Electric heating arrangement & fluid flow heater

Abstract

An electric heating arrangement (10) for heating a flow of fluid, the electric heating arrangement (10) comprising at least one jacket element (12), a plurality of fluid channels (14), whereby each fluid channel (14) extends along a longitudinal axis through the, or each jacket element (12), and has an opening at one or both longitudinal ends The electric heating arrangement also comprises at least one heating element comprising a plurality of heating element sections (16, 16a, 16b), each extending along a longitudinal axis through a fluid channel (14) and having at least one longitudinal end that is positioned at at least one open longitudinal end of the fluid channel (14), and at least one connector (18) connecting a longitudinal end (16e) of a first heating element section (16a) to a longitudinal end of a second heating element section (16b), The, or each connector (18) comprises a connector body (18b) comprising a first bore (20) configured to receive a longitudinal end (16e) of the first heating element section (16a), and a second bore (22) configured to receive a longitudinal end (16f) of the second heating element section (16b), a central part (18c) extending between the first bore (20) and the second bore (22), and at least one fixation element (24) that extends between the connector body (18b) and a jacket element (12), whereby at least one of the following ratios is / are met: R1, R2 where: - h is the height of the at least one fixation element (24) which protrudes from the, or each connector body (18b), - L is the length of the connector body (18b), measured along a longitudinal axis of the connector body (18b), - A FS is the free channel area in a fluid channel (14) around a heating element section (16, 16a, 16b) through which a fluid flows during operation, measured in a plane that is perpendicular to a longitudinal axis of the fluid channel (14), and - A c is the cross-sectional area of the, or each connector (18), measured in a plane that is perpendicular to the longitudinal axis of the fluid channel (14).

Description

[0001] ELECTRIC HEATING ARRANGEMENT & FLUID FLOW HEATER

[0002] Field of Invention

[0003] The present disclosure relates to an electric heating arrangement for heating a flow of fluid, i.e. liquid and / or gas. The present disclosure also relates to a fluid flow heater comprising at least one such heating arrangement.

[0004] Background

[0005] An electric fluid flow heater is a device designed to heat a flow of fluid. The heater relies on the heat produced through the Joule effect within its heating elements when an electric current passes through them.

[0006] An electric fluid flow heater typically comprises one or more jacket elements containing a plurality of fluid channels, which are usually open at both ends, to guide a fluid from a fluid inlet to a fluid outlet. The, or each jacket element provides insulation, prevents heat loss, enhances the heater's efficiency, and protects its internal components from external damage and environmental factors. Heating elements, such as wires or rods, are placed inside the fluid channels and transfer heat to the fluid as it flows over and around them during operation. The ends of the wires or rods usually protrude from the open ends of the fluid channels and are connected to form a continuous current path, using U-shaped end sections, for example.

[0007] Establishing durable and reliable connections between the wires or rods in a fluid flow heater is crucial for the heater's operation and efficiency. For example, when the ends of the wires or rods are connected using a technique during which conductive molten material is produced, such as welding, brazing or soldering, there is a risk of forming unintended current paths if molten material spreads to unintended areas, such as to neighbouring wires and rods. Such stray electrical pathways can adversely affect the performance and structural integrity of the heating elements, as well as the safety, reliability, and efficiency of the heater.

[0008] Ideally, the fluid in a fluid flow heater should flow smoothly in parallel layers, known as laminar flow. However, pressure loss can occur when the fluid encounters resistance as it moves through the fluid channels and over the wires or rods. This resistance, due to frictional forces between the fluid and the surfaces it encounters, can cause the fluid to change direction abruptly, forming eddies and vortices. Misaligned wires or rods can also act as obstacles, causing fluid layers to mix and create turbulence. This turbulence leads to variations in flow velocity, with fluid speeding up in narrow spaces and slowing down in wider spaces, resulting in uneven heating and temperature gradients within the fluid. Consequently, extra energy may be required to maintain a desired flow rate, and the efficiency of the fluid flow heater may be reduced. Additionally, pressure loss can strain components like pumps, valves, and pipes, leading to premature wear, leaks, or system failures, and consequently extended downtime and increased operational costs.

[0009] Description

[0010] In an aspect of the disclosure, there is provided an improved electric heating arrangement for heating a flow of fluid, i.e. a liquid and / or a gas, comprising the features recited in claim 1.

