Patent Application
20230321627
The disclosure claims the benefit of priority of co-pending European Patent Application No. 22166908.8, filed on Apr. 6, 2022, and entitled “Heat Exchange Module,” the contents of which are incorporated in full by reference herein.
The disclosure relates to a heat exchange module including a corrugated top heat exchange substrate and a corrugated bottom heat exchange substrate, the substrates being spaced apart in a transverse direction, each substrate having ridges and channels that extend in a length direction, the channels and ridges of the top substrate extending parallel to the channels and ridges of the bottom substrate. The disclosure also relates to an assembly of such heat exchange modules, to a catalyst/steam reforming assembly in a vehicle with an internal combustion engine (ICE), and to a vehicle with an internal combustion engine including such a catalyst/steam reforming assembly.
Fuel Reforming technology that uses the heat available in the exhaust to upgrade ethanol fuel to a higher energy level hydrogen fuel is applied in the combustion engines with higher thermal efficiency for the ICE as a result.
To manufacture the heat exchanger with different pressures and tightness requirements for the two sides is a challenge.
Another challenge is to stack and assemble the components in the correct position for a rapid and reliable automated process of welding or soldering of the pipes.
A third challenge is to manage the thermal expansion on both sides of the heat exchanger without introducing tension that may lead to cracks.
It is an object to solve these issues and to provide a heat exchange module that enables cheaper automatic production in higher volumes. It is also an object to provide a heat exchanger that can accommodate thermal expansion and contraction that occurs in process involving temperatures above 4000C that are subject to rapid variations, so that it can be used in the high temperature process of steam reforming and that has good tightness properties for H2. The heat exchanger should be compact and sturdy so that it is suitable for automotive applications.
Furthermore, the heat exchanger should be easily adaptable to provide the required capacity. It is again an object to provide a vehicle with an internal combustion engine (ICE) having an ethanol fuel reformer including one or more heat exchanger modules according to the disclosure.
A heat exchange module according to the disclosure includes tubes extending in a width direction between the top and bottom substrates, in heat exchanging contact with the ridges, the width direction being oriented transversely to the length direction of the channels and the ridges, from an inflow side to an outflow side, a top and a bottom casing member including casing surfaces adjacent the top and bottom substrates and having at the inflow and outflow sides a transverse side wall with slits oriented in the transverse direction and accommodating the tubes, the side walls of the top and bottom casing members overlapping and being mutually connected by soldering or brazing.
The tubes can accommodate thermal expansion and contraction while maintaining fluid tightness.
The tubes are maintained clamped between the top and bottom corrugated substrates and can freely mover relative to the substrates so that thermal expansion and contraction of the different components is allowed while maintaining good heat transfer contact.
The tubes maintain secure fluid tightness at high and varying temperatures and pressures. This makes the module suitable for use in an ethanol steam reformer, to operate at temperatures between 400° C. and 1000° C.
The slits in the casing side walls, which may be formed of sheet metal, receive the tubes in a high-speed automated assembly process, and align the tubes in accurately defined positions. The slits can effectively be sealed by welding or soldering to seal the passage of each tube through the side wall.
The overlapping side walls of the casing members result in gas-tight connection by welding or soldering.
The modules according to the disclosure can be stacked and combined to form a heat transfer unit that is suited for specific applications, such as a combined three-way catalyst and steam reforming unit for ethanol for use in vehicles including an internal combustion engine.
Substrates may be connected to a casing member along a casing side edge that is situated along a lower part of a respective casing side wall.
By welding or brazing the substrates along their edges to the side walls of the casing, a strong and reliable interconnection is obtained allowing sufficient relative movement between the casing and the substrate for accommodating thermal expansion while maintaining a defined position.
The tubes at the position of the transverse side walls may have a straight section extending in the width direction, transversely to the side walls.
The straight end parts of the tubes allow strong and fluid tight connection of the tube exterior to the slits in the side walls, which is particularly suitable in cases the heat exchange module is used in applications in which hydrogen is present in the module.
The slits in the side walls can include at their free end a V-shaped receiving part for guiding of the tubes upon placement of the tubes in the slits.
The V-shaped receiving part centers the tubes on placing in the slits and facilitates automated positioning and welding/brazing at high speeds.
The tubes may extend along an undulating trajectory with undulations in the width direction.
