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2005-01-1378
Innovative Engine Cooling Systems Comparison
Ngy-Srun Ap and Michelle TarquisVALEO Engine Cooling
Reprinted From: Thermal Management Systems, Modeling, and
Components(SP-1945)
2005 SAE World CongressDetroit, MichiganApril 11-14, 2005
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ISSN 0148-7191Copyright 2005 SAE International
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ABSTRACT
In order firstly to reduce weight, packaging and cost of engine
cooling system and secondly to reduce fuel consumption and
pollutants in the exhaust we have seen, over the last twenty years,
several innovative engine cooling system offers. These innovative
engines cooling were:
Nucleate boiling engine cooling, THEMIS cooling system,
Precision cooling
system, Intelligent cooling System, , CoolMaster
UltimateCooling
For each cooling system several vehicles were tested in the
climatic wind tunnel, on road in real conditions and on fuel
consumption and pollution facilities. The comparison of these
innovative engine cooling systems will be presented in this paper,
in terms of:
System weight, packaging and cost, Fuel consumption and
pollutants in the
exhaust, Thermal comfort, Heat performance of engine cooling
system.
INTRODUCTION
Adiabatic engine excepted, the conventional ICE always needs an
engine cooling system. In order firstly to reduce weight, packaging
and cost of these systems and secondly to reduce fuel consumption
and pollutants in the exhaust we have seen, during the last twenty
years, several innovative engine cooling systems offers. Some of
them are more or less interesting in terms of their breakthrough
levels. These innovative engines cooling were:
Nucleate boiling engine cooling: stagnant boiling or convective
boiling in the engine [see references 1 to 4] adopted and tested by
different car manufacturers,
THEMIS system [references 6 to 8], Precision system, Intelligent
System: coolant flow rate and coolant temperature control are
ensured by an electric water pump and an electric water valve
instead of a conventional mechanical driving
pump and of a conventional thermostat respectively,
CoolMaster: coolant temperature control is ensured by an
electric water valve instead of an electric thermostat or the
conventional thermostat,
UltimateCooling: water is the only one coolant for all of engine
fluids [reference 5].
These different innovative engine cooling systems should be
validated according to the engine cooling specifications. Several
vehicles were tested in the climatic wind tunnel, on road in real
conditions and on fuel consumption and pollution facilities. The
comparisons of these innovative engine cooling systems will be
presented in this paper, particularly the first four systems above,
in terms of:
System weight, packaging and cost, Fuel consumption and
pollutants in the exhaust, Thermal comfort, Heat performance of
engine cooling system.
There are other innovative engine cooling systems:
Split Cooling: two separate flow rate loops in the cylinder head
and cylinder bloc. This concept is being introduced to the market
right now by some car manufacturers,
Reverse cooling: engine coolant inlet on the cylinder head
instead of cylinder bloc and radiator coolant inlet at the bottom
instead of the top of radiator. According to our tests effected in
the climatic wind tunnel, there were no big differences between
this system and the conventional system,
Cooling jets: coolant jet directly on the inter-valve of
cylinder head [reference 9]. The total coolant flow rate through
the engine could be reduced to 40 L/mn. Cylinder head has to be
modified in order to install the coolant injection system. System
cost should be completed.
2005-01-1378
Innovative Engine Cooling Systems Comparison
Ngy-Srun Ap and Michelle TarquisVALEO Engine Cooling
Copyright 2005 SAE International
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NUCLEATE BOILING ENGINE COOLING SYSTEM
There are two coolant architectures for nucleate boiling engine
cooling:
partially filled coolant architecture: there is coolant in the
cylinder bloc and the cylinder head and all the rest of the coolant
circuit remains empty. This coolant architecture was adopted and
studied by two car manufacturers (Nissan and BMW).
Completely filled coolant architecture: there is coolant in the
whole coolant circuit. That means the coolant circuit is
practically the same as the conventional engine cooling today. This
is our coolant architecture and was adopted and studied by two car
manufacturers (Renault and VW).