[0011] The electric heating arrangement comprises at least one jacket element, i.e. a single jacket element or a plurality of jacket elements, such as tubular or elongated jacket elements, and a plurality of fluid channels, whereby each fluid channel extends along a longitudinal axis through the, or each jacket element, and has an opening at one or both longitudinal ends. The electric heating arrangement also comprises at least one heating element comprising a plurality of heating element sections, each extending along a longitudinal axis through a fluid channel and having at least one longitudinal end that is positioned at at least one open longitudinal end of the fluid channel, and at least one connector connecting a longitudinal end of a first heating element section to a longitudinal end of a second heating element section, whereby the plurality of heating element sections and the at least one connector create the heating element when connected. The, or each connector comprises a connector body comprising a first bore configured to receive a longitudinal end of the first heating element section, and a second bore configured to receive a longitudinal end of the second heating element section, such as a longitudinal end of a second heating element section that is adjacent to the longitudinal end of the first heating element section. The, or each connector also comprises a central part extending between the first bore and the second bore, and at least one fixation element that extends between the connector body and a jacket element, whereby at least one of the following ratios is / are met: 0.6 - 1.6 0.3 to 0.9 where:

[0012] - h is the height of the at least one fixation element which protrudes from the, or each connector body

[0013] - L is the length of the connector body, measured along a longitudinal axis of the connector body,

[0014] - AFS is the free channel area in a fluid channel around a heating element section through which a fluid flows during operation, measured in a plane that is perpendicular to a longitudinal axis of the fluid channel, and

[0015] - Ac is the cross-sectional area of the, or each connector, measured in a plane that is perpendicular to the longitudinal axis of the fluid channel, including the cross-sectional area of the electrical conductors a.

[0016] The ratio R.1 can in some examples be in the range of from 0.7 to 1.6, or from 0.6 to 1.5.

[0017] The ratio R.2 can in some examples be in the range of from 0.4 to 0.9.

[0018] The, or each connector helps to maintain the alignment and position of the heating element sections within the fluid channels, which helps to maintain a stable and efficient flow of fluid through the electric heating arrangement, thereby facilitating optimal heat transfer and consistent performance. Additionally, uniform fluid flow reduces the likelihood of wear and tear on the components of the electric heating arrangement, thereby extending its operational life; it minimizes the risk of overheating and the potential safety hazards associated with overheating; it conserves energy and reduces operational costs.

[0019] The, or each connector also provides a reliable mechanical and electrical connection. Additionally, the at least one fixation element will absorb forces and / or moments from the heating element sections during operation and transfer those forces and / or moments to the at least one jacket element.

[0020] Fulfilment of ratio R.1 means that the inlet cross-section, i.e. h*L, is the same as, or similar to, the free channel area of the two fluid channels through which the heating element sections extend, i.e. 2*AFS, which is equal to the surface area of a connector minus the cross-sectional area of the heating element sections connected thereto. The height of the fixation element, h, is designed to regulate and minimize pressure loss and thereby ensure an even distribution of fluid flow. By adjusting the height of the fixation element, h, to meet the ratio R.2, a controlled pressure loss may be achieved. The greater the height of the fixation element, h, the less resistance there will be to fluid flow.

[0021] One or more connectors meeting at least one of the ratios R.1 and / or R.2 thereby optimizes the fluid dynamics within the electric heating arrangement and equalizes flow distribution so that a consistent flow pattern and flow rate are achieved. This allows the electric heating arrangement to operate efficiently, reliably, safely, and cost-effectively over its intended lifespan.

[0022] Furthermore, pressure loss is minimized since the resistance that the fluid encounters as it moves through the electric heating arrangement is reduced due to the design of the, or each connector. By minimizing pressure loss, the electric heating arrangement can operate more efficiently, as less energy is required to push the fluid through the electric heating arrangement, and a desired fluid temperature may be reached more quickly and more controlled.

[0023] According to embodiments, R1 is at least or equal to 0.6, such as at least or equal to 0.7, such as at least or equal to 0.8, such as at least or equal to 0.9, such as at least or equal to 1.0, such as at least or equal to 1.1, such as at least or equal to 1.2, such as at least or equal to 1.3. According to embodiments, R1 is up to a maximum of 1.1, or 1.2, or 1.3, or 1.4, or 1.5, or 1.6.

[0024] According to embodiments, R2 is at least or equal to 0.3, such as at least or equal to 0.4, such as at least or equal to 0.5, such as at least or equal to 0.55, such as at least or equal to 0.6, such as at least or equal to 0.65, such as at least or equal to 0.7, such as at least or equal to 0.75, such as at least or equal to 0.8. According to embodiments, R2 is up to or equal to 0.6, such as up to or equal to 0.65. such as up to or equal to 0.7, such as up to or equal to 0.75, such as up to or equal to 0.8, such as up to or equal to 0.85, such as up to or equal to 0.9.

