Is it time to stop using R404A?It is one of the most popular refrigerants, but the conversion from R404A will increase the operator’s environmental credentials and profits.
In the past 10 to 15 years, R404A has become one of the most widely used refrigerants. It was introduced in the mid-1990s as an alternative to ozone-depleting refrigerants, including CFCs (such as R12 and R502) and recently replaced HCFCs (such as R22). In the supermarket sector, it has become the main refrigerant for refrigeration in frozen and frozen foods in Europe. It is also widely used in other commercial systems, industrial refrigeration and refrigeration.
I often wonder why R404A has become so successful because it is not a particularly good refrigerant! It fills an urgent gap of the 1990s and it is already on the market. End users and refrigeration contractors are familiar with fluids and continue to use them as “refrigerants” in many different applications. It is still used in many new systems, even though there are now better refrigerants. It is time to stop complacent refrigerant selection and use better alternatives. Switching away from the R404A can help the environment quickly and cost-effectively and reduce operating costs. For all new refrigeration systems and most existing refrigeration systems, cost-effective alternatives can be used.
What’s wrong with R404A?
The two key issues of R404A are (a) it does not achieve the best energy efficiency in many applications, and (b) it has particularly high global warming potential (GWP).
The relatively poor energy efficiency leads to additional operating costs as well as additional CO2 emissions from the power stations that generate the electricity used. In many applications, alternative refrigerants can save 7% to 12% of electricity.
The GWP of R404A at 3922 is the highest of all commonly used refrigerants. R134a is only 1,430 and R407F (Performax LT) is 1850. Therefore, compared with other HFC refrigerants, leakage of 1 kg R404A is 2 to 3 times higher than global warming.
Interestingly, supermarkets have historically used two different refrigerants; R12 for cooling systems and R502 for refrigeration systems. Each refrigerant can be optimized to its operating temperature. When these ozone-depleting systems were phased out, most supermarkets decided to rationalize their use of refrigerants – most British supermarket freezers and freezers now use R404A. This may be convenient, but it creates a certain degree of compromise in the design of the plant and leads to an overall loss of efficiency.
New Refrigerator Strategy
A very simple strategy can be applied immediately – Do not use R404A in any new system! This is a practical and cost-effective strategy because there are a wide variety of refrigerants available for all R404A applications and can increase efficiency and significantly reduce GWP.
When purchasing new refrigeration equipment, there are three key design factors to consider:
- How to achieve maximum energy efficiency? This is the most important issue in terms of operating costs and energy-related CO 2 emissions. The choice of refrigerant has an impact on energy efficiency – and R404A is a poor choice! For cooling systems, R134a should increase efficiency by 10%, although it requires a slightly larger compressor. Alternatively, refrigerants such as R407A or recently published R407F contribute less than 50% of the GWP of R404A to GWP. It is also important to remember that many other design parameters have a greater impact on efficiency than refrigerants. When purchasing a new system that can operate in the next 20 years, every effort must be made to maximize efficiency.
- What type of refrigerant should be used? For a new factory, you have many options that can help you avoid R404A. These are divided into 3 main groups:
n Medium GWP HFCs such as R134a, R407A, R407F, and R410A. These can provide better energy efficiency and much lower GWP than R404A. These medium-term GWP options represent a good short- to medium-term alternative.
n Newly developed very low GWP hydrofluoroolefin (HFO). HFO1234yf has a GWP of only 4 and properties similar to R134a. It will be used by automakers to solve the R134a ban applicable to the 2011 new model mobile air conditioning. The HFO1234yf is slightly flammable and requires a relatively high energy ignition source and is classified as A2 refrigerant – requiring proper design measures to ensure its safe use. Refrigerant manufacturers are also looking for various blends that combine HFOs with HFCs that can eliminate flammability issues while providing good performance with a GWP in the range of 500 to 1000. Unfortunately, HFOs do not become commercially available for stationary refrigeration applications for 2 or 3 years – so although these fluids can be considered, they cannot be immediately used in new systems.
n Refrigerants, such as ammonia, CO 2 and hydrocarbons (HCs), are often referred to as “natural” refrigerants. These have a very low GWP (between 0 and 5) and can provide effective performance in many applications if they are carefully designed. They all have practical problems and often make them more expensive than HFCs. Ammonia is highly toxic; it is well-suited for large industrial systems but is less cost-effective for small and medium-sized equipment. HCs are highly flammable; they are excellent refrigerants for very small sealing systems, but safety is a problem for medium and large sizes. In the past few years, CO 2 has become a strong contender for supermarket refrigeration and other applications. There are many design issues that need to be addressed because CO 2 operates at much higher pressure than other types of refrigerants, but it can be a good alternative to R404A; however, the investment costs can be high.
