January 5, 2023 tms_dijital

Transition to New Generation, Low GWP Refrigerants, in Industrial Type Air Conditioners, That Can Operate in Heavy Conditions, and High Ambient Temperatures, Such as Steel Plants, Rolling Mills

Murat Yıldırım & Ahmet Kutsal Erdoğan

TMS Endüstriyel Soğutma Sanayi Ticaret A.Ş.

 

Definition and Historical Development of Cooling Systems

Including air conditioning systems, vapor compression cycles, which have a history of approximately 200 years, are widely used today for the purpose of air conditioning. By the help of the refrigerant used in the cycle, the heat is drawn from the cold area, and transferred to the hot area. In this way, the cooling process takes place by drawing heat from the hot environment.  

Development of Cooling Systems

With the widespread use of vapor compression cycles, the use of cooling systems in every field has become possible. In parallel with comfort type air conditioners, customized cooling cycle designs were made in industrial areas as well. Special refrigerants have been developed for the cooling processes, especially for various ambient temperatures. While high-pressure fluid is selected for devices used in facilities such as cold rooms and freezers and capable of cooling at sub-zero temperatures, low-pressure refrigerants are preferred for cooling areas in facilities such as foundries and rolling mills, where the ambient temperatures sometimes reach above 80 °C ~ 90 °C. In this way, the desired efficient cooling performance is achieved.

In the iron and steel industry, one of the vital need is an uninterrupted cooling in the operator cabins and electrical rooms located on the cranes working in facilities such as foundries. Industrial type air conditioners, operating in these areas have to continue the cooling process uninterruptedly. In order to achieve this, refrigerants, with low operating pressures such as R227ea, R236fa belonging to the HFC group have been preferred in refrigeration cycle designs until today. Air conditioners using R227ea refrigerant can operate in working environments up to 85 °C, while R236fa refrigerant enables uninterrupted cooling in working environments up to 90 °C.

If we review the history of the refrigerant, in the beginnings, natural substances were used as refrigerants in different areas of the industry. However, the fact that most of these substances were flammable and their toxic effects have slowed down the use. In the 1930s, the use of refrigeration systems became widespread on a global scale with the emergence of synthetic refrigerants called chlorofluorocarbon (CFC), including R12 refrigerant. This was followed by the development of hydrochlorofluorocarbon (HCFC) refrigerants, including R22, which was widely used for a long time.

Effects of Cooling Systems on Global Warming 

While cooling systems are rapidly becoming widespread all over the world, it has been determined that these fluids play a role in the depletion of the ozone layer. In order to measure this effect on the basis of refrigerant, the ozone depletion potential (ODP) was defined and the ODP value of R-11 refrigerant was determined as 1.0. The effectiveness of other refrigerants in ozone depletion was calculated as equivalent. Although HCFCs are less effective than CFCs, they are among the substances that deplete the ozone layer. The Montreal Protocol was adopted in September 1987 on the prohibition of ozone-depleting chemicals, including refrigerants. Turkey became a party to this protocol on 19 December 1991.

In order to eliminate this negative effect, the Hydrofluorocarbon (HFC) group was developed as an alternative in the 1990s. The ODP of the HFC group is zero. All commonly used today’s refrigerants such as R134a, R410a, R407c, R404a belong to this group. With the use of HFCs, the ozone layer has been improved, but the problem of global warming, also called the greenhouse gas effect, has emerged with this fluid group. Most of the fluorocarbon chemicals are in the group defined as greenhouse gases. Although HFCs have different uses, according to 2012 data, approximately 80% of the total use is in the air conditioning (HVAC) sector. [2]

In order to evaluate the effects of refrigerants on global warming, the concept of global warming potential (GWP) has emerged. GWP is a measure of the relative global warming effects of different gases. The GWP indicates the amount of heat trapped by 1 ton of a refrigerant in a given period of time, relative to the amount of heat trapped by 1 tonne of carbon dioxide (CO2) gas. Here, the GWP value of the CO2 gas is defined as 1.0. Considering that the GWP value of R236fa refrigerant is 9810, the effect of R236fa refrigerant on global warming is 9810 times more than CO2 gas.

