SE542237C2 - A cooling system for a combustion engine and a WHR system - Google Patents

A cooling system for a combustion engine and a WHR system

Info

Publication number
SE542237C2
SE542237C2 SE1750553A SE1750553A SE542237C2 SE 542237 C2 SE542237 C2 SE 542237C2 SE 1750553 A SE1750553 A SE 1750553A SE 1750553 A SE1750553 A SE 1750553A SE 542237 C2 SE542237 C2 SE 542237C2
Authority
SE
Sweden
Prior art keywords
coolant
inlet line
coolant flow
radiator
circuit
Prior art date
Application number
SE1750553A
Other versions
SE1750553A1 (en
Inventor
Thomas Sederholm
Zoltan Kardos
Original Assignee
Scania Cv Ab
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Scania Cv Ab filed Critical Scania Cv Ab
Priority to SE1750553A priority Critical patent/SE542237C2/en
Priority to DE102018003322.9A priority patent/DE102018003322A1/en
Publication of SE1750553A1 publication Critical patent/SE1750553A1/en
Publication of SE542237C2 publication Critical patent/SE542237C2/en

Links

Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01P—COOLING OF MACHINES OR ENGINES IN GENERAL; COOLING OF INTERNAL-COMBUSTION ENGINES
    • F01P7/00—Controlling of coolant flow
    • F01P7/14—Controlling of coolant flow the coolant being liquid
    • F01P7/16—Controlling of coolant flow the coolant being liquid by thermostatic control
    • F01P7/165—Controlling of coolant flow the coolant being liquid by thermostatic control characterised by systems with two or more loops
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01K—STEAM ENGINE PLANTS; STEAM ACCUMULATORS; ENGINE PLANTS NOT OTHERWISE PROVIDED FOR; ENGINES USING SPECIAL WORKING FLUIDS OR CYCLES
    • F01K23/00—Plants characterised by more than one engine delivering power external to the plant, the engines being driven by different fluids
    • F01K23/02—Plants characterised by more than one engine delivering power external to the plant, the engines being driven by different fluids the engine cycles being thermally coupled
    • F01K23/06—Plants characterised by more than one engine delivering power external to the plant, the engines being driven by different fluids the engine cycles being thermally coupled combustion heat from one cycle heating the fluid in another cycle
    • F01K23/065—Plants characterised by more than one engine delivering power external to the plant, the engines being driven by different fluids the engine cycles being thermally coupled combustion heat from one cycle heating the fluid in another cycle the combustion taking place in an internal combustion piston engine, e.g. a diesel engine
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01K—STEAM ENGINE PLANTS; STEAM ACCUMULATORS; ENGINE PLANTS NOT OTHERWISE PROVIDED FOR; ENGINES USING SPECIAL WORKING FLUIDS OR CYCLES
    • F01K23/00—Plants characterised by more than one engine delivering power external to the plant, the engines being driven by different fluids
    • F01K23/02—Plants characterised by more than one engine delivering power external to the plant, the engines being driven by different fluids the engine cycles being thermally coupled
    • F01K23/06—Plants characterised by more than one engine delivering power external to the plant, the engines being driven by different fluids the engine cycles being thermally coupled combustion heat from one cycle heating the fluid in another cycle
    • F01K23/10—Plants characterised by more than one engine delivering power external to the plant, the engines being driven by different fluids the engine cycles being thermally coupled combustion heat from one cycle heating the fluid in another cycle with exhaust fluid of one cycle heating the fluid in another cycle
    • F01K23/101—Regulating means specially adapted therefor
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01K—STEAM ENGINE PLANTS; STEAM ACCUMULATORS; ENGINE PLANTS NOT OTHERWISE PROVIDED FOR; ENGINES USING SPECIAL WORKING FLUIDS OR CYCLES
    • F01K23/00—Plants characterised by more than one engine delivering power external to the plant, the engines being driven by different fluids
