Flammable Refrigerants Research Articles

Research on the lubricating oil leakage characteristics in the vapor compression heat pump system under refrigerant leaking

Refrigerant leakage is a situation that often occurs in refrigeration equipment such as heat pumps. However, certain alternative refrigerants, while exhibiting superior environmental performance, possess varying levels of flammability. The leakage of flammable refrigerants into confined spaces can pose a significant risk of explosion. The amount of lubricant in the leaking refrigerant will undoubtedly affect the flammability characteristics of the refrigerant. In this paper, the content of PVE32 oil in the leaking refrigerant during the operation of a heat pump was investigated. The results showed that, under the five leakage rate scenarios set up in the experiment, the oil concentration was highest when the leakage occurred at the condenser inlet and lowest when the leakage was at the evaporator outlet. During the leakage process of the experiment, as the mass flow rate of the leakage increased, the oil content in the early stage of the leakage increased, but the oil content in the late stage of the leakage decreased. The reasons for the change in oil content were analyzed by the oil circulation rate and the degree of phase separation. The decrease of the oil circulation rate and the change of the degree of phase separation were the key factors affecting the magnitude of the oil content as the leakage proceeded. The results of the study reveal the leakage characteristics of lubricating oil with refrigerant leakage.

Comprehensive risk assessment of flammable refrigerants in HVAC systems based on Bayesian networks and consequence modeling

Promoting environmentally friendly refrigerants is a global imperative. However, their excellent thermal properties often come with flammability risks, raising concerns about HVAC safety. Existing studies focus on basic flammable characteristics and concentration distribution, neglecting comprehensive risk assessment for refrigerant leakage, diffusion, and fire. This paper fills this gap by constructing a comprehensive risk assessment model. The model integrates Bayesian networks to analyze causes of refrigerant leakage and employs CFD to evaluate distribution and residence time of flammable clouds, ignition sources, and consequences of ignition. Validation using real incident events quantitatively assesses risks associated with leaks, flammable cloud migration, ignition probability, and fire hazard. Critical failure points like improper welding and compressor exhaust are identified. Increasing ventilation speed from 0 to 1 m/s and 2 m/s reduces fire probability from 1.65 × 10−9 to 1.0 × 10−9 and 2.5 × 10−10, respectively. Effective measures to reduce leakage and fire risk are proposed based on accident experience and risk acceptability. The model is applicable not only to R290 chillers but also to other vapor compression cycles, aiding safety measures and emergency response plans for accidents involving flammable refrigerants in HVAC systems.

Mitigation of safety and environmental challenges posed by refrigerants

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 mildly and highly flammable refrigerants contributes significantly to minimizing the greenhouse gas impact on the environment, aligning with global climate and sustainability goals. However, it is essential to address safety concerns and potential environmental implications associated with the end use of these refrigerants.A method to mitigate the safety risk in a flammable refrigerant based heating, ventilation, air-conditioning, and refrigeration (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 materials 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. Quantitative analysis reveals the adsorbent's effectiveness in reducing leak potential in the range of 40 %–100 % for various refrigerants. Strategic placement and active leak management with negative pressure offer promising avenues for capturing leaked refrigerants, enhancing overall safety.

Heating and cooling challenges for electric vehicles: A comprehensive experimental study

An efficient mobile air conditioning (MAC) system using a safe and climate-friendly refrigerant is necessary for human comfort, increasing the vehicle’s energy performance, and reducing the fuel/electricity consumption. In the current work, we perform a drop-in experimental comparison for low GWP alternatives to R134a in reversible MAC systems. The study compares two lower global warming potential (GWP) refrigerants; R456A, a non-flammable refrigerant for R134a direct MAC replacement, and R1234yf, an ultra-low GWP and mildly flammable refrigerant that is the standard for new MAC systems. The system’s operational and energy performance is investigated, simulating a wide range of indoor and outdoor steady-state conditions. The measurements are recorded operating a fully monitored vapour compression test rig that uses secondary circuits to set the target conditions. In the heating mode (heat pump), the evaporation temperatures are set at −10 °C, −5 °C, and 0 °C, and condensation temperatures at 40 °C, 50 °C, and 60 °C. In cooling mode (air conditioning), the condensation temperatures are 37.5 °C, 45 °C, and 52.5 °C and are combined with evaporation temperatures of −7.5 °C, 0 °C, and 7.5 °C. In the heating mode, R456A presented a competitive COP to R134a with a reduction of less than 5 %, more remarkable at lower evaporation temperatures. In the cooling mode, R456A showed the lowest COP at a low condensation temperature. R456A and R1234yf COP are comparable at a higher condensation temperature, which suits the T3 climate conditions.