[0025] According to embodiments, at least one of the following ratios is / are also met: w

[0026] R3 = - = 1.7 - 2.3 h 0.7 — 1.6 where:

[0027] - w is the maximum width of the, or each connector body, measured along an axis perpendicular to the longitudinal axis of the, or each connector body,

[0028] - h is the height of the at least one fixation element which protrudes from the, or each connector body (18b) ,

[0029] - A is the cross-sectional area of the central part of the, or each connector, through which electric current flows during operation, measured in a plane that is perpendicular to the longitudinal axis of the connector body, and

[0030] - a is the cross-sectional area of a heating element section, measured in a plane that is perpendicular to a longitudinal axis of the heating element section.

[0031] The cross-sectional area, A, of the central part of the, or each connector, through which electric current flows during operation, is thereby dimensioned to be the same as, or similar to, the cross-sectional area of the heating element sections connected to the, or each connector.

[0032] In some examples R3 can be calculated as: b R3 = - h where: b is the width of the, or each connector body, measured along an axis perpendicular to the longitudinal axis of the, or each connector body. In one example b is less than w. In one example b is equal to w. h is the height of the at least one fixation element which protrudes from the, or each connector body.

[0033] In one example, R.3 is in the range of from 1.75-2.25.

[0034] According to embodiments, R3 is at least or equal to 1.70, such as at least or equal to 1.80, such as at least or equal to 1.85, such as at least or equal to 1.9, such as at least or equal to 1.95, such as at least or equal to 2.0. According to embodiments, R3 is up to or equal to 1.9, such as up to or equal to 1.95, such as up to or equal to 2.0, such as up to or equal to 2.05, such as up to or equal to 2.1, such as up to or equal to 2.15, such as up to or equal to 2.2, or such as up to or equal 2.3.

[0035] In one example c.s.a is in the range 0.7-1.5.

[0036] According to embodiments, Rc.s.a is at least or equal to 0.7, such as at least or equal to 0.8, such as at least or equal to 0.9, such as at least or equal to 1.0, such as at least or equal to 1.1, such as at least or equal to 1.2, such as at least or equal to 1.3, such as at least or equal to 1.4. According to embodiments, Rc.s.a is up to or equal to 0.8, such as up to or equal to 0.9, such as up to or equal to 1.0, such as up to or equal to 1.1, such as up to or equal to 1.2, such as up to or equal to 1.3, such as up to or equal to 1.4, such as up to or equal to 1.5, or such as up to or equal to 1.6.

[0037] According to embodiments, the, or each connector comprises a first bore wall that extends at least partly around the first bore and / or a second bore wall that extends at least partly around the second bore.

[0038] According to embodiments, at least one bore wall comprises an inner chamfered edge having a first depth, and an inner chamfer angle at the central part of the connector body, and an outer chamfered edge having a second depth, and an outer chamfer angle located at an external end of the connector body, whereby the inner chamfered edge and the outer chamfered edge are tapered inwards towards the respective bore, and the inner chamfer angle is either the same as the outer chamfer angle or differs from the outer chamfer angle. Additionally, or alternatively the first depth is either the same as the second depth or differs from the second depth. The inner chamfer angle may namely be the same as, or greater, or smaller, than the outer chamfer angle, and / or the first depth may be the same as, or greater, or smaller, than the second depth.

[0039] Such bore walls with chamfered edges, or asymmetrical chamfered edges, facilitate a directional flow of molten material towards the centre of the connector during its connection to the longitudinal ends of the two heating element sections, using a connection process, such as welding, brazing or soldering, rather than towards the external ends of the connector or towards neighbouring heating element sections. This reduces the risk of unintended current paths being formed. The chamfered edges will therefore ensure that conductive material remains confined to the desired areas. This reduces the risk of shortcircuiting the electric heating arrangement, which could otherwise lead to its complete failure.

[0040] According to embodiments, the following ratio is met: where:

[0041] - Awis the cross-sectional area of the bore wall both surrounding the conductor measured in a plane along an axis perpendicular to the longitudinal axis and the conductor center axis;

[0042] - a is the cross-sectional area of the first and second electrical conductors measured in a plane that is perpendicular to a longitudinal axis of the first or second electrical conductor.

