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Facility characteristics favoring heat-recovery-chiller systems are:

• Year-round requirement for space heating or reheat, as in laboratories and hospitals.

• HVAC systems that accept recovered heat at heating water temperatures of 155°F or below.

• Relatively high natural-gas costs and relatively low electrical costs.

• Machines sized so that recovered heating matches minimum steady reheat load.

Facility characteristics favoring cogeneration options are similar, exceptions being:

• The availability of higher-temperature hot water or steam.

• The favoring of relatively high electrical costs and relatively low natural-gas costs.

References

1. EIA. (2009). Annual energy review. Retrieved from http://www.eia.doe.gov/emeu/aer/pdf/aer.pdf

2. EPA. (2009). Energy star performance ratings methodology for incorporating source energy use. Retrieved from http://www.energystar.gov/ia/business/evaluate_performance/site_source.pdf

Did you find this article useful? Send comments and suggestions to Executive Editor Scott Arnold at scott.arnold@penton.com.

A principal of 8760 Engineering and a longtime member of HPAC Engineering's Editorial Advisory Board, Gerald J. Williams, PE, LEED AP, is an expert on chilled water, air systems, and system analysis. Since 1973, he has taught as an affiliate professor of mechanical engineering at Washington University in St. Louis, which awarded him its School of Engineering and Applied Science Alumni Achievement Award in 2009. From 1984 to 1995, he taught air-system design for energy and cost-effectiveness as part of the American Society of Heating, Refrigerating and Air-Conditioning Engineers' (ASHRAE's) Professional Development Seminar series. He is a past president of the St. Louis chapter of ASHRAE.

CARBON-DIOXIDE PRODUCTION IN COMBUSTION PROCESSES

In a combustion process, energy is liberated by the chemical reaction and combination of the combustible portions of a fuel -- carbon, hydrogen, and sulfur -- with oxygen contained in atmospheric air.