Experimental and Theoretical Assessment of Inverter-Operated Split Air Conditioner with Low GWP Alternative Refrigerants

This article presents experimental evaluation and comparative analysis of low GWP alternative refrigerants, namely HC-290 (propane), HC-1270 (propylene), HC/HC-1270 blend, and HFC-32 (difluoro methane) as drop-in replacements for HCFC-22 (Chloro difluoro methane) in a typical 1.5 TR capacity inverter operated split type air conditioner (SAC). The experimental setup consisted of retrofitting an original HCFC-22 test unit following the soft optimization of the SAC system for each alternative refrigerant, followed by testing under controlled operating conditions as per the IS 1391, Part-1 standard at the half capacity and the rated capacity of inverter SAC. The results obtained were compared against the baseline HCFC-22 test unit. The optimized SAC gave EERIS (Indian Seasonal Energy Efficiency Ratio) of 4.63 for HC-290, 4.71 for HC-1270 and 4.87 for HC-290/HC-1270 blend, respectively increased by 8.94 %, 10.82 % and 14.58 % compared to HCFC-22. HFC-32 delivered the maximum cooling capacity of 6.78 kW, 3.67 % higher than baseline unit at the rated capacity. HC-290/HC-1270 blend exhibited the lowest power consumption and discharge temperature amongst all the refrigerants considered. The charge of flammable refrigerants has been optimized below LFL satisfying EN378 standard for the safety of inverter SAC in domestic applications.

Effect of H2O on macroscopic flame behaviors and combustion reaction mechanism of 1,1-difluoroethane (R152a)

1,1-difluoroethane (R152a) is one of the most prospective low GWP refrigerants but may trigger fires and explosions once it leaks. Understanding the flame propagation process and combustion mechanisms at different relative humidity conditions is essential to use flammable refrigerants safely. In this study, a high-speed camera has recorded the flame propagation of R152a combustion near the flammability limit. Combining with macroscopic experimental phenomena, we revealed the effect of H2O on the microscopic mechanism of R152a combustion by using reactive force field molecular dynamics simulations with a reliable force field. The promotion effects of H2O on the oxidation of R152a were revealed from an atomistic perspective. The differences of oxidation intermediates and products in different environments were analyzed for the first time. The H2O/O2 environment was the most potent promoter of R152a decomposition, followed by the O2 and the pyrolysis environment. The O2/H2O environment reduced the apparent activation energy of R152a, significantly enhanced the consumption rate of R152a, and enriched the number of species. O2 reacts with H2O or H to form OH to accelerate the reaction process. The H2O could provide more OH active fragments for the reaction. Moreover, it promotes the formation of HF and H2, H2O + F→HF + OH, H2O + H→H2 + HO. This study aims to provide a guiding theory for the safe application and disaster prevention of flammable refrigerants.

Towards a defossilized building sector with field tests in the lab: Review, development, and evaluation

The transformation process in the building sector towards future city concepts requires changes in our society that aim for significant emission reduction until 2045. Currently, buildings in Germany are constructed and operated in such a way that no changes need to be made to them for decades. Therefore, any upcoming changes that do not achieve the climate goals must be avoided immediately. However, making the optimal decision for a change is complex due to (a) multi-domain (e.g., design and control), (b) multi-scale (e.g., single-family building and urban energy system), (c) multi-stakeholder (e.g., users and practice), and (d) long-term implications (up to decades). Conventional testing facilities and methods do not account for the integration of (a)-(d). Therefore, their technology readiness level is limited by 6. This paper introduces an approach that aims at (1) a multi-domain and multi-scale approach by applying process systems engineering to the building sector and that aims at (2) stakeholder integration already in the research process by applying the living lab approach. We combine the two methods, yielding a field test in the lab infrastructure pushing the technology readiness level to 7–8. In all, it consists of five test benches (Refrigerant Cycle Lab, FlexFass, RT-Lab, Raumklimalabor, and InFis). This work focuses on the Refrigerant Cycle Lab. Its concept is based on two further Hardware-in-the-Loop test benches which are extended by a safety system that ensures automated operation dedicated to heat pumps with flammable refrigerants. In two case studies, we show that field tests in the lab allow multi-domain and multi-scale testing. Both aspects support accelerating the transformation process towards a defossilized building sector. In the next step, the combination of test benches at different locations is promising to reduce the need to set up identical experiments at different locations. In the long term, the laboratory is designed to include external stakeholders to avoid time-consuming iterations and can, therefore, save resources, time, and money for our complex transformation process.

