|Title of Invention||
METHOD OF COOLING ENGINE APPLICATIONS
|Abstract||The invention relates to a method for cooling an engine having a cooling system. which comprises introducing into the cooling system a coolant fluid which comprises an aqueous solution of trimethyl glycine anhydrate or monohydrate and 2-6% by weight of additives wherein the engine is selected from engines used in automobiles, trucks. motorcycles. aircrafts. trains, tractors, generators, compressors, and from stationary engines and equipment, marine engines, power systems, industrial engines, electric engines, fuel cell engines and hybrid engines.|
|Full Text||A METHOD OF COOLING ENGINE APPLICATIONS
Field of invention
The present invention relates to a coolant and/or protective composition for use in engine
applications, and in particular a water-based coolant fluid containing trimethyi ghcinc for engine
applications, such as engines commonly used in automobiles, trucks, motorcycles, aircratls. trains,
tractors, generators, compressors, for various stationary engine and equipment applications, marine
engine applications and the like wherein cooling systems are used. This invention also relates to a
method of cooling and/or protecting engine applications with said coolant.
Backg:round of Invention
The primary role of a coolant fluid is to remo\e heat and thus cool the engine. The fluid operates in a
closed loop system. To pro\ide efficient cooling the fluid must have a high specific heat and thermal
conductivit>' and low viscosity^ at operating temperatures which generally may \ar> in the range of
-40°C - + 120°C. lypically internal combustion engines operate at approximatcK + 95"C\ The fluid
must keep the engine operational also at subfreezing temperatures and provide maximum freeze
Normal pressure boiling point elevation is also a beneficial propert\- of the fluid in engine coolant
applications. Hnabling the coolant to remove more heat can be achieved by increasing the s\stem
pressure and thus boiling point of the coolant which allows the coolant to circulate at a higher
Another important propert\' of coolants is the corrosion protection they pro\'ide. Automotive heal
exchangers and their construction are well known in the art. They contain eiastomeric materials,
rigid polymeric materials and multiple metals including aluminium, aluminium allo\s. steel, cast
iron, brass, solder and copper, all of which may with time be dissohed in the working coolant
composition within a cooling system by physical abrasion and chemical action. Automotixc
manufacturers have tried to reduce car weight to improve fuel efficiency Ijy in-
creasing the use of aluminium in engines.
During operation of the heat transfer system many factors, particularly elevated
temperatures and contaminants may accelerate con'osion and because corrosion is
an oxidative process the most critical factor is the amoimt of oxygen tn the sys-
tem. In glycol systems oxygen accelerates the oxidative degradation of the glycol
to forai corrosive acids. For light-duty automotive applications where the engme
operates inteimittently, the corrosion inhibitors must protect the system during
operation and while idle. Film-fonning silicates are widely used foi corrosion
protection of heat-emitting aluminium surfaces but Ihey have the disadvantage of
reducing the heat-transfer efficiency of the coolant, and they react witli time with
the glycol and any salts to fomi gels which may cause engine failure.
Cavitation corrosion is a phenomenon which relates particularly to modem thui-
wallcd automotive engines containing aluminium, particularly to aluminium cyl-
inder liners and water-pumps which are exposed constantly to aqueous systems
such as internal combustion engine coolants. Pitting of aluminium surfaces can be
detected and further, corrosion products and deposits can interfere wiili heat trans-
fer. Overheating and engine failure from thennal related stress are possible
Commercially available engine coolants are generally mixtures of vaiious chi'ini-
cal components and an alcohol, the prefeiTcd alcohols being selected ironi Jie
group consisting of ethylene glycol, diethylene glycol, propylene glycol, dipio-
pylene gl>'col and mixtures thereof. Usually coolants contain mainly ethylene uly-
col because of foaming tendency of other alcohols, and other components om-
j^nsc water and additional chemical compound which provide coiTosion proiec-
tion. Said glycols bring about coiTosion problems, produce unpleasant odour ;iiid
diev are rather toxic and thev must be treated as hazardous v/aste.
Engine coolants containing inorganic components like silicates, phosphates, ni-
trates, borates and nitrites have problems due to inhibition depletion. The deple-
tion of these components, particularly the silicates have led to concerns about life-
time. High solids loading from inorganic salts presents potential deposit issues.