    • F01K23/12—Plants characterised by more than one engine delivering power external to the plant, the engines being driven by different fluids the engines being mechanically coupled
    • F01K23/14—Plants characterised by more than one engine delivering power external to the plant, the engines being driven by different fluids the engines being mechanically coupled including at least one combustion engine
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01K—STEAM ENGINE PLANTS; STEAM ACCUMULATORS; ENGINE PLANTS NOT OTHERWISE PROVIDED FOR; ENGINES USING SPECIAL WORKING FLUIDS OR CYCLES
    • F01K9/00—Plants characterised by condensers arranged or modified to co-operate with the engines
    • F01K9/003—Plants characterised by condensers arranged or modified to co-operate with the engines condenser cooling circuits
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N5/00—Exhaust or silencing apparatus combined or associated with devices profiting by exhaust energy
    • F01N5/02—Exhaust or silencing apparatus combined or associated with devices profiting by exhaust energy the devices using heat
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01P—COOLING OF MACHINES OR ENGINES IN GENERAL; COOLING OF INTERNAL-COMBUSTION ENGINES
    • F01P3/00—Liquid cooling
    • F01P3/20—Cooling circuits not specific to a single part of engine or machine
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01P—COOLING OF MACHINES OR ENGINES IN GENERAL; COOLING OF INTERNAL-COMBUSTION ENGINES
    • F01P9/00—Cooling having pertinent characteristics not provided for in, or of interest apart from, groups F01P1/00 - F01P7/00
    • F01P9/06—Cooling having pertinent characteristics not provided for in, or of interest apart from, groups F01P1/00 - F01P7/00 by use of refrigerating apparatus, e.g. of compressor or absorber type
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02G—HOT GAS OR COMBUSTION-PRODUCT POSITIVE-DISPLACEMENT ENGINE PLANTS; USE OF WASTE HEAT OF COMBUSTION ENGINES; NOT OTHERWISE PROVIDED FOR
    • F02G5/00—Profiting from waste heat of combustion engines, not otherwise provided for
    • F02G5/02—Profiting from waste heat of exhaust gases
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02G—HOT GAS OR COMBUSTION-PRODUCT POSITIVE-DISPLACEMENT ENGINE PLANTS; USE OF WASTE HEAT OF COMBUSTION ENGINES; NOT OTHERWISE PROVIDED FOR
    • F02G5/00—Profiting from waste heat of combustion engines, not otherwise provided for
    • F02G5/02—Profiting from waste heat of exhaust gases
    • F02G5/04—Profiting from waste heat of exhaust gases in combination with other waste heat from combustion engines
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01K—STEAM ENGINE PLANTS; STEAM ACCUMULATORS; ENGINE PLANTS NOT OTHERWISE PROVIDED FOR; ENGINES USING SPECIAL WORKING FLUIDS OR CYCLES
    • F01K25/00—Plants or engines characterised by use of special working fluids, not otherwise provided for; Plants operating in closed cycles and not otherwise provided for
    • F01K25/08—Plants or engines characterised by use of special working fluids, not otherwise provided for; Plants operating in closed cycles and not otherwise provided for using special vapours
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01P—COOLING OF MACHINES OR ENGINES IN GENERAL; COOLING OF INTERNAL-COMBUSTION ENGINES
    • F01P3/00—Liquid cooling
    • F01P3/18—Arrangements or mounting of liquid-to-air heat-exchangers
    • F01P2003/182—Arrangements or mounting of liquid-to-air heat-exchangers with multiple heat-exchangers
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01P—COOLING OF MACHINES OR ENGINES IN GENERAL; COOLING OF INTERNAL-COMBUSTION ENGINES
    • F01P3/00—Liquid cooling
    • F01P3/18—Arrangements or mounting of liquid-to-air heat-exchangers
    • F01P2003/185—Arrangements or mounting of liquid-to-air heat-exchangers arranged in parallel
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T10/00—Road transport of goods or passengers
    • Y02T10/10—Internal combustion engine [ICE] based vehicles
    • Y02T10/12—Improving ICE efficiencies