Indoor space risk assessment based on Co-analysis strategy in split room air conditioning

The use of environmentally friendly hydrocarbon refrigerants in air conditioning systems is being promoted worldwide as a proactive measure to combat global warming and ozone depletion. A comprehensive analysis of hydrocarbon refrigerant leakage and the resulting fire risk is essential for split room air conditioning (SRAC) systems. The study presents a novel Co-analysis strategy that integrates the operation of SRAC systems with the assessment of indoor space fire risk. Experiments involving the leakage and diffusion of R-290 in SRAC system have been conducted to substantiate the validity of the Co-analysis strategy. This model is used to analyze the dynamic parameters of leakage and distribution patterns of hazardous areas within the SRAC indoor unit. The study considers various leakage hole sizes (1 mm, 2 mm, 3 mm) under both cooling and heating operating modes. The results show the leaking refrigerant flow rate presents different attenuation types under cooling and heating modes. When the leakage hole diameter is less than 2 mm in the cooling mode, the concentration of R-290 in the space is below 50 % lower flammable limit. The comprehensive fire risk probability of the R-290 indoor unit is 1.0 × 10−11∼5.0 × 10−10 for the cooling model and 1.0 × 10−11∼9.0 × 10−10 for the heating model. Effective methodologies for mitigating risks and optimizing the system are also proposed. Based on the Co-analysis strategy, this study presents a scientifically grounded assessment of the fire risk associated with air conditioning uses flammable refrigerants inside buildings. The strategy aims to enhance building safety.

О возможности взрыва при применении экологически безопасных хладагентов в холодильном оборудовании

Today, the most common domestic electric equipment is a household refrigerator. The use of flammable substances as refrigerants for refrigerators can lead to severe consequences. As the production of hydrofluorocarbon class refrigerants for refrigeration equipment was restricted by the Kigali amendment to the Montreal Protocol, refrigeration technologies have been transferred from using hydrofluorocarbon class refrigerants to natural refrigerants (propane, butane, isobutane). The replacement of hydrofluorocarbon class refrigerants with natural refrigerants is already noticeable since in many cases isobutane (R-600a) is used as a refrigerant for refrigeration equipment. Isobutane is a combustible substance with a wide explosion limit (1.8–9.5 % vol.); hence, it is classified as an A2 refrigerant class of hazard (combustible substances). As R-600a is classified as an A2 class of fire hazard, its use in refrigeration technologies is limited with the refrigerant mass; therefore, the use of R-600a for refrigeration equipment is considered safe. According to international and Russian data, however, some accidents involving the use of flammable refrigerants in refrigeration equipment were registered. In the US, two explosions of serviceable household refrigerators were registered; in the Russian Federation, one explosion of refrigeration equipment during repair jobs was registered. According to the parameters of refrigeration equipment explosion, R-600а was used as a refrigerant. This study provides a calculation of excess pressure of explosion in case of leakage of R-600a from a refrigerator in the volume of a living accommodation (kitchen) in order to estimate the fire safety of combustible refrigerants. Based on the results of calculations, it has been concluded that the existing norms of the use of combustible refrigerants are insufficient and cannot ensure fire-explosion and fire safety for a person and refrigeration equipment.

A validated model for variable-speed multi-chillers to assess different operation modes