 

The value, expressed in tonnes of CO2 equivalent, is the GWP-weighted amount of a refrigerant and is the mass of the refrigerant multiplied by the GWP value.

 

CO2 equivalent = mass (tonnes) x GWP [2]

For example, calculating for 50 kg of R236fa refrigerant used in an air conditioner;

CO2 equivalent = 0.05 (tonnes) x 9810

CO2 equivalent for this device; It will be 490.5 tons.

 

Studies have been carried out around the world in order to control the emission of greenhouse gases that cause global warming and to limit their use within a calendar. Following the Montreal Protocol to which 196 countries are parties, the Paris Agreement was signed on 12 December 2015 and opened for signature. Later, the 28th Meeting of the Supporters of the Montreal Protocol was held in Kigali, the capital of Rwanda, on October 10-14, 2016, and on October 15, 2016, the Kigali Amendment entered into force on January 1, 2019, with the ratification of the amendment by 65 parties to the protocol. Although fluorinated greenhouse gases (HFC) do not harm the ozone layer, their effect on global warming can reach up to 23 thousand times that of carbon dioxide. With the Kigali Amendment, it is foreseen that the emissions of these gases will be reduced by 80 Gigaton-carbon dioxide equivalent until the end of the approved calendar. [8]

Figure-1 shows the timetable for limiting the use of HFC.

 

Figure-1 Kigali Amendment, HFC Reduction Schedule [2]

 

Group A5 countries are defined in Article 5 of the Montreal Protocol. Parties that fit the definition given in Article 5 of the Montreal Protocol are generally economically developing countries. Parties that are not Article 5 countries (non-A5) or do not meet the definition given in Article 5 of the Montreal Protocol are generally economically developed countries. [9]

Within the framework of this calendar, it is aimed to reduce the carbon footprint by reducing the quotas determined every year. [6] In this calendar, 4 categories have been determined according to country groups. Category A5 covers developing countries. In the non-A5 category, there are developed countries (A2). Turkey is among the developing countries in the A5 Group1.

As part of the Kigali Amendment, the use of HFC gases in use will be reduced by 85% until 2047. In this way, it is aimed to reduce global warming by 0.4 °C ~ 0.5 °C and keep it at 1.5 °C levels.

In accordance with the publication of the F-Gas regulation and EU legislation, on January 1, 2020, the production of cooling systems using refrigerants with a global warming potential (GWP) of more than 2500 was prohibited and to be allowed only for maintenance purpose. It is allowed to be used for service operations. Fluid charge uses for service purposes are also limited to 40 tons of CO2 equivalent. [5] By 2030, the use of new refrigerants for maintenance or recharging will be completely prohibited.

 

Kigali Amendment and Turkey 

In our country, the Kigali amendment was submitted to the Grand National Assembly of Turkey on May 25, 2019 and was adopted on March 4, 2021. With the F-Gas regulation, which came into effect at the beginning of 2020, our country has also entered this path. Finally, Turkey signed the Paris Climate Agreement on October 7, 2021. [4]

With the Kigali Amendment, new alternative fluids were needed in the field of refrigerants, with the restriction of HFCs after CFCs and HCFCs. New alternative development studies continue in two categories. In the first category, natural fluid alternatives such as CO2 (R744), Propane (R290), ammonia (R717), which were known before, are studied. In the second category, there are refrigerants in the Hydrofluoroolefins (HFO) group, which is called the new generation environmentally friendly refrigerants. The most widely known of these are the R1234yf and R1234ze refrigerants. These fluids have been developed as an alternative to R134a, which is one of the most used fluids in the current HFC group. [3] The GWP values of these fluids, which are considered as alternatives, are very low when compared to HFC group fluids. If you want to compare the example, Table-1 can be examined;

 

Table – 1 GWP values for various refrigerants

 

Natural fluids have important limitations especially in terms of working environment conditions and service. Its highly flammable feature, such as R290 (Propane), limits the amount of use in the air conditioner. Again, when the ambient temperature is above 20 °C, CO2 systems operate in transcritical mode, which is defined as a cooling system whose evaporator operates below the critical temperature and its condenser operates above the critical temperature.

