Thermera ®
Heat transfer fluid
A natural solution for heat transfer in HVAC systems
Neste Oil Corporation in brief
Thermera
Environment,
health and safety
Physical
properties of Thermera
Comparison
of properties with conventional heat transfer fluids
Density
Kinematic viscosity
Specific heat
Thermal conductivity
Thermera use
Corrosion and additives
Calculation
Thermera’s
areas of application
Neste Oil Corporation in brief
In brief Neste Oil Corporation is a leading independent northern European oil
refining and marketing company. We focus on high-quality traffic fuels and other
high value-added petroleum products with reduced environmental impact. Neste Oil
had net sales of EUR 7,909 million for the year ended December 31, 2004. As of
December 31, 2004, it had 4,271 employees. We have four divisions: Oil Refining,
Components, Oil Retail and Shipping. Our activities cover the production,
refining and marketing of oil, Shipping and Engineering services. Our main
products are gasolines, diesel fuels, aviation fuels, marine fuels, heating
oils, heavy fuel oils, base oils, lubricants, traffic fuel components, solvents,
LPGs and bitumen. Most of the oil products are sold in the domestic market.
Exports of oil products amounted to 5.3 million tonnes, of which gasolines
accounted for 2.7 million tonnes and diesel fuels for 1.8 million tonnes. The
Nordic countries and North America were our largest export markets. Neste Oil´s
Porvoo and Naantali refineries have a combined refining capacity of about 14
million tonnes a year. In 2004, Neste Oil supplied 8,3 million tonnes of
petroleum products to Finland and exported 5,3 million tonnes. Neste Oil has
some 900 Neste service stations, diesel fuel outlets and other sales points in
Finland, and some 180 Neste stations and outlets and diesel fuel outlets in the
Baltic states, Russia and Poland. In 2004, retail sales of main oil products
totalled 4,000 thousand cubic meters. Neste Oil´s fleet comprises about 30
tankers plus tug boats and barges. SeverTEK, a joint venture equally owned by
Fortum and Lukoil, commenced oil production in the South Shapkino oil field in
north-west Russia in July 2003. In 2004, the average oil production of SeverTEK
totalled approximately 27,500 barrels per day (approx. 1,4 million tonnes per
year), of which Fortum´s share was 50 %
Thermera
Thermera, a new heat transfer fluid with extremely low environmental impact,
was developed and tested in co-operation with end users and raw material
manufacturers. The main raw materials of Thermera are betaine, a by-product of
the sugar manufacturing process, and water. Betaine is a natural product, which
makes Thermera a product with an extremely low impact on the environment. As
Thermera is non-toxic and environmentally acceptable, it is suitable for a wide
range of applications. Thermera is designed for use in closed circuits operating
within the fluid temperature range of –45 °C - +110 °C. Thermera fluid is
excellent for the needs of HVAC systems in buildings and industry. This product
is always delivered as a ready-to-use solution. New uses can be found,
particularly in areas in which health factors, in addition to environmental
aspects, are important. In the proper areas of application Thermera’s thermal
performance is at least equal to that of conventional heat transfer fluids.
Compared with conventional fluids, Thermera offers the additional advantages of
excellent cold-flow and anti-corrosive features.
What is Thermera
History of product development
The development work of the new heat transfer fluid was market-oriented. New
systems are vulnerable to propylene glycol’s poor flow and heat transfer
features under cold circumstances. In many cases ethylene glycol cannot be used,
because of its toxicity, and salt solutions often cause difficult corrosion
problems. We aimed at developing a heat transfer fluid with a wide operating
temperature range, good corrosion properties, less toxicity than ethylene
glycol, and better heat transfer characteristics than propylene glycol. The
research and development work resulted in Thermera. Thermera was tested at
laboratories and application sites during the period 1995-2000, and the product
was launched on the Finnish market in autumn 2000. The other nordic countries
and Germany and the Benelux saw Thermera launch in 2002.
Thermera®
Thermera is a new environmentally acceptable heat transfer fluid, which is
excellent for building HVAC systems, food and refrigeration technologies, and
for industrial heat transfer needs. Thermera is a mixture of ion-exchanged water
and betaine, completed with non-toxic additives. Betaine, or trimethylglycine,
is a natural product, which is a by-product of the sugar manufacturing process.
The natural raw material makes the end product environmentally very acceptable.
Betaine is used in several products of the food, pharmaceutical and cosmetics
industries. As a chemical, it has been known for decades. Thermera’s thermal
performance has been proved to be of the same class as that of the conventional
heat transfer fluids. Thermera offers the advantages of non-toxicity, water
solubility, and excellent cold-flow and anti-corrosive features.
