Mass, energy, entropy, and exergy balances and exergy efficiency relations are developed for common air-conditioning processes that include simple heating and cooling, heating with humidification, cooling with dehumidification, evaporative cooling, and adiabatic mixing of airstreams. An illustrative example of a heating process with humidification is considered and the effects of air temperature and relative humidity at the inlet and exit, the temperature of steam used for humidification, and the dead state properties of exergy efficiency and exergy destruction are investigated. The results indicate that processes with low exergy efficiency and high exergy destruction have significant potential for improving performance. A parametric investigation shows that exergy efficiency and exergy destruction are very sensitive to air properties and dead state conditions. It is seen that the use of exergy in assessing HVAC&R systems can be highly advantageous, leading to technical advantages such as improved efficiency as well as environmental improvements through reduced emissions and economic benefits. Many of the benefits of applying exergy analysis are not necessarily attainable via energy methods.
Units: SI
Citation: ASHRAE Transactions, vol. 113, pt. 2
Product Details
- Published:
- 2007
- Number of Pages:
- 9
- File Size:
- 1 file , 970 KB
- Product Code(s):
- D-LB-07-020
