“This is a historical agreement and the decision to phase-down in Europe will encourage a transition to low GWP in Europe with global impact,” says Mogens Terp Paulsen, President Danfoss Refrigeration & A/C Controls. “The industry will now take up the challenge to ensure sustainable solutions which include energy efficiency, safety and low GWP refrigerants. It is doable through a close collaboration across the value chain.”
“The decision has removed the uncertainty in the market. The Political Agreement will now need to be formally endorsed by the European Parliament and the Council. The new regulations are expected by summer 2014, and the rules should become applicable from 2015, subject to approval," explains Torben Funder-Kristensen, Danfoss Head of Public Industry Affairs.
Danfoss is encouraging the further development and use of low-GWP refrigerants, both natural and synthetic; In the case of hydrocarbons, ammonia and carbon dioxide, it focuses on solving the challenging application difficulties related to flammability, toxicity, corrosiveness and extreme pressures, while enabling cost competitive and highly energy-efficient systems. Danfoss will also develop and support products for low-GWP synthetic refrigerants, particularly for those applications where natural refrigerants are not practical or economically feasible.
To understand the implications of refrigerant transition, it is also necessary to consider the system design and the possible risks. Even if alternative refrigerants are viable in thermodynamicterms, they cannot always be used in existing systems.
The following aspects must be considered when selecting a future refrigerant (in no specific order):
Efficiency (theoretical, volumetric, potential for optimisation of the working process);
Safety (including toxicity, flammability, and high pressure);
Environmental impact (refrigerants should have zero ODP and low GWP);
Thermophysical properties (Critical point and triple point, low pressure level, pressure ratio of the refrigerant in the application)
Chemical properties (material compatibility, miscibility with oil, chemical stability, and miscibility with water)
Economic viability (including the initial cost of the system and the life cycle cost)
The four main groups of refrigerants are the natural refrigerants: Hydrocarbons (HCs), Carbon dioxide (CO2), and Ammonia (NH3); and also the synthetic Hydroflorocarbons (HFCs) and hydrofluoroolefins (HFOs).
Hydrocarbons belong to the group of natural refrigerants and have zero ODP and negligible GWP. As a rule, hydrocarbons are by-products from the petrochemical industry.
Hydrocarbons are flammable and must be handled with care. If they are used responsibly, hydrocarbons can be employed in a variety of refrigeration and air conditioning applications. In order to ensure safety, hydrocarbon applications are governed by various international, regional and national standards and legislation.
The following types of hydrocarbons are commonly used as refrigerants:
The main use for R600a is in domestic refrigeration where specifically in Europe there has been a migration away from HFC's such as R134a to R600a, this trend is also taking place across the world in countries such as Japan, US, China and Latin American countries.
R290 is typically being used to replace R22, R404A and R134a in light commercial applications such as ice cream freezers, bottle coolers, beverage coolers, heat pumps, dehumidifiers etc.
Propylene (R1270) has been used as a replacement for R22 and R502 with applications ranging from commercial refrigeration, Industrial refrigeration, cold stores, small air conditioning units and larger air conditioning units and chillers.
In acknowledgment of the increased use of flammable refrigerants including hydrocarbons, Danfoss has revaluated its policies on sales of products for flammable refrigerants. The result is Danfoss selling components for flammable refrigerants for larger systems all over the world; and in EU and other selected countries Danfoss will no longer require a special agreement on flammable refrigerants to be signed. This is a change from previously where sales where restricted to systems with less than 150g charge and industrial refrigeration. With the new ISO5149 safety standard, soon to be published, there is now an international safety standard for larger systems.
The other relaxation is that Danfoss will no longer require a special agreement regarding flammable refrigerants for certain countries: EU, EFTA, US, Canada, New Zealand, Australia and China. Previously agreements were needed all over the world. The reason for exempting these selected countries is that these are areas where safety standards are an integrated part of the legislative system, and there is therefore a strong pressure on system builders to follow these standards.
Due to the lower flammability of the new HFC refrigerants, Danfoss does not require special agreements to be signed for R32 and the currently available HFOs R1234yf and R1234ze.
Carbon Dioxide (CO2)
CO2 is a high-pressure refrigerant. The operating pressure of CO2 is high and typically lies between 20 and 50 bar on the low pressure side or subcritical system and between 60 and 130 bar in the transcritical part of the system (typically between the compressor and high-pressure regulating device). During standstill the pressure where liquid is present can reach and exceed the saturation pressure at the ambient temperature. Hence systems are typically designed either with a small standstill condensing unit, or designed to withstand pressures up to 90 Bar.