Thermera and environmental features
Thermera has top-quality environmental features, which provide it with a wide
operating range. The first areas in which Thermera’s technical suitability has
been proved are various HVAC building systems, and food and refrigeration
technologies. Other suitable objects of use are being developed.
Thermera and the operating range See item 4. Uses of Thermera.
Environment,
health and safety
Betaine
Betaine is one of the main raw materials of Thermera, in addition to water.
Betaine, or trimethylglycine, is an amino acid, and it occurs in all living
organisms. It is also used as an additive in foodstuffs, medicines, cosmetics,
and animal feeds. Betaine as a chemical is well known and there is a lot of
literature on this subject. Betaine used in Thermera is acquired from sugar
beet.
Biodegradation of betaine
In general a substance is defined as easily biodegradable, if the
mineralization degree after 28 days exceeds 60%. In the case of betaine, this
value exceeds 88%, so it can be called highly biodegradable.
Stability of betaine
Betaine is very stable, both in view of temperature and microbiology. Betaine
endures a continuous temperature of more than 110 °C. Betaine prevents the
growth of micro-organisms, when the betaine content of a fluid is over 20 w-%.
Solubility of betaine Betaine is completely water-soluble. This means a
completely homogeneous aqueous solution under all circumstances. For comparison,
glycols just mix with water (water and glycol may later separate in a solution).
Non-toxicity of Thermera
Betaine, the main raw material, is an absolutely non-toxic natural product,
which is verified as a material suitable for several drugs by the United States
FDA (Food and Drug Administration). Such small amounts of additives have been
used in Thermera as to keep the end product non-toxic. (Cf. VTT Technical
Research Centre of Finland’s statement).
Combustibility of Thermera
Thermera is not a combustible fluid. See also the safety data sheet.
Destructibility of Thermera
Thermera can be disposed from the HVAC systems directly to the sewer system.
However, the correct procedure shall always be checked with the local sewage
treatment plant. Betaine does not cause any risk to a biological purification
plant.
Storage and transportation of Thermera
Because of Thermera’s non-toxicity, no official licences are needed for the
storage and transportation of Thermera (Cf. Safety data sheet). Thermera should
be stored protected from direct sunlight. Thermera should always be stored in a
sealed container, to avoid evaporation of water from the product. Betaine which
has possibly crystallized on the container edge (white deposit or powder) can be
easily dissolved back to the solution by shaking the container.
Physical
properties of Thermera
Operating temperature ranges
Thermera products can be used within a very extensive operating temperature
range. Freezing point is used as a basis for product classification. Standard
products
The standard Thermera products are:
Thermera -15
Thermera -35
Some other possible customized products:
Thermera -10
Thermera -20
Thermera -25
Thermera -30
Thermera -40
The figure in the product name indicates the freezing point of the product in
question, i.e. the recommended lowest continuous operating temperature of the
fluid. In addition to the above standard products, Thermera can be delivered, in
order to optimise large systems, with any frost resistance specified by the
user, down to -50°C. The continuous maximum operating temperature for all
Thermera products is +110°C. In temperatures exceeding this point, betaine
begins to degrade slowly, and in temperatures exceeding 150°C the degradation
is quick. The degradation products of betaine are not corrosive or otherwise
harmful to people or the environment.
Freezing point
The method used for determination: ASTM D 2386-97
Freezing point is the temperature below which solid crystals may build up in
a solution. To determine the freezing point, a solution is cooled down while
stirring, until crystals appear. After the first crystals have built up, the
solution is left to warm up slowly while stirring. The temperature in which all
the crystals have disappeared is the freezing point of the solution. It is most
common that the freezing point value is given for heat transfer fluids according
to this method. At the freezing point, and at least 4 degrees centigrade below
this point, the product is still completely reliable. This means that Thermera
-20, for instance, can be used in a continuous temperature of -20°C, and for
short periods of time it endures even about -24°C.
Congealing point (or solidifying point)
The method used for determination: ASTM D 1177-65
Congealing point is another term frequently used for cold endurance.
Congealing point is determined in the same way as freezing point, but cooling is
continued as long as the sample has undergone so-called thickening, i.e. the
viscosity has increased so much that the solution cannot be pumped any longer.
So congealing point is the temperature in which the product does not work any
longer. For low-concentration solutions, Thermera products’ congealing point
is about 4 degrees lower than the freezing point, and for high-concentration
solutions it is about 10 degrees lower.
Frost resistance measurements of Thermera products
In addition to the manufacturer’s own laboratories, the VTT Technical
Research Centre of Finland has also measured the Thermera products. VTT is an
impartial research organisation of 3,000 employees, which produces a wide range
of technology and research services for both Finnish and international customers,
companies and the public sector.