Environmental protection drives the replacement of environmentally harmful refrigerants with potentially flammable alternatives, necessitating efficient cooling strategies for varying loads. Legislation limits flammable refrigerant charge, leading to the adoption of multi-chiller systems with smaller charges and therefore also smaller loads per chiller. However, operating such systems requires complex strategies, addressable through fast and reliable models. This study presents a semi-empirical model predicting the behaviour of variable-speed multi-chiller systems. The model focuses on predicting cooling capacity and coefficient of performance (COP) for cooling, with input parameters of evaporation and condensation temperatures, and compressor speed. Experimental validation of the parameterized model shows COP predictions within 3 % for a two-module system using R-290 (propane) under different conditions and compressor speeds. The model assesses various operation strategies, including the conventional mode with fewer chiller modules running at high speed, compared to modes where all chillers run but at reduced speeds. Comparing COP values in these modes reveals energy-saving potentials of up to 14.57 % for constant condensation temperatures. Moreover, strategies involving condensation temperature reduction, or a combination with compressor speed reduction are analysed for energy-saving potentials. Reducing the condensation temperature by 3 K results in savings of up to 13.25 % and combined with the compressor speed reduction savings of up to 23.54 % are feasible. These findings emphasize the importance of considering compressor speed when operating multi-chiller systems to maximize energy savings. The presented model effectively evaluates various strategies and implements variable-load control in multi-chiller systems, serving as a valuable tool for optimising energy efficiency and promoting environmentally friendly cooling practices.

Explosion risk analysis of isobutane leakage in the freeze and cold storage system

The leakage and explosion of flammable refrigerant in household air-conditioning, domestic refrigerators, and heat pump system, which could pose huge threats to the building, ecological environment and the human health. Isobutane (R600a) is expected to be employed in the small-sized freeze and cold storage (FCS) system, nevertheless, the flammability slows down its development. Leakage, diffusion, distribution, and deposited characteristics of refrigerant in limited space are essential for explosion risk analysis in public places. To promote the safety application of R600a, a three-dimensional refrigerant leakage numerical model based on refrigerant leakage and diffusion (RLD) is established for RLD process, and the reliability of the model is verified by the experimental results. On this basis, the effects of different factors on the RLD process are analyzed by the numerical simulation. The results indicate that there is pessimism in the fan speed of the supply-air fan to obtain the highest average R600a concentration of defrost heater (DH) in the deposition process. The refrigerant explosion risk with the system door opened in the deposition process is markedly superior to that of the system door closed. As the leakage hole diameter increases from 1.0 mm to 2.5 mm, the average R600a concentration of the DH at the simulated time of 300 s is increased by 1.71 vol%. This study, not only reaffirms the benefit of using a three-dimensional refrigerant leakage numerical model for flammable refrigerant of the FCS system in a limited space, but also provides some rules of the RLD process with different factors.

Flame Propagation in Blends of R-152a, R-134a, and R-1234yf with Air

ABSTRACT Some new, low-global warming potential refrigerants will be flammable, and the laminar burning velocity is a useful parameter for quantifying fire risk. Laminar burning velocity measurements have been made using a constant volume experiment with dry air and the refrigerant R-152a (CH3CHF2), pure and blended with R-134a (CH2FCF3), or R-1234yf (CF3CFCH2). The resulting burning velocity data deduced from the pressure rise in the chamber are presented for a range of fuel air equivalence ratio and loading of the less flammable refrigerant, for unburned gases at 298 K and 101 kPa as well as at 375 K and 253 kPa. For comparison, the 1-D, planar laminar burning velocity was numerically simulated using a recently developed kinetic mechanism that includes a wide range of refrigerants with air. The predicted burning velocities agree reasonably well with the experimental values, and the numerical results are used to understand the kinetic mechanism of the reaction of the refrigerants. Uncertainties in the experimental data from radiation heat losses as well as extrapolation to ambient conditions are explored.

A Review of Sensing Technologies for New, Low Global Warming Potential (GWP), Flammable Refrigerants

Commercial refrigeration systems currently utilize refrigerants with global warming potential (GWP) values ranging from 1250 to 4000. The advent of low GWP alternatives (GWP <150) is expected to significantly curtail direct emissions from this segment and greatly influence the ongoing electrification and decarbonization efforts. Most of the low GWP alternatives exhibit flammability risk and hence require robust sensing solutions for a reliable and safe operation of the equipment. This review article aims to provide an overview of different sensing mechanisms suitable for potential applications in systems employing flammable refrigerants, particularly those designated as A2L class. A summary of different A2L refrigerants and their properties is provided followed by a broad review of different classes of sensors, their working principle, transduction method, features, advantages, and limitations. Additionally, key performance characteristics of accuracy, selectivity, sensitivity, dynamic characteristic, and durability among other properties are discussed. Finally, areas of improvement and corresponding approaches are suggested for potential sensors in the successful adoption of A2L class refrigerants.