WORKING PRINCIPLE
This concept (called REROM) is developed in the references 1 to
4 by using a small electric water pump of 30 to 80 W, instead of
the conventional driven pump of 1 to 2 kW. This small electric
water pump provides a flow rate of approximately 1 000 to 1 500 l/h
depending on the pressure drop of coolant circuit. Coolant
temperature is ensured by a conventional wax thermostat. Other
features of this concept are:
low relative pressure in the coolant circuit ; only 0.2 bar
instead of 1.5 bar for example,
maximum coolant temperature of 115C, conventional engine cooling
for low and medium
engine load (until 140 km/h of vehicle speeds), nucleate boiling
engine cooling for high engine load
(max. speeds and hill climbing).
Coolant architecture
Practically the same components as the conventional engine
cooling have been used, except:
a small electric water pump of 50W instead of a conventional
mechanical driven pump,
a special expansion tank equipped with a membrane inside (see
figure 3) allowing to absorb the coolant coming from the engine and
the radiator when the engine works under nucleate boiling (high
speeds > 140 km/h or hill climbing conditions),
only one small diameter of hoses. That means same heater core
hoses have been used for the whole coolant circuit and most
importantly these hoses have not reinforced due to the very low
pressure of coolant circuit (max. pressure of
0.2 bar instead of 1 to 2 bars for the conventional coolant
circuit).
Figure 1: Example of coolant architecture
Figure 2: Example of 3D coolant architecture
Figure 3: Expansion tank for Renault Twingo
MAIN TEST RESULTS
Several vehicles (see table 1 below) have been equipped with
this system and tested in the climatic wind tunnel and on road
under real conditions.
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Vehicle Engine Displacement Max power(Liter) (HP)
Renault Twingo Gasoline 1,2 60Renault Clio Gasoline 1,4
80Renault 19 Diesel ID 1,9 70VW GOLF Diesel TDI 1,9 90VW Passat
Gasoline 1,8 90Seat Arosa Diesel SDI 1,7 60
Table 1: Test vehicles
Engine cooling performance
Compared to the conventional cooling system, the REROM system
exhibits the following features :
the cylinder head temperature is approximately 5 to 10C hotter.
These results confirm the test bench results. The values remain
below the critical limit (200C). A modification of the cooling
circuit in the cylinder head is therefore not needed.
the cooling flow rate is 1300 to 1400 l/h instead of 4300 to 5
300 l/h ( 4 times less) for the Renault Twingo engine and 1500 l/h
instead of 8000 to 8700 l/h (5.5 to 6 times less) for the Seat
Arosa engine.
the circuit pressure is around 100 mbar instead of 650 mbar for
the gasoline engine and less than 100 mbar instead of 800 mbar for
the diesel engine.
the oil sump temperature is increased by approximately 2 to 3
C.
Even if the cylinder head, coolant and oil sump temperatures are
higher than the conventional cooling system, the cooling
performance of the REROM system is still good according to the
engine cooling specifications.
Figure 4: Engine cooling performance at 50 km/h, hill climbing,
Ta = 30 C for Renault Twingo
Thermal comfort performance
The heater core air temperature and the passenger compartment
air temperature are almost the same for the two systems except at
idle. During idling, the heater core air temperature is increased
by approximately 15 to
20C. The increase is 5 C on the passenger compartment air
temperature (see figure 5). This increase is directly related to
the REROM high flow rate (1 300 l/h) through the heater core,
versus the conventional system (300 l/h) at idle. This is the
counterpart of the high heater core performance. The heat given to
the air is extracted from the coolant and the engine.
Figure 5 : Thermal comfort at 18 C for Renault Twingo
Fuel consumption and Pollution reduction
Fuel consumption and pollution measurement according to MVEG
cycle shows (figures 6 and 7):
2 to 3% fuel consumption reduction, 10% CO and 3% HC emissions
reduction.
