WO2011000852A1

WO2011000852A1 - Heat exchange system for use on vehicles

Info

Publication number: WO2011000852A1
Application number: PCT/EP2010/059250
Authority: WO
Inventors: Klaus-Jurgen Satzger; Andreas Reisch; Johann Klock; Peter Jekel; Franz Barnsteiner
Original assignee: Agco Gmbh
Priority date: 2009-07-02
Filing date: 2010-06-30
Publication date: 2011-01-06
Also published as: GB2471506A; GB0911479D0

Abstract

A heat exchange system (1b) to cool and/or heat at least one fluid on a vehicle having a cooling and/or heating circuit (1a) through which a refrigerant flows. The refrigerant flows in a refrigeration cycle through the circuit (1a) and a portion of the circuit (1a) exchanges heat with said at least one fluid.

Description

Heat Exchange System for use on Vehicles

This invention relates to a heat exchange system to heat and/or cooi fluids on vehicles, in paiticular on tractors and agricultuial machinery

It is well known to prov ide a vehicle exhaust gas treatment system in which a urea solution, (^"or example AdBlue® is injected into a catalytic converter located in the exhaust system of an internal combustion engine to ieduce the level of exhaust pollutants such as carbon monoxide, nitrogen oxide and particle matter in the exhaust gases.

Problems arise with such treatment systems since if the temperature of the urea solution exceeds 60⁰C due to exposure to the sun, or the close proximity of hot components on the vehicle, the urea solution starts to break down into corrosive constituents which can damage the components of the Ueatment system. It is known to cool various components on a vehicle by prov iding an air flow. It is also known to use a heat exchanger in which a fluid flow, such as an air or water flow is used to cool down cooling water, oil and fuel on a vehicle. However this is not effective for cooling a large volume of fluid and does not always cool the liquid to a desired temperature,

Pioblems also arise in low outdoor temperatures since the addition of antifreeze substances to a urea solution can alter the composition of the urea solution and generate undesnable components in the cleaned exhaust gases For this ieason antifree/e is not added to urea solutions AdBlue®, for example has a freezing point of about -l l ° C

EP 1698769 discloses a method of heating up a urea solution on a vehicle by using the coolant from a diesei engine

POBO¹V)II! KT It is also known to equip modem vehicles with HVAC (Heating, Ventilation and Air Conditioning) systems to cool down, or heat up drivers¹ cabs to keep the cab at a comfortable temperature despite the ambient temperature

It is an object of the present invention to provide a heat exchange system to cool and/or heat at least one fluid on a vehicle which is cheap and simple to install and use.

According to the invention there is provided a heat exchange system to cool and/or heat at least one liquid on a vehicle on a vehicle, said system comprising a cooling and/or heating circuit through which a refrigerant flows in a refrigeration cycle, the said at least one liquid to be cooled and/or heated being stored in a tank on the vehicle, said tank provided with a liquid outlet and wherein the refrigerant exchanges heat with said at least one liquid

By refrigerant, it is meant here a compound used in a heat cycle that undergoes a phase change from a gas to a liquid and back. By refrigeration cycle it is meant the thermodynamic cycle which is used by both refrigerators and heat pumps.

The cooling and/or heating circuit may be an HVAC circuit. The cooling and/or heating circuit is preferably an HVAC circuit for a vehicle cab.

Preferably, the HVAC circuit comprises a compressor, a condenser, an expansion valve and an evaporator.

Preferably, a portion of the circuit between the evaporator and the condenser exchanges heat with the fluid. More preferably, a portion of the circuit between the evaporator and the compressor exchanges heat with the fluid.

The invention makes use of the fact that an HVAC circuit and refrigerant is usually already installed on a vehicle to cool and/or heat up a driver's cab. It is therefore

FVGB09/022PCT lelatively cheap and simple to use this HVAC circuit to cool and/or heat fluids on the vehicle and minimal extra space is required on the vehicle for installing the heat exchange system The HVAC circuits installed on vehicles usually comprise a compiessor, a condensei, an expansion vahc and an evaporator thiough which an HVAC iefngerant is pumped Il the HVAC cucuit is used as a cooling cncuit, the refrigerant is pumped through a vapoui-comptession cycle By leversing the flow of the refrigerant through the cncuit components, an HVAC cooling cncuit can be used as a heat pump to provide heat An HVAC circuit may be provided with a reversing valve, or other additional means which enables the direction of refrigerant flow to be changed

