Why do ships use iron anchors instead of rust-proof steel anchors?

The role of the anchor in the ship accessories is to place the ship floating, so heavy objects are needed. Cast iron is cheap and easy to process, because the large volume can neglect the corrosion caused during use. There is no need to use expensive materials such as stainless steel. Stones and sandbags were used in ancient times.

At the same time, iron is more cost-effective here. Generally speaking, the choice of material mainly considers its performance and economic benefits, that is, high cost performance is the best. Iron is an alloy of iron and carbon (and other elements such as a small amount of S, P, O) with a carbon content of more than 2.11%. The molten iron in the blast furnace is directly cast and processed (this process will not be repeated), and steel generally needs to be processed by molten iron. In pretreatment, converter steelmaking, refining outside the furnace, continuous casting and other processes, most of the steel contains less than 1.2% carbon. Iron is hard and brittle, steel is slightly softer than iron, but has better toughness (small deformation is easy to recover). For a ship anchor, it is just a weight-fixed device, and iron is enough. As for anti-corrosion, it is a secondary factor, which can be solved in other ways. Even if it can't be solved (it's really difficult to solve), it is more cost-effective than steel.

Turbocharger

Principle of operation: The exhaust gas of the engine is guided to the turbine. The turbine blades are driven to rotate by the exhaust gas, and the compression blades on the other side of the intake section are driven to rotate, thereby increasing the intake pressure and achieving a supercharging effect.

Advantages: Does not consume engine output power, and has higher efficiency.

Disadvantages: due to the use of engine exhaust, there will be turbo lag, which has been a major bottleneck in development since the Second World War. At present, marine accessories include twin turbo systems and variable geometry turbocharging. To improve, but still incomplete. In addition, the blades are directly in contact with high-temperature exhaust gas, and the materials used must be able to work continuously at high speeds and high temperatures.

Supercharger

Principle of operation: Using the transmission device, the power of the engine crankshaft drives the rotation of the compressor blades to increase the intake pressure and achieve the supercharging effect. Transmission devices include belts, gearboxes or liquid gearboxes.

Advantages: There will be no hysteresis, and the power output is easier to control.

Disadvantages: engine output power will be consumed, especially when used in high-altitude aircraft, the horsepower ratio consumed is quite high and the efficiency is poor.

Principle of operation: Directly use an electric motor to drive the blades to rotate and pressurize the air.

Advantages: There will be no hysteresis, and the power output is well controlled. Electricity is an energy that can be stored. It can be stored in advance when the output demand is low, or it can be obtained by regenerative braking; the energy of a mechanical supercharger cannot be stored in advance.

Disadvantages: If the amount of current is not very large and the degree of boost is limited, the self-installed electric turbocharger has almost no effect; the effective electric turbocharger requires a lot of electric energy, which depends on a specially strengthened power supply design and is powered by electricity To transmit energy, its loss will be much higher than that of a mechanical supercharger that transmits energy by a leather belt, but electrical energy is energy that can be stored.

Dual supercharger

Two superchargers are installed at the same time. Take mechanical and turbocharging systems as an example. At low speeds, mechanical supercharging is used, and at high speeds, mechanical supercharging is turned off. At this time, turbocharging can already provide enough supercharging capacity; car manufacturers are also developing and installing electric supercharging and With a turbocharged twin-turbo system, BMW has even developed a triple turbocharger.

Advantages: If you want to reduce fuel consumption by reducing engine displacement, dual supercharging can provide enough horsepower and better torque, especially when Z often has low speed, it will have better torque performance.

Disadvantages: The system is complicated and maintenance is not easy, so mass production is only in the near future.