Improving the Performance of a Roof Top Air-Conditioning Unit by Refrigerant Circuitry Optimization
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Improving the Performance of a Roof Top Air-Conditioning Unit by Refrigerant Circuitry Optimization
EN NWISBN: 9781496033192 bzw. 1496033191, in Englisch, neu.
Lieferung aus: Vereinigtes Königreich Großbritannien und Nordirland, in-stock.
This study demonstrates the performance improvement of anair-to-air roof top unit (RTU) achieved by optimizing an evaporator s refrigerantcircuitry using evolutionary algorithms. The subject of this study is a unit with acooling capacity of 7.5 Tons (26.4 kW). The RTU employs two separate refrigerantcycles having separate compressors, condensers, and thermostatic expansionvalves (TXV) but using a single evaporator slab in which two separate refrigerantcircuits are implemented. We modified the RTU by replacing the refrigerant-to-air condensers with watercooled brazed plate heat exchangers in order to facilitate testing. Performancetests were conducted in a conditioned environmental chamber in line with AHRIstandard 340/360; in order to accomplish this, we maintained the liquid linesaturation pressure and subcooling from the manufacturer s test data byadjusting the condenser water flow rate and temperature. We also measured thein-situ air velocity profile using Particle Image Velocimetry (PIV), a non-intrusive, laser-based technique. The measurements showed that the range of air velocitiespassing through the heat exchanger varied from 0.5 ms-1 to 3.0 ms-1, with theintegrated average of the measurements being 1.75 ms-1. The PIV data was usedto generate a map of the air flow distribution through the heat exchanger, whichserved as the basis for refrigerant circuitry optimization.
This study demonstrates the performance improvement of anair-to-air roof top unit (RTU) achieved by optimizing an evaporator s refrigerantcircuitry using evolutionary algorithms. The subject of this study is a unit with acooling capacity of 7.5 Tons (26.4 kW). The RTU employs two separate refrigerantcycles having separate compressors, condensers, and thermostatic expansionvalves (TXV) but using a single evaporator slab in which two separate refrigerantcircuits are implemented. We modified the RTU by replacing the refrigerant-to-air condensers with watercooled brazed plate heat exchangers in order to facilitate testing. Performancetests were conducted in a conditioned environmental chamber in line with AHRIstandard 340/360; in order to accomplish this, we maintained the liquid linesaturation pressure and subcooling from the manufacturer s test data byadjusting the condenser water flow rate and temperature. We also measured thein-situ air velocity profile using Particle Image Velocimetry (PIV), a non-intrusive, laser-based technique. The measurements showed that the range of air velocitiespassing through the heat exchanger varied from 0.5 ms-1 to 3.0 ms-1, with theintegrated average of the measurements being 1.75 ms-1. The PIV data was usedto generate a map of the air flow distribution through the heat exchanger, whichserved as the basis for refrigerant circuitry optimization.
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Improving the Performance of a Roof Top Air-Conditioning Unit by Refrigerant Circuitry Optimization
EN PB NWISBN: 9781496033192 bzw. 1496033191, in Englisch, CreateSpace Publishing, Taschenbuch, neu.
Lieferung aus: Vereinigte Staaten von Amerika, In Stock.
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