CO2 is a by-product in a number of industries, so the price of CO2, as a refrigerant, is very low. As the number of CO2 installations increases, the cost approaches the cost of the reference systems (using HFCs) and the energy savings available make their life-cycle cost lower.
Secondary CO2 systems, especially in industrial refrigeration, may be less expensive to build than their glycol counterparts and thus offer lower initial and life-cycle costs.
Unlike most other refrigerants, CO2 is used in practice in three different refrigeration cycles:
Subcritical (cascade systems)
Transcritical (CO2-only systems)
Secondary fluid (CO2 used as a volatile brine)
The technology used depends on the application and the intended location of the system.
There are a several applications where CO2 may be attractive and is already used today, for instance
Industrial refrigeration. CO2 is generally used in combination with ammonia, either in cascade systems or as a volatile brine
Food/retail sector, sometimes in cascade with HFCs, hydrocarbons, or ammonia
Ammonia (NH3) is a well known refrigerant. It is especially popular in large industrial plants, where its advantages can be fully utilised without compromising the safety of the personnel working with the refrigeration installation. Ammonia has very favourable thermodynamic properties. In a wide range of applications, it outperforms synthetic refrigerants such as R22, which is one of the most efficient HCFCs. However, it has a number of drawbacks that prevent it from being used in commercial refrigeration. These drawbacks include material compatibility, toxicity, and flammability.
Ammonia is a natural refrigerant. It has zero ODP and zero GWP. In combination with its efficiency, it is one of the most environmentally friendly refrigerants. It is a very inexpensive and abundantly available refrigerant. Ammonia installations tend to be relatively expensive due to the requirement for steel tubing, open compressors, and the installation of a number of safety devices, such as gas detectors.
There are ongoing efforts to develop low-charge ammonia systems in order to utilise the beneficial thermodynamic and environmental properties of ammonia. These include:
Development of low-charge systems and associated control algorithms
Optimisation of heat exchangers
Cascade systems or combination with secondary systems with CO2 as a brine
Today ammonia is primarily used in industrial refrigeration applications:
Distribution cold stores
Food processing plants (slaughterhouses, ice cream factories, etc.)
Hydroflourocarbons (HFCs) and Hydrofluoroolefins (HFOs)
HFCs are synthetic refrigerants and comprise a wide range of individual compounds and mixtures. The main single-compound refrigerant is R134a, while the main HFC mixtures are R404A (R125/ R143a / R134a), R507 (R125 / R143a), R407C (R32 / R125 / R134a), and R410A (R32 / R125). Mixtures of HFCs can be designed to suit all types of applications.
As most current HFCs have significant GWP values (typically 1300 to 4000), they are under pressure from regulators and environmental agencies. The latest TEAP proposal classifies GWP from 300 to 1000 as “moderate”, 1000 to 3000 as “high” and from 3000 to 10,000 as “very high”. Traditional HFCs will continue to be used, but in fewer applications with increased attention on leaks and in systems with reduced refrigerant charges. Several refrigerants are considered to replace the traditional HFCs.
R407A and R407F are HFC blends originally develloped as alternatives for R22 but as they have a GWP below 2000, considerably lower than the 3900 of R404, they are now seen as interim drop-ins for R404A and R507.
The GWP of R32 (675) is much lower than R22 (1810) and R410A (2100). Compared with traditional low GWP refrigerants such as R290 (3.3) R32 still has a high GWP but seen in the light of increased efficiency, safety and ease of implementation R32 constitutes a very viable interim solution on the way to phase down the refrigerant GWP impact from the current level.
R1234yf and R1234ze are two unsaturated HFCs also known as HFOs. R1234yf has been selected by the car industry as the replacement for R134a in Europe for automotive A/C, while R1234ze is a promising candidate to replace R134a in large centrifugal chillers. Both substances have the potential
to be important ingredients in future HFC blends.
Due to the lower flammability of these refrigerants, Danfoss do not require special agreements to be signed for R32, R1234yf and R1234ze.
Several other substances and blends are on the way to the market. In general there is a tendency for low GWP HFCs to be mildly flammable.