Landscapes

  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Cooling, Air Intake And Gas Exhaust, And Fuel Tank Arrangements In Propulsion Units (AREA)
  • Heat-Exchange Devices With Radiators And Conduit Assemblies (AREA)

Abstract

The present invention relates to a cooling system comprising a first circuit (A) in which coolant flows through a first radiator (14) and a combustion engine (2), and a second circuit (B) in which coolant flows through a second radiator (12) and a condenser (16) of the WHR-system. The second circuit (B) comprises a first inlet line (11a) receiving a first coolant flow of a first temperature (Ti) from the first circuit (A), a second inlet line (11b) receiving a second coolant flow from the first circuit (A) which is cooled in the second radiator (12) to a second temperature, a condenser inlet line (15) receiving the coolant flows from the first inlet line (11a) and the second inlet line (11b) and direct a third coolant flow of a third temperature to the condenser (16), and valve arrangement (13, 21, 32-35) by which it is possible to adjust the coolant flow in at least one of the inlet lines (11a, 11b) such that the condenser inlet line (15) directs a third coolant flow of a third temperature to the condenser (16) at which the working medium is cooled to a desired condensation temperature.

Description

A cooling system for a combustion engine and a WHR system BACKGROUND OF THE INVENTION AND PRIOR ART The present invention relates to a cooling system for a combustion engine and a WHR-system according to the preamble of claim 1.
A WHR system (Waste Heat Recovery System) can be used in vehicles for recovering waste thermal energy and convert it to mechanical energy or electric energy. The waste heat energy from, for example, the exhaust gases from a combustion engine can be recovered by means of a WHR-system. Consequently, a WHR-system can reduce the fuel consumption of a combustion engine. In order to achieve a high thermal efficiency in a WHR-system, the working medium in the condenser is to be cooled to a condensation temperature as low as possible and substantially without subcooling. Consequently, in order to achieve a high thermal efficiency in a WHR-system, the working medium is to be cooled with a suitable cooling effect. However, the suitable cooling effect of the working medium in the condenser varies during different operating conditions such as with the heat effect supplied from, for example, the exhaust gases to the working medium in the evaporator. Since the supplied heat effect from exhaust gases can vary rapidly, it is difficult to continuously provide a cooling effect of the working medium in the condenser resulting in a high thermal efficiency of a WHR-system.
It is desired to cool the WHR system and the combustion engine by a common cooling system. However, it is difficult to design such a cooling system in view of the fact that the required cooling effect for cooling of the working medium can vary rapidly and that the combustion engine and the WHR system require cooling by coolants of different temperatures.
WO 2016/089276 shows a cooling arrangement for a combustion engine and a WHR system. The cooling arrangement comprises a high temperature circuit, an intermediate temperature circuit and a low temperature circuit each comprising a radiator in which coolant is cooled to different temperatures. Coolant from the high temperature circuit or coolant from the low temperature circuit is mixed with coolant from the intermediate temperature circuit in order to create a coolant mixture of a suitable temperature for cooling the working medium in the condenser to a desired condensation temperature.
SUMMARY OF THE INVENTION The object of the present invention is to provide a relatively simple cooling system which is able to provide an efficient cooling of a combustion engine and a working medium in a condenser of a WHR-system.
The above mentioned object is achieved by the cooling system defined in claim 1. Thus, the cooling system comprises a first circuit in which the coolant cools the combustion engine and a second circuit in which the coolant cools the working medium in the condenser of the WHR system. In order to provide an efficient cooling of the combustion engine and the WHR system, it is necessary to cool the combustion engine and the working medium in the condenser by coolant of different temperatures. The second circuit comprises a first inlet line and a second inlet line directing a respective coolant flow from the first circuit to the second circuit. The second inlet line comprises a second radiator. Thus, the coolant flow in the second inlet line is cooled to a lower temperature than the coolant flow in the first inlet line. Consequently, the second circuit receives two separate coolant flows of different temperatures from the first circuit. By means of a valve arrangement it is possible to adjust the coolant flow in at least one of the inlet lines during different operating conditions such that a mixture of the two coolant flows having the ability to cool the working medium to a desired condensation temperature in the condenser.
According to the invention, the second inlet line is configured to receive coolant from a position in the first circuit at which the coolant has its lowest temperature. Such a position may be in a first radiator outlet line which receives cold coolant from the first radiator. Thus, this coolant has already been cooled in a first step before it is directed to the second inlet line where it is cooled in a second step in the second radiator. In this case, it is possible to give the second coolant flow a very low temperature. In any event, the temperature of the second coolant flow has to be equal or lower than the temperature of the coolant flow directed to the condenser. The required cooling effect for cooling the working medium to a desired condensation temperature can be achieved at different combinations of coolant flows and coolant temperatures. In order to create a large number of such combination options, it is favorable that the temperature difference between the first coolant flow in the first inlet line and the second coolant flow in the second coolant line is relatively large.