Numerical investigation on flammability of R32 leakage in heat pump outdoor unit with CFD simulation

R32 is receiving significant attention as an alternative refrigerant owing to its higher operating efficiency and lower environmental impact; however, it is classified as flammable refrigerants. There have been some studies on R32 leakages about indoor unit rooms but extremely limited studies about outdoor unit rooms. The outdoor unit room is more cramped than the indoor one, and leakage easily occurs due to high-temperature and high-pressure operating conditions. In this study, the flammability risk was evaluated through a comprehensive R32 leak study in the outdoor unit room. Critical factors including the leak diameter, unit installation height, refrigerant charge, air infiltration, window opening, and room size were carefully selected, and parameter studies and correlation analysis were conducted. As the leak diameter increased from 2 to 8 mm, the R32 volume fraction increased from 7.7 to 46.3%, indicating that the leak diameter is the most significant factor in increasing the R32 volume fraction. Considering that the leak diameter is less than 1 mm in a typical leak accident and the leak occurs with a diameter of 2 mm or more in a catastrophic case, the risk of R32 leak was found to be low under the conditions. By increasing the window opening and unit installation height, the concentration of R32 can be lowered below the LFL, thereby reducing the flammable volume to close to zero.

Research on the field strength characteristics and the flammable area of refrigerants leakage into a confined space

Some target refrigerants used in refrigeration systems have various flammability. Once the flammable refrigerants leak into a confined space, it is easy to pose safety hazards. Moreover, the leakage refrigerants undergo continuous expansion and compression processes in the near field of the confined space, and the field strength of the refrigerants changes dramatically, which has an impact on the diffusion and the concentration distribution of the refrigerant in the far field of the confined space. The differences in the field strength and the flammable area for different refrigerants are largely determined by the thermophysical parameters of the refrigerants. Therefore, to better assess the hazards of refrigerant leakage, R717, R290, R161, R32, R152a and R1234yf were selected as the targeted leakage refrigerants in this paper, R744 and R134a were selected as the referenced refrigerants, the temperature, velocity and concentration fields of the refrigerants leaking into a confined space were studied, the influence of thermophysical parameters on the field strength of the refrigerants in the near field was further analyzed, and the flammable area formed in the space was explored. The results found that the temperature field was mainly affected by the density and the specific heat of the refrigerant. The velocity field was mainly affected by the density and viscosity of the refrigerant. The concentration field was mainly influenced by the density, viscosity and diffusion coefficient of the refrigerant. When the density was close, Schmidt number could be used to assess the influence of the viscosity and the diffusion coefficient on the concentration field. Under the same leakage pressure, the range of the flammable area formed by the leakage of R290 was the largest, followed by R161 and R152a, the flammable areas of R1234yf and R717 were very close, and the flammable area formed by R32 was the smallest.

Leakage, diffusion and distribution characteristics of refrigerant in a limited space:A comprehensive review

The leakage and direct emission of high GWP HFC refrigerants in refrigeration, air-conditioning and heat pump systems increase the greenhouse effect, which pose huge threats to the ecological environment and the human health. Meanwhile, some alternative refrigerants with excellent environmental performance have different degrees of flammability. When the flammable refrigerants catastrophically leak from the refrigeration system into a limited space, it is easy to cause an explosion accident, the safety of people and property in the space is greatly threatened. In addition, the operating conditions of refrigeration systems, thermophysical properties of the refrigerants, obstacles and ventilation conditions of the space have a great impact on the process of refrigerant leakage and diffusion, the explosion risks formed in the external space have certain differences. To promote the security application of the alternative refrigerants, the leakage, diffusion, and distribution characteristics of the refrigerants from both theoretical and experimental aspects were reviewed in this work. The potential causes of leakages and common types of leakage holes in refrigeration systems were summarized, and the advantages and disadvantages of the existing leakage and diffusion theoretical models were concluded. The impact of the micro-sized leakage of the refrigerant on the internal of the system was discussed. The diffusion and distribution of the refrigerants in the external space after they catastrophically leaked from different types of systems were analyzed, and the influence of different parameters on the refrigerant distribution and the explosion risk based on the catastrophic leakage was also presented. The future work was prospected. The review is expected to provide a valuable reference for the safety risk assessment of the flammable refrigerants.