Comparison
of properties with conventional heat transfer fluids
Thermera use
System
Thermera is a completely dissolved solution of water and betaine. It is
intended mainly for closed systems and circuits. In an open system, part of
Thermera’s water content might evaporate and the concentration of the fluid
change. In an open circuit, oxygen also dissolves in the solution, and corrosion
prevention becomes more difficult, as with all heat transfer fluids. So
technically Thermera can be used in open systems as well, but careful condition
monitoring is essential. General instruction for the choice of materials: system
components are selected in the same way as in the use of glycols. General
instruction for the dimensioning of the components and heat transfer:
dimensioning is done specifically for each system using Thermera’s physical
properties (cf. also the appended CDROM). It is usually observed that in heat
recovery, and heat pump applications, the replacement of ethylene glycol with a
Thermera product with corresponding freezing point does not lower the efficiency
of the system.
Temperature range
The highest operating temperature recommended for Thermera products is
110°C. This is the temperature above which betaine is no longer completely
stable; a certain amount of degradation may occur. In practice the temperatures
of building systems are below 50°C. If Thermera is used in higher temperatures,
the seller’s expert should be consulted. The name of the Thermera product
refers to the lowest operating temperature. Consequently the lowest operating
temperature of Thermera -20 is -20°C. It is highly important to note that the
lowest operating temperature refers to such temperature of Thermera fluid in
which the fluid starts to crystallize and viscosity starts to increase to a
great extent. So in normal operation the lowest operating temperature does not
refer to the outdoor temperature. If a Thermera fluid is kept for a long time in
a temperature which is much lower than its lowest operating temperature
(Thermera -10 is used in the temperature of -20°C, for instance), the fluid
crystallises heavily. This can be seen as similar partial phase transition as in
conventional glycols; Thermera fluid turns into snow-like mass. However, only
minor thermal expansion will occur, so pipe burst protection reaches
considerably beyond the lowest operating temperature. Extreme-temperature tests
have shown that use of the Thermera product has caused no damage to pipes or
heat exchangers.
Materials
Thermera is completely compatible with all the used pipe and equipment
materials. We have test results and operating experiences of copper, carbon
steel, brass, solder, cast iron, and stainless steel. All the used elastomers
and sealants have also been tested to be compatible with Thermera products. A
universally applicable rule is that the system shall be implemented in the same
way as in glycol use. So the sealants shall be chosen to be glycolresistant.
Consequently, Thermera products are directly compatible to replace glycols in
existing systems.
Deaerators
Spindle-operated, automatic deaerators are not
recommended. A moving spindle is a potential leakage point.
Filters
If the
system includes filters, they should be cleanable.
Pumps
All the general pumps
made for heat transfer fluids are suitable for Thermera, if they are equipped
with so-called glycol-resistant seals. (for example Grundfos R) Valves Ball
valves are recommended.
Connections
Welded and flanged joints are recommended.
Seals should be glycol-resistant.
Filling and changing a heat transfer fluid
Generally the equipment manufacturer’s instructions are followed.
Cleanliness
of the system shall be checked before the system is filled with the fluid.
Effective flushing with water and careful draining are sufficient. Thermera
products are always ready-to-use, so no water or other materials are added when
filling a system. It is recommendable to make a note of the product used in the
system and reserve a full canister of corresponding Thermera product in the
vicinity of the system. This guarantees that the system’s fluid concentration
and protection against freezing does not change with later fill-ups. The system
should be filled through the lowest filling valve, thus taking full advantage of
the deaeration system. The installation personnel should know the theoretical
volume of the system. If the input amount of fluid is much smaller than the
theoretical volume, this may be an indication of an air lock, for instance.
After the test run of the system, please check the volume of heat transfer fluid.
If there has been air in the system, it may be necessary to add fluid. If the
condition of the fluid is intended to be monitored during operation, the first
sample should be taken in this phase, and later operation-time measurements
should be compared to this sample. When filling an old system with Thermera
fluid, it should be carefully drained and flushed. The earlier used fluid, which
may be toxic, shall also be disposed of in an environmentally acceptable and
legal way.
Condition monitoring
Thermera has operated well up to expectations
and maintained its condition at all sites. If you want to monitor the
conservation of Thermera’s condition, you can take a sample every second year,
for example, and compare this sample with the first sample. Usually the freeze
protection properties, pH and condition of the additives are measured. The
condition monitoring of the system also covers monitoring of possible leaks. If
Thermera seeps through the system, there will be small white flakes at the
leaking point, as water evaporates from the fluid, leaving harmless betaine
crystals. This makes a leaking point easily detectable. The flakes are
completely non-toxic and they can be wiped from all the surfaces with a wet
towel. If it will be necessary to fill the system, simply add the correct
Thermera product. Filling shall be done from a container, which has been closed
during storage.
Operating characteristics
Temperature stability.
