Rocks & mirror

WÄRTSILÄ
Encyclopedia of Marine and Energy Technology

D

348 results

Devil’s claw

marine

A stretching screw with two heavy hooks or claws. It is used to secure an anchor in a hawse pipe.

Dew point

marine

The temperature below which water vapour in the air condenses.

Dew point temperature

energy

The saturation temperature of the moisture present in the sample of air, it can also be defined as the temperature at which the vapour changes into liquid (condensation).

DF-electric concept, also dual-fuel/diesel-eletric propulsion

marine

The propulsion plant developed by Wärtsilä for LNG carriers. It is an electric propulsion with main generators driven by dual-fuel engines that can run on either boil-off gas or MDO.

Diabatic storage

energy

Diabatic storage dissipates much of the heat of compression with intercoolers into the atmosphere as waste, essentially wasting the energy used to perform the work of compression.

Diamagnetism

energy

Diamagnetic materials are repelled by a magnetic field; an applied magnetic field creates an induced magnetic field in them in the opposite direction, causing a repulsive force.

Diaphragm

marine

1. A circular plate made up of two halves. It fits between the rotor wheels of a steam turbine and has nozzles in its upper half.

Diaphragm seal

energy

A diaphragm seal is a flexible membrane that seals and isolates an enclosure.

Dichlorodifluoromethane

energy

A colorless gas usually sold under the brand name Freon-12, and a chlorofluorocarbon halomethane (CFC) used as a refrigerant and aerosol spray propellant.

Die (manufacturing)

energy

A die is a specialized machine tool used in manufacturing industries to cut and/or form material to a desired shape or profile.

Dielectric

marine

A solid, liquid or a gas in which electric field can be maintained with little or no external electrical energy supplied. It is therefore called an insulator.

Dielectrics

energy

A dielectric material is an electrical insulator that can be polarized by an applied electric field.

Diesel Combined Cycle (DCC)

marine

Technology utilizing both the shaft output and thermal output of a diesel engine. The thermal output is used to drive a steam turbine, for example.

Diesel electric transmission

energy

A diesel–electric transmission, or diesel–electric powertrain is a transmission system for vehicles powered by diesel engines in road, rail, and marine transport.

Diesel engine

energy

The diesel engine, named after Rudolf Diesel, is an internal combustion engine in which ignition of the fuel is caused by the elevated temperature of the air in the cylinder due to the mechanical compression; thus, the diesel engine is a so-called compression-ignition engine.

Diesel-electric propulsion

marine

Electric propulsion with diesels used as prime movers. Diesel-electric drive takes less space than the equivalent direct-drive two-stroke engine allowing the aft section to be slimmer and giving better flow over the propeller.

Differential Global Positioning System (DGPS)

marine

An advanced form of GPS navigation which provides greater positioning accuracy than the standard GPS.

Differential pressure

energy

Differential pressure is the difference in pressure between two points.

Diffuse sky radiation

energy

Diffuse sky radiation is solar radiation reaching the Earth's surface after having been scattered from the direct solar beam by molecules or particulates in the atmosphere.

Diffuser

marine

A chamber, which surrounds the impeller of a centrifugal pump or a compressor, in which some of the kinetic energy of the fluid is converted into pressure energy due to an increasing cross-sectional area of the flow path.

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