Investigation and Analysis of R463A as an Alternative Refrigerant to R404A with Lower Global Warming Potential

: This research presents the development of R463A refrigerant, a nonﬂammable refrigerant that was retroﬁtted to replace R404A. R463A is primarily composed of hydroﬂuorocarbons / hydrocarbons / carbon dioxide (HFCs / HCs / CO 2 ), and has global-warming potential (GWP) of 1494. It is a nonazeotropic mixture of R32 (36%), R125 (30%), R134a (14%), R1234yf (14%), and R744 (6%). R463A is composed of polyol ester oil (POE), and it is classiﬁed as a Class A1 incombustible and nontoxic refrigerant. high-capacity, low-operating-pressure, and nontoxic refrigerant.


Introduction
Energy use in Thailand's business sector is ranked second among overall energy users in the country, and is thus being targeted for energy-saving options [1]. The number of convenience stores in Thailand numbered to more than 20,000 locations in 2019, and this continuously increases on an annual basis. The majority are open 24 hours per day, so the retail sector is the fourth largest consumer of energy in the business sector, consuming more energy than residences do [2]. The components that contribute to energy consumption of convenience stores in Thailand, ranked from highest to lowest, are refrigeration systems, air-conditioning systems, electrical equipment, and lighting [3,4]. However, proportions of energy use in convenience stores in Taiwan were previously ranked as shown in Figure 1 below [5]. The best options for reducing energy consumption in convenience stores in Thailand are high energy efficiency and an efficient energy-management system. A good example of energy savings in refrigeration systems is shown in Figure 2 below [6]. Energy savings in refrigeration systems can be achieved through decreased power consumption of the compressor, as this is the component that utilizes the most energy.   [6].
Refrigerant trends in Thailand have shown improvements in increasing energy efficiency and decreasing global-warming potential (GWP), as shown in Figure 3 [7,8], which is related to the  [5].
Energies 2020, 13, x FOR PEER REVIEW 2 of 18 annual basis. The majority are open 24 hours per day, so the retail sector is the fourth largest consumer of energy in the business sector, consuming more energy than residences do [2]. The components that contribute to energy consumption of convenience stores in Thailand, ranked from highest to lowest, are refrigeration systems, air-conditioning systems, electrical equipment, and lighting [3,4]. However, proportions of energy use in convenience stores in Taiwan were previously ranked as shown in Figure 1 below [5]. The best options for reducing energy consumption in convenience stores in Thailand are high energy efficiency and an efficient energy-management system. A good example of energy savings in refrigeration systems is shown in Figure 2 below [6]. Energy savings in refrigeration systems can be achieved through decreased power consumption of the compressor, as this is the component that utilizes the most energy. Figure 1. Proportions of energy use in Taiwanese convenience stores [5].

Figure 2.
Examples of energy savings in refrigeration systems [6].