The precipitating solids may scale and plug passages within the engine coolant
Engine coolants based primarily on carboxylic acid technolog\' have been devel-
oped. A combination of a monobasic or a dibasic carboxylic acid and a tiiazole
are used in combination with odier optional additives. Triazoles are requiied usu-
ally for the protection of yellow metals such as copper, brass and solder
Several methods have been proposed for improving propenics of engine coolants.
A combination of water soluble phosphate with tungstate, selenate and molybdatc
for the proiection against cavitation coirosion of aluminiuni is proposed in patent
US 4,404,116 teaches tlie use of polyhydric alcohols as corrosion inhibiting and
cavitation reducing additives for coolants.
US 4.440, ".11 discloses the combination of a water-soluble phosphate witii a w.i-
tcr-soluhle molybdatc, tungstate and selenate for providing a protective efi'cci
against the cavitation corrosion of aluminium in aqueous liquids.
WO 00/50532 proposes a monocarboxylic acid based anliA-ee/e composition lor
ciesel engines. Said fommlatiou comprises a combination of a mixture of ethylene
or propylene glycol, a monobasic aliphatic organic acid, azoles, low levels of mo-
lybdates, a combination of nitrite and/or nitrate salts, polyvinylpynolidonc, a liy-
(iroxide .salt, silicates and/or siloxane stabilized silicates with transition metal
compounds which provide a protective effect against the cavitation corrosion or'
aluminium in aqueous liquids.
wo 97/3198S discloses a non-toxic heat transfer/cooling fluid containing tn-
methyl glycine and water for solar panels, refiigeration equipment, ventilation and
air-conditioning equipment and heat pumps.
It can be seen that the prevention of cavitation corrosion, particularly of aiumiii-
iiun in engine applications is a difficult task. Efforts have been made in the state
of art to solve the problem by the use of alkylene glycol based fonnulations and
dicarboxylic acid based fonnulations with heavy loads of additives. Said fonnula-
tions result often in high solid contents, they are expensive and cause environ-
mental problems when disciu-ded. Based on the above it can be seen that there
exists a need for a stable, non-toxic, water-based, non-glycol containing coolant
Quid for engine applications with superior coiTOsion protection and particularly
improved inlribition of cavitation corrosion of aluminium.
Object of the inventiou
An object of the mvention is to provide a water-based efficient, stable, envii'on
menially acceptable non-toxic coolant fluid for engine applications v,iih improved
cavitation conosion prevention properties.
A further object of the invention is the use of a water-based tn methyl dycine cdh-
taining fluid as a coolant for engine applications.
The characteristic features of the coolant fluid and its use are pro /ided in ihe
Summary of the invention
It has been discovered that an aqueous solution containing trimethyl gl\'cme, also
known as betaine, or salts or derivatives thereof, may be used as a coolant fluid m
various engine applications, such as engines commonly used in automobiles,
tiiicks, motorcycles, aircrafts, trains, tractors, generators, compressors, m station-
ary engine and equipment applications, in marine engine applications, in power
systems, in industrial engines, in electric engines, in fuel cell engines and m hy-
bride engines and the like wherein cooling systems are used, and particularly ui
internal combustion engmes in automobiles.
Detailed description of the invention
The coolant fluid according to the invention containing trimethyl glycine oi- sails
or derivatives thereof may suitably be used at temperaturps ranging betw een - 40
+ 120"C. According to the invention, said water based coolant fluid ¦:ompnses
trimethyl glycine as an anhydrate or monohydrate, or salts of trimethyl glycine
such as hydrochloride, or derivatives of trimethyl glycine such as dimethyl glv-
cine, or mixmres thereof. Trimethyl glycine monohydrate is the preferable com-
pound. Trimethyl glycine, or betaine, may for instance be produced syiitheticallv
or by extracting from natural sources like sugar beets, thus enabling the produc-
tion of the water-based coolant fluid of biological origin having a favo.irable lite
According lo the invention, the coolant fluid usefiil in engine iipplicaiions coui-
pnses I to 60 % by weight, preferably 20 to 55 % by weight of trimethyl glycme
as an anhydrate or monohydrate, or salts or derivatives of tnniethyl ilycine ov
mixtures thereof, and 40 to 99 % by weight, preferably 45 to SO % by weight I'f
water. The water used in said coolant fluid compositions is suitably ion exchanged
water or tap water of drinking water quality, preferably ion e.xchanged \vatcr
The coolani according to the invention perfomis well even witliout any additive-,
which can he seen fi"om tlie examples, but in cases where there are .-pecial re-
quirements for engine coolant fluids, additives known in the art cai; be useo
However, tlie amount of additives required is significantly below the amounts
used in the coolants according to the state of the art.
