Refrigerants - freon in a heat pump or air conditioner. How do they differ and what heat exchanger to use for them?

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Posted on: 2024-05-02
 

The shift from older refrigerants like R134 or R410A to the new refrigerant R32 in heat pumps and air conditioners. What is R32, its origin, and how does it contrast with older refrigerants like R134 or R410A?

What are another options for coolants in heat pumps or air conditioners?

Additionally, what factors should be considered when selecting a heat exchanger for R32?

Refrigerant R32 - what is it and why are older refrigerants slowly being phased out?

✅ In the refrigeration and heating industry utilizing a wide range of fluorinated gases and similar substances - known as refrigerants such as R404a, R410A, R407c, R134a - there is currently an evolution (some might even say revolution) underway to align with broader environmental trends. The aim is to be more efficient and eco-friendly.

♻️ Continuous improvement of heat pumps, air conditioners, and refrigeration units is sought with a focus on minimizing their environmental impact, such as by replacing older refrigerants with new ones. This is where R32 comes into play - it is expected to have a smaller environmental footprint.

On the other hand, this is partially motivated by natural technological and qualitative development. R32 is said to possess several advantages that give it an edge over other refrigerants - such as the popular R410a or R134a - which will eventually be phased out and potentially administratively banned. Many in the heat pump industry consider R32 to be the best solution currently available.

Why is R32 better for heat pumps or air conditioning?

We'll try to outline this issue to gain a full understanding of why R32 is better for heat pumps and air conditioning units - and what its advantages are over previously used refrigerants such as R134a, R410A, R407C, etc.:

  • ✅ First and foremost, R32 has higher heat absorption, so the efficiency of heat pumps increases by at least a few percent without increasing energy consumption. R32 also transfers heat to the liquid more effectively when flowing through the heat exchanger (condenser) than older refrigerants like R134a, R410A, or R407C.
  • ♻️ It has several ecological advantages - it does not contribute to the enlargement of the ozone hole, which cannot be said about its predecessors.
  • It does not contribute to climate warming to the same extent as older refrigerants (this is, of course, an argument that should be mentioned regardless of whether we believe in human impact on global warming).
  • It is easier to recycle (R32 is a single-component refrigerant, so it degrades more quickly).
☑️ Ultimately, I'm not sure if this can be considered a full-fledged argument because it is a politically mandated decision, but R32 has one very, very important advantage. Namely, other refrigerants may soon become unavailable on the market. Hard do say how about the British market, but in the EU it is already sure. Nonetheless, it is an advantage that it will still be available.

Potential drawbacks of using R32 compared to, for example, R134a

✅ From a user or component selection perspective, the older refrigerant R134a had a certain advantage - namely, it operated at lower pressures compared to similar temperature ranges as R32. The same was true for R407C.

This was significant because achieving high pressures and sudden pressure increases required and still require the selection of a heat exchanger capable of handling high pressure, whether it's for R134a, R410a, or now R32. Such a condenser, if not selected correctly - meaning it is not a heat exchanger certified for use with F-gases - may fail, leading to refrigerant leakage. The phasing out of R134a and R407C will mean that standard plate heat exchangers cannot be used for this purpose because they simply cannot withstand such pressures. Special heat exchangers designed to work as condensers for R32 will be absolutely necessary for this.

Below is a diagram illustrating this:

Refrigerants pressures Nordic Tec Blog

How to select a plate heat exchanger for R32, R134a, or R410a?

✅ Firstly, it should not be just any plate heat exchanger from an online marketplace. We should ensure that it is a high-pressure plate heat exchanger - as mentioned above.

In the Nordic Tec product range, plate heat exchangers for R32, R134a, or R410a are specially marked and include information in the description about the nominal power of the potential air conditioning unit or heat pump - expressed in kilowatts (kW). This is a significant facilitation, and the selection process should not take longer than a few seconds. This power has been calculated for roughly optimal operating parameters - assuming R410a refrigerant and a condensing temperature of approximately 40°C. This can also be applied to R32 or R134a refrigerants or others, as these refrigerants are very similar in this regard.

Selection of a heat exchanger for refrigerant systems with oversizing

✅ It's worth selecting a plate heat exchanger with some margin - i.e., for heat pump units up to 10-12 kW, choose a heat exchanger so that there is a surplus of around 1.5-2 kW. For example, for a 3.5 kW air conditioner, select a 5 kW heat exchanger, and for a 7 kW unit, choose a 9 kW heat exchanger. This guarantees optimal operation even in the case of setting less favorable operating parameters for the unit.

For larger units - more likely heat pumps than air conditioners - in the range of 15-20 kW, it's even worth increasing this margin slightly, to at least 2-3 kW, and for units above 30 kW, even up to 3-4 kW.

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Also, check out the post on soldering basics in air conditioning and heat pump systems - including in the context of heat exchangers for refrigerants and their connection to copper pipes.

