Conference Agenda

As the regulation is involving, there are limited refrigerant options that can be used for commercial refrigeration. R454C and R455A are regulatory compliant mildly flammable refrigerants (A2L) with less than 150 GWP for commercial refrigeration applications. To enhance energy efficiency and minimize environmental impact, system optimization strategies are explored to be implemented with A2Ls. These include combining low and medium temperature systems with a liquid line subcooler and incorporating adiabatic condensers. In this paper, overall enviromental impacts are studied for various cities in U.S. with A2L options with system enhancements to compare with baseline R448A/R449A system and CO2 commercial refrigeration systems.

The abatement of safety and environmental burden associated with low and ultra-low Global Warming Potential (GWP) refrigerants is a critical undertaking. As the industry shifts towards more environmentally friendly alternatives, mitigating the potential risks and ensuring safety standards becomes paramount. The adoption of low GWP and ultra-low GWP refrigerants contributes significantly to minimizing the greenhouse gas impact on the environment, aligning with global sustainability goals. However, it is essential to address safety concerns and potential environmental implications associated with the manufacturing and usage of these refrigerants.

A method to mitigate the explosion risk in a flammable refrigerant based HVACR system is the primary focus of this paper. Advent of A2L and A3 refrigerants as replacements to high GWP refrigerants requires careful handling of leak episodes to lower or eliminate the risk associated with creating flammable mixtures capable of fire/explosion hazard. Solid-gas interactions enabled by shape-selective structures, molecular attractive forces, polarization, and catalytic activation have been successfully exploited in this gas treatment application. Activated carbons, zeolites, and various metal oxides tailored to target the molecule of interest (i.e., refrigerant.) by engineering the microporous structure as well as chemically functionalizing the surface to attract and hold on to the chemical compound being removed from the gas stream was realized.

In this paper, we will formulate a hypothesis, verify it, and examine the LCCP evaluation of air-to-air heat pump air conditioners using next-generation refrigerants.This report mainly provides an overview of the LCCP evaluation method and the verification based on the concept and hypothesis of the study using market data.

Specifically, we selected a representative model of a typical split-type air conditioner, and examined drop-in and system optimization using R32, R454C, R290, R410A, and R22 as refrigerants. In this report, assuming this system, we will examine optimization calculation methods for each refrigerant based on actual products using performance simulations used as a standard tool by JRAIA (Japan Refrigeration and Air Conditioning Industry Association).

We will discuss the LCCP evaluation. In particular , this time we examined new LCCP evaluation concepts and hypotheses that utilize market air conditioner-related data for Japan and India.

The recent commercial introduction of new refrigerants based on hydrofluoroolefins (HFOs) and hydrochlorofluoroolefins (HCFOs) has been accompanied by a number of misconceptions and confusion concerning the atmospheric fate and environmental impact of the refrigerants and their atmospheric degradation products. In this paper we address issues concerning the environmental impact of the new HFO/HCFO refrigerants, including their impact on ozone depletion, global warming, and the production of ground level ozone (i.e., smog). The atmospheric chemistry of the new refrigerants is also detailed, including discussion of their degradation mechanisms, their ultimate atmospheric degradation products, and the environmental impact of these degradation products. In particular, the production and fate of the degradation product trifluoroacetic acid (TFA) is detailed, including discussion of its natural and anthropogenic sources, estimated production quantities from HFO/HCFO use, and the impact of its formation on the various environmental compartments.

Refrigerants have evolved through the years to reduce their global warming potential while providing sufficient cooling. Replacements for hydrofluorocarbons (HFCs) and chlorofluorocarbons (CFCs) are the hydrofluoroolefins (HFOs) which contain reactive double bond that decreases the atmospheric lifetime of fluorinated compounds. However, the transformation of unsaturated fluorinated compounds in the atmosphere could generate persistent pollutants, particularly trifluoroacetic acid (TFA) which is the simplest Perfluoroalkyl carboxylic acids (PFCAs). Understanding the transformation of refrigerants is critical in assessing their contribution to atmospheric levels of TFA and their impact on watersheds and human health. This article will present the atmospheric oxidation source and sink processes of fluorinated refrigerants under daytime conditions, which impact the molar yield and dispersion of TFA. Moreover, the discussion will include the experimental procedures that can quantify the low concentration (~parts per trillion) of TFA generated from the transformation of HFOs. New state-of-the-art techniques such as chemical ionization mass spectrometers (HR-CIMS) will be assessed in providing high temporal resolution (minutes to hourly) to fully capture the atmospheric sources and variability of TFA. Likewise, local, regional, and global concentrations of TFA accounted from the oxidation of refrigerants will be examined. This will include data from both experimental procedures and simulation models. Participation of TFA in critical atmospheric processes such as new particle formation will also be included in this study. Lastly, overall knowledge gaps related to the oxidation products and their dispersion in the environment will be summarized to guide future research needs.

Hydrofluoroolefins, HFOs, and hydrofluorochloroolefins, HCFOs, are environmentally-friendly replacements for saturated halocarbons used as refrigerants, propellants, solvents and other applications. HFOs and HCFOs are unsaturated compounds (>C=C< double bond) a feature that dictates their much shorter atmospheric lifetime as compared to their saturated analogues. This paper will discuss the existing peer-reviewed literature on atmospheric chemistry, relevant policy metrics and degradation products of several commercially available HFOs and HCFOs. The very short atmospheric lifetimes (days to weeks) of HFOs and HCFOs lead to favorable policy metrics, i.e. negligible global warming potentials (GWPs), ozone depletion potentials (ODPs) and photochemical ozone creation potentials (POCPs). Their atmospheric oxidation mechanism is also discussed and is concluded that their atmospheric degradation products, at the concentrations expected, do not pose any risk to humans or the ecosystem.