Figure 6: Fuel consumption comparison results for Renault Twingo
and Seat Arosa
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Figure 7: Pollution test results for Renault Twingo and Seat
Arosa
BENEFITS
Compared to the conventional cooling system and based on the
Renault Twingo and the Seat Arosa SDI, nucleate boiling system
exhibits the following results :
good performance of engine cooling. Even if the cylinder head,
the coolant and the oil sump temperatures are slightly higher, they
still fall within the engine cooling specifications,
slightly better (+2 C) for passenger compartment heating, but
really better at idle (+5C),
10 to 15 % cost reduction, 20 to 25 % weight reduction, 20 to 25
% coolant volume reduction, 2 to 3% fuel consumption reduction
(MVEG cycle) 10% CO and 3% HC emissions reduction (MVEG
cycle)
DISADVANTAGES AND CONSEQUENCES
This is a new concept of engine cooling, particularly in the
cylinder head. Several tests like durability, reliability, aging
test, should be effected on a minimum vehicle fleet.
THEMIS SYSTEM
WORKING PRINCIPLE
Our THEermal Management Intelligent System THEMIS system [see
references 6 to 8] or Precision system from Visteon company or
Intelligent System from Dana company has the following main
characteristics: coolant flow rate and coolant temperature control
are ensured by an electric water pump and an electric water valve
instead of a conventional mechanical driving pump and of a
conventional thermostat respectively. That means the mechanical
driving pump has been replaced
by an electric water pump of 200 to 600 W depending on the
engine size and the conventional wax thermostat has been replaced
by an electric water valve. An appropriate control strategy has
been built allowing to drive the three actuators which are the
electric water pump, electric water valve and electric fan with
feedback from the coolant temperature sensor.
There is an other similar concept, called CoolMaster. This is a
THEMIS with mechanical water pump instead of main electric water
pump. CoolMaster could have an additional small electric water pump
for auxiliary functions like cab heating booster, post cooling, cab
heating after engine is off,
Coolant architecture of THEMIS
Figure 8 below shows the coolant architecture. This architecture
has been used for different vehicles (see table 2).
Figure 8: Coolant architecture of THEMIS
The THEMIS control strategy is divided in to 3 main parts, as
described in figure 9. Using usual sensors and engine management
information, the first part is the steady state model. Steady state
engine heat release, radiator efficiency and coolant temperature
are then entering the second part, the dynamic models of engine
heat release and cooling radiator efficiency. Multiple data are
then forwarded to the third part, the control strategy.
Figure 9 : Synoptic of THEMIS strategy control
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Coolant architecture of CoolMaster
Coolant architecture of CoolMaster is similar to THEMIS one,
using the mechanical water pump instead of an electric water pump.
A small electric water pump of 20 to 30 W has been mounted on the
heater core hoses in order to boost their heat performance.
Figure 10: Coolant architecture of CoolMaster
MAIN TEST RESULTS
Several vehicles (see table 2 below) have been equipped with
this system and tested in the climatic wind tunnel and on road in
real conditions. Contrary to the above concept, THEMIS system works
practically in the same way as the conventional engine cooling with
mechanical driving pump for the worst conditions like max speeds
and hill climbing. There is no nucleate boiling in the engine even
if the main coolant flow rate is 30 to 50 % less.
Vehicle Engine Displacement(Liter)
VOLVO S80 Gasoline 2,4Mercedes A class Gasoline 1,6Renault
Megane Gasoline 1,4
Chrysler Minivan V6 Gasoline 3,8OPEL Vectra Diesel TDI 1,2
Table 2: Test vehicles for THEMISsystem and/or CoolMaster
Thermal comfort performance
Benefits on cabin comfort are obtained by a correct management
of coolant flow rate inside the cooling system. By increasing the
coolant flow rate in the heater core, the heating performance is
enhanced. Like REROM (see above) system, thermal comfort at the
idle condition could be reached up to 4 or 5 C improvement versus
the baseline.
