Radiator for automotive heat transfer

Abstract

An automotive cooling system, the system including: a PCM cooling circuit, the PCM cooling circuit in heat transfer communication with an automotive battery; the circuit including a fluid pathway loop directed from a coolant pump to a battery cooling circuit and a PCM radiator; said PCM radiator arranged to receive coolant from PCM cooling circuit to dissipate heat to a PCM filled heat exchanger.

Description

[0001] RADIATOR FOR AUTOMOTIVE HEAT TRANSFER

[0002] Field of the Invention

[0003] The invention relates to systems and methods for the heat transfer of energy within an automotive vehicle.

[0004] Background

[0005] A hybrid vehicle comprises an internal combustion engine, which transmits drive torque to the driving wheels via a mechanical transmission or to an electric generator, and at least one electric drive mechanically connected to the driving wheels and electrically powered by an electrical energy storage system. Normally, the electrical energy storage system comprises a pack of electrochemical batteries, i.e. electrostatic storage systems, which are connected to each other in parallel and series.

[0006] An electric vehicle comprises at least one electric drive mechanically connected to the driving wheels and electrically powered by an electrical energy storage system. Normally, the electrical energy storage system comprises a pack of electrochemical batteries that are connected to each other in parallel and series.

[0007] In the typical use of electrical energy storage systems, their use generates heat. To avoid irreparable damage to the storage systems, i.e. stopping the vehicle due to exceeding the temperature limit, the cooling systems of electrical energy storage systems need to dissipate the generated heat. To dissipate the generated heat, different types of cooling methods are used, including forced air, forced water (indirect cooling), and forced oil (direct or indirect cooling). Forced air-cooling systems do not have the thermalperformance to meet the demands of overall high-performance applications (such as in racing cars).

[0008] In liquid cooling systems (either direct or indirect), a radiator and / or HVAC is used to reduce the temperature of the fluid entering the electrical energy storage system; a pump moves the liquid within the cooling circuit.

[0009] A radiator is able to exchange heat power in relation to the surface area through which the air passes, the speed of the air itself, and the temperature of the liquid inside.

[0010] An HVAC is a component that exchanges thermal power using electrical energy drawn from the storage system. The electric drive of electric or hybrid vehicles also requires a cooling system, commonly realised by means of a radiator and a pump moving a fluid, usually water and glycol. Electric drives with low power densities make use of forced air movement via fans or natural convection to dissipate heat.

[0011] In the case of both the liquid-cooled electric drive and the liquid-cooled electrical energy storage system, heat is generated which must be dissipated via a radiator. The liquid-cooled systems described above are plagued by radiator issues. By way of non-limiting example, it should be noted that the low air flow to the radiator, either due to the radiator's small size or the low velocity of the air flow through it, leads to an inability to dissipate all the heat from the electrical energy storage system and / or the electric drive.

[0012] In the classical dimensioning of a vehicle cooling system, the thermal output for which the cooling circuit is constructed, whether including HVAC or equipped with a radiator only, is less than the maximum output that the electrical energy storage system or the electrical machine is capable of producing, depending on the fact that the average performance is considerably lower than the maximum.Summary of the Invention

[0013] In one aspect, the invention provides an automotive cooling system, the system including: a PCM cooling circuit, the PCM cooling circuit in heat transfer communication with an automotive battery; the circuit including a fluid pathway loop directed from a coolant pump to a battery cooling circuit and a PCM radiator; said PCM radiator arranged to receive coolant from PCM cooling circuit to dissipate heat to a PCM filled heat exchanger.

[0014] An objective of the present invention is to provide a cooling system for electric energy storage systems for vehicles with electric or hybrid propulsion, which cooling system is free from the drawbacks described above.

[0015] According to the present invention, a cooling system is provided for an electric energy storage system for a vehicle with electric propulsion.

[0016] The invention, in broad terms, is directed to the use of two different sources of cold energy to extract heat from the cooling fluid of an electrochemical or electrostatic storage system for automotive and stationary applications.

