what refrigerant should i use to replace r744

 It's clearly known that the growing dimensions of the hole in the ozone layer take very important damages and effects on living creatures today. Investigations evidence that refrigerants that commonly used in air conditioning have great impacts on the damage to the ozone layer. For this reason, researches on alternative refrigerants to be used for air conditioning is even so continuing. In this written report, the performance of different refrigerants like R600a, R134a, R290, R1270, R32, R22, and R152a and R744.

The table below shows the properties of the refrigerants:

• Difluoroethane or R152a is a pure fluorinated hydrocarbon with a formulation very similar to R134a. Information technology has a vapor pressure curve equivalent to R134a, with deviations of only 2K, and has equivalent chemical characteristics, and is therefore compatible with all materials, refrigeration components, thermostatic valves, compressors, and lubricating oils.

• R152a besides has superior thermodynamic characteristics to R134a and HFOs. The heat transfer coefficient of the refrigerant in evaporators is increased past about xx% due to the ameliorate concrete properties of R152a compared to R134a. Due to the lower gas viscosity, the pressure drop in the suction lines will exist reduced by 30%. The lower molecular weight of R152a gives it a high latent heat of vaporization, a higher volumetric efficiency of the compressor, and a better COP performance of the refrigeration wheel, with a higher discharge temperature of about 10K compared to R134a.

• R152a (1, 1-difluoroethane) tin can be a possible substitute for R134a if safety measures are provided. Refrigerating effect is 64.eight% higher while compressor work is 3.nine% lower compared to R134a. Belch temperature is 13.2% is higher but COP is 4.i% higher compared to R134a. The pressure level ratio is most similar to that of R134a. The main advantages of R152a refrigerant are that it has low GWP and higher COP compared to R134a. The primary disadvantage is that it is a combustible refrigerant and discharge temperature is college than R134a.

• In practice, by combining all the factors in the same refrigeration system, the energy efficiency of R152a is 20% higher than that of R134a and fifty-fifty higher than that of R1234yf. Also, in the same system, the reduction of the R152a refrigerant charge is twoscore% by weight due to the lower molecular weight.

Safety requirements of R152a:

• R152a is classified equally a medium-safe refrigerant, class A2, non-toxic but slightly combustible. While the refrigeration plant safety regulation limits the use of medium-safe refrigerants in direct expansion commercial refrigeration applications, it does allow their use without charge limit in indirect systems and in direct expansion industrial applications.

• Due to the slight flammability of group 2 refrigerants, higher safety levels are required which imply specific solutions in the design of the systems together with the corresponding risk assay. The regulation on safety in explosive atmospheres (RD 681/2003) would classify such refrigeration installations as Zone 2 risk, i.eastward., every bit working areas in which the formation of an explosive atmosphere is not likely under normal operating weather. The nomenclature would not, in principle, entail the application of ATEX measures, but its usefulness would merely be for the purpose of establishing the areas probable to exist declassified or their nomenclature modified by the implementation of preventive measures (such equally the implementation of localized extraction, ensuring sufficient natural ventilation, etc.

• To mitigate the take a chance in cold rooms, it is recommended to install a leak detector that isolates the evaporator from the residual of the installation, thus preventing the formation of an explosive atmosphere. Indeed, the refrigerant charge remaining within an evaporator is usually less than 20 grand per m3 of cold room, well below the flammability limit of 0.137 kg/m3.

• In machine rooms, it is recommended to install an automated extraction organisation in case of leakage to ensure sufficient ventilation flow.

• Piping in pipes that are technically watertight, e.g., effectually welded pipelines, does non constitute a risk area.

Properties of Co2 (R744) Refrigerant:

R744 (CO2) is refrigerant grade CO2, used as a replacement for R134a and R404A in ultra-depression, low, and medium temperature refrigeration applications. R744 (CO2) is becoming increasingly popular due to its splendid properties. With an Ozone Depleting Potential (ODP) of 0 and a Global Warming Potential (GWP) of one, R744 (CO2) is a natural refrigerant.

• However, the extremely high operating pressures of R744 and hazards associated with potentially loftier concentrations of CO2 in vehicle cabins or working environments means this refrigerant must exist used with care.

• R744 can exist in all three states, vapor, liquid, and solid (dry ice) and, equally such, the skills of the technician are critical.

• Dry ice changes from a solid to a vapor (sublimates) at -78°C and the boiling point of liquid CO2 at atmospheric pressure is also -78°.

R744 Hazards:

Asphyxiation

R744 is odorless, heavier than air, and is an asphyxiant. The practical limit of R744 is lower than hydrofluorocarbons (HFCs) because of its potential for high toxicity (HFCs are not-toxic):

• Practical limit of R744: 0.i kg/m3 (56,000 ppm);

• Practical limit of R404A: 0.48 kg/m3 (120,000 ppm)

Annotation: The practical limit is divers in EN378 simply may vary in regional regulations.

CO2 TLV Threshold Limit Value is 5000PPM (0.5%), and Ammonia TLV is 25 PPM (0.0025%), which is the highest concentration for an viii-60 minutes limit.

If a leak of R744 could result in a concentration exceeding the practical limit in an enclosed occupied infinite such equally a cold room, precautions must be taken to forbid asphyxiation. These include the use of permanent leak detection, which activates an alarm in the event of a leak.

Reference:

[one]-https://www.ashrae.org/file%20library/technical%20resources/refrigeration/factsheet_ashrae_english_20200424.pdf

[two]- https://world wide web.intarcon.com/en/refrigerante-r152a/

[3]- https://www.arctick.org/data/autogas/r744-co2-carbon-dioxide/

[four]- https://www.agas.com/european union/products-services/products-refrigerants/natural-refrigerants/r744-co2/

[5]- https://emersonclimateconversations.com/2015/07/02/co2-as-a-refrigerant-5-potential-hazards-of-r744/

[6]- comparative-evaluation-of-an-automobile-air conditioning-system-using-r134a-and-its-alternative-refrigerants.pdf

[7]- CIB8439.pdf

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