Research results indicate that Thermera products are highly stable up to a
temperature of 110 °C, and no degradation has been detected in the tests.
Microbiological stability.
The research results indicate that Thermera products are highly stable. No
fungal, yeast or bacterial growth has been found. The research and practical
experiences have shown that betaine, the raw material of Thermera, prevents
microbial growth in fluid concentrations of over 20 w-% of betaine.
Foaming.
Thermera does not foam in normal applications.
Operating life.
As Thermera has a good thermal and microbiological stability and it contains
only a very small amount of inhibitors, its operating life is most often longer
than that of the conventional heat transfer fluids. The exact operating life
always depends on the specific system, and no exact life span can be given.
Disposal.
As Thermera is a completely non-toxic and environmentally acceptable natural
product, it can be disposed of with normal sewage water. In case of major
volumes, the local sewage treatment plant or the municipality should be
consulted for detailed instructions.
Storage
Thermera should be stored in a closed and air-sealed container. This
guarantees that no water will evaporate into the air and Thermera heat transfer
fluid will remain in top condition. A container possibly located under the
filling pump shall also be hermetically closed. A stored product shall be
protected against direct sunlight.
Corrosion and additives
Corrosion, or rusting, is a well-known chemical effect. Corrosion refers to a
phenomenon, in which a metal or an alloy is partly oxidized as a result of air
or other gases and solutions. Corrosion may be wet (effect of a solution) or dry
(effect of dry gases). Dry corrosion is less frequent and it occurs in special
circumstances, as a metal surface which is in contact with air is always in
contact with moisture as well.
Corrosion is classified into two categories:
chemical corrosion and electrochemical corrosion
In electrochemical corrosion, two metals form an electric couple. In this
reaction, the metal which is more electronegative corrodes. In chemical
corrosion, a metal reacts with oxygen in the air or an acid solution. This can
be avoided by using corrosion inhibitors. An inhibitor forms a protective
coating on the metal surface. However, there will be problems if a lot of
inhibitors are required. They decompose and lose their effect as a result of
heat, flow and pressure. This is how corrosion starts to take affect, although
the heat transfer fluid would not otherwise have lost its properties. Another
corrosion effect which is typical of heat transfer fluids is the impact of
organic acids. It is possible that acid is formed in heat transfer fluids
following a chemical reaction, and this acid results in corrosion in the
structural material. This is particularly typical of glycols.
Thermera and corrosion
Consequently, corrosion refers to material wear and thinning as a result of
an electrochemical effect. This thinning rate is described with the term
corrosion rate, and the unit used is micrometer per year, µm/a. The corrosion
rate can be measured by measuring the electric current of corrosion, or directly
the thinning of the raw material. To improve reliability, both of these
quantities are often measured, as was done with Thermera in the product
development stage.
Additives
With Thermera, the need of additives is considerably smaller than with
conventional products. So there is no major concern about the durability or
toxicity of additives as long as Thermera is used. Neither does betaine, the
main raw material, form any corrosive disintegration products, unlike
conventional products. Even a Thermera product without any additives has better
anti-corrosive features than water. So betaine is a natural corrosion preventing
agent. Thermera is slightly scented with an odorant used in the food industry
(< 1w-%). Because of its good anti-corrosion features, only a minor amount of
corrosion inhibitors have been added to Thermera (< 1w-%, active ingredients
total less than 0,1 w-% in the end product). The additives used do not have any
effect on Thermera’s toxicity. (Cf. VTT Technical Research Centre of Finland’s
statement). As Thermera is always a ready-to-use product, each Thermera product
has always the correct additives, despite varying betaine concentrations. For
example: the corrosion protection of Thermera –10 corresponds thus completely
with that of Thermera –40.
Calculation
Thermera’s
areas of application
The development of Thermera was initiated on the basis of the end users’
need to replace conventional glycols with a more environmentally benign option
with no compromises over the most important characteristics in view of the use.
So the general principle can be considered to be that Thermera can be used
everywhere where ethylene and propylene glycols are used today. Thermera is
excellent for buildings’ HVAC systems: it can be used for cooling in air
conditioning systems and for heat recovery in office buildings, shopping centres
and industrial buildings. Thermera is also suitable for geothermal heat pumps.
Heated pedestrian streets, which are becoming common in urban areas in the north,
are another significant use for Thermera. Thanks to Thermera’s environmental
acceptability and non-toxicity, it can be used in systems in which ethylene
glycol is not acceptable. Thermera is an excellent heat transfer fluid for the
food industry, for instance. Thermera is used as heat transfer fluid in the
secondary circuit in refrigeration systems. In several applications, Thermera
competes successfully with salt solutions. However, extremely cold circumstances,
i.e. continuous operation under –25 °C, are not the best operating areas for
Thermera.