[0017] Certain embodiments of the invention may be applied to:

[0018] Indirect liquid cooling systems, making use of "cooling plate" where the coolant of the storage system flowsIndirect liquid cooling systems with "tube cooling" where the cooling liquid of the storage system flows

[0019] • direct liquid cooling systems, where the cooling liquid flows in direct contact with the electrochemical or electrostatic cells of the storage system.

[0020] The heat extracted by means of the coolant from the electrochemical or electrostatic storage system must be appropriately and effectively dispersed to the environment by the use of room air / cooling liquid radiator or by the use of liquid air conditioning (HVAC) refrigeration cycle systems.

[0021] In one embodiment, a radiator according to the present invention may use, as cooling sources, either ambient air conveyed to the radiator in the traditional way, thus either free or forced through a fan, or a special phase change material (PCM) with phase change temperature from solid to liquid in a specific window depending on the type of electrochemical or electrostatic cell used in the storage system.

[0022] Brief Description of Drawings

[0023] It will be convenient to further describe the present invention with respect to the accompanying drawings which illustrate possible arrangements of the invention. Other arrangements of the invention are possible, and consequently the particularity of the accompanying drawings is not to be understood as superseding the generality of the preceding description of the invention.

[0024] Figure 1 is a schematic view of a heating and cooling system according to one embodiment of the present invention;Figure 2A and 2B are isometric views of a radiator according to one embodiment of the present invention;

[0025] Figure 3 A and 3B are plan view and sectional view of the radiator of Figures 2A and 2B; Figure 4 is an isometric view of a radiator according to a further embodiment of the present invention;

[0026] Figure 5 is a plan view of a radiator according to a further embodiment of the present invention, and;

[0027] Figures 6A, 6B and 6C are isometric views of a radiator according to a further embodiment of the present invention.

[0028] Detailed Description

[0029] A phase-change material (PCM) is a substance which releases / absorbs sufficient energy at phase transition to provide useful heat or cooling. Generally, the transition will be from one of the first two fundamental states of matter - solid and liquid - to the other. The phase transition may also be between non-classical states of matter, such as the conformity of crystals, where the material goes from conforming to one crystalline structure to conforming to another, which may be a higher or lower energy state. The energy released / absorbed by phase transition from solid to liquid, or vice versa, the heat of fusion is generally much higher than the sensible heat.

[0030] By melting and solidifying at the phase-change temperature (PCT), a PCM is capable of storing and releasing large amounts of energy compared to sensible heat storage. Heat is absorbed or released when the material changes from solid to liquid and vice versa orwhen the internal structure of the material changes; PCMs are accordingly referred to as latent heat storage (LHS) materials.

[0031] There are two principal classes of phase-change material: organic (carbon -containing) materials derived either from petroleum, from plants or from animals; and salt hydrates, which generally either use natural salts from the sea or from mineral deposits or are byproducts of other processes. A third class is solid to solid phase change.

[0032] In one embodiment, a radiator according to the present invention may be equipped with ducts for the passage of the coolant of the electrochemical or electrostatic storage system, moved by external pump.

[0033] The radiator may be equipped with fins for the optimization of heat exchange between the coolant of the electrochemical or electrostatic storage system and the ambient air, provided with forced motion by fan or free to flow over the radiating surface of the radiator fins.

[0034] In a further embodiment, the radiator may be equipped with special ducts for housing an appropriate amount of phase change material. These ducts may be in close contact with the coolant ducts of the electrochemical or electrostatic storage system, so as to have ample surface area for heat exchange between the two media, the liquid precisely and the phase-change material. In addition to or as an alternative to ductwork, the phase-change material may be housed in cylindrical chambers formed inside the coolant manifolds entering and leaving the radiant mass. These hermetically sealed cylindrical chambersallow only for heat exchange between the coolant and the phase-change material, and are provided with a threaded hole for inlet or replacement of the phase-change material.