The undulating path of the tubes causes turbulence in the gases flowing over and under the tubes in crossflow, and results in improved heat transfer.
The undulating trajectory includes bend parts at a distance from a line that is parallel to the width direction, a distance of the two adjacent undulations being between 1.5 and 5 times a width of a channel.
The dimensions of the undulations in the pipe allow specific tailoring of the contact area for heat transfer between the pipe and the corrugated substrates. A larger area towards the gases flowing through the channels may balance the inner surface area that is in contact with the contents of the tubes. This ratio can be established using tests or CFD to work at peak efficiency for both sides of the heat exchanger.
The position of the ridges of the upper substrate in the width direction may correspond to the position of the channels of the lower substrate.
The tubes are firmly clamped between the ridges of the upper and lower substrate for obtaining good positioning and heat transfer while allowing sufficient relative movement for accommodating thermally induced movements.
The substrates may be coated with a platinum group metal.
In addition to the substrates, that may act as a three-way catalyst (TWC), the tubes may be coated with a platinum-group metal (PGM) to activate the reforming process. The coating of the tubes may have a different specification of PGM than the TWC substrate.
The modules of the disclosure can be formed into an assembly of at least two modules stacked on top of each other, the bottom surface of the upper casing member being soldered or brazed to the top surface of the lower casing member.
A combined catalyst/steam reforming assembly may be formed, including a heat exchange module according to disclosure, exhaust gases being led through the channels and ethanol and steam through the tubes.
A vehicle is provided including an internal combustion engine with cylinders that are connected to a fuel inlet and to an exhaust outlet, the exhaust outlet being in fluid contact with a catalyst/steam reforming assembly, such that exhaust gases flow through the channels, an evaporator that is in heat exchanging contact with the exhaust gases, a water and ethanol supply unit flowing water and ethanol through the evaporator for forming water and ethanol steam, the water and ethanol steam being passed into the tubes, and a reformed fuel duct connected to an outflow side of the tubes and being connected to a fuel inlet of the cylinders.
The heat exchange module according to the disclosure provides a compact and stable combined catalyst/steam reforming unit for the treatment of exhaust gases and for forming H2 from ethanol, such as from bio-fuel, in automotive applications.
A heat exchange module according to the disclosure will, by way of non-limiting example, be described in detail with reference to the accompanying drawings. In the drawings:
As can be seen in
The heat exchange substrates 16,17 are brazed against the lower edges of the sidewall 33 so that the corrugated parts can slide with respect to the casing members 35, 36 while being kept firmly in place.
A turbocharger 48 compresses the air that is supplied from an air intake 49 and transports the intake air through a cooler 45 to the intake manifold 51 for supply to the cylinders 43. The exhaust gases of the fuel that has been burned in the cylinders 43, leave the engine 42 via an exhaust manifold 52 and flow through an exhaust duct 56 to drive the turbocharger 48. After passing through the turbocharger 48, the exhaust gases flow via the duct 53 into an integrated catalytic converter/fuel reformer unit 54 that is formed from stacked heat exchange modules that are described in
A pump 63 is connected to a water/ethanol tank 64 and supplies water and ethanol from the tank 64 to the evaporator 57 where the water/ethanol, that is at ambient temperature, is brought in heat exchanging contact with the exhaust gases. The ethanol steam and water steam that is produced in the evaporator 57, is supplied via a duct 61 to a pre-heater/cooler unit 75.
The pre-heated water steam and ethanol steam mixture is fed from the unit 75 to the integrated catalytic converter/fuel reformer unit 54 through duct 76, where the water and steam are flowing through the tubes 8 shown in
The exhaust gases flow from the duct 53 in the reformer unit 54 through the channels 20,21 of the top and bottom heat exchange substrates 6,7; 16,16 that are shown in
The syngas that is formed in the integrated catalytic converter/fuel reformer unit 54 is transported via a syngas outlet duct 77, through the pre-heater/cooler unit 75 and preheats the water and ethanol by being brought in heat exchanging contact with the water/ethanol steam that is supplied at the inlet of the unit 75.
Via an outlet duct 80 and a reduction valve 81, the syngas is supplied to a gas inlet manifold 85 that is connected to the cylinders 3.
| Number | Date | Country | Kind |
|---|---|---|---|
| 22166908.8 | Apr 2022 | EP | regional |
