| Improving the Performance of a Roof Top Air-Conditioning Unit by Refrigerant Circuitry Optimization Contributor(s): Nist (Author) |
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ISBN: 1496033191 ISBN-13: 9781496033192 Publisher: Createspace Independent Publishing Platform OUR PRICE: $13.29 Product Type: Paperback Published: February 2014 |
| Additional Information |
| BISAC Categories: - Science | Energy |
| Physical Information: 0.15" H x 8.5" W x 11" (0.43 lbs) 74 pages |
| Descriptions, Reviews, Etc. |
| Publisher Description: This study demonstrates the performance improvement of an air-to-air roof top unit (RTU) achieved by optimizing an evaporator0/00s refrigerant circuitry using evolutionary algorithms. The subject of this study is a unit with a cooling capacity of 7.5 Tons (26.4 kW). The RTU employs two separate refrigerant cycles having separate compressors, condensers, and thermostatic expansion valves (TXV) but using a single evaporator slab in which two separate refrigerant circuits are implemented. We modified the RTU by replacing the refrigerant-to-air condensers with water cooled brazed plate heat exchangers in order to facilitate testing. Performance tests were conducted in a conditioned environmental chamber in line with AHRI standard 340/360; in order to accomplish this, we maintained the liquid line saturation pressure and subcooling from the manufacturer0/00s test data by adjusting the condenser water flow rate and temperature. We also measured the in-situ air velocity profile using Particle Image Velocimetry (PIV), a non-intrusive, laser-based technique. The measurements showed that the range of air velocities passing through the heat exchanger varied from 0.5 ms-1 to 3.0 ms-1, with the integrated average of the measurements being 1.75 ms-1. The PIV data was used to generate a map of the air flow distribution through the heat exchanger, which served as the basis for refrigerant circuitry optimization. |