For cooling/heating a driver's cab, the e\ aporator and expansion valve are typically situated in the cab of the vehicle and the remaining components placed in the engine bay To cool the air in the cab, a fan cπculates the hot an in the cab over the evapoiator which contains the HVAC refrigerant in a liquid-vapoui state The heat energy from the air is absorbed by the liquid-vapour mixture and causes the hquid pan of the refrigerant to evaporate The absorption of the heat from the cab lowers the temperatmes of the cab The refπgeiant is earned along a return hne to a compressor and then a condensei where the heat energy is subsequently rejected from the HVAC circuit

The fluid to be heated or cooled, tor example, a urea solution is pieterably stored in a tank on the vehicle The tank is connected to a fluid outlet. The tank may be connected, for example to a dosing module tor injecting the solution into the exhaust ducting In this way the uiea solution can be injected into the exhaust gas

In a first embodiment of the invention, a portion of the HVAC circuit is located in the fluid tank Preferably, a portion of the circuit between the evaporator and the compressor of the HVAC circuit is located within the tank When used as a cooling circuit the temperature of the HVAC circuit between the evaporator and the

P/GB⁽WCP:PCΓ compressor is approximately between 2-6⁽ C degrees even at

hot ambient temperatures The section ol the HVAC circuit in the fluid tank thus cools down the fluid

Alternatrvely, if the HVAC cπcυit is used as a heat pump, the portion of the HVAC circuit between the evaporator and the compressor can be used to heat the fluid

A suitable HVAC refrigerant for use in the HVAC circuit is for example, hydrofluorocarbon R 134a, or carbon dioxide R744. R744 is most suitable for use in a reversible refrigerant cycle

In a further embodiment of the invention, the HVAC circuit is provided with a heat exchanger through which the refrigerant and the fluid flows The first embodiment may also include a heat exchanger The heat exchanger is preferably provided between the evaporator and the condenser of the HVAC circuit and between the fluid tank and the fluid outlet An advantage of this arrangement is that a complete length of piping between the fluid tank (which may be located under the cab) and the dosing module (located in the engine bay) can run through the heat exchanger with the return line of the HVAC circuit thus maximising the surface area available for heat exchange and providing the fluid with as much insulation as possible from the heat of the engine bay.

Such an arrangement may also include a further line connecting the fluid tank and the heat exchanger so that fluid m the tank can continuously flow through the heat exchanger and back to the tank. In this respect the fluid m the tank can be continually cooled, or heated allowing the overall tempeiature of the fluid in the tank to be kept between - 15 to 60⁰C degrees

In yet a further embodiment of the invention the heat exchange system further comprises a secondary cooling and/or heating circuit carrying a cooling/heating fluid

P/GB09/022PCT In such an arrangement the HVAC refrigerant: provides a heat exchange for the fluid in the secondary circuit. The secondary circuit may pass through the evaporator of the HVAC circuit so that the evaporator acts as a heat exchange for the secondary circuit More preferably, a portion of the secondary circuit is located in the fluid tank to heat and/or cool the fluid.

The secondary circuit preferably comprises a pump

More preferably the secondary circuit comprises a storage tank for storing the secondary circuit fluid. The storage tank is preferably insulated. This means that even if engine is stopped the cooling/heating fluid in the storage tank can be circulated to cool, or heat the cab.

Additionally, the secondary circuit may comprise an additional heat core to cool down the fluid, for example, the urea solution even when the engine is not working. In this arrangement the heat core is placed in the secondary circuit so that fluid from the fluid tank can be pumped through it continuously thus maintaining the temperature of the fluid in the tank below 60⁰C.

The invention will now be described, by way of example only with reference to the following drawings in which:

Figure 1 is a circuit diagram of a heat exchange system for cooling and/or heating fluids in accordance with the present invention.

Figure 2 is a circuit diagram of a further embodiment of the heat exchange system, in accordance with the invention,

Figure 3 is a circuit diagram of an alternative arrangement of the heat exchange system of figure 2 in accordance with the invention, and

Figure 4 is a circuit diagram of a yet a further embodiment of the heat exchange system which comprises a secondary heating/cooling circuit.

