A solar energy array that follows the path of the sun to maximize the solar radiation incident on the PV surface. The two most common orientations are (1) one axis where the array tracks the sun east to west and (2) two-axis tracking where the array point ...

This is the concept of how long a device or process can operate properly without needing maintenance or replacement.

This is a positive constant, k, that is a property of a substance and is used in the calculation of heat transfer rates for materials. It is the amount of heat that flows through a specified area and thickness of a material over a specified period of time ...

The energy liberated in a chemical reaction, as in the combustion of fuels.

An approximate unit of heat produced by a resting person, equal to about 18.5 Btu per square foot per hour.

A clear, colorless, very mobile liquid that is flammable and poisonous; used as a fuel and fuel additive, and to produce chemicals.

A device used to compress air for mechanical or electrical power production, and in air conditioners, heat pumps, and refrigerators to pressurize the refrigerant and enabling it to flow through the system.

The total radiation incident on a specific surface area over a time interval.

Period of time a system or appliance (or component of) is expected to function at its nominal or design capacity without major repair.

A door-like device located at the mouth of a fireplace chimney flue for controlling the direction and flow of the draft in the fireplace as well as the amount of oxygen that the fire receives.

A device, or system of devices, that allows electrical current to flow through it and allows voltage to occur across positive and negative terminals.

A family of chemicals composed primarily of carbon, hydrogen, chlorine, and fluorine whose principal applications are as refrigerants and industrial cleansers and whose principal drawback is the tendency to destroy the Earth's protective ozone layer.

A type of hydropower turbine that contains a runner that has water passages through it formed by curved vanes or blades. As the water passes through the runner and over the curved surfaces, it causes rotation of the runner. The rotational motion is transm ...

A type of furnace or reactor in which the emission of sulfur compounds is lowered by the addition of crushed limestone in the fluidized bed thus obviating the need for much of the expensive stack gas clean-up equipment. The particles are collected and rec ...

A fluorescent lamp that has a tubular shape.

Chemical reactions, typically associated with combustion processes; the balancing of chemical reactions by providing the exact proportions of reactant compounds to ensure a complete reaction; all the reactants are used up to produce a single set of produc ...

The environmental, social, and economic impacts of producing a good or service that are not directly reflected in the market price of the good or service.

A type of heating system where water is heated in a boiler and either moves by natural convection or is pumped to heat exchangers or radiators in rooms; radiant floor systems have a grid of tubing laid out in the floor for distributing heat. The temperatu ...

The production of energy by a system or appliance at a level less than its design or nominal capacity.

The duration and periodicity of the operation of a device.