PROSPECTS FOR CONVERTING SPLIT AIR CONDITIONERS TO HFC 410A

ABSTRACT

The article provides a detailed description of the ozone layer and the causes of its destruction, the history of efforts to prevent it, and the work currently being done in Uzbekistan. Information about the ozone-depleting refrigerant R22 is provided. R410A is recommended as an alternative to R22. R22 and R410A refrigerants were compared in terms of cooling capacity, energy consumption, and cooling coefficient. All scientific results are presented in the form of diagrams and explained to the reader using the scientific comparison method. Scientific experiments were conducted in a split air conditioner in Uzbekistan, and conclusions were made based on the results.

АННОТАЦИЯ

В статье подробно рассказывается об озоновом слое и причинах его разрушения, истории усилий по его предотвращению, а также о работах, которые в настоящее время ведутся в Узбекистане. Предоставляется информация об озоноразрушающем хладагенте R22. В качестве альтернативы хладагенту R22 рекомендуется хладагент R410A. Хладагенты R22 и R410A сравнивались по показателям холодопроизводительности, энергопотребления и коэффициента охлаждения. Все научные результаты представлены в виде диаграмм и объяснены читателю с использованием метода научного сравнения. В Узбекистане были проведены научные эксперименты в сплит-кондиционере, по результатам которых сделаны выводы.

Keywords: split air conditioners, refrigerant, ozone, cooling capacity, coefficient of performance.

Ключевые слова: сплит-кондиционеры, хладагент, озон, холодопроизводительность, коэффициент полезного действия.

Introduction

The production of artificial cold, i.e. achieving temperatures below the ambient temperature, and the implementation of various technological processes at these temperatures are finding ever-expanding application in many sectors of the national economy. Refrigeration technology has proven to be necessary in almost all areas of human activity [1].

Life has Earth been protected for thousands of years by a protective atmospheric layer. This layer, made of ozone, protects the Earth from the harmful ultraviolet radiation of the sun. As far as we know, this is a unique property of our planet. If this protective layer is destroyed, the ultraviolet radiation of the sun will sterilize the surface of the globe, destroying most of the life on the earth's surface.

In the 80s of the last century, it was proven that chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons (HCFCs) are capable of destroying the ozone layer that protects the Earth's flora and fauna from the harmful effects of solar ultraviolet radiation [2].

In accordance with the Vienna Convention for the Protection of the Ozone Layer of 1985 and the Montreal Protocol on Substances that Deplete the Ozone Layer of 1987 and subsequent amendments to it (Uzbekistan ratified the Montreal Protocol and its subsequent amendments), the consumption of CFCs in developed countries has been discontinued since 1996, and in developing countries it has been discontinued since January 1, 2010. The consumption of HCFCs in developed countries must be discontinued by 2020, and in developing countries by 2030.

In Uzbekistan, scientific research work is also being carried out to solve such global problems.

Coefficient [3].

Research methodology and results

This experimental research stand consists of two rooms-one of which provides the outside temperature, and the second room provides the temperature of the internal environment. With the help of this stand, it is possible to obtain research data in the above-mentioned tabular form for creating an environment of any time of year. Below are the research results in the form of a graph at outside temperatures of 30, 40, 50 ⁰C [4].

Figure 1 shows a graph of the relationship between pressure and temperature for refrigerants R22 and R410A. It can be seen that the operating mode of the split air conditioner is in the range (20 – 60 ⁰C), and the pressure with R410A is on average 1,58 times higher than with R22.

Figure 1. Graph of the relationship between pressure and temperature for refrigerants R22 and R410A

This circumstance should be taken into account when switching a split air conditioner operating on R22 refrigerant to R410A refrigerant, while taking into account the increased strength of the walls of the pipes of the heating devices. This means that a slightly higher pressure when operating R410A refrigerant than R22 refrigerant is its only drawback.

Figure 2. Graph of the relationship between cooling capacity and outside temperature for refrigerants R22 and R410A

Fig. 2 shows a graph of the ratio of the cooling capacity and the outside temperature of a split air conditioner with a cooling capacity of 12,000 Btu/h. In this case, the air conditioner had the same boiling point in both refrigerants, i.e. t₀ = 12⁰C. For Uzbekistan, this means 40-50⁰C in the summer. It was found that in this range, the performance of the two refrigerants is very close to each other. A decrease in the outside temperature leads to an increase in the performance of the air conditioner operating on the R410A refrigerant by 1,24 times. But in the summer, there is no particular difference. This means that such features of R410A are not visible in the summer.

Figure 3. Graph of the dependence of the energy consumed by a split air conditioner on refrigerants R22 and R410A and the outside air temperature

Fig. 3 shows a graph of the dependence of the energy consumed by a split air conditioner and the outside air temperature. Based on the research results, it was found that, with an increase in the ambient air temperature, the energy consumption of an air conditioner operating on R410A refrigerant is on average 1,07 times greater. This means that R410A refrigerant consumes more energy than R22 refrigerant, and this is another disadvantage. But in the range of 30-35 ⁰C, it is more useful.

The dependence of the cold coefficient value on the outside temperature is shown in Fig. 4.

Figure 4. Graph of the dependence of the cooling coefficient of refrigerants R22 and R410A on the outside temperature

The essence of this cold coefficient means how much energy is spent to obtain cold. So the higher the value of this coefficient, the better for us. In neutral conditions, it was found that the cold coefficient of the refrigerant R410A is higher than that of the refrigerant R22 by 1,40 times. As can be seen from the graph, at summer temperatures, the indicators are almost the same. So we can get more cold on R410A by spending less energy.

Conclusions

• A study was conducted on a split air conditioner with a capacity of 12,000 Btu/h using R22 and R410A refrigerants. The results of the study were conducted at an ambient temperature of 20 – 60 ⁰C.
• During the spring-autumn period (20-30 ⁰C), the performance of the R410A refrigerant was 28% higher than that of the R22 refrigerant. In summer, this figure is 3%.

Reference:

1. Azizov D.H., Norkhujaev A.S., Research of split air conditioner in environmentally friendly cooling agent // Scientific and technical journal of Chemistry and Chemical Technology. №2, 2017 - pages 75-78
2. Azizov D.H., Norkhojayev A.S., Research of a split air conditioner on environmentally friendly refrigerants // Collection of scientific papers international scientific and technical on-line conference. - Tashkent. TashSTU, 2020. pp. 285-288
3. Bolaji B.O., Experimental Analysis of Reciprocating Compressor Performance with Eco- Friendly Refrigerants. // Journal of Power and Energy. №224. 2012. pp. 781-786
4. Tsvetkov O.B. Laptev Yu.A. On the thermal conductivity of diftormethane (HFC – 32) in the composition of razre-zhennogo gas // Vestnik Mezhdunarodnoy akademii xoloda. - 2014. - № 3. - p. 22–26.
5. Coulomb D. The refrigerant’s future: The phase down of HFCs and its consequences // Vestnik Mejdunarodnoy akademii xoloda. № 1 2014. S. 3-6
6. Nurmatov T.B., Norkhujaev A.S., Khasanov B.B., Testing of split-conditioners with low pressure with the use of refrigerants R22 and R410A // Texnika i teknologii mashinostroeniya. Materials of the VII International scientific-technical conference. Omsk, May 21-23, 2018 C. 178-180
7. Koraboev A.S., Norkhujaev A.S., Maxmudov O.O., Study of compressors with split conditioners with low pressure // Texnika i teknologii mashinostroeniya. Materials of the VII  International scientific-technical conference. Omsk, May 21-23, 2018 S. 174-177