In this study, the performance of two HVAC distribution systems is evaluated using the first and second laws of thermodynamics. The constant-air-volume (CAV) and variable-air- volume (VAV) systems are modeled using the TRNSYS simulation program. A first law analysis is used to investigate the relationship between building loads, distribution system loads, and plant energy consumption. A combined law analysis is completed to determine exergy flows and the useful work depleted by system components. To measure distribution system design advancements, the second law efficiencies of the two systems are compared. Applications of exergy analysis for making better informed operation and maintenance (O&M) decisions are also explored. In one application, an exergy analysis is used to quantify the thermodynamic effect of a VAV system malfunction. The other investigates how well distribution system exergy can be used to identify distribution system controller set points that minimize plant energy consumption.
Units: Dual
Citation: Symposium, ASHRAE Transactions, vol. 105, pt. 1
Product Details
- Published:
- 1999
- Number of Pages:
- 10
- File Size:
- 1 file , 560 KB
- Product Code(s):
- D-7637