Results and Discussion
The results of the boiling point, shown in Figure 8 below, indicate that the lowest normal boiling point of R463A was −60.13 • C, which was lower than that of R404A by 23%. This was due to hydrofluorocarbons (HFCs) R32 (36%) and carbon dioxide (CO 2 ) R744 (7%) in its composition, which were consistent with those of R445A and R455A. R445A [61] and R455A [68] displayed low boiling points of −49.15 and −52.0 • C, respectively, and are attractive as an alternative refrigerant with a lower GWP, to R134A and R404A [62], due to CO 2 R744 contents of 6% and 3%, respectively, in their compositions. R448A and R449A displayed the lowest GWP values at 1273 and 1282, respectively, due to the HFOs from R1234yf and R1234ze in their compositions [58,59], as shown in Figure 9. The GWP of R463A was found to be 1377, with a lower boiling point than that of R404A by 23%, even though the ratio of R1234yf in R463A was less than that in both R448A and R449A. However, the GWP of R463A was found to be slightly higher than that of R448A and R449A. The cost of R463A is also lower than that of R448A and R449A. Hydrofluorocarbons can also be combined with carbon dioxide (CO 2 ), which has a lower GWP and boiling point [54]. The lower boiling point and GWP are consistent with the evolution of the fourth-generation refrigerants that contain a mixture of HFCs, HFOs, HCs, and natural refrigerants, which are required to produce a low-GWP, zero-ODP, high-capacity, low-operating-pressure, and nontoxic refrigerant.  Results related to Cp liquid are shown in Figure 10, and they present the highest values for R410A and R463A at 1.708 and 1.694 kJ/kg.K, respectively, which are higher than those of R404A by 9.72% and 8.97% due to the HFCs and carbon dioxide (CO2) from R744. This is consistent with boiling points of R410A and R463A; the highest boiling points were -51.  Results related to Cp liquid are shown in Figure 10, and they present the highest values for R410A and R463A at 1.708 and 1.694 kJ/kg.K, respectively, which are higher than those of R404A by 9.72% and 8.97% due to the HFCs and carbon dioxide (CO2) from R744. This is consistent with Results related to Cp liquid are shown in Figure 10, and they present the highest values for R410A and R463A at 1.708 and 1.694 kJ/kg.K, respectively, which are higher than those of R404A by 9.72% and 8.97% due to the HFCs and carbon dioxide (CO 2 ) from R744. This is consistent with boiling points of R410A and R463A; the highest boiling points were −51.6 and −60.3 • C due to the hydrofluorocarbons (HFCs) and carbon dioxide (CO 2 ) from R744. The 6% R744 in the composition of R463A affects the normal boiling point of R463A, which is higher than that of R410A by 14.5% even though R32 is in the composition of R410A 50%. The Cp result is consistent with that of liquid conductivity in Figure 11, but the effect of R32 is greater than the effect of R744 because the liquid conductivity of R32 is higher than that of R744. The boiling point, GWP, Cp, and liquid conductivity provide the basis to design the refrigerant. For the next steps, the Qevap, Qcond, work, evaporator pressure, and condenser pressure are considered.  The result of the refrigerant effect in Figure 12 shows that R463A has the highest refrigerant effect, at 194.65, 186.07, and 168.25 kJ/kg for low, medium, and high conditions, respectively. This is 57% and 25% higher for low and medium conditions, respectively, compared to R404A. The result of heat rejection, shown in Figure 13, indicates that the maximal heat-rejection values for R463A were  The result of the refrigerant effect in Figure 12 shows that R463A has the highest refrigerant effect, at 194.65, 186.07, and 168.25 kJ/kg for low, medium, and high conditions, respectively. This is 57% and 25% higher for low and medium conditions, respectively, compared to R404A. The result of heat rejection, shown in Figure 13, indicates that the maximal heat-rejection values for R463A were 340.43, 273.5, and 239.3 kJ/kg for the low, medium, and high conditions, respectively, which were  The result of the refrigerant effect in Figure 12 shows that R463A has the highest refrigerant effect, at 194.65, 186.07, and 168.25 kJ/kg for low, medium, and high conditions, respectively. This is 57% and 25% higher for low and medium conditions, respectively, compared to R404A. The result of heat rejection, shown in Figure 13, indicates that the maximal heat-rejection values for R463A were 340.43, 273.5, and 239.3 kJ/kg for the low, medium, and high conditions, respectively, which were 53% and 27% higher for the low and medium conditions, respectively, compared to those of R404A. The refrigerant effect and heat rejection of R463A were found to be higher than those of R404A due to the presence of 36% hydrofluorocarbons (HFCs) R32 and 7% carbon dioxide (CO 2 ) R744 in its composition, which is consistent with R424A [45] and R453A [57], which are composed of hydrocarbons (HCs) at contents of 1.8% and 1.2%, respectively. The mixed-refrigerant design should be comparable to natural refrigerants in terms of having a strong refrigerant effect and high heat rejection.  