P/GB09/022PCT Figure 1 shows a heat exchange system I b to cool and/or heat fluids on a vehicle, for example, a tractor in accordance with the invention. In this example, the system Ib provides a cooling means for a urea solution for an exhaust gas treatment system 30 on a tractor 1 , although the system can also be used for heating and/or cooling other fluids on a vehicle.

As is usual on modern tractors and agricultural machinery with a driver's cab/compartment, an HVAC cooling circuit I a is installed for providing air conditioning in the driver's cab 3. A refrigerant flows around the HVAC circuit Ia in a refrigeration cycle in the direction indicated by the arrows. The refrigerant may be for example, hydrofluorocarbon R 134a, or carbon dioxide R744. With the refrigerant flowing in the direction shown, the refrigerant undergoes a vapour-compression cycle and is a cooling circuit.

The tractor is shown diagrammatically as being separated into an engine bay 2, a cab 3 and chassis area 4. The evaporator 19, fan 20 and compression valve 18 are located in the cab 3 and the remaining components, compressor 10, condenser 12, accumulator 16 and blower 14 are located in the engine bay 2. The refrigerant enters the compressor 10 as a saturated vapour and is compressed by a compressor 10 resulting in an increase in temperature and pressure. The compressor 10 may be driven by the main belt drive system of the tractor (not shown), or by electric power provided by the supply network of the tractor. The refrigerant exits the compressor 10 as a superheated vapour and is routed through a first pipe 1 1 into the condenser 12. The condenser 12 is integrated in the cooling arrangement 13 of the tractor 1 and usually comprises one or more tubes, or a coil through which the HVAC refrigerant flows. The tubes, or coil may be cooled down by a water, or air flow. The cooling arrangement 13 may be used as a heat exchanger to cool down other components on the tractor such as cooling water, oil for the gear box or hydraulic circuit, fuel or combustion air.

P/GBW/022PCT In figure 1 the cooling arrangement 13 and there! oie condenser 12 is cooled by an ambient air stream A which is blown by blower 14 resulting in the HVAC refrigerant coolmg and condensing The refrigerant is then touted via a second pipe 15 to an accumulator 16. The accumulator 16 provides a reservoir for the refrigerant fluid It contains a granulated material filter which absorbs water droplets in the iefrigerant and thus protects the compressor from damage from water such as erosion

The iefiigerant is then routed through a third pipe 17 to an expansions valve 18 which adiabatically decreases the pressuie of the refrigerant The expansion valve 18 can be integrated with the evaporator 19, the next component in the circuit Ia The rapid drop m pressure iesults in a huge temperature drop to around 2° C which also cools down the evaporator 19 An air stieam from the driver's compartment/cab 3 is fed through the evaporator 19 by an HVAC blower 20, cooled down and then fed back to the driver's compartment/cab 3 The cab air is cooled down by the refrigerant absorbing some of the heat energy from the cab air. The temperature of the refrigerant rises due to the energy absorption but still remains at a low temperature level. The refrigerant is fed back to the compressor 10 via the return pipe 21 and the circuit continues Following the diiection of flow around the circuit the part of the circuit between the compressor 30 and evaporator 19 which carries the warmer refrigerant is known as the high pressure side of the circuit. The part of the circuit between the evaporator 19 and the compressor 10 is known as the low pressure side of the circuit which carries the cooler refrigerant The return pipe 21 carries the refrigerant at a very low temperature of between 2 to 6⁰C similar to the temperature inside the evaporator 19 The piping 17, 21 , 1 1 , 15 used within the refrigerant circuit is Ia is usually made from steel tubes, or a combination of steel tubes and flexible rubber hoses The means to control the cooling system and to move the refrigerant through the circuit is well known and therefore not described here.

