Wednesday, 29 June 2016: 8:00 AM-9:30 AM
Advances in Refrigeration Systems and Alternative Refrigerants
Chair:
Christopher Seeton, Ph.D., Shrieve
Technical Committee: 03.01 Refrigerants and Secondary Coolants
This session investigates the energy efficiency of several alternative Low Global Warming Potential refrigerant blends. The presentations address the thermodynamics of the blends, including the associated temperature glide in the heat exchangers. They also focus on the types of application whether the blend is intended for drop-in or near drop-in service or whether intensive changes are required to capture the best performance. Comparisons from the recent AHRI alternative refrigerants program are also presented to show the most recent developments and state of the art.
1 The Thermodynamic Efficiency of Refrigerants: a History of a Downhill Slide?
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Kenneth Schultz, Ph.D., Ingersoll Rand |
The thermodynamic properties of refrigerants modeled in a simple single-stage vapor compression cycle can provide insight into the potential benefits or challenges associated with new generations of refrigerants. This presentation outlines a simple thermodynamic cycle model and discuss various aspects important to system performance, including the impact of temperature glide when using zeotropic blends. The thermodynamic performance of a range of next generation low GWP refrigerants will be reviewed, highlighting the potential benefits and challenges in front of us as we transition yet again. Maybe not everything is going downhill?
2 A Total System Analysis of Air and Water Cooled Lower GWP Refrigerants
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Richard Lord, United Technologies Carrier Corp |
The total environmental impact of leading lower GWP replacement refrigerants for R410A and R134a based chillers must be considered. There are several alternate refrigerants with lower GWP’s than R410A and R134a, but the direct emissions are only one contributor to the total global warming impact. The impact on efficiency must also be considered. Chillers are very high efficiency and low leak products so the impact from direct emissions is low compared to indirect. Results on annualized analysis of the efficiency including the impact of refrigerant cycle performance changes and heat transfer changes across all 19 climate zones will be presented.
3 Low GWP (A2L) Refrigerant Evaluation on a 10-Ton Rooftop Air-Conditioner
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Matthew Clark, Lubrizol Advanced Materials Inc. |
With environmental concerns on high global warning potential (GWP) refrigerants used in HVACR industry, Carrier Commercial Engineering participated in the AHRI Alternative Refrigerants Evaluation Program (AREP). This study is to understand the Low GWP refrigerant options available to replace R-410A. A 10 ton Rooftop air conditioning unit was tested evaluating four Low GWP refrigerant candidates. The test consisted of EER and high ambient conditions. The refrigerants evaluated were R-32, R-454B, R-446A and R-447A as well as baseline refrigerant R-410A. The current and future regulations for Low GWP refrigerants, energy efficiency, and operation envelop were considered in the investigation.
4 Evaluation of a Lower GWP Refrigerant Option for R404A in Commercial Refrigeration Applications
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Brian Fricke, Ph.D., Oak Ridge National Laboratory |
A lower global warming potential (GWP) refrigerant blend, R448A, composed of hydrofluorocarbon (HFC) and hydrofluoro-olefin (HFO) refrigerants, has been proposed as an alternative to R404A. An evaluation of these two refrigerants in a laboratory-scale commercial refrigeration system is presented in this session. The system COP when operating with R448A was found to be up to 7% higher than that of R404A, while compressor power decreased by up to 6% when operating with R448A versus R404A. Given that R448A exhibits lower GWP than R404A, with similar operating characteristics and no energy penalty, R448A is a suitable lower GWP replacement for R404A.