It is clear that there is no ideal refrigerant. Some refrigerants have adverse effects on the environment, while others pose safety risks. Other requirements for refrigerants include economic acceptability and energy efficiency. Danfoss assesses refrigerant options for various applications and develops technologies that can address the challenges of the best alternative. Some of the proposed solutions are already commercially available, so the more environmentally friendly systems can already be built now.
Controls for hydrocarbons
Danfoss offers a range of commercial refrigeration controls for Hydrocarbon applications including Thermostatic Expansion Valves, Solenoid Valves, Pressure & Temperature Controls and Line Components. Where possible Danfoss will now consolidate the product offering by upgrading standard products to flammable refrigerants, this will mean in some cases the special code numbers for hydrocarbons will disappear. The process has begun with the line components; NRV (Non return valves), BML (Stop Valves) and SGP & SG (Sight Glasses) with DCL Filter
Driers scheduled to follow.
Direct weld components and valve stations
Danfoss has developed a range of direct weld control valves and valves stations (ICV and ICF types) for industrial refrigeration applications. The valves reduce the number of flanged and welded connections in the system, which dramatically reduces the risk of leaks. In addition, the components are designed for higher pressures, so they can be used in subcritical CO2 systems.
DX ammonia applications
A combination of a motorised valve (ICM) and an electronic controller (EKC 315A) together with a pressure sensor and a temperature sensor helps meet the challenge of using ammonia in compact DX chillers. The system has a very short response time, and it maintains a very stable, low superheat level under all load conditions, thereby minimising the risk of liquid flow back to the compressor and maximising energy efficiency.
Components for subcritical CO2 applications
Danfoss has a full range of valves and controls for commercial and industrial CO2 cascade systems. Although the products for commercial refrigeration applications are the same as for R410A, a separate industrial refrigeration product line has been developed specifically to meet CO2 requirements. As seen on pages 5 & 6 we can also offer the new NRV check valve and GBC ball valves both capable of a MWP of 90 bar. Finally the AKVH electronic expansion valves also have a MWP of 90 bar.
Components for transcritical CO2 applications
The challenge with transcritical CO2 systems is even higher than with subcritical systems because the high pressure level is around three times as high as the pressure level of any other refrigerant used in commercial applications. Danfoss has already developed a high pressure controlled valve (ICMTS) and a high pressure expansion valve (CCMT) both of which have a maximum working pressure (MWP) of 140 bar.
ADAP-KOOL control system and variable-speed drives
Danfoss has developed fully integrated electronic control systems that manage, monitor and optimise the performance of commercial refrigeration systems for supermarkets and/or industrial refrigerated processing installations. ADAP-KOOL combines specially designed refrigeration controllers and valve combinations and utilises adaptive control algorithms for liquid injection to evaporators, while compressor and condenser pack controllers are used to ensure ensure an efficient and effective energy optimisation strategy and handle overall system management. Extension functions enable continuous monitoring and status reports on refrigerant gas leak detection (to facilitate end user compliance, such as with the F-GasRegulation), energy consumption and efficiency, product temperature status summaries to support compliance with food hygiene (HACCP) requirements, and overall system supervision and maintenance.
Compressors for hydrocarbons
Danfoss is one of the market leaders in supplying light commercial compressors for hydrocarbons. In addition to a product line of household compressors that work with R600a, Danfoss has introduced compressors for light commercial applications, such as integral ice-cream cabinets, using propane as a refrigerant. Compressors for R407A & R407F. Danfoss Commecrcial Compressors has made a guideline for installing or retrofitting MTZ and MLZ compressors with R407A and R407F. Both of these alternatives are fully compatible with the POE and PVE oils used with these compressors, however, due to the large glide of R407A and R407F some components may need to be requalified.
Micro channel heat exchangers
Danfoss offers a range of micro channel heat exchangers for the refrigeration industry. Micro channel heat exchangers made from aluminium
need only a small refrigerant charge (thus reducing environmental impact and improving cost effectiveness), and they are very compact and light compared with conventional fin and tube heat exchangers. MCHE technology was developed by the automotive industry in the 1980s. It has been used more and more in air conditioning systems since 2004, and it is now starting to be used in the refrigeration industry as well. Micro channel heat exchangers can be used with conventional refrigerants such as HFCs and with natural refrigerants, including ammonia, hydrocarbons, and even CO2 in transcritical systems.