11 March 2021
Heat transfer fluids are antifreeze and inhibitor-based and come in concentrated solutions for dilution with water or as ready to use products.
The antifreeze protection of a heat transfer fluid is the first criterion to take into account when choosing a product. Still, it is essential to look beyond this by taking safety and the environmental impacts into consideration. The basis of the fluid has an environmental impact by virtue of the source of the raw material, its production, and not forgetting its biodegradability. It also impacts personal safety, thermodynamic systems, and their implementation (whether they are harmful or harmless).
The formulation bases of heat transfer fluids determine the characteristics and physical properties used to size an installation (viscosity, compatibility, etc.) and its performance (heat exchange, bacteriostatic, etc.). The projects ecological footprint may be reduced by choosing a heat transfer fluid with low viscosity, minimising energy consumption.
Reading material safety data sheets (MSDS)
Reading safety data sheets is not always easy, but it is the first thing you should think about. In particular, you should look at the hazard pictograms and read the physical hazard phrases for health and the environment (H) and precautions (P)
Toxicity and harmfulness of heat transfer fluids
A number of formulation bases are available on the market. Depending on the application (refrigeration, air conditioning, heating, etc.) and the type of industry (food processing, construction, chemistry, etc.), the selection of heat transfer fluid must consider the toxicity of the formula being used. Choosing a heat transfer fluid based on mono ethylene glycol (MEG)which is harmful, will only be possible in applications where there is no risk of contact with food products or substances or sanitary water supply, even accidentally.
To limit the impact on human health, a bittering agent is present in MEG-based heat transfer fluids to avoid any risk of ingestion. In addition, all Climalife heat transfer fluids are nitrate- and amine-free to avoid the formation of harmful compounds such as nitrosamines. Climalife also bans the use of phosphates and borates and all other CMRs (Carcinogenic, mutagenic and reprotoxic agents/substances) in its formulations.
To prevent wear and attack on installation components, the heat transfer fluid selected must contain inhibitors to combat corrosion, limiting the risk of leakage. On the other hand, when diluting a concentrated heat transfer fluid, it is important to use demineralised water not to import contaminants when starting the system.
The operating temperature ranges of the fluid must also be adhered to. Depending on the selected heat transfer fluid base, this may range from -55 °C to +200 °C.
For example, in a solar heating system, the heat transfer fluid circulates in the primary circuit of a heating or hot water system and in solar thermal panels that may be subject to high temperatures, particularly during periods of stagnation when the system is shut down.
The formulation base of bio-sourced 1,3-propanediol of the Greenway® Neo Solar N, which is very stable at high temperatures, causes only a slight deterioration in the circuits and reduces ageing. It prevents the “tarring” of the sensors and circuits and increases the lifespan of the installations. At +150 °C for 150 hours, Greenway® Neo Solar N degrades 3 times slower than a 50% of Mono Propylene Glycol solution.
The formulation of the range of Greenway Neo® heat transfer fluids, present in the market since 2010, has evolved. Greenway® Neo is now National Sanitation Foundation HT1 registered for accidental food contact. It is now called Greenway® Neo N. It maintains the same heat transfer efficiency as the previous formula and, in particular, meets all requirements for food processing applications. This new formula will be available in 2021.
Greenway® Neo N has a viscosity less than that of conventional heat transfer fluids (with MPG base) and can reach temperatures as low as -50 °C, which is not possible with an MPG.
In certain cases, it is possible to reduce the size of piping and pumps, thus reducing system energy consumption.
Focus on food applications
Heat transfer fluids are frequently used to lower temperatures in storage areas, manufacturing processes, and food and drink processing. For consumer safety, it is necessary to select a non-toxic heat transfer fluid in these instances.
It should be noted that there is no such thing as a “food grade” heat transfer fluid or even one of “food-grade quality”. A heat transfer fluid is not a food-grade ingredient. However, there are heat transfer fluids registered by the National Sanitation Foundation (NSF) for accidental contact with foods. NSF HT1 registration does not imply that the contaminated food product can be consumed.
NB: in the event of being in contact with a heat transfer fluid, the contaminated food product must not be placed on the market.
Further details on sanitary hot water applications
There are several techniques for heating sanitary hot water, such as heat exchange with a water loop -from a solar source, which is hotter than the water to be heated.
To limit risks associated with accidental ingestion in the event of leaks to the SHW, Climalife has added a bittering agent to the Greenway® Neo Heat Pump N and Greenway® Neo Solar N.
The formulation bases of Climalife heat transfer fluids
o Bio-sourced 1,3-propanediol
o Mono propylene glycol (MPG)
o Mono ethylene glycol (MEG)
o Potassium acetate and formate
Did you know?
With formulae based on renewable plant-based raw materials, the Greenway® Neo N product range provides environmental consistency.
Plus, the life cycle analysis* shows that its production offers significant environmental advantages: less greenhouse gas emissions (-56%) and less non-renewable energy (-38%) used in production compared with conventional heat transfer fluids based on fossil fuels (petroleum) such as the MPGs.
*The Life Cycle Analysis is an analysis that considers the environmental impact of the product from cradle to grave.