Absorptance absorbed portion of the radiant energy striking a surface ratio of the radiant flux absorbed by a body to that incident upon it.

Absorber area (in a solar collector) total heat transfer area from which the absorbed solar irradiance heats the transfer fluid 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 total area onto which incident solar radiation is absorbed.

It may possess a surface through which energy is transmitted to the transfer fluid however, the transfer fluid itself can be the absorber.

Absorber device containing fluid, or other material, for absorbing refrigerant vapor or other vapors chill factor part of the solar collector receiving the incident radiation energy and transforming it into thermal energy.

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.

Absorbent A material which, due to an affinity for certain substances, extracts one or more such substances from a liquid or gaseous medium with which it is in contact and which changes physically or chemically, or both, during the process.

Absorbate that substance absorbed by an absorbent.

Absolute Zero Temperature Temperature at which all molecular motion ceases (-460o F.

Absolute viscosity (dynamic viscosity) force per unit area required to produce unit relative velocity between two parallel areas of fluid unit distance apart, also called coefficient of viscosity.

Absolute vacuum space totally void of matter (theoretical).

Absolute temperature (thermodynamic temperature) temperature as measured above absolute zero.Degrees Rankine, where absolute 0°R.

Absolute pressure pressure above a perfect vacuum the sum of gage pressure and atmospheric pressure.

Absolute humidity (vapor concentration water-vapor density number) a mixture of water vapor and dry air, the mass of water vapor in a specific volume of the mixture.

Absolute filter filter having an efficiency of 99.90% or higher, capable of dealing with particle sizes down to 0.01 micrometre a HEPA filter.

Abatement Reduction or removal of a contaminant.

A set of specifications (envelope dimensions) for centrifugal pumps manufactured in the United States Standard American National Standards Institute.

What does tfu mean