The results of the refrigerant work, shown in Figure 14, demonstrate a relationship between evaporator pressure, shown in Figure 15, and condenser pressure, shown in Figure 16. Refrigerants operated under low pressure display low refrigerant work value; in this case, the lowest refrigerant work of R452A was found to be 75.91, 49.36, and 40.12 kJ/kg for low, medium, and high conditions, respectively. This refrigerant possesses HFOs from R1234yf and R1234ze (E) in its composition. R463A also demonstrated the highest evaporator pressure at 209.1, 554.1, and 934.7 kPa for low, medium and high conditions, respectively, and operated at the highest evaporator pressure of 2748.7, 2988.1, and 3784.7 kPa for low, medium and high conditions, respectively. The highest refrigerant work values for R463A were 145.78, 87.43, and 71.05 kJ/kg, which contained 36% hydrofluorocarbons (HFCs) R32 and 7% carbon dioxide (CO2) R744, and operated at the highest evaporator pressure of 209.1, 554.1, and 934.7 kPa for low, medium and high conditions,  The results of the refrigerant work, shown in Figure 14, demonstrate a relationship between evaporator pressure, shown in Figure 15, and condenser pressure, shown in Figure 16. Refrigerants operated under low pressure display low refrigerant work value; in this case, the lowest refrigerant work of R452A was found to be 75.91, 49.36, and 40.12 kJ/kg for low, medium, and high conditions, respectively. This refrigerant possesses HFOs from R1234yf and R1234ze (E) in its composition. R463A also demonstrated the highest evaporator pressure at 209.1, 554.1, and 934.7 kPa for low, medium and high conditions, respectively, and operated at the highest evaporator pressure of 2748.7, 2988.1, and 3784.7 kPa for low, medium and high conditions, respectively. The highest refrigerant work values for R463A were 145.78, 87.43, and 71.05 kJ/kg, which contained 36% hydrofluorocarbons (HFCs) R32 and 7% carbon dioxide (CO2) R744, and operated at the highest evaporator pressure of 209.1, 554.1, and 934.7 kPa for low, medium and high conditions, The results of the refrigerant work, shown in Figure 14, demonstrate a relationship between evaporator pressure, shown in Figure 15, and condenser pressure, shown in Figure 16. Refrigerants operated under low pressure display low refrigerant work value; in this case, the lowest refrigerant work of R452A was found to be 75.91, 49.36, and 40.12 kJ/kg for low, medium, and high conditions, respectively. This refrigerant possesses HFOs from R1234yf and R1234ze (E) in its composition. R463A also demonstrated the highest evaporator pressure at 209.1, 554.1, and 934.7 kPa for low, medium and high conditions, respectively, and operated at the highest evaporator pressure of 2748.7, 2988.1, and 3784.7 kPa for low, medium and high conditions, respectively. The highest refrigerant work values for R463A were 145.78, 87.43, and 71.05 kJ/kg, which contained 36% hydrofluorocarbons (HFCs) R32 and 7% carbon dioxide (CO 2 ) R744, and operated at the highest evaporator pressure of 209.1, 554.1, and 934.7 kPa for low, medium and high conditions, respectively, and operated at the highest evaporator pressure of 2748.7, 2988.1, and 3784.7 kPa for low, medium and high conditions, respectively. This means that a refrigerant system that is operated at low pressure should be mixed with refrigerants that can operate under low pressure, such as R1234yf, R1234ze, and R134A. R450A [49], R456A [50], R513A [51] and R515A [50], which were mixed with hydrofluoroolefins (HFOs) and operated under low pressure, achieving similar results to R463A operating under high pressure with 36% hydrofluorocarbons (HFCs) R32 and 7% carbon dioxide (CO 2 ) R744 contents in its composition.        