Additives are selected taking into accoimt the intended object of use of tlae coolant
and the compatibility of the chemical compounds. Additives, such as stabilizers,
corrosion iiiliibitors, agents for adjusting the viscosity, surface tension and pH,
common in water based engine coolants, may if desired be added to the coolant
fluid. Especially, compounds not harmful to the environment are used. Examples
of commonly used additive/inliibitor mixtiu^es are XLI and AFB from company
Chevron Texaco and additive/inhibitor mixture BAYinBIT from company Bayer,
Some suitable additives are presented in the following.
Antiabrasion agents reduce abrasion of metal components. Examples of conven-
tional antiabrasion agents are zinc dialkyl thiophosphate and zinc diaryl dithio-
phosphate. Typical antiabrasion agents also include metal or amine salts of or-
ganic sulphur, phosphorus or boron derivatives, or of carboxylic acids. .As exam-
ples, salts of aliphatic or aromatic Ci - C22 -carboxylic acids, salts of sulphur-
ous/sulphuric acids such as aromatic sulphonic acids, phosphorous, irosphoi :c
acids, acid phosphate esters and analogous sulphurous/sulphuric compounds, e,^^,
thiophosphoric and dithiophosphoric acids, maybe mentioned.
Corrosion inhibitors, also laiown as anticorrosion agents, reduce the desuiiction ol
metal components in contact with the coolant fluid. Examples of con¦o,'^io[l niliib', ¦
tors include phosphosulphurated hydrocarbons and products obtained hy reactuij
a phosphosulphurated hydrocarbon with an alkaline earth metal oxide ,3r hydrcN.-
ide. Fiu'ther, agents preventing metals ixom coiTodjng may also include organic ..ir
inorganic compounds such as metal nitrites, hydroxyl amines, neutralized :aiiy
acid carboxylates, phosphates, sarcosines and succimmides, etc, .-Vmines .such .is
alkanol ammes, e.g. ethanol amine, diethanol amine and trietlianol amine are suit-
able. Aromatic triazoles may be mentioned as examples of coiTosion ir-hibitor.s of
non-iron metal type.
A surface active agent, either non-ionic, cationic, anionic or amphoteric one, may
be incorporated into the composition. Examples of suitable surface active agents
include linear alcohol alkoxylates, nonyl phenol ethoxylates, fatty acid soaps,
aiiiine oxides, etc.
Aiitifoam agents may be used to control foaming. Foaming may be controlled
with high molecular weight dimethyl siloxanes and polyethers. Silicone oil and
polydimethyl siioxane are some examples of antifoam agents of polysiloxane
Detergents and antimst agents for metals include metal salts of sulphonic acids,
alkyl phenols, sulphurized alkyl phenols, alkyl salisylaces, naphtenates and otliei
oil soluble mono- and dicarboxylic acids. Very basic metal salts like \ei'y basiv
alkaline carfh metal sulphonates (particularly Ca and Mg salts) are often used a.s
As examples of suitable viscosity controlling agents, all kinds of agent.s known i;i
the field for this purpose like polyisobutylene, copol>Tners of ethylene and p\pylene, polyTO.etacrylates, metacrylaie copolymers, copolymers of uusaiuraieii
dicarboxylic acid and a vinyl compound, inteipolymers of styrene and :icryac cb-
ters, and partly hydvogenated styrenc/isopropylene, st\Tene/hutadieiic ami isi
prene/butadiene copolymers as well as partly hydrogenatcd homopolynisrs if bi
tadiene and isoprcne, respectively, may be mentioned.
.'Vntioxidants include alkaline earth metal salts of alkyl phenol rhioestcis pieferc;-
bly having C',- - C..2 -allcyl side chains, e.g. calcium nonyl phenol sulphide, bai
ium octyl phenyl sulphide, dioctyl plienyl amine, phenyl alphanaphiyl ainnn..
phosphosuiphurized or sulphurized h^'drocar-bons, etc.