Figure 11: Heating boost during idle for Volvo S80
Thermal comfort after engine off
The control of the coolant flow that conveys heat from the
engine to the cabin allows us to keep high level cabin temperature
under very cold winter conditions, even after the engine has
stopped. With low coolant flow rate and low blower speeds through
the heater core, thermal comfort remains practically the same when
the engine is ON (see figure 12) even 30 minutes after the engine
is OFF.
Fugure 12: Cab heating after engine off for Volvo S80 at Ta = -
20C
Post cooling
A precise coolant flow rate control has evidenced to affect the
engine protection positively. Heat soak and boiling can be
prevented after the engine has been stopped by controlling the
operation of electric water pump and electric fan. With this
strategy control, coolant temperature drops down quickly (see
figure 13). This after running function allows the extensive use of
high temperature running at city driving, low and medium speeds
(partial engine load).
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Figure 13: Post cooling after engine stop for Volvo S80
Fuel consumption and Pollution
After extensive development and applications on different
engines and cars (see table 2), a reduction of 5% fuel consumption,
20% CO and 10% HC tail pipe emissions can be announced as average
gain. The fuel consumption reduction is due to the faster and
higher temperature level of average temperature during the test
cycle:
110 C instead of 90 C for coolant temperature (figure 14).
150 C instead of 120 C for cylinder head temperature (figure
15).
10 to 20 C warmer for oil sump temperature. These possible
temperature levels are due to the very good response time (3 to 5
times quicker) and accuracy (+/- 2 C) of electric water valve
versus the conventional wax thermostat heated or not (+/- 5 to 7
C). Moreover, zero coolant flow strategy has a positive effect. On
some applications no less than 5% fuel consumption saving has been
measured on the high speed part of the EUDC cycle.
Figure 14: Coolant temperature during fuel consumption tests
(MVEG cycle)
Figure 15: Cylinder head temperature during fuel consumption
tests (MVEG cycle)
BENEFITS
Compared to the conventional cooling system, THEMIS system
exhibits the following results :
Fuel consumption reduction up to 5% depending on the size and
type of engine,
Pollution reduction up to 20% for CO and up to 10% for HC,
Good response time on coolant and cylinder head temperature due
to the very good response of electric water valve instead of wax
thermostat,
Cab heating booster at idle, up to + 5 C improvement of thermal
comfort,
Cab heating after engine is off, thermal comfort could be
maintained up to 30 minutes after engine is OFF,
Good post heating.
DISADVANTAGES AND CONSEQUENCES
This system needs two new main components: an electric water
pump and an electric water valve. There is an additional cost due
to these two components (see table 3 below).
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System Functions MW
P, h
eate
d W
ax T
h.
Coo
lMas
ter
with
out s
mal
l
Elec
tric
al W
ater
Pum
p
Coo
lMas
ter
with
sm
all
Elec
tric
al W
ater
Pum
p TH
EMIS
Total functions
achieved % 25 75 100 100
Cooling loop
Over-cost*
+ 12
to 15
+ 25 to
28
+ 35 to
40
+ 55 to
75
* Compared to a traditional cooling loop with wax thermostat
Table 3 : System cost comparison
ULTIMATECOOLING SYSTEM
The detail of this UltimateCooling system concept has been
showed in the reference [5].
WORKING PRINCIPLE
UltimateCooling has been achieved by using engine coolant
exclusively to cool all the various fluids in the vehicle, i.e.
air, refrigerant, oil, exhaust gas and fuel. Thus, the air to air
CAC was replaced by an air to water (coolant) CAC (WCAC) and the
refrigerant to air A/C condenser by a refrigerant to water
(coolant) A/C condenser (WCDS). These new heat exchangers were
located close to the heat source, resulting in shorter hoses. As a
result, the air, refrigerant and coolant hoses architecture became
all the more compact. The cooling radiator in our project is the
only heat exchanger that remains in the forefront of the vehicle.