[0043] The area a depends on the type or shape of the electrical conductor and must be calculated based on the cross-sectional shape. In some examples a can be calculated with the following expression, i.e. for a circular conductor: where: d is the diameter of the electrical conductor.

[0044] In some examples the Rwis in the range of 0.4 - 0.8.

[0045] Awcan in some examples be calculated as H*t, where H is the height of the electrical conductor along which the bore wall extends, measured along a longitudinal axis of the electrical conductor and t is the thickness of the bore wall, measured along the longitudinal axis of the connector body.

[0046] In other examples, the chamfered edge of the bore wall must be taken into account and in these cases the Aw is defined as the cross-sectional area of the bore wall both surrounding the conductor measured in a plane along an axis perpendicular to the longitudinal axis and the conductor center axis.

[0047] Selecting a bore wall thickness, t, to meet the ratio, Rw, reduces the risk of electric flashovers and arcing between pairs of connectors.

[0048] According to embodiments, the minimum distance between connectors is at least or equal to 0.5 mm, such as at least or equal to 1.0 mm, such as at least or equal to 1.5 mm, such as at least or equal to 2 mm, such as at least or equal to 2.5 mm, such as at least or equal to 3.0 mm, such as at least or equal to 3.5 mm, such as at least or equal to 4.0 mm, in order to reduce the risk of electric flashovers and arcing between pairs of connectors.

[0049] According to embodiments, the central part of the connector body comprises a ridge, of any suitable uniform or non-uniform width, extending between the first bore and the second bore and at least one inclined surface sloping downwards from the ridge. The ridge and the inclined surface also facilitate a directional flow of molten material towards the centre of the connector during its connection to the longitudinal ends of the two heating element sections, using a connection process, such as welding, brazing or soldering, rather than towards the external ends of the connector or towards neighbouring heating element sections, which reduces the risk of unintended current paths being formed. The ridge and the at least one inclined surface will therefore also ensure that conductive material remains confined to the desired areas. This reduces the risk of short-circuiting the electric heating arrangement, which could otherwise lead to its complete failure.

[0050] The width of the ridge may be up to or equal to 0.5 mm, such as up to or equal to 1 mm, such as up to or equal to 2 mm, such as up to or equal to 3 mm, such as up to or equal to 4 mm, such as up to or equal to 5 mm, or greater than 5 mm. According to embodiments, the width of the ridge is less than or equal to 50 mm. According to embodiments, the width of the ridge is 0.5 to 50 mm. According to embodiments, the width of ridge may be 0.5 to 40 mm, such as 0.5 to 30 mm, such as 0.5 to 20 mm.

[0051] Using a connector comprising a ridge and at least one inclined surface sloping downwards from the ridge, and / or at least one bore wall comprising chamfered edges if a connection method during which conductive molten material is produced is used to connect the connector to the longitudinal ends of two heating element sections reduces the complexity of the manufacturing process since such a connector will be easy to weld, which may in turn, reduce manufacturing time and costs of an electric arrangement or a fluid flow heater comprising such connectors.

[0052] Using a connector with a ridge and at least one inclined surface sloping downwards from the ridge, and / or at least one bore wall with chamfered edges, simplifies the manufacturing process when connecting the longitudinal ends of two heating element sections to the connector using a method during which conductive molten material is produced since the connector is easier to weld. This may reduce manufacturing time and costs for an electric arrangement or fluid flow heater comprising at least one such connector.

[0053] According to embodiments, the, or each connector is connected to the longitudinal end of the first heating element section around at least 40%, such around at least 50%, such as at least 60%, such as at least 70%, such as at least 80%, such as least 90%, such as 100% of the circumference of the longitudinal end of the first heating element section, and / or to the longitudinal end of the second heating element section around at least 40%, such as at least 50%, such as at least 60%, such as at least 70%, such as at least 80%, such as at least 90%, such as 100% of the circumference of the longitudinal end of the second heating element section. According to embodiments, the, or each connector and / or the at least one fixation element comprise(s) or consist(s) of at least one of the following materials: metallic material and / or ceramic material, such as an iron-chromium-aluminium (Fe-Cr-AI) alloy, an iron- chromium-aluminium-molybdenum (Fe-Cr-AI-Mo) alloy, a nickel-chromium (Ni-Cr) alloy, a nickel-chromium-iron (Ni-Cr-Fe) alloy, tungsten (W), molybdenum (Mo), silicon carbide (SiC), a silicide, molybdenum disilicide (MoSi?), molybdenum disilicide alloyed with tungsten (W) or aluminium (Al) or chromium (Cr), molybdenum disilicide containing an oxide or AI2O3 particles.