[0035] In a further embodiment, the radiator may have three separate, non-miscible environments, one used for the flow of electrochemical or electrostatic storage system coolant, which is the medium from which heat is extracted, the second used by the ambient air flow, a medium engaged for the removal of some of the heat from the electrochemical or electrostatic storage system coolant, the third, finally, occupied by the phase-change material, also engaged for additional heat removal from the coolant of the electrochemical or electrostatic storage system during the phase-change phase of the phase-change material, in order to use the latent heat of liquefaction to impart a cooling "boost" to the coolant of the electrochemical or electrostatic storage system.

[0036] In one embodiment, the cooling system according to the present invention may provide a fluid circulating inside the battery pack, driven by an external pump. At the module outlet, the fluid is sent to the special an air / liquid radiator with fan and to a filter. The proposed system includes using the circuit external to the battery pack and modules by designing a special PCM / dielectric fluid heat exchanger, to be used instead or in series with the air / dielectric fluid radiator. In fig.2 the effect on a typical temperature rising ramp is represented.

[0037] One object of the present invention may be to delay or avoid, during a vehicle mission, the achievement of the maximum temperature limit allowed for each single cell, which may be equal to 60 ° C, which would force the car to stop and shutdown. The solution istherefore exploiting the latent heat of liquefaction of the PCM using PCM together with the liquid cooling of the modules, in this special heat exchanger PCM / dielectric fluid.

[0038] Figure 1 shows a schematic view of an external cooling circuit of an automotive battery pack 5 with HVAC. A coolant pump 40 drives coolant through a coolant heater 50, to cool (or heat) the battery cooling circuits 75.

[0039] The HVAC system includes an AC condenser 10, with an HVAC circuit which includes a typical expansion valve 45 with an evaporator 35 and driven by a compressor 25. The HVAC circuit also includes thermal coupling with the coolant system passing directly through the battery cooling circuit 75.

[0040] The battery cooling circuit includes a 3 way coolant control valve 70 providing three alternative flow paths for the coolant, being:

[0041] A. A maximum heat loop;

[0042] B. A maximum cold loop, and;

[0043] C. A temperature regulating loop.

[0044] For the maximum heat loop A, the coolant is diverted away from the battery cooling radiator 15 and HVAC circuit, to recirculate via the coolant pump. Any heat received from the battery cooling circuit 75 remains undissipated.

[0045] The maximum cooling loop B is arranged to take advantage of the HVAC circuit. Here, the coolant is directed to the battery chiller 60, which is thermal coupled, and so in heattransfer communication with the expansion valve 55 of the HVAC circuit. In this way, the coolant receives additional cold energy from the evaporation of the coolant with the HVAC circuit, further reducing the temperature of the coolant, before being applied to the battery cooling circuit 75.

[0046] For temperature regulation C, the coolant is directed through the battery cooling radiator 15, which includes an air separator 20 and surge tank 30, and so the coolant receives cold energy directly from the radiator 15.

[0047] Figures 2A and 2B show one embodiment of a cooling system 85, having a volume for the positioned phase change material of the inlet and outlet manifolds. The system 85 includes an inlet 95 for receiving the cooling fluid of the electrostatic or electrochemical storage system into an inlet manifold 115. The inlet 90 and outlet 100 manifolds include PCM inlets 120, 125 for inserting PCM material. Intermediate the inlet and outlet manifolds is a heat transfer portion 105 acting as an air / fluid radiant mass.

[0048] Figures 3A and 3B show cross-sectional views of the cooling system 85, whereby the inlet 90 and outlet 100 manifolds include an array of conduits 130, 140 for receiving the PCM material, with the conduits 130, 140 surrounded by a chamber within each manifold 90, 100 to allow the cooling fluid / coolant to be in heat transfer communication with the PCM, through the walls of the conduits 130. 140. The coolant then passes from the inlet manifold 90 to the outlet manifold 100 through helicoidal piping of the heat transfer portion 105, and in so doing dissipate heat to the atmosphere.The heat transfer portion can take several forms, with Figure 4 having a conventional spike air fin heat transfer profile 170. The radiator of Figure 4 include similar features including inlet and outlet manifolds 160, 180, inlets 165, 175 for inserting the coolant and a PCM inlet 150. A further connection 155 allows for attaching a coolant expansion tank (not shown).