This could reduce repair cost significantly after a small impact in
city driving, since only one cooling radiator would have to be
replaced instead of the combination of CAC, A/C condenser and other
heat exchangers. This cooling radiator is a multi-temperature
radiator in which the amount of high temperature and low
temperature water can be modulated, according to engine operating
conditions, engine load priorities and the thermal comfort
required.
Figure 16: Todays design of cooling system
Figure 17: UltimateCooling design
Coolant architecture
Figure 18: Coolant architecture of UltimateCooling for Mercedes
C class 220 CDI
Figure 18 above shows an example of coolant architecture. There
are only two radiators (HT and LT) at the front end. The HT
radiator ensures the engine cooling, oil cooling and EGR cooling.
The LT radiator ensures the water charge air cooling (WCAC), water
condenser (WCDS) and fuel cooler (FC). HT and LT could be
integrated in one multi-temperature radiator. Thus there will be
only one radiator located at the front end. LT loop needs a small
electric water pump of 50 Watts in order to ensure the heat
performance of WCAC, WCDS and FC.
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MAIN TEST RESULTS
A turbo diesel vehicle Mercedes C class 220CDI, has been
equipped with this system and tested in the climatic wind tunnel
and on road in the real conditions.
Packaging balance
Figure 19: Packaging balance on Mercedes C class 220CDI
Packaging balance, based on Mercedes C class 220 CDI has been
carried out (figure 19). All calculations are based on the last
components that the general good performances have been obtained
(see chapter below). Compared to the baseline equipped with the
conventional cooling system, UltimateCooling has the following
advantages:
10 liters reduction of cooling module at the front end by moving
WCAC, WCDS to the underhood.
6 liters reduction of overall thermal system volume due to the
reduction of air manifold hoses length, packaging of WCAC
(integrated on the top of engine) and packaging of WCDS.
4 liters volume increases in the underhood because WCAC and WCDS
are now located in the engine compartment.
Charger air cooling (CAC)performance
The performance of CAC for the conventional system and WCAC for
UltimateCooling has been obtained by the climatic wind tunnel tests
with A/C on and off according to the worst conditions of
engine:
hill climbing of 10 % grade with trailer and Ta of 30 C,
hill climbing of 60 % grade without trailer and Ta of 40 C,
full load of engine at flat road, 200 km/h and Ta of 35 C.
Table 4: CAC performance comparison for A/C on
Table 4 above shows that air CAC temperature is 4 to 10 C better
than baseline if A/C is on.
Table 5: CAC performance comparison for A/C off
Table 5 above shows that air CAC temperature is 13 to 20 C
better than baseline if A/C is off.
Thermal comfort performance: A/C system
Figure 20: Cab temperature during cool down test under Ta = 45 C
and solar radiation of 1000 W/m
A/C performance of UltimateCooling system is similar to baseline
system.
Engine cooling performance
For different worst conditions of engine (see WCAC test
conditions above), the engine cooling performance of
UltimateCooling system is similar to the baseline system (table
6).
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10% Grade with Trailer, 30C 6% Grade without Trailer, 40 C 40
km/h, Gear 2, A/C ON 90 km/h, Gear 3, A/C ON
Baseline Ultimate Baseline Ultimate Coolant T (C) 119 119 117
114
Oil Sump T (C) 140 141 136 133
180 km/h Flat Road 35C 200 km/h Full Load 35C
Baseline Ultimate Baseline Ultimate Coolant T (C) 106 102 110
110
Oil Sump T(C) 125 123 127 129
A/C ON A/C ON
Table 6: Coolant and Oil sump temperature comparison
Fuel consumption
The Mercedes C class 220CDI has been equipped with the
UltimateCooling system and tested on the fuel consumption facility
according to the MVEG cycle under ambient temperature of 28 and 35
C. Two test conditions of A/C system have been effected:
Condition 1: A/C max and blower max, Condition 2: A/C with set
temperature of 22 C
and blower at n4 position.