According to the invention, the valve arrangement comprises a valve member configured to provide an adjustable first coolant flow in the first inlet line.
The valve member is a three way valve provided with an inlet configured to receive coolant from the combustion engine, a first outlet configured to direct an adjustable first coolant flow to the first inlet line and a second outlet configured to direct a remaining coolant flow to the first radiator. In this case, it is possible to provide a first coolant flow which together with a second coolant flow creates a mixture having the ability to cool the working medium to a desired condensation temperature in the condenser.
According to an embodiment of the invention, the first inlet line is configured to receive coolant from a position in the first circuit at which the coolant has its highest temperature. Such a position may be in an engine outlet line which receives warm coolant from the combustion engine. In this case, the first coolant flow may be given a relatively high temperature. In any event, the temperature of the first coolant flow has to be equal or higher than the temperature of the coolant flow directed to the condenser.
According to an embodiment of the invention, the valve arrangement comprises a valve member configured to provide an adjustable second coolant flow in the second inlet line. The temperature of the coolant leaving the second radiator is related to the second coolant flow through the second radiator. By means of such valve member, it is possible to adjust the second flow as well as the temperature of the coolant before it is mixed with the first coolant flow. Such a valve member can be designed in different ways.
According to an alternative, the valve member is configured to provide an adjustable second coolant flow from the first radiator outlet line to the second inlet line. Such a valve member may be a three way valve provided with an inlet configured to receive coolant from the first radiator, a first outlet configured to direct an adjustable second coolant flow to the second inlet line and a second outlet configured to direct a remaining part of the coolant to the combustion engine. In this case, it is possible to provide an adjustable second coolant flow with a high accuracy which is mixed with the first coolant flow before the mixture is directed to the condenser. Furthermore, the valve member is configured to direct a coolant flow to the combustion engine such that it receives a desired cooling. Alternatively, the valve member is a two way throttle valve arranged in the first radiator outlet line in a position downstream of a connection point between the first radiator outlet line and the second inlet line. In this case, the throttling degree of the valve member is related to how much part of the coolant flow is directed to the second inlet line.
According to an embodiment of the invention, the second circuit comprises a return line directing coolant from the condenser to a position in first circuit upstream of a coolant pump. In this case, it is possible to use a common pump for pumping coolant through the first circuit and the second circuit.
According to an embodiment of the invention, the cooling system comprises a control unit configured to receive information about at least one operating parameter and to control the valve arrangement in view of this information. The control unit may, for example, receive information from a sensor sensing the actual condensation temperature in the condenser. In case the condensation temperature is too high, the control unit may control the valve arrangement such that coolant of a lower temperature is directed to the condenser. In case the condensation temperature is too low, the control unit may control the valve arrangement such that coolant of a higher temperature is directed to the condenser. Alternatively or in combination, the control unit may receive information about operating parameters related to the required cooling effect for cooling the working medium to a desired condensation temperature in the condenser. In view of this information, the control unit may estimate suitable combinations of coolant flow and coolant temperature to be directed to the condenser in order to obtain the desired condensation temperature of the working medium in the condenser.
The control unit may control the valve arrangement such that the coolant directed to the condenser has a temperature which results in a cooling of the working medium in the condenser to a condensation pressure just above 1 bar. It is nearly always possible to provide a temperature of the coolant which results in a cooling of the working medium in the condenser to a desired condensation temperature. However, by practical reasons, it is many times suitable to avoid negative pressures in a WHR-system. In this case, it is suitable to obtain a condensation pressure just above 1 bar. The desired pressure range may, for example, be in the range 1,1 - 1,5 bar. It is to be noted that a condensation temperature for a working medium has a corresponding condensation pressure.
The invention is also related to a vehicle comprising a cooling system according to any of the embodiments described above.
BRIEF DESCRIPTION OF THE DRAWINGS In the following preferred embodiments of the invention are described, as examples, with reference to the attached drawing, in which: Fig. 1 shows a cooling system according to a first embodiment, Fig. 2 shows the two radiators in Fig. 1 more in detail, Fig. 3 shows a cooling system according to a second embodiment, Fig. 4 shows a cooling system according to a third embodiment, Fig. 5 shows a cooling system according to an embodiment of the invention and Fig. 6 shows a cooling system according to another embodiment of the invention.