The COPc results in Figure 17 show that R453A had the highest COPc at 1.45, 2.3, and 2.607 for low, medium and high conditions, respectively, as R453A did not have the highest refrigerant effect and heat rejection, nor the lowest boiling point, but could be operated under low pressure, which has an impact on low refrigerant work. The COPc level of R463A was recorded at 1.34, which was 10% higher than that of R404A under low-temperature conditions only. The promising results for COPc obtained by R407F, R448A, and R449A were due to the refrigerants being operated under low pressure, which has an impact on low refrigerant work. The same effect was observed for R453A, and these four refrigerants do not have a low normal boiling point or high Cp liquid/vapor or liquid/vapor conductivity. This shows that a mixed-refrigerant design should consider all parameters, such as the GWP, boiling point, Cp liquid/vapor and liquid/vapor conductivity, refrigerant effect, heat rejection, refrigerant work, evaporator pressure, high pressure, and COPc. The COPc results in Figure 17 show that R453A had the highest COPc at 1.45, 2.3, and 2.607 for low, medium and high conditions, respectively, as R453A did not have the highest refrigerant effect and heat rejection, nor the lowest boiling point, but could be operated under low pressure, which has an impact on low refrigerant work. The COPc level of R463A was recorded at 1.34, which was 10% higher than that of R404A under low-temperature conditions only. The promising results for COPc obtained by R407F, R448A, and R449A were due to the refrigerants being operated under low pressure, which has an impact on low refrigerant work. The same effect was observed for R453A, and these four refrigerants do not have a low normal boiling point or high Cp liquid/vapor or liquid/vapor conductivity. This shows that a mixed-refrigerant design should consider all parameters, such as the GWP, boiling point, Cp liquid/vapor and liquid/vapor conductivity, refrigerant effect, heat rejection, refrigerant work, evaporator pressure, high pressure, and COPc.   The COPc results in Figure 17 show that R453A had the highest COPc at 1.45, 2.3, and 2.607 for low, medium and high conditions, respectively, as R453A did not have the highest refrigerant effect and heat rejection, nor the lowest boiling point, but could be operated under low pressure, which has an impact on low refrigerant work. The COPc level of R463A was recorded at 1.34, which was 10% higher than that of R404A under low-temperature conditions only. The promising results for COPc obtained by R407F, R448A, and R449A were due to the refrigerants being operated under low pressure, which has an impact on low refrigerant work. The same effect was observed for R453A, and these four refrigerants do not have a low normal boiling point or high Cp liquid/vapor or liquid/vapor conductivity. This shows that a mixed-refrigerant design should consider all parameters, such as the GWP, boiling point, Cp liquid/vapor and liquid/vapor conductivity, refrigerant effect, heat rejection, refrigerant work, evaporator pressure, high pressure, and COPc.

Conclusions
The results for R463A and R404A using REFPROP and CYCLE_D-HX software, and following the CAN/ANSI/AHRI540 AHRI standards, indicate that the normal boiling point of R463A was higher than that of R404A by 23%, with a high cooling capacity and a lower GWP than that of R404A by a margin of 63%. The critical pressure and temperature of R463A were found to be higher than those for R404A; R463A could operate at a higher ambient temperature, has a higher refrigerant effect and heat rejection, and lower global warming potential (GWP) than that of R404A by 52% due to the presence of the HFOs of R1234yf in its composition. The COP of R463A was found to be higher than that of R404A in a low-temperature application. This means that the mixed-refrigerant design should consider all of the parameters, such as the GWP, boiling point, Cp liquid/vapor and liquid/vapor conductivity, refrigerant effect, heat rejection, refrigerant work, evaporator pressure, high pressure, and COPc. R463A is another alternate refrigerant option that is composed of 7% carbon dioxide (CO 2 ), and is consistent with the evolution of the fourth-generation refrigerants that contain a mixture of HFCs, HFOs, HCs, and natural refrigerants, which are required to produce a low-GWP, zero-ODP, high-capacity, low-operating-pressure, and nontoxic refrigerant. In the future, researchers should incorporate R744 at contents above 7% in order to use natural refrigerants that are low-cost. The problems of high evaporator pressure and high condenser pressure that impact high refrigerant work can be solved by adjusting the composition of the refrigerant or mix using a refrigerant that operates at low pressure, thereby improving the COP of the refrigerant.