Compared to the baseline system, UltimateCooling has fuel
consumption:
up to 6% for condition 1 at Ta = 28 C and cold start of
engine,
similar for condition 1 at Ta = 28 C with warm engine,
similar for other test conditions.
BENEFITS
Compared to the conventional cooling system and based on
Mercedes C class 220CDI, UltimateCooling system exhibits the
following results :
Packaging reduction in Front End by -10 Liters (- 40%),
Danner crash repair cost reduction, Green House Gas benefit
(750g of R134a ~
1000 kg of CO), Better WCAC performance (4 to 10 C better if
A/C is ON, and 13 to 20 C better if A/C is OFF, its very
interesting for downsizing of ICE, Better engine performances
and dynamic
response (turbo lag), Mutualization of thermal exchange
potential : all
heat exchangers being cooled down by the same fluid, A/C, Charge
Air and Engine cooling operates by sharing power depending on the
vehicle speed conditions,
Could supply low temperature coolant to other fluids : fuel
cooler, EGR cooler, oil cooler,
electronic cooler and electric power-train cooler for HEV,
FCEV,
Less high cost hoses: A/C, OC, CAC, Cross-line component
standardisation : WCAC,
WCDS
DISADVANTAGES AND CONSEQUENCES
Based on Mercedes C class 220CDI, there is an additional weight
of 2 to 2.5 kg due to the additional coolant volume in the LT loop
for WCAC and WCDS.
ENGINE COOLING SYSTEMS COMPARISON
The four engine cooling systems: REROM, THEMIS, CoolMaster and
UltimateCooling present the different benefits and disadvantages in
terms of fuel consumption, pollution, global weight and packaging,
cooling module weight and packaging at the front end, thermal
comfort performance, engine performance and finally the system
cost. Tables 7a to 7c below, show these engine cooling systems
comparison versus the baseline equipped with the conventional
system today, that means with mechanical driving pump, wax
thermostat, air CAC and air CDS. However these four innovative
systems have the different specificities in terms of vehicle ranges
and engine types (see figure 21), that is to say:
REROM system is a very advantageous system application for the
small and compact vehicles equipped with the small gasoline or
small diesel engine.
THEMIS and CoolMaster system are a very good system for medium
and high vehicle ranges equipped with the gasoline engine (diesel
engine has to be confirmed).
UltimateCooling system is preferable to medium and high vehicle
range equipped with the turbo diesel engine and also to high
vehicle range equipped with a big turbo gasoline engine.
Figure 21: Engine cooling system application versus vehicle
range
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Engine Fuel Pollution Post EngineCooling consumption cooling
PerformanceSystemREROM +++ +++ +++ 0
THEMIS +++ +++ +++ 0CoolMaster ++ ++ +++ (*) 0
UltimateCooling + ++(**) + (**) +++ (*) +++
(*): with small electric water pump (**): MVEG cycle with A/C ON
at Ta = 28 C +++ = very good, --- = very bad, 0 = same Table 7a:
Engine cooling systems comparison
Engine CoolingSystem
Packaging Weight Packaging WeightREROM ++ ++ + +
THEMIS - - 0 0CoolMaster 0 0 0 0
UltimateCooling ++ - +++ +++
systempackaging of cooling
Global weight & Cooling module weight & packaging
(*): with small electric water pump (**): MVEG cycle with A/C ON
at Ta = 28 C +++ = very good, --- = very bad, 0 = same Table 7b:
Engine cooling systems comparison
Engine Cooling Engine Engine A/CSystem on off performance
Cab heating Cab heatingREROM +++ +++ 0
THEMIS +++ +++ 0CoolMaster +++ (*) +++ (*) 0
UltimateCooling +++ (*) +++ (*) + (**)
Thermal comfort
(*): with small electric water pump (**): MVEG cycle with A/C ON
at Ta = 28 C +++ = very good, --- = very bad, 0 = same Table 7c:
Engine cooling systems comparison
Engine Fuel SystemCooling consumption costSystem MVEG cycleREROM
up to - 3% "- 15 to - 20 "
THEMIS up to - 5% "+ 55 to + 75 "CoolMaster(*) up to - 3% " + 35
"CoolMaster up to - 3% "+ 25 "
MWP& Heated Th. up to - 2% "+ 15 "UltimateCooling up to -
6%(**) 0
(*): with small electric water pump (**): MVEG cycle with A/C ON
at Ta = 28 C Table 7d: Engine cooling systems comparison
FUEL CONSUMPTION AND POLLUTION
Thanks to the electric water pump or electric water valve, zero
coolant flow rate at the engine cold start could be used. Thus
metal temperature, exhaust gas, oil sump and coolant rise quickly
and lead to fuel consumption and pollution reduction. These are
REROM, THEMIS and CoolMaster systems.