[0054] These materials exhibit good corrosion resistance to several process fluids. The ceramic materials have a high melting point and good oxidation resistance. The physical properties of a silicide, such as MoSi?, for example its high temperature strength, thermal stability and fracture toughness at elevated temperature, can be improved by alloying with tungsten (W) or aluminium (Al) or chromium (Cr).

[0055] According to embodiments, the at least one fixation element comprises at least one of the following, or a combination of the following: at least one pin, at least one projection, at least one plate, at least one rod, at least one screw, at least one bolt, or at least one element of any size and shape that secures the connector body in place at a desired distance from the at least one jacket element.

[0056] According to embodiments, the at least one jacket element comprises non-electrically conducting material, such as refractory material, ceramic material, or ceramic fibre insulation material. The at least one jacket element may be configured to provide thermal insulation, resistance to one or more process fluids, heat resistance, and / or thermal degradation resistance.

[0057] According to embodiments, the, or each connector is connected to the longitudinal end of the first heating element section and / or to the longitudinal end of the second heating element section by one of the following: a welded joint, a brazed joint, a soldered joint, an adhesive joint, a co-fired joint, a mechanical joint.

[0058] According to embodiments, the, or each connector comprises a connector body having a first external end comprising the first bore, and a second external end comprising the second bore, whereby the width, b, of the central part of the connector body is the same as, or smaller than the width, w, of first external end and the width of the second external end of the connector body, measured along an axis perpendicular to the longitudinal axis of the connector body. According to embodiments, the at least one fixation element is integrally formed with the connector body of the, or each connector. Alternatively, the at least one fixation element is attached to the connector body of the, or each connector, using any suitable attachment method.

[0059] According to embodiments, the at least one jacket element comprises at least one recess, such as at least one slot, groove, opening, or notch, which is configured to receive the at least one fixation element, such as an end of a fixation element, to securely hold or lock the at least one fixation element in place and prevent it from movement or dislodgement from its installation position. The at least one recess ensures that the at least one fixation element is properly aligned with the jacket element and facilitates the assembly of the electric heating arrangement.

[0060] In an aspect of the disclosure, there is provided a fluid flow heater for electrically heating a flow of fluid, whereby the fluid flow heater comprises at least one electric heating arrangement according to any of the embodiments described herein.

[0061] Definitions

[0062] Unless otherwise indicated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0063] The term "during operation" is intended to mean during the time the at least one heating element is being used convert electrical energy into heat.

[0064] The term "heating element section" is intended to mean a component, such as a wire or a rod, or a strip, or a bar, or a ribbon, or a coil, which can produce heat through the Joule effect when an electric current passes through it. Each heating element section is configured so that it can be connected to at least one other heating element section end- to-end via the at least one connector to create a continuous path for electric current. Each heating element section is configured to fit inside a fluid channel and come into direct contact with a fluid, such as a liquid and / or a gas, during operation. When an electric current is applied, it flows through the connected heating element sections and the at least one connector and generates heat along the length of the resulting heating element. As the fluid flows through the fluid channels, it absorbs the heat generated by the heating element, thereby heating the fluid. The term "adjacent" as used in to describe adjacent components, such as heating element sections, longitudinal ends, or fluid channels, is intended to mean that the components are positioned next to each other without any additional such component between them.

[0065] The term "height" of the at least one fixation element is intended to mean the magnitude of the extension of the fixation element from the connector body and is not necessarily intended to mean that the fixation element extends in a vertical direction.

[0066] A connector, connector body, a fixation element, and central part of a connector do not necessarily have to have a uniform length or width or height, and a bore wall does not necessarily have to have a uniform thickness or depth. In cases where the length or width or height or thickness of a component is not uniform, the terms "length", "width", "height", "thickness" and "depth" are intended to mean "maximum length", "maximum width", "maximum height" and "maximum thickness" respectively.

[0067] Terms such as "diameter", "circumference" and "radially inwards" are not intended to imply that a component is necessarily circular but should be interpreted to mean an equivalent term, such as "width", "perimeter" or "towards the centre" if a component is not circular.

[0068] The term "positioned at at least one open longitudinal end of the fluid channel" is intended to mean that one or both longitudinal ends of a heating element section is / are located at, above, or below an open longitudinal end of a fluid channel, i.e. the, or each longitudinal end of a heating element section protrudes from, or is positioned beneath, or lies flush with an open longitudinal end of a fluid channel. The longitudinal ends of the plurality of heating element may namely be located in any position that allows them to be connected to at least one connector.