- How does the new design minimize leakage? There is no better time to reduce leaks than on a drawing board! Regardless of which refrigerant option is selected, low leakage is critical. For HFC, we try to avoid emitting high GWP gas. With “natural” refrigerants, leaks can cause safety problems. HFO may be more expensive than HFC – so the leak will cost money! A little extra cost on valves, fittings, pipes, etc. can create a new system with a much lower risk of leakage. Ensuring the good installation quality of on-site construction piping systems is critical – many leaks from large systems come from poor installation.
Existing refrigeration equipment strategy
What about all those R404A that are already in use? Do we fall into the low efficiency and emissions of low GWP gas in the lives of these factories? The good news is that there is a cost-effective strategy that can be implemented in many factories that can significantly reduce operating costs and greenhouse gas emissions.
Most supermarket cooling systems can be retrofitted with medium GWP refrigerants such as R407A or R407F. In a carefully planned retrofit plan, switching to one of these refrigerants can have 4 separate benefits:
1) Energy efficiency can be increased by 7% to 12% because the new refrigerant has an efficiency characteristic superior to that of R404A. Some minor design changes may be required (for example, changing the expansion valve), but the cost of this change is small.
2) The new refrigerant’s GWP is less than half that of R404A – therefore, any leaked refrigerant’s greenhouse gas emissions will be immediately reduced.
3) In the “best practice” retrofit program, some components of the old system can be upgraded to reduce the risk of leakage. In many cases, some small investments in valves, fittings, and seals will greatly reduce the historical rate of refrigerant leakage – a 50% reduction in leak rate is a realistic goal.
4) The renovation plan should also include a thorough inspection of all parts and factory re-commissioning. There are many examples of this process that have identified previous problems and led to overall energy savings that are well above the 7% to 12% target.
Combining these advantages can reduce the impact of up to 75 percent of the direct global warming of the old R404A system and reduce indirect power related CO2 emissions by 10% to 15% through further reductions. The reduction in power usage provides very useful cost savings. The investment recovery period for the transformation of a typical supermarket system will be in the range of 3 to 5 years. In addition, major UK supermarket chains are participating in carbon emission reduction commitments to energy efficiency programs, which means that they must purchase carbon dioxide at a price of £12 per ton of carbon dioxide emissions quotas from the use of electricity, making the investment payback period short.
Given the tremendous pressure to reduce CO2 emissions throughout Europe, it is good to find opportunities that will significantly reduce greenhouse gas emissions and add additional profit to the bottom line!
Some end users lack an excellent opportunity for this short-term greenhouse gas reduction. They are focusing on their new equipment strategy, such as using CO 2 on new systems. This is an effective long-term method, but will only slowly, with the effect of replacing old plants. The
Most supermarket refrigeration systems have a lifetime of 15 to 20 years. It is important to have an investment plan that combines the best refrigeration strategies for new and existing plants. This is illustrated graphically in the following diagram. The figure shows three different strategies that can be used by a supermarket company with many stores:
- a) Strategy 1: The company retains R404A equipment in all new and existing systems (this is the “base case” of comparison).
- b) Strategy 2: The company slowly eliminated its R404A equipment within 20 years; As each old R404A plant reached its end of life, it was replaced with a new plant based on very low GWP technology.
- c) Strategy 3: Companies combine short-term and long-term strategies. The existing R404A equipment is converted to R407A or R407F within 4 years. All old plants that reach the end of life are replaced by very low GWP systems.
The figure clearly shows that the early emission reductions for Strategy 3 are much larger than the emission reductions for Strategy 2. The total savings achieved in 20 years is equivalent to the area under each curve – which is also much greater for Strategy 3. Savings are summarized in the table below. In the first 10 years, the double strategy (strategy 3) achieved twice the amount of emission reductions as the strategy to deal only with new plants (strategy 2). Because the energy efficiency is improved when the R404A cooling system is converted to R407A or R407F, these additional emissions reductions are achieved at a lower total cost.
We are in an era of increasing concern about climate change. All European countries are implementing strict policies to reduce greenhouse gas emissions. There are two types of greenhouse gas emissions from cooling plants – from the energy they consume and from the leaking refrigerants. R404A has proven to be a convenient “temporary” refrigerant to help us replace old ozone-depleting refrigerants. But it has a very high global warming potential and is not particularly effective – it is time to stop using R404A in applications where better alternatives exist. The
For new plants, there are many ways to increase efficiency and reduce leakage-related emissions. Large step change improvements can be achieved, especially if the energy efficiency is maximized. The new plant will often run for more than 20 years – so every opportunity is essential to improve cost-effectiveness. R404A should be avoided in all new plants.
For existing plants running on R404A, there are some good opportunities for improvement using medium GWP refrigerants such as R407A or R407F. The total GWP of these refrigerants is less than half that of R404A, which is usually increased by 10% to 15% in a well-managed renovation program. In many cases, this increase in efficiency will provide sufficient energy savings to provide a good payback for the investment needed to convert to new refrigerants, and at the same time reduce greenhouse gas emissions.