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Characteristics of Basic Refrigerants

Below, we'll present basic information about the most commonly used or mentioned refrigerants in equipment descriptions. You can encounter them in heat pumps, air conditioners, but also refrigerators. The first refrigerant, known as Freon-12 with the designation R-12, was invented as early as 1928. However, the development of this industry sector has progressed so far that all original refrigerants have basically been phased out and replaced by newer ones.

☑️ Refrigerant R32

Refrigerant R32, also known as difluoromethane (or CH2F2), is one of the environmentally friendly hydrofluorocarbons used in air conditioning and heat pumps. Attention is drawn to the environmental friendliness of R32 - which has gained favor with legislators and creators of EU directives. Thanks to its lower climate warming potential and single-component structure, R32 is becoming an increasingly preferred choice in modern cooling systems, providing efficiency and minimal environmental impact. R32 is likely the future - as it's hard to deny its greater efficiency.

☑️ Refrigerant R134a

Refrigerant R134a is one of the popular hydrofluorocarbons used as a refrigerant - traditionally in air conditioning, refrigerators, and freezers. It is a colorless, non-toxic, and essentially non-flammable substance - making it safe to use.

R134a has gained popularity as a substitute for more harmful refrigerants such as R12. It is relatively more environmentally friendly, with a lower potential for ozone depletion and a reduced impact on the greenhouse effect.

As a refrigerant, R134a is characterized by good thermodynamic properties, allowing for efficient cooling of spaces and maintaining stable temperatures in refrigerators and freezers. Therefore, in cooling, it appears to be particularly efficient.

☑️ Refrigerant R410a

Once extremely popular, refrigerant R410A is mainly used in air conditioning and heat pumps. It is a mixture of two hydrofluorocarbons: difluoromethane (R32) and pentafluoroethane (R125). R410A gained popularity as a replacement for older refrigerants, such as the notorious and harmful R22.

The main advantage of R410A is its high energy efficiency and refrigeration effectiveness, which even supporters of R32 acknowledge. Cooling and air conditioning systems using R410A can achieve good energy performance, sometimes better than systems using other refrigerants. Its environmental impact is still not excessively severe, considered moderate.

☑️ Refrigerant R290 - Propane

Refrigerant R290 - also known as propane, is an interesting option - it's one of the natural refrigerants used in refrigeration equipment such as refrigerators, freezers, air conditioners, and of course - heat pumps. It's a pure hydrocarbon characterized by a low potential for ozone depletion and minimal contribution to global warming. It can be found in a vast number of HVAC systems on the market.

R290 - propane is gaining popularity as an environmentally friendly alternative to synthetic hydrofluorocarbons, which can be harmful to the environment (according to some). Propane offers fairly good thermodynamic properties and energy efficiency, making it an attractive choice for refrigeration equipment manufacturers. Especially in the context of increasing pressure on ecology.

One of the advantages of R290 is that it is readily available and relatively inexpensive - both in production and processing. Despite some safety challenges, such as its flammability (for sure), propane is widely used in many countries as a refrigerant, particularly in smaller systems, such as small AC units.

☑️ Refrigerant R404A

Refrigerant R404A - a mixture of hydrofluorocarbons, mainly composed of 3 other gases. Still widely used in commercial refrigeration systems such as coolers and freezers, both in supermarkets and food warehouses.

Its thermodynamic properties are considered good - making R404A an effective refrigerant for a wide range of temperatures. It's relatively chemically stable.

However, due to its high global warming potential, R404A is already partially phased out - subject to restrictions and regulations on its use in some countries, especially in new equipment applications. There's speculation that it will eventually be phased out like the infamous R22.

☑️ Refrigerant R22 - the progenitor of today's coolants (phased out)

Refrigerant R22, also known as Freon-22, is now almost an "extinct species," encountered less and less frequently as in 1997, many countries decided to phase it out under the Kyoto Protocol. We describe it as a curiosity. It was a chlorinated hydrofluorocarbon characterized by a very decent cooling efficiency. R22 was widely used in various types of air conditioning systems, refrigerators, freezers, and heat pumps.

However, its use had a negative impact on the ozone layer - so despite dominating the refrigerant market for four decades - it was deemed harmful. As a result of international agreements, R22 was phased out of production and gradually replaced by more environmentally friendly alternatives, such as R410A or R134a. Currently, the use of R22 is limited, and its use is regulated by environmental protection regulations. Interestingly, its successors - R410a and R134a - did not dominate the market for as long. Their time is limited, and they will be replaced by the better R32. This probably indicates how rapidly the industry and technology are developing. However, some skeptics add that the lobby promoting ecological solutions in the industry is also developing rapidly.

 
Posted in: Refrigerants and heat exchangers for gas, Heat pumps and all aspects of their operation

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