[0069] As used herein, the term "comprises" will take its usual meaning in the art, namely indicating that the component includes but is not limited to the relevant features (i.e. including, among other things), the term "comprises" also includes references to a component "consisting of" the relevant feature(s) or material(s).

[0070] Description of the Figures

[0071] Figure 1: schematically shows a side view of an electric heating arrangement according to an embodiment of the invention, Figure 2: schematically shows a cross-section of a fluid channel of an electric heating arrangement according to an embodiment of the invention through which a circular heating element section extends,

[0072] Figure 3: schematically shows a perspective view of a connector of an electric heating arrangement according to an embodiment of the invention,

[0073] Figure 4: schematically shows a plan view of the connector shown in Figure 3,

[0074] Figure 5: schematically shows a plan view of the connector shown in Figures 3 and 4 connected to the longitudinal ends of two adjacent heating element sections,

[0075] Figure 6: schematically shows a perspective view of one half of a connector of an electric heating arrangement according to another embodiment of the invention,

[0076] Figure 7: schematically shows a cross-sectional view of the connector shown in Figures 3-5,

[0077] Figure 8: schematically shows a plan view of the connector shown in Figures 3-5 and 7,

[0078] Figure 9: schematically shows a perspective view of one half of the connector shown in Figures 3-5, 7 and 8,

[0079] Figure 10: is a cross-sectional side view of a fluid flow heater according to an embodiment of the invention.

[0080] Figure 11: is a cross-sectional view of a connector body according to an embodiment of the invention,

[0081] Figure 12: schematically shows a perspective view of a connector according to an embodiment of the invention,

[0082] Figure 13: schematically shows a perspective view of one half of a connector according to an embodiment of the invention,

[0083] Figure 14: is a side view of a connector according to an embodiment of the invention, and Figure 15: is a cut-out view of a connector hole of a connector body according to an embodiment of the invention.

[0084] All of the drawings have not necessarily been drawn to scale and the dimensions of certain features may have been exaggerated for the sake of clarity.

[0085] Examples

[0086] The disclosure is illustrated by way of the following examples, which are not intended to be limiting on the general scope of the disclosure.

[0087] Figure 1 schematically shows a side view of an electric heating arrangement 10 for heating a flow of fluid according to an embodiment of the invention. The electric heating arrangement 10 comprises a single jacket element 12 comprising a plurality of fluid channels 14 extending therethrough. Alternatively, an electric heating arrangement 10 may comprise a plurality of jacket elements 12, such as elongated or tubular jacket elements 12 each comprising a fluid channel 14 extending therethrough.

[0088] In the illustrated embodiment, each fluid channel 14 extends along a longitudinal axis and is open at both longitudinal ends, i.e. at the top and the bottom of the jacket element 12 in Figure 1. A plurality of heating element sections 16 each extends along a longitudinal axis though the plurality of fluid channels 14, i.e. one heating element section 16 in each fluid channel 14. A plurality of heating element sections 16 may however extend though a single fluid channel 14. The extension of two adjacent heating element sections 16a, 16b inside two adjacent fluid channels 14a, 14b are indicated using dashed lines in Figure 1. Both longitudinal ends of each heating element section 16 protrude from the open longitudinal ends of the fluid channels 14.

[0089] Fluid channels 14 and / or heating element sections 16 need not necessarily be arranged in a vertical manner and need not necessarily be arranged parallel to one another.

[0090] A plurality of connectors 18 is connected between adjacent pairs of longitudinal ends of the heating element sections 16 at both the top and the bottom of the jacket element 12. For example, a connector 18 is connected to the longitudinal end 16e of a first heating element section 16a and to a longitudinal end 16f of a second heating element section 16b which protrude from the bottom of the jacket element 12. The opposite longitudinal end of the first heating element section 16a is connected to a third heating element section via a connector 18 at the top of the jacket element 12. The opposite longitudinal end of the second heating element section 16b may be connected to an electrical power source (not shown). When the plurality of connectors 18 and the heating element sections 16 are connected together, a continuous current path, and consequently a heating element, is created. An electric heating arrangement 10 according to any of the embodiments described herein may comprise a plurality of heating elements created in this way.

[0091] Each connector 18 comprises at least one fixation element 24 which extends between the connector body 18b and the jacket element 12. In the illustrated embodiment, each connector comprises one fixation element 24 that extends between a lower surface of the connector body 18b and an upper