Steam

Article By:

Baumeister, Theodore Formerly, Department of Mechanical Engineering, Columbia University, New York, New York; Editor in Chief, "Standard Handbook for Mechanical Engineers"

Last reviewed:January 2020

DOI:https://doi.org/10.1036/1097-8542.652800

Water vapor, or water in its gaseous state. Steam is the most widely used working fluid in external combustion engine cycles, where it will utilize practically any source of heat, that is, coal, oil, gas, nuclear fuel (uranium and thorium), waste fuel, and waste heat. It is also extensively used as a thermal transport fluid in the process industries and in the comfort heating and cooling of space. The universality of its availability and its highly acceptable, well-defined physical and chemical properties also contribute to the usefulness of steam. The engineering profession has developed so much evaporative and condensing equipment for changing the state of water that its properties can be utilized from pressures ranging from 0.18 in. Hg or 0.61 kilopascal (ice point) to supercritical (>3208.2 lb/in.² absolute or 22.120 megapascals absolute pressure and 705.47°F or 374.15°C). These temperature ranges are readily adaptable for use with ferrous and nonferrous metal structures at costs which dominate the design, selection, and use of many applications.

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