P/GBW/O22PCT The urea solution 31a is stored in a urea tank 31 which is situated close to the circuit J a₁ below the cab 3 in the chassis area 4. The urea tank 31 is a part of the urea exhaust gas treatment system 30 which also comprises a supply module 32 having a pump 32a and a urea return line 32b, a dosing module 34 and a level indicator (not shown). The dosing module 34 ts situated m the engine bay 2 close to the exhaust gas ducting system 33. The pump 32a of supply module 32 can circulate urea solution 31a in the urea exhaust gas treatment svstem 30. Depending on the exhaust gases emitted by the tractor, the dosing module 34 will inject urea solution by an injector (not shown) into the exhaust gas through the ducting system 33. Urea solution which has been pumped from the tank 31 but which is not injected into the ducting system 33 is returned to the uiea tank 31 via the return line 32b.

To prevent the temperature level inside the tank 31 from exceeding the critical level of 60⁰C, a portion 22 of the return pipe 21 of the HVAC ciicuit between the evaporator 19 and compressor 10 is placed inside the urea tank 31 and acts as a heat exchanger. Thus the HVAC refrigerant in the pipe 21 and the urea solution 31a in the tank 31 exchange heat and this way the urea can be kept at a desired temperature. . Using portion 22 of the return pipe 21 between the evaporator 19 and compressor 10 as a heat exchanger does not affect the performance of the HVAC circuit.

Figure 2 shows a further embodiment of the heat exchange system Ib in accordance with the invention. Here, the return pipe 21 which carries an HVAC refrigerant from the evaporator 19 to the compressor 10 is equipped with an heat exchanger 35 to cool down the urea solution 31 a on its way from tank 31 and supply module 32 to dosing module 34. Since both the return pipe 21 and the urea pipe 36 are routed parallel to one another from cab 3 and/or chassis 4 to engine bay 2, a compact, pipe-in-pipe heat exchanger 35 maximises the heat exchange surface area between the urea solution and the refrigerant but does not require a large amount of installation space. The refrigerant can be fed into the outer piping of the pipe-in-pipe heat exchanger whilst the urea solution is guided through the centre pipe. The use of the heat exchanger 35

PΛJB09/0.2PCT further provides insulation of the urea against heat from the engine bay 2, however, since in this arrangement the system I h is only cooling down the urea solution when it is fed to the dosing module 34, the temperature of the urea solution 3 Ia in the tank 31 is not affected.

In a further arrangement of the system 3 Ib shown in figure 3, the heat exchanger 35 is connected to urea pipe 36 and urea return line 32c which leads back to the tank 31, Pump 32a is constantly pumping urea solution to the dosing module 34. If the dosing module is not injecting urea solution into the exhaust ducting 33, urea solution returns to the tank 31 through return line 32c. With this arrangement the urea solution is pumped through the heat exchanger 35 and returned to the tank 31 ensuring the urea solution 31a in the tank 31 is maintained below a critical temperature. If dosing module 34 is injecting urea solution into the exhaust ducting 33, the pump 32a supplies the dosing module 34 with urea solution from the tank 31 which flows through the heat exchanger 35 and urea pipe 36.

The configuration of pump 32a, tank 31 or dosing module 34 relative to the heat exchanger 35 is variable and can be adapted according to the applicational needs. For example, the heat exchanger could also be installed in the return line 32, or the pump 32a could be installed between dosing module 34 and heat exchanger 35.

By reversing the direction of flow of refrigerant in the circuit, the HVAC circuit Ia can be used as a heat pump to heat fluids. It uses the same basic refrigeration cycle as with the cooling circuit, however when used as a heat pump the evaporator 19 absorbs heat and rejects the heat through the condenser 12. Additional components needed to reverse the circuit are known in the art and are therefore not described.

The heat exchange system 31b described in figures 1 to 3 can only provide HVAC heat exchange when the combustion engine is ainning and the compressor 10 is driven. If the compressor 10 is driven by electric energy supplied by a battery system,

P/GB(^"W/D22PCT IO

an HVAC system could be provided for an independent HVAC system working without a running engine. It is common in trucks to provide independent HVAC systems with means for storing a second heating/cooling fluid which can be used for heating/cooling on the vehicle when the main HVAC system is not operated.

It is well known to cool down the injector of the dosing module 34 which heats up due to the hot exhaust gases. The heat exchange circuit Ib may be used to cool down the injector.

