material which, due to an affinity, extracts one or more substances from a liquid or gaseous medium with which it is in contact and which changes physically or chemically, or both, during the process. Cal­cium chloride is an example of a solid absorbent, while solu­tions of lithium chloride, lit­hium bro­mide, and the ethylene glycols are examples of liquid absorbents.

1. device contain­ing fluid, or other material, for ab­sorb­ing refri­gerant vapor or other vapors.

1. total heat transfer area from which the absorbed solar irradiance heats the transfer fluid.

2. area of the absorber medium if both transfer fluid and solid surfaces jointly perform the absorbing function; i.e., total area onto which incident solar radiation is ab­sorbed.

3. total area onto which incident solar radiation is absorbed.

1. absorbed portion of the radiant energy striking a surface.

2. ratio of the radiant flux ab­sorbed by a body to that incident upon it. Compare reflectance

1. process whereby a porous material extracts one or more substances from an atmosphere, a mixture of gases, or a mixture of liquids.

2. transformation of radiant energy to a different form of energy by interaction with matter.

3. absorption of acoustical energy by acoustical materials and air.

absorbed portion of the radiant energy strik­ing unit area of a substance. Compare absorptance.

alternating current.

rate of increase in velocity of a body falling freely in a vacuum; its value varies with latitude and elevation. The International Standard, derived from the value at sea level and 45^° latitude, is 9.806 65 metres per second per second (m/s²), or 32.174 feet per second per second (ft/s²)

angular zone within which radiation is accepted by the receiver of a con­centrator. Radiation is said to be accepted if radiation incident within this angle reaches the absorber after passing through the aperture.