Detection of R290 leaks in RACHP equipment using ultrasonic sensors

There is a growing need for cost-effective leak detection in smaller RACHP equipment that uses R290 and other flammable hydrocarbon refrigerants. Gas detection technology may not be suitable in many cases due to cost and reliability implications whilst detection with system parameters can suffer long response times. Ultrasonic leak detection can be an economical and reliable method. This study presents the development and testing of an ultrasonic leak detector using off-the-shelf components, within a conventional split type wall-mounted air conditioner indoor unit. Depending upon the chosen sensor, a fast and effective response to simulated “small” R290 leaks was achieved. Measurements of potential interference from environmental noise across ultrasonic frequencies suggests false alarms are unlikely. Such a leak detector was found to be potentially effective.

Effects of N2 and CO2 on the flammability of 2,3,3,3-tetrafluoropropene at elevated temperatures

The flammability characteristics of refrigerants are affected by environmental factors, making them prone to flammability and explosion accidents in cooling systems. In this paper, the flammability characteristics of R1234yf–air mixtures with N2 and CO2 were investigated comparatively at temperatures between 20 and 50 °C at 80% relative humidity. The lower and upper flammability limits of R1234yf were measured. The limiting oxygen concentration (LOC), critical flammable ratio (CFR), and critical flammable concentration (CFC) of the R1234yf–air mixtures with inert gases were investigated. The paper developed a linear formula between the flammability limit of R1234yf and the temperature. The changes in CFC with different temperatures were negligible for R1234yf. Furthermore, the mixed refrigerant had both non-flammability and the lowest vapor pressure when the CFR of the R1234yf/CO2 mixture was 2.9. The experimental results were used to propose a new prediction model to estimate the flammability limits of R1234yf. Finally, molecular simulation explained the effect of inert gases on the flammability of R1234yf from a microscopic point of view. The research aimed to provide valid evidence and data for preventing flammable and explosive refrigerant incidents.

Effects of trifluoroiodomethane and pentafluoroethane on combustion characteristics of flammable refrigerant propane

For the environmentally friendly refrigerant R290, the flammability is the biggest concern for its applications. In this paper, the inhibition of trifluoroiodomethane (R13I1) and pentafluoroethane (R125) on laminar burning velocity (LBV), lower flammable limit (LFL) and heat of combustion (HOC) of R290 have been researched. The laminar burning velocities were obtained at elevated temperature by an externally heated diverging channel method, and the lower flammable limits were measured in a glass tube under different humidity conditions. R13I1 showed a greater inhibition effect than R125 on the flammability of R290. The LBV decreased exponentially and the LFL increased markedly with addition of R13I1. The computation of LBV for R290/R13I1 mixtures showed an average relative error within 7.4%. The inhibition effectiveness of R13I1 on the LFL was reduced in wet air, mainly by the chemical effect of water molecules. And the linear relationship was found at LFL between calculated adiabatic flame temperature and the proportion of R13I1. The model was proposed to calculate the LFL and demonstrated a good prediction accuracy of 3.2% for LFL of R290/R13I1 mixtures. This study set out to investigate the inhibition of R13I1 and R125 on the flammability of R290 and assess the flammability of R290/R13I1 mixtures to provide low GWP and less flammable alternative refrigerants in air conditioners or heat pumps.

Estimation of greenhouse gas mitigation potential from refrigerant switching and energy efficiency improvement in Thai air conditioners

Thailand is an important manufacturing and export center of Refrigeration and Air Conditioning (RAC), especially wall-typed air conditioners (ACs). Environmentally friendly refrigerant such as Hydrofluorocarbons (HFCs) have become the future substitute potential due to their zero-ozone depleting potential (ODP) with lower global warming potential (GWP). In this paper, we focus on country-wide GHG mitigation potential from refrigerant switching from R-32 to R-290 in Thai air conditioners. We found that there are GHG mitigation opportunities with overall 1.48 MtCO 2eq from the switching in the year 2020 from two concept as follows; (i) GHG mitigation from refrigerant leakage results at around 0.50 MtCO 2eq, (ii) GHG mitigation from energy efficiency improvement result at around 0.98 MtCO 2. However, there are some safety concerns of R-290 which is flammable refrigerants, hence, the relevance government agencies have to be seriously considered especially the installation and operation of R-290 in Thai air conditioners. The well-designed capacity building and awareness for manufacturers, technical service, provider, and user have to be set. Technology transfer from industrialized country to Thailand is essential. All activities have to be implemented along with the Kigali Amendment which will be aligned with the national NDC Roadmap.