The force per unit area acting on the surface of a solid boundary parallel to the flow.

Turbines in which the axis of the rotor's rotation is parallel to the wind stream and the ground.

A value that describes the ability of a material to conduct heat. The number of Btu that flow through 1 square foot of material, in one hour. It is the reciprocal of the R-Value (U-Value = 1/R-Value).

A term used to describe heat energy lost from a water heater tank.

The actual power rating that is developed by a motor before losses occur.

A byproduct of low-temperature carbonization of a solid fuel.

An energy system in which the fuel production equipment is in close proximity, or connected to, the fuel using equipment.

A solar collector that uses reflective surfaces to concentrate sunlight onto a small area, where it is absorbed and converted to heat or, in the case of solar photovoltaic (PV) devices, into electricity. Concentrators can increase the power flux of sunlig ...

The process by which water in air changes from a vapor to a liquid due to a change in temperature or pressure; occurs when water vapor reaches its dew point (condensation point); also used to express the existence of liquid water on a surface.

A unit of work done by the force of one dyne acting through a distance of one centimeter.

The process by which a power plant, apparatus, or building is approved for operation based on observed or measured operation that meets design specifications.

The nominal voltage for which a conductor or electrical appliance is designed; the reference voltage for identification and not necessarily the precise voltage at which it operates.

A container that holds rock used as the thermal mass to store solar energy in a solar heating system.

The production of hydrogen using a photoelectrochemical cell.

The duct(s) of a forced air heating/cooling system through which heated or cooled air is supplied to rooms by the action of the fan of the central heating or cooling unit.

In refrigeration, an evaporating temperature of 5 degrees Fahrenheit (F), a condensing temperature of 86 degrees F., liquid temperature before expansion of 77 degrees F., and suction temperature of 12 degrees F.

The abrupt and large increase in electrical conductivity exhibited by some metals as the temperature approaches absolute zero.

In a solar photovoltaic device, an n-type dopant, such as phosphorus, that puts an additional electron into an energy level very near the conduction band; this electron is easily exited into the conduction band where it increases the electrical conductivi ...

A large power plant that generates power for distribution to multiple customers.

A type of solar thermal collector that has tubes (pipes) that the heat transfer fluid flows through that are connected to a flat absorber plate.