DETAIFED DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION Fig. 1 shows a schematically disclosed vehicle 1 powered by a combustion engine 2. The vehicle 1 may be a heavy vehicle and the combustion engine 2 may be a diesel engine. The cooling system comprises a coolant pump 3. The coolant pump 3 may be a mechanical pump operated by a component in the powertrain of the vehicle 1. The coolant pump 3 is arranged in an engine inlet line 4 directing coolant to the combustion engine 2. The coolant leaving the combustion engine 2 is received in an engine outlet line 5. The coolant in the engine outlet line 5 has the highest temperature in the first circuit A. A thermostat valve 6 is arranged at an end of the engine outlet line 5. The thermostat valve 6 has one inlet receiving coolant from the engine outlet line 5, a first outlet directing coolant to a first radiator inlet line 7 and a second outlet directing coolant to a first radiator bypass line 8. The outlets of the thermostat valve 6 are adjustable in a stepless manner. Thus, the thermostat valve 6 can distribute the coolant flow from the engine outlet line 5 between the first radiator inlet line 7 and the first radiator bypass line 8 in a stepless manner. The first radiator inlet line 7 directs coolant to a first radiator 9. The coolant leaving the first radiator 9 is received in a first radiator outlet line 10. The combustion engine 2, the coolant pump 3, the engine inlet line 4, the engine outlet line 5, the thermostat valve 6, the first radiator inlet line 7, the first radiator bypass line 8, the first radiator 9 and the first radiator outlet line 10 are arranged in a first circuit A of the cooling system.
The cooling system comprises a second circuit B. The second circuit B comprises a first inlet line 11a receiving a first coolant flow Image available on "Original document" of a first temperature Ti from the engine outlet line 5 in the first circuit A and a second inlet line 11b receiving a second coolant flowImage available on "Original document" from the first radiator outlet line 10 in the first circuit A. The second inlet line 11b comprises a second radiator 12 in which the second coolant flowImage available on "Original document" is cooled to a second temperature T2. The second circuit B comprises further a three way valve 13. The three way valve 13 comprises a first inlet receiving the first coolant flow Image available on "Original document" from the first inlet line 11a and a second inlet receiving the second coolant flowImage available on "Original document" from the second inlet line 11b and an outlet directing a third coolant flow Image available on "Original document" of a third temperature T3, via a condenser inlet line 15, to a condenser 16 of a WHR system. Furthermore, the second circuit B comprises a return line 17 directing coolant from the condenser 16 to an upstream position of the coolant pump 3 in the first circuit A. A control unit 14 controls the thermostat valve 6 and the three way valve 13. In this case, the first inlet and the second inlet of the three way valve 13 are adjustable. Thus, the three way valve 13 can receive an adjustable first coolant flow Image available on "Original document" from the first inlet line 11a and an adjustable second coolant flow from the second inlet line 11b. A temperature sensor 18 senses the temperature in the engine outlet line 5 and a temperature sensor 19 senses the third coolant temperature T3in the condenser inlet line 15.
Thus, the vehicle is provided with a WHR-system (Waste Heat Recovery system). The WHR- system comprises a working medium pump 21 which pressurizes and circulates a working medium in a closed a circuit 22. In this case, the working medium is ethanol. However, it is possible to use other kinds of working mediums such as for example R245fa. The working medium pump 21 pressurizes and circulates the working medium to an evaporator 23. The working medium is heated in the evaporator 23, for example, by exhaust gases from the combustion engine to a temperature at which it evaporates. The working medium is circulated from the evaporator 23 to the expander 24. The pressurised and heated working medium expands in the expander 24. The expander 24 generates a rotary motion which may be transmitted, via a suitable mechanical transmission 25, to a shaft 26 of the powertrain of the vehicle 1.
Alternatively, the expander 24 may be connected to a generator transforming mechanical energy into electrical energy. The electrical energy may be stored in a battery. The stored electrical energy can be supplied to an electrical engine for driving of the vehicle 1 or a component on the vehicle 1 in a later state.
After the working medium has passed through the expander 24, it is led to the condenser 16. The working medium is cooled in the condenser 16 by coolant from the cooling system to a temperature at which it condenses. The working medium is led from the condenser 16 to a receiver 27. The pressure in the receiver 27 can be varied by means of a pressure regulator 27a. The working medium pump 21 sucks working medium in a liquid state from the receiver 27. A second control unit 29 controls the operation of the WHR-system. The second control unit 29 controls the operation of the working medium pump 21 and the expander 24. The WHR-system makes it possible to transform thermal energy from the exhaust gases to mechanical energy or electrical energy. A temperature sensor or a pressure sensor 30 senses the condensation temperature or the condensation pressure in the condenser 16.
The temperature of exhaust gases and thus the heating effect of the working medium in the evaporator 23 varies during different operating conditions. In order to maintain a substantially continuously high thermal efficiency in the WHR-system, the working medium in the condenser 16 is to be cooled with an adjustable cooling effect. It is favourable to establish a condensation pressure as low as possible at the different operating conditions. However, it is suitable to avoid negative pressure in the WHR-system by practical reasons. In view of these facts, it is suitable to provide a cooling of the working medium in the condenser 16 to a condensation pressure just above lbar. Consequently, in order to maintain a high thermal efficiency it is necessary to adjust the cooling effect of the working medium in the condenser 16 in view of the supplied heat energy from the exhaust gases such that the condensation pressure will be just above 1 bar. The working medium ethanol has a condensation temperature of 78°C at 1 bar. In this case, it is suitable to accomplish a condensation temperature of just above 78°C in the condenser 16.