Figure 4 shows an HVAC circuit 31 1a which is not directly connected to the cab 3 but via a secondary circuit 200. The HVAC circuit is similar to those shown in figures 1 to 3 in that the refrigerant is compressed by compressor 10. cooled by condenser 12, fed through accumulator 16 and then expanded by expansion valve 18 and fed into the evaporator 100. The evaporator 100 functions as an heat exchanger to cool down a secondary circuit 200 which does not contain a refrigerant but a cooling fluid similar to standard engine cooling fluids, such as a water glycol mixture. The secondary circuit fluid is pumped to the heat exchanger 202 in the cab 3 to cool down the cab interior similar to the previous mentioned systems. The secondary circuit fluid is then guided into an insulated storage tank 203. Even if the cab 3 does not require cooling down, the secondary circuit fluid can be circulated to cool down and thus cooled fluid is stored inside the storage tank 203. If the vehicle engine is stopped, the secondary circuit fluid in the storage tank 203 cab can still be circulated to cool down the cab which may be necessary in hot climates, for example during a driver's rest period.

In addition, the secondary circuit fluid is guided through the urea tank 301, or connected to the urea circuit 36 by an additional core heater 302 to cool down the urea solution 301a during off operation of the engine.

By reversing the flow of refrigerant around the HVAC circuit 311a, the circuit may be used as a heat pump to heat a fluid (and a cab). A particularly good refrigerant to be

P/GBOW22PCT used for this purpose is R744 carbon dioxide. By reversing the cucuit, the evaporator 100 of the cooling circuit becomes a condenser and the condenser 100 of the cooling circuit becomes an evaporator. The refrigerant flowing through the heat pump evaporator absorbs heat from the an and the refrigerant is compressed and flows to the heat pump condenser where the heat is rejected. The high pressure and low pressure sides of the circuit are swapped so that a heated refrigerant fluid flows through pipe 21 of the HVAC circuit which can be used to heat a fluid. This means that the secondaiy circuit 200 shown in figure 4 can also be used to heat the cab 3 and the fluid 301a.

The invention has the advantage that it makes use of an HVAC circuit already installed on a vehicle to heat/ cool a liquid, thus reducing cost and saving space on a vehicle.

P/GBOWO22PCT

Claims

1. A heat exchange system to coo! and/or heal at least one liquid on a vehicle, said system comprising a cooling and/or heating circuit through which a refrigerant flows in a refrigeration cycle, the said at least one liquid to be cooled and/or heated being stored in a tank on the vehicle, said tank provided with a liquid outlet and wherein the refrigerant exchanges heat with said at least one liquid.

2. A heat exchange system as claimed in claim 1 wherein the circuit comprises a compressor, a condenser, an expansion valve and an evaporator.

3. A heat exchange system as claimed in any preceding claim wherein the cooling and/or heating circuit is an HVAC circuit for a vehicle cab..

4. A heat exchange system as claimed in claim 2 or claim 3 wherein a portion of the circuit between the evaporator and the condenser exchanges heat with the fluid.

5. A heat exchange system as claimed in any preceding claim wherein a portion of the circuit is located in the fluid tank and exchanges heat with the fluid.

6. A heat exchange system as claimed in any of claims 1 to 4 wherein the circuit comprises a heat exchanger through which the refrigerant and the at least one fluid flow.

7. A heat exchange system as claimed in claim 5 or claim 6 comprising a return connection between the fluid tank and the heat exchanger so that fluid in the fluid tank can flow through the heat exchanger and back to the fluid tank.

G B (W< 122 PCT claims

8 A heat exchange system as claimed in any preceding claim wherein the heat exchange system further comprises a secondary heating/cooling ciicuit carrying a secondary circuit heating/cooling fluid

9 A heat exchange system as claimed in claim 8 wherein the evaporator of the circuit is as a heat exchanger with the secondary circuit

10 A heat exchange system as claimed in claim 8 or claim 9 wherein a portion of the secondary circuit is located m the fluid tank.

1 1. A heat exchange system as claimed in any of claims 8 to 10 wherein the secondary circuit comprises a storage tank for storing the secondary circuit fluid

12 A heat exchange system as claimed in any of claims 8 to 11 wherein the secondary circuit comprises a heating core through which the secondary ciicuit fluid and (he at least one fluid flow

13. As heat exchanger as claimed in any preceding claimed wherein the refrigerant is one of either a hydrofluorocarbon R134A or carbon dioxide R744.

GB(Wf)^PCT ϋaims