Although the newly developed alternative fluids (HFO) have a low impact on global warming, their flammable and toxic classes are higher than the HFC group, which hinders their use. In order to eliminate these negative features, new refrigerants are developed by mixing HFO and HFC group fluids in certain proportions. These new fluid mixtures are being developed for use in the vapor compression cycle. Thus, fluids with flammable classes A3 and A2, defined by ASHREA and seen in Figure-2, shift to the safe class classified as A2L and A1.

 

Figure-2 ASHRAE Classes for Flammability and Toxicity

 

For example; Instead of using the R1234yf refrigerant belonging to the HFO group directly, as an alternative to R134a, which is widely used in industrial cooling systems such as chillers, R513a refrigerant belonging to A1 flammable class has been developed. It is an azetropic mixture obtained with a mixture of 56% R1234yf and 44% R134a. Pressure – enthalpy (p-H) graph and cooling performance are very close to R134a. On the other hand, considering that the GWP value is 631, the effect of R513a fluid on global warming has been improved by approximately 55% compared to R134a. These developments contribute positively to the extremely important product life cycle and product disposal from an environmental point of view.

The similar thermodynamic properties of alternatively developed mixing fluids and HFC fluids enable refrigerant conversions at low costs in existing air conditioners.

The use of R227ea (GWP: 3220) and R236fa (GWP: 9810) refrigerants in air conditioners used for cooling in high temperature working environments has been banned in Europe, in line with the F-Gas regulation. The production and import of new devices using these fluids is prohibited within the borders of Europe. In addition, new sanctions are introduced regarding the existing refrigerants, which are widely used in air conditioners. For example, for R134a (GWP: 1430) refrigerant, which is one of the most widely used in industrial air conditioners, an additional tax of 1.095.38 Norwegian Krone (approximately 2.000 TL) per kg has begun to be charged in Norway. The tax amount increases according to the GWP value of the refrigerant, reaching over 10,000 Norwegian Krone per kg. Similar applications have been started in many other European countries. For this reason, new generation alternative refrigerants with low GWP have been developed. In this context, a transition to non-flammable alternative fluids can be possible. The main new alternative refrigerants that can be used are:

 

  • R513a (56% R1234yf / 44% R134a – GWP : 631) – instead of R134a
  • R450a (58% R1234ze / 42% R134a – GWP : 605) – instead of R227ea
  • R515b (91.1% R1234ze / 8.9% R227ea – GWP : 293) – instead of R227ea and R236fa

 

The transition process continues in Turkey. It is estimated that this transition will be accelerated with the Kigali Amendment and F-Gas regulations adopted previously, and the Paris Climate Agreement signed in October 2021. In particular, 2024 will be considered as the start, for A5 Group 1 included in the Kigali Amendment HFC mitigation calendar. In addition, the transition process was accelerated, in Turkey, with the “Regulation on Fluorinated Greenhouse Gases” published on 29 June 2022. Commercial refrigerators and freezers (hermetically sealed equipment) containing hydrofluorocarbons with a GWP of 2500 or more (hermetically sealed equipment) from 1/1/2025 and commercial refrigerators and freezers containing hydrofluorocarbons with a GWP of 150 or more (hermetically sealed equipment) from 1/1/2029, will be prohibited.

TMS Industrial Refrigeration Inc. started low GWP refrigerant studies in 2019. A result of the R&D studies, our product range, which is VKS Series crane cabin coolers, have been adopted.  At VKS Series crane cabin coolers, especially designed according to the harsh working conditions of iron and steel plants, R134a, R227ea and R236fa refrigerants were used.  The alternative designs for the new generation low GWP refrigerants were completed and new product ranges were introduced. (Figure-3) TMS Industrial Refrigeration Inc. offers air conditioners in which R513a, R450a or R515b refrigerants are used as an alternative to its customers, in accordance with the temperature of the working environment. In this context, since 2020, products, having refrigerants with low GWP values have been produced for different countries of the world, especially for European countries.  

Figure – 3 TMS Brand Crane Cab coolers designed for heavy working (high temperature and corrosive environment) conditions

It is predicted that the transition to new generation refrigerants will be very fast in the near future due to both the regulations and agreements to which our country is a party, and the increasing environmental awareness.

References:

Leave a comment