Increasing the efficiency and environmental safety of ship power plants cooling systems with jet heat removal devices

Abstract

There are numerous cases when during the ship operation it is advisable to exclude for some time the intake of sea water used to cool the ship’s power plant. The issues of the possibility of such operation of widely used open double-circuit cooling systems are considered. To this end, the systems can be switched to the sea water tanks available on board. Work according to this scheme is limited by the time of heating the available water to the maximum allowable temperature. The issues of increasing this time by rising the heat removal through the ship’s plating are considered. To do this, the heated water is not simply discharged into the tank, but is jet supplied through the pipeline system directly to the inner surface of the ship’s plating. Conducted visual and thermal engineering studies have shown that the best results are achieved with the use of a jet supply, supplemented by a screen one. As a result, a channel for hot water movement is formed between the screen and the ship’s plating. Water radially spreads outward from the center of the screen, forming a fan jet. At the same time, the maximum flow velocity around the ship’s plating and the temperature difference between hot and outboard water are ensured. The advantages of this method for supplying cooled water are confirmed by the thermal engineering studies. It is shown that in this case the heat transfer increases by 25…30 %, compared with the case of a simple jet water supply. As a result of processing numerous experimental data, generalizing similarity equations have been obtained. They allow you to calculate the heat transfer for various water flow regimes. The use of these devices allows you to increase the time of systems operation in a closed loop without receiving outside water. These devices are quite simple in design and can be used both at the stage of building a new ship, and when modernizing existing ships. An example of such devices introduction on self-propelled floating cranes is given.