POST COOLING
Thanks to the main electric water pump for REROM and THEMIS
system, and the additional electric water pump for CoolMaster and
UltimateCooling, post cooling could be solved. With the
complementary of electric fan the coolant temperature drops down
quickly.
ENGINE PERFORMANCE
Due to the very good performance of WCAC for UltimateCooling
system, air manifold temperature is lower than the baseline. Good
performance of engine has been obtained, particularly the dynamic
response. These good results represent a large potential for
downsizing of turbo diesel engine.
GLOBAL WEIGHT AND PACKAGING
Due to the system concept by using nucleate boiling in the
engine, REROM concept presents real advantages of global weight and
packaging reduction: coolant volume reduction (- 25%), hoses (same
small diameter of heater core hoses for all coolant circuit) and
small water boxes of radiators. UltimateCooling also has a slight
advantage.
PACKAGING OF COOLING MODULE
Concerning the cooling module at the front end UltimateCooling
has a very important packaging reduction by moving the CDS, CAC, OC
and TOC to the inside of under-hood. This advantage is very
beneficial in terms of front end design in order to satisfy the
pedestrian crash norms in the near future.
THERMAL COMFORT
Cab heating when the engine is ON
Thanks to the main electric water pump for REROM and THEMIS
system, and the additional electric water pump for CoolMaster and
UltimateCooling, thermal comfort could be improved, particularly at
the idle.
Cab heating when the engine is OFF
When the engine is OFF the 4 systems above could maintain the
thermal comfort during at least 30 minutes under outside
temperature of - 20 C. This benefit is
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possible by managing the coolant flow rate and the blower
through the HVAC.
A/C performance
Compared to the baseline vehicle, the 4 systems have almost the
same A/C performance. However, due to the thermal inertia of water
(coolant), UltimateCooling has a little advantage at the cold start
of engine. The electric fan operates later than usual and could
represent a benefit for fuel consumption tests, particularly for
the official MVEG cycle. Concerning THEMIS and CoolMaster, A/C
performance (thermal comfort) is slightly better due to the EWV
operation by suppressing the hot coolant through the heater core
during hot summer driving.
System cost
Table 7d above shows that the most economical system is the
nucleate boiling system called REROM due to low cost of hoses
particularly. UltimateCooling has a system cost similar to the
baseline. THEMIS and CoolMaster system have 25 to 75 over cost
depending on the THEMIS level applications; that means, compare to
the conventional engine cooling system with MWP and wax
thermostat:
CoolMaster without small EWP has 25 over cost,
CoolMaster with small EWP has about 35 more,
THEMIS has about 55 to 75 more.
CONCLUSION
Valeo has a complete innovative engine cooling system with high
breakthrough levels. These systems have been validated in the
climatic wind tunnel, road tests under real conditions, including
hot missions in the south of Europe and cold missions near the
polar circle. These systems are available for car manufacturers
wishing to improve their engine cooling systems. Good performance
of thermal comfort was obtained at idle during engine ON and during
engine OFF.
Our recommendations are:
THEMIS or CoolMaster could be used if the fuel consumption and
pollutions reduction are really the main target. Also its very good
for the medium and high vehicle range equipped with the gasoline
engine.