Frictional properties of the coolant fluid may be controlled by means of agents for
adjusting friction. Examples of suitable agents for adjusting friction include fatty
acid esters and amides, molybdenum complexes of polyisobutenyl succmic anliy-
dride amino allcanols, glycerol esters of dimerized fatty acids, alkane pnosphonjc
acid salts, phosphonate combined with oleamide, S-carboxy alkylene hydrocai-
byle succinimide, N-(hydroxyalk:5d)-alkenyl succinamic acids or succinimides, di-
(lower alkyl) phosphites and epoksides, as well as alkylene oxide addition prod-
ucts of phosphosulphurated N-(hydroxyalkyl) alkenyl succinimides.
Suspension of msoluble matter present in the coolant fluid during use is assured
with dispersing agents, thus preventing the slurry from flocculating and precipitni-
ing or depositing on metal parts.
Mineral oils act as swelling agents for scaling means, and accordingly. th£y ha\ e
a swelling effect on the sealing means of the equipment. They include aliphatic l s
- Ci3 alcohols such as the tridecyl alcohol.
The coolant fluid may also contain other additional components such a;, agents lov
extreme boundary lubrication, additives resisting high pressures, dyes pei :umcs.
antimicrobial agents and similar agents familiar to those skilled in the a:;t.
I'he coolant fluid according to the invention has several ad\'antages. ft pievciiis
cavitation con'osion surprisingly well also on aluminium surfaces, the foamini'. >>!
the coolant is insignificant and the coolant is chemically and thermally ver> stable
which results in that there is no need to replace it frequently. The possible degra-
daiion products of trimethyl glycine, if any, are not corroding compounds. On 'iic
contrar}', glycol based coolants are usually changed every two to five _\eal¦^ and i)<:> inhibitors are added because glycol degrades and the degiMJation products ,i.'e
coiTosive compoiuids. The coolant fluid according to the invention \i non-toac
and as such it may not require hazai'dous waste treatment when discarded.
Table I below compai-es the toxicity of triraethyl glycine with that of ethylene
glycol and propylene glycol based on LD50 values found in the literature. The
LD50 values used are tested orally in rats.
Much less additives are needed if any, when compared with conventional coolaiu
fluids. Further, additives compatible with trimethyl glycine but incompatible wiih
glycol based coolants, can be used in the coolant fluid according to the invention
Tabic Ila shows the effect of a fluid containing 50 % trimethyl glycine on the cor-
rosion of various metals detennined as thinning thereof at 40 'C or belo'v:
Higher values show the coiTOsion rate at the beginning of die tests, lower values
represent the situation stabilized with time.
Table lib shows the effect of a fluid containing 35 % trimethyl glycine on the cor-
rosion of metals. Tap water and MEG 30% (ethylene glycol) and MPG 30 %
(propylene glycol) were used as reference materials. Corrosion tests were earned
out according to the test ASTM 1384 at the temperature of 50 'C in a closed con-
tainer of 500 ml.
* = with commercial coiTosion inhibitor
Table UI below shows the effect of trimethyl glycine on fi-eezing poinis ot aquc
llie pH of the coolant fluid keq>s always above 7 as trimcthyl glycine itself is a
buffering substance. Witliout any pH-adj listing additives ihe pH of the coolant
typically ranges between 8 and 10, with additives it may range between S - 11.
The lubrication properties of the coolant fluid ais significantly better than those of
corresponding glycol based coolants. Further, tl\e boiling point of the coolant fluid
under normal pressure is well above 100°C, for example of a 50 % thir.ethyl gly-
cine solution it is 10? - 112 °C. Tlie coolant fluid also has excellent .'tnti-free/e
The L-ooIam fluid gives very good results in glasswai-e corrosion test, hot plaie
corrosion test and simulated corrosion test. The pH and reserve alkalinity keep in
acceptable ranges and the coolant meets foaming requirements, particl.-; counting;
requirenienis (class 11) and elastomer compatibility requirements. The cavitation
coiTosioii lest (Double chamber test) gives very good results with c.-u>t iron anil
The coolant tluid according to the invention can be used in vanous en.^ine uppli-
catious. such as engines commonly used in automobiles, inicks, moton yclcs, air -
craits, trains, tractors, generators, compressors, in stationary engine :iiid equip-
ment applications, in marine engine applications, in power systems, ir. industrial
engines, in electric engines, in fiiel cell engines and in hybride engines and ihc
like wherein cooling systems are used, and particularly in internal combustion
engines in automobiles and in engines and water pumps with sensitive ;duminium
components. The coolant fluid is also particularly suitable for protection of
equipmenL'engines under storage and warehousing.
