The exhaust pipe of the diesel engine on board is divided into dry exhaust and wet exhaust according to whether the exhaust gas is discharged together with the cooling water. Dry exhaust is not only easy to blacken the hull shell and deck equipment, but also causes the higher exhaust pipe temperature (up to 400~600℃) and serious noise pollution. Wet exhaust has the advantages of the low exhaust temperature (40~60℃), light weight, low noise and environmental protection. It is therefore suitable for those high-speed ships with appearance concerns, compact machinery space, sensitivity of equipment weight and higher requirements of noise and infrared radiation, such as patrol ships and yachts. This article introduces the arrangement scheme and the design method of the wet exhaust system (cooling water mixed with diesel engine exhaust gas) of the main engine in high-speed ships, and the issues to be taken into account in the arrangement and installation. It can provide reference for the design of civil high speed ship.

As an alternative marine clean energy, the liquefied natural gas (LNG) has become more and more popular. However, the particularity of gas fuel brings great safety risk. Therefore, specific safety measures need to be considered in the design of the LNG carrier in order to ensure the safety of the entire gas system. A well-designed ventilation system should be required to ensure the ship safety in case of the accidental gas leakage. An integral LNG double wall piping ventilation system has been established and completely calculated from the ventilation resistance, the ventilation volume and the model selection of the ventilation fan. The corresponding ventilation fan parameters are also selected referring to the calculation results. It can provide reference for the model selection of the relative dual-fuel double wall piping ventilation fan.

The design scheme of the variable frequency fan for a 20 000 TEU container ship is given as the optimum efficiency point of the engine-room fans under the variable working conditions are determined by fitting the efficiency curve. The energy-saving effect that can be produced by installing the variable frequency system on the engine-room fan is estimated by analyzing the environmental climate and the different working conditions of the typical Eurasian routs. A reasonable economic benefit analysis method is finally put forward for the fan with the variable frequency system.

Side exhaust system is an exhaust system configuration which is suitable for small ships that cannot install exhaust pipe due to the limited space arrangement. It can be characterized of the high flexibility, aesthetics and stealthiness. There are many factors involved in the design of this exhaust system. The current study carries out the simulation of this exhaust system from the arrangement and back pressure of exhaust pipes, and provides suggestions for the preliminary design. This article simulated the back pressure and arrangement for the design, and provided some advice of the preliminary design.