REROM could be a good system in order to reduce fuel
consumption, pollution and system cost. Its very beneficial for low
vehicle range equipped with small gasoline and small diesel
engine.
UltimateCooling is a good system in order to reduce the
packaging of cooling module at the front end. Its an ideal system
for high vehicle range equipped with the turbo diesel or turbo
gasoline engine.
Of course the combination of the two innovative systems is
possible, for example, UltimateCooling with THEMIS or CoolMaster
allows cooling module reduction at the front end, thermal comfort
improvement, post cooling improvement, fuel consumption and
pollution reduction.
ACKNOWLEDGMENTS
The authors acknowledge and give thanks to Michel FORISSIER,
R&D Director of Valeo Engine Cooling, for his assistance and
his advice and special thanks to vehicle tests team and components
team for their very interesting work and their participation during
the preparation of this paper.
REFERENCES
1. N.S.AP, A.MAIRE, P.POROT, P.MENEGAZZI, F.SOUIDI, C.LE
DEVEHAT, D.GODEAU, P.OLIVIER, J.B.VINOT, and G.VINCENS
New Components Development for New Engine Cooling System
VTMS4 1999 paper n C543/04/99 London 2. N.S.AP and N.C.GOLM, New
Concept of
Engine Cooling System (Newcool) , VTMS3 Congress, paper n971775
1997 Indianapolis
3. P.A.POROT, P.MENEGAZZI and N.S.AP, Understanding and
Improving Evaporative Engine Cooling at high load, high speed by
Engine Tests and 3D Calculations , VTMS3 Congress, paper n 971792
1997 Indianapolis.
4. N.S.AP and M.PRETSCHER, Nucleate Boiling Engine Cooling
System - Vehicle Study , VTMS1 Congress, paper n931132, 1993,
Columbus
5. N.S.AP P.GUERRERO P.JOUANNY M.POTIER J.GENOIST J.L.THUEZ
Ultimate Cooling New Concept Of Cooling System by using the same
Coolant to Cool all of Vehicle Fluids, VTMS6 congress 2003
Brighton
6. P.Y.GEELS Advanced Control strategy for modern engine cooling
thermal systems, and effect on CO and pollutant reduction, VTMS6
congress 2003 Brighton
7. M.CHANFREAU B.GESSIER A.FARK P.Y.GEELS The need for an
Electrical Water Valve in a THErmal Management IntelligentSystem
(THEMIS) SAE n2003-01-0274
8. H.COUETOUX D.GENTILE Cooling System Control in Automotive
Engines, SAE paper n 920788
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9. A.VAGENAS J.G.HAWLEY C.J.BRACE M.C.WARD On Vehicle
Controllable Cooling Jets SAE paper n 2004-01-0049
CONTACT
Ngy-Srun AP Dr. Ing. from Pierre & Marie CURIE University
(Paris - France) and Senior Expert of Engine Cooling System in
VALEO Engine Cooling company, 8 rue Louis Lormand 78321 La Verriere
Cedex FRANCE Email: [email protected]
DEFINITIONS, ACRONYMS, ABBREVIATIONS
A/C: Air Conditioning CAC: Charge Air Cooler WCAC: Water Charge
Air Cooler CDS: Condenser WCDS: Water Condenser EGR: Exhaust Gas
Recirculation EWP: Electric water pump FCEV: Fuel Cell Electric
Vehicle HEV: Hybrid Electric Vehicle ICE: Internal Combustion
Engine LT, HT: Low Temperature, High Temperature MVEG: European
cycle for fuel consumption and pollution test MWP: Mechanical water
pump OC: Oil Cooler Ta: Ambient temperature TOC: Transmission Oil
Cooler REROM: Nucleate Boiling Engine Cooling system THEMIS:
THEermal Management Intelligent System CoolMaster: THEMIS with
mechanical water pump instead of main electric water pump. It could
be with or without small electric water pump UltimateCooling: All
engine fluids cooled by water
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