The invention is illusti-ated in the following with examples. However, the scope
of the invention is not limited to these examples.
LUBRICATION PROPERTIES according to ISO 12156-1
Lubrication properties of aqueous solutions containing 40 wt-% and 50 \\\.-% dt
triraeihyl glycine with commercial conventional inhibitor for engine:: coolants
were comptu-ed with conmiercial engine coolant products containing propylene
glycol and ethylene glycol using HFFR Lubrication test ISO 12156-1 at 25 '(
The lower numerical value coixesponds to better lubrication properties.
DOUBLE CHAMBER CAVITATION CORROSION TEST according to
40 wt-% trimethyl glycine + 3 wt-% commercial inhibitor (Chevron Texaco)
HIGH TEMPERATURE STAEILITY TEST OF ENGINE COOLANTS ac-
cording to CEC C-21-T-00
40 wt-% irimetliyl glycine + 3 wt-% commercial inliibitor (Che-vTon Texaco)
KINEMATIC VISCOSITY accoi ding to ASTM D 445
40 wt-% trimethyl glycine + 3 wt-% commercial inliibitor (Chevron Te.vacoi
OXIDATION STABILITY TEST according to ASTM D 943
40 wt-% trimethyl glycine + 3 wt-% commercial inliibitor (Chevron Texaco)
- 300 ml oil;
- 95"C ± 0.2 °C;
- 3 1O2/h±0.1 1/h;
1. A method lor cooling an engine iiaving a cooling system, which comprises
introducing into the cooling system a coolant fluid which comprises an aqueous
solution ol irimeth\l glycine anhydrale or monohydrate. and 2-6 % by weight ol
2. The method as claimed in claim 1 wherein the engine is selected from engines
used in automobiles, trucks, motorcycles, aircrafts. trains, tractors, generators
compressors, and tVom stationary engines and equipment, marine engines, powei
systems, industrial engines, electric engines, iiiel cell engines and h\brid englne^
3. i he method as claimed in claim 1 or 2. wherein the engine is an internai
combustion engine used in automobiles.
4. 1 he method as claimed in claim 1. wherein the engine is selected trom an
engine having a water pump with aluminum components.
5. The method as claimed in claim 1. wherein the coolant tluid comprises ,=, -.
aqueous solution of 1 to 60 % by weight of trimethyl glycine as an anh\diate or
6. 1 he meiliod as claimed in claim 1. wherein the coolant tluid comiirises 20 in
45 % b\ weight of trimethyl glycine as an anhydrate or monoh>drate.
T'. I he method as claimed in claim 1. wherein the additives are selected from the
group consisting of stabilizers, corrosion inhibitor.s. agents for adjusting jill.
antiabrasion agents, surface actise agents, antifoam agents. \ iscosit> controlling
agents, antio.xidants. agents for adjusting friction, dispersing agents, swelling agellt^.
agents foi' extreme boundaiy lubrication, additixes resisting high pressure--.. iKcn.
perfumes and antimicrobial agents.
8. The method as claimed in claim 5. wherein the additives are selected tVoni the
group consisting of stabilizers, corrosion inhibitors, agents tor adjusting pH.
antiabrasion agents, suriace active agents, antifoam agents. viscosity controlling
agents, antioxidants, agents lor adjusting friction, dispersing agents, swelling agents,
agents lor extreme boundary lubrication, additives resisting high pressure's. dyes.
perfumes and antimicrobial agents.
The invention relates to a method for cooling an engine having a cooling system. which
comprises introducing into the cooling system a coolant fluid which comprises an
aqueous solution of trimethyl glycine anhydrate or monohydrate and 2-6% by weight of
additives wherein the engine is selected from engines used in automobiles, trucks.
motorcycles. aircrafts. trains, tractors, generators, compressors, and from stationary
engines and equipment, marine engines, power systems, industrial engines, electric
engines, fuel cell engines and hybrid engines.
|Indian Patent Application Number||845/KOLNP/2005|
|PG Journal Number||11/2010|
|Date of Filing||09-May-2005|
|Name of Patentee||NESTE OIL OYJ|
|Applicant Address||KEILARANTA 8, FI-02150 ESPOO|
|PCT International Classification Number||C03K 5/20|
|PCT International Application Number||PCT/FI2003/000802|
|PCT International Filing date||2003-10-29|