for the consumption of seawater are subject to clogging, especially in polluted waters, which can lead to a shutdown of the power plant. Attention is drawn to the fact that, especially when operating a vessel in areas of intensive fishing, significant damage is caused to fish resources, and plankton as the basis of the food chain is intensively destroyed. An intensification of heat removal processes is proposed, which allows reducing the weight and size indicators of closed systems, thereby ensuring their wider implementation in shipbuilding. The objective of the study is to determine the most effective methods of such intensification. Using a ship casing heat exchanger as an example, the possibility of using gasliquid jets for this purpose was studied. Visual and thermal engineering studies were carried out on models of casing devices. The worst conditions of their operation (heat transfer under free convection) were simulated, when the outside water is motionless relative to the vessel hull. Visual studies showed that the emerging air bubbles have transverse pulsations that destroy the wall boundary layer formed along the heat transfer surface, which impedes the heat removal process. Thermal engineering studies confirmed a significant (ten times or more) increase in heat transfer. Moreover, this effect increases as the temperature difference between the heattransfer surface and the outside water decreases. This is important when the vessel is in equatorial waters. This method of process intensification is compared with the case of creating (for example, by means of a pump) a local flow of intake water along the surface of such a heat exchanger. It was determined that the latter is inferior in efficiency to gasliquid jets. It is concluded that the use of this fairly simple method of intensifying heat removal of closed cooling systems will ensure their wider implementation in shipbuilding practice.

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