2016 ASHRAE Winter Conference

This paper summarizes an experiment campaign on alternative refrigerant evaluation for R-22 and R-410A mini-split systems. The experimental evaluation was performed according to ANSI/ASHRAE Standard 37 and the performance was rated according to ANSI/AHRI 210-240 standard. The paper presents the relative performance (efficiency and capacity) of the alternative refrigerant compared to the baseline refrigerant at the different operating conditions. The paper ends with concluding remarks about the alternative refrigerants for R-22 and R-410A applications in high ambient temperature regions.

In this paper, the oil retention in a microchannel type evaporator was measured and its effects on heat transfer and pressure drop characteristics are presented. The microchannel heat exchanger was a single pass, aluminum louvered-fin type evaporator with multi-port microchannel tubes installed vertically.

Flammability testing studies were conducted to support a methodology to optimize GWP to flammability for blends of R32, R1234yf and R125. Performance modeling studies were conducted to guide the best design of experiments for the flammability testing that optimize performance. Minimum ignition energy and burning velocity characteristics were determined for various blends of R32, R1234yf and R125 to determine flammability characteristics. This paper will discuss the results of these studies.

Global pressure to control climate change is driving the development of new regulatory policies that restrict and/or lower the direct GWP impact of fluorocarbons (or F-gases). These demands have resulted in researching a whole new class of fluorocarbons called unsaturated fluorocarbons or commonly referred to as hydrofluoroolefins (HFOs).  This paper provides an overall assessment of the application of the new HFO refrigerant R-1233zd(E) in stationary HVAC chillers. The presentation also reviews thermodynamic cycle performance and heat transfer characteristics relative to R-123, R-245fa and R-134a in a centrifugal chiller application.

Regulatory and voluntary actions are beginning to limit the direct global warming potential (GWP) of refrigerants used in many applications. A new class of fluids called unsaturated hydrofluorocarbons or hydrofluoroolefins has been developed to address this concern. These new fluids are being blended with existing HFCs to obtain lower GWP replacements or substitutes for today’s refrigerants. This paper provides an overall assessment of the application of R513A, an azeotropic blend of R1234yf and R134a (56%wt/44%wt), as an alternative to R134a. R513A provides specific environmental and safety features of interest including: no impact to stratospheric ozone, 56% reduction in GWP compared to R134a, no significant secondary adverse environmental impacts, low toxicity and non-flammability. This paper reviews the thermodynamic cycle performance and heat transfer characteristics of R513A relative to R134a.