[0049] Figure 5 shows a further embodiment, whereby the spike heat transfer fins of the heat transfer portion 195 is replaced by herringbone air fins 190. The radiators 145, 187 of Figures 4 and 5 are otherwise identical.

[0050] In a still further embodiment, Figures 6A, 6B and 6C show a radiator 193 having separable portions 197, 235. When the portions are connected, the radiator 193 has a similar arrangement of inlet and outlet manifolds 200, 225, with PCM inlet 205 and coolant inlet and outlets 210, 220.

[0051] The removable cartridge 197 of the radiator 193 may be equipped with vertical channels 260 of the heat transfer portion 215 and an upper reservoir 200 in which to house phasechange material. This solution allows rapid replacement of the cartridge with another cartridge containing phase-change material with a different melting point. This arrangement may be particularly suitable for motorsports applications of the invention.

[0052] The innovative radiator aims to amplify the thermal output of the system by realizing greater heat extraction from the cooling liquid of the electrochemical or electrostatic storage system. The innovative radiator will be equipped with:• Ducts for the passage of the coolant of the electrochemical or electrostatic storage system, moved by external pump.

[0053] o Fins for the optimization of heat exchange between the coolant of the electrochemical or electrostatic storage system and the ambient air, provided with forced motion by fan or free to flow over the radiating surface of the radiator fins.

[0054] o Special ducts for housing an appropriate amount of phase change material .

[0055] These ducts will be in close contact with the coolant ducts of the electrochemical or electrostatic storage system, so as to have ample surface area for heat exchange between the two media, the liquid precisely and the phase -change material.

[0056] o

[0057] Finally, the special radiator can be made, as a design and construction variant, with a removable cartridge equipped with vertical channels and an upper reservoir in which to house phase-change material. This solution allows rapid replacement of the cartridge with another cartridge containing phase-change material with a different melting point.

[0058] The operating principle on which the special radiator is based is the exploitation of the latent heat of liquefaction of the PCM; as the batteries heat up, the temperature of the liquid coolant of the electrochemical or electrostatic storage system increases until it reaches the melting point of PCM and then temperature stays stagnant until all the PCM material has been melted. Afterward, the temperature starts to increase again.

Claims

Claims1. An automotive cooling system, the system including:a PCM cooling circuit, the PCM cooling circuit in heat transfer communication with an automotive battery;the circuit including a fluid pathway loop directed from a coolant pump to a battery cooling circuit and a PCM radiator;said PCM radiator arranged to receive coolant from PCM cooling circuit to dissipate heat to a PCM fdled heat exchanger.

2. The system according to claim 1, further including an HVAC circuit, said HVAC circuit in heat transfer communication with a battery chiller;said battery chiller in selective heat transfer communication with the PCM cooling circuit;wherein the PCM cooling circuit is arranged to be selectively switched from the PCM radiator to the battery chiller, such that in a first arrangement the PCM cooling circuit is arranged to receive cold energy from the PCM radiator and in a second arrangement the PCM cooling circuit is arranged to receive cold energy from the HVAC circuit via the battery chiller.

3. The system according to claim 1 or claim 2, wherein the PCM radiator comprises an inlet manifold for receiving coolant and an outlet manifold for releasing coolant, each of said manifolds including the PCM filled conduits for applying cold energy to the coolant;said manifolds separated by an intermediate heat exchanger through which the coolant passes.

4. The system according to claim 3, wherein the intermediate heat exchanger includes piping having a heat exchange profile for the dissipation of heat from the coolant.

5. The system according to claim 3 or 4, wherein the PCM radiator is separable, such that one of said manifolds is removable from the PCM radiator.

6. The system according to claim 5, wherein the separable manifold includes at least a portion of the intermediate heat exchanger.

7. The system according to claim 4, wherein the heat exchange profile includes an array of spike fins.

8. The system according to claim 4, wherein the heat exchange profile includes an array of herringbone fins.

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