Fig 2 shows a front view of the first radiator 9 and the second radiator 12. In this case, the first radiator 9 and the second radiator 12 are arranged in a common vertical plane. A not indicated radiator fan and ram air provide a cooling air flow through the first radiator 9 and the second radiator 12 during operation of the vehicle 1. The first radiator 9 receives coolant from the first radiator inlet line 7. The coolant leaves the first radiator 9 via the first radiator outlet line 10. The coolant is cooled in a first step in the first radiator 9. A part of the coolant flow in the first outlet line 10 is directed to the second inlet line 11b in the second circuit B. This part of the coolant flow is cooled in a second step in the second radiator 12.
During operation, the control unit 14 estimates a desired condensation temperature of the working medium in the condenser 16. When ethanol is used as working medium, a condensation temperature of about 80°C is desirable during most operating conditions. The control unit 14 receives information from the second control unit 29 about relevant operating parameters of the WHR system. Furthermore, the control unit 14 may receive information from the temperature sensor 18 about the temperature of the coolant in the engine outlet line 5 and information 31 about the coolant flow pumped by the coolant pump 3. In view of this information, the control unit 14 estimates or calculates suitable combinations of flow Image available on "Original document" and temperature T3of the coolant to be directed to the condenser 16 at which the working medium is cooled to a desired condensation temperature.
A part of the coolant flow in the engine outlet line 5 is directed to the first inlet line 1 la in the second circuit B. The control unit 14 controls the coolant flow through the first inlet line 1 la by means of the valve member 13. The control unit 14 controls the thermostat valve 6 such that a remaining part of the coolant flow in the engine outlet line 5 is distributed between the first radiator inlet line 7 and the bypass line 8. In case there is a low cooling demand of the combustion engine 2, a main part of or the entire coolant flow is directed to the bypass line 8. In case there is a high cooling demand of the combustion engine 2, a main part or the entire coolant flow is directed to the first radiator inlet line 7. A part of the coolant flow leaving the first radiator 9 enters the second inlet line 11b in the second circuit B. The coolant flow in the second inlet line 11b which is defined as a second coolant flow Image available on "Original document" is cooled in a second step in the second radiator 12 to the second temperature T2.
The control unit 14 controls the valve member 13 such that it receives a first coolant flow rhi at the temperature Ti via the first inlet line 11a and a second coolant flow Image available on "Original document" at the second temperature T2from the second inlet line 11b such that a mixture of said flows creates a third coolant flow rh3of a third temperature T3which cools the working medium in the condenser 16 to the desired condensation temperature. The coolant flow to the engine inlet line 4 and the combustion engine 2 is a mixture of the coolant flows from the bypass line 8, the coolant flow from the radiator outlet line 10, and the coolant flow from the return line 17. The control unit 14 also controls the thermostat valve 6 and the valve member 13 such that the coolant flow to the combustion engine 2 has a suitable temperature for cooling of the combustion engine 2.
Fig. 3 shows an alternative embodiment of the cooling system having a corresponding basic layout as in Fig. 1 but with an additional valve member 20 in the form of a two way throttle valve. The additional valve member 20 is arranged in a downstream position of a connection point between the first radiator outlet line 10 and the second inlet line 11b. The additional valve member 20 is a throttle valve which is adjustable in a stepless manner between a closed position and a fully open position. In the closed position, the additional valve member 20 directs the entire coolant flow from the first radiator outlet line 10 to the second inlet line 11b at the same time as the entire coolant flow from the bypass line 8 is directed to the engine inlet line 4. In a more or less open position, a part of the coolant flow from the first radiator outlet line 10 is directed to the second inlet line 11b and a remaining part of it is directed to the engine inlet line 4. In case the thermostat valve 6 directs the entire coolant flow to the bypass line 8, it is possible to set the additional valve member 20 in an open position such that a part of the coolant flow from the bypass line 8 is directed to the second inlet line 11b. The additional valve member 20 makes it easier to distribute the second coolant flow rh2to the second inlet line 11b with a high accuracy. In this case, it is enough that the three way valve 13 has an adjustable first inlet which controls the first coolant flow riu through the first inlet line 11a.
Fig. 4 shows a further embodiment of the cooling system. In this case, a three way valve member 32 is arranged in a position downstream of a connection point between the first radiator bypass line 8 and the first radiator outlet line 10. The three way valve 32, which has an adjustable inlet receiving a mixed coolant flow from the first radiator 9 and the first radiator bypass line 8, is used to direct a coolant flow to the first inlet line 11a. The inlet is adjusted such that the second inlet line 11b receives a second coolant flow Image available on "Original document" . The valve member 32 has a first adjustable outlet directing a first coolant flowImage available on "Original document" to the first inlet line 11a and a second outlet directing a remaining coolant flow to the engine inlet line 4. The control unit 14 adjusts the thermostat valve 6 in view of information from the temperature senor 18 about the coolant temperature in the engine outlet line 5.
During operating condition when the coolant temperature in the engine outlet line 5 is low, thermostat valve 6 directs the entire coolant flow to the bypass line 8. The control unit 14 adjust the inlet of the three way valve 32 such that a first coolant flow Image available on "Original document" is directed to the second inlet line 11b. The control unit 14 adjust the first outlet of the three way valve 32 such that a first coolant flowImage available on "Original document" is directed to the first inlet line 11a. The second outlet of the three way valve 32 directs the remaining coolant flow to the engine inlet line 4. During operating condition when the thermostat valve 6 directs a part of the coolant flow to the bypass line 8 and a remaining part of the coolant flow to the first radiator 9, a part of the coolant flow from the first radiator 9 is directed to the second inlet line 11b. A remaining part of the coolant flow from the first radiator 9 and the entire coolant flow from the bypass line 8 are directed to the inlet of the three way valve 32. The three way valve adjusts the first outlet such that a first coolant flowImage available on "Original document" is directed to the first inlet line 11a and a remaining part of the coolant flow is directed, via the second outlet, to the engine inlet line 4. During operating condition when the thermostat valve 6 directs the entire coolant flow to the first radiator 9, a part of the coolant flow from the first radiator 9 is directed to the second inlet line 11b. A remaining part of the coolant flow from the first radiator 9 is directed to the inlet of the three way valve 32. The three way valve adjusts the first outlet such that a first coolant flow Image available on "Original document" is directed to the first inlet line 11a and a remaining part of the coolant flow is directed, via the second outlet, to the engine inlet line 4.
The control unit 14 may control the three way valve 32 in view of feedback information from the temperature sensor 19 such that the first coolant flow Image available on "Original document" and the second coolant flowImage available on "Original document" in a mixed state form a desired third coolant flowImage available on "Original document" of a third temperature T3. It is to be noted that the temperature of the first coolant flow Image available on "Original document" directed to the first inlet line 11a has an equal or higher temperature than the second coolant flow Image available on "Original document" directed to the second inlet line 11b. In view of this fact and that the second coolant flowImage available on "Original document" is cooled in the second radiator 12, it is evident the second coolant flowImage available on "Original document" has a considerably lower temperature than the first coolant flowImage available on "Original document" before they are mixed.
Fig. 5 shows a further embodiment of the cooling system. In this case, a first inlet line 11a directs a first coolant flow rhi from an engine outlet line 5 of the first circuit to the second circuit B. A first three way valve 33 is arranged in a connection point between the engine outlet line 5 and the first inlet line 11a. The three way valve comprises an inlet, a first adjustable outlet directing a first coolant flow to the first inlet line 11a, and a second outlet directing a remaining coolant flow to the first radiator 9. The control unit 14 controls the first outlet of the first three way valve 33, such that a desired first coolant flow Image available on "Original document" is directed to the first inlet line 11a. A second inlet line 11b directs a second coolant flowImage available on "Original document" from a first radiator outlet line 10 to the second circuit B. A second three way valve 34 is arranged in a connection point between the first radiator outlet line 10 and the second inlet line 11b. The second three way valve 34 comprises an inlet, an adjustable first outlet directing a second coolant flowImage available on "Original document" to the second inlet line 11b, and a second outlet directing a remaining coolant flow to the engine inlet line 4.
The control unit 14 controls the first three way valve 33, such that a desired first coolant flow Image available on "Original document" is directed to the first inlet line 11a and the second three way valve 34 such that a desired second coolant flowImage available on "Original document" is directed to the second inlet line 11b. In this case, each inlet line 11a, 11b is provided with a separate three way valve 33, 34.
Thus, it is possible to control the coolant flows in the respective inlet lines 11a, 11b individually and independently of each other. In this case, the first circuit A does not comprise a first radiator bypass line. During operating conditions when the combustion engine has no cooling demand, the control unit 14 controls the second three way valve 34 such that the coolant flow to the combustion engine will be very small.
Fig. 6 shows an alternative embodiment of the cooling system having a corresponding basic layout as in Fig. 5 but with a second valve member 35 in the form of a two way throttle valve which is adjustable in a stepless manner. The second valve member 35 is arranged in a downstream position of a connection point between the first radiator outlet line 10 and the second inlet line 11b. By adjusting the throttling degree the second valve member 35, is possible to direct a desired second coolant flow m2to the second inlet line 11b while a remaining part of the coolant flow is directed to the engine inlet line 4. Also in this case, each inlet line 11a, 11b is provided with a separate valve members 33, 35 making it is possible to control the coolant flows in the respective inlet lines 11a, 11b individually and independently of each other. Also in this case, the first circuit A does not comprise any first radiator bypass line. During operating conditions when the combustion engine 2 has no cooling demand, the control unit 14 controls the second valve member 35 such that the coolant flow to the combustion engine 2 will be very small.
The invention is not restricted to the described embodiment but may be varied freely within the scope of the claims.

Claims (9)

Claims
1. A cooling system for a combustion engine (2) and a WHR-system (22), wherein the cooling system comprises a first circuit (A) allowing a coolant flow through a first radiator (9) and the combustion engine (2), and a second circuit (B) allowing a coolant flow through a second radiator (12) and a condenser (16) of the WHR-system, and wherein the second circuit (B) comprises a first inlet line (11a) configured to receive a first coolant flow Image available on "Original document" of a first temperature (T1) from the first circuit (A), a second inlet line (11b) configured to receive a second coolant flow Image available on "Original document" from the first circuit (A), which is cooled in the second radiator (12) to a second temperature (T2), a condenser inlet line (15) configured to receive the first coolant flow (rhi) from the first inlet line (11a) and the second coolant flow Image available on "Original document" from the second inlet line (11b), after the cooling of the second coolant flowImage available on "Original document" in the second radiator (12), and direct a mixture of said two coolant flowsImage available on "Original document" to the condenser (16), and a valve arrangement (33-35) by which it is possible to adjust the coolant flowImage available on "Original document" in at least one of the inlet lines (11a, 11b) such that the condenser inlet line (15) directs a third coolant flowImage available on "Original document" of a third temperature (T3) to the condenser (16) at which a working medium of the WHR-system is cooled to a desired condensation temperature, characterized in: - that the second inlet line (11b) is configured to receive coolant from the first circuit (A) in a position at which the coolant has its lowest temperature; and - that the valve arrangement comprises a valve member (33) configured to provide an adjustable first coolant flow Image available on "Original document" in the first inlet line (11a), wherein this valve member comprises a three way valve (33) provided with an inlet receiving coolant from the combustion engine (2), a first outlet configured to direct an adjustable first coolant flowImage available on "Original document" to the first inlet line (11a) and a second outlet configured to direct a remaining coolant flow to the first radiator (9).
2. A cooling system according to claim 1, characterized in that the first inlet line (11a) is configured to receive coolant from first circuit (A) in a position at which the coolant has its highest temperature.
3. A cooling system according to any one of the preceding claims, characterized in that the valve arrangement comprises a further valve member (34, 35) configured to provide an adjustable second coolant flow (rh2) in the second inlet line (11b).
4. A cooling system according to claim 3, characterized in that the further valve member (34, 35) is configured to provide an adjustable second coolant flow (m2) from the first radiator outlet line (10) to the second inlet line (11b).
5. A cooling system according to claim 3. characterized in that the further valve member (35) is a two-way throttle valve arranged in a first radiator outlet line (10) in a position downstream of a connection point between the first radiator outlet line (10) and the second inlet line (11b).
6. A cooling system according to claim 3, characterized in that the further valve member comprises a three way valve (34) provided with an inlet configured to receive coolant from the first radiator (9), a first outlet configured to direct an adjustable second coolant flow (m2) to the second inlet line (11b) and a second outlet configured to direct a remaining part of the coolant to the combustion engine (2).
7. A cooling system according to any one of the preceding claims, characterized in that the second circuit (B) comprises a return line (17) directing coolant from the condenser (16) to a position upstream of a coolant pump (3) in the first circuit (A).
8. A cooling system according to any one of the preceding claims, characterized in that the cooling system comprises a control unit (14) configured to receive information about at least one operating parameter and to control the valve arrangement (33-35) in view of this information.
9. A vehicle comprising a cooling system according to any one of the preceding claims 1-8.
SE1750553A 2017-05-08 2017-05-08 A cooling system for a combustion engine and a WHR system SE542237C2 (en)

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DE102018003322.9A DE102018003322A1 (en) 2017-05-08 2018-04-24 Cooling system for an internal combustion engine and an AR system

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US11434810B2 (en) * 2021-02-04 2022-09-06 GM Global Technology Operations LLC Vehicle thermal management system including mechanically driven pump, rotary valve(s), bypass line allowing engine outlet coolant to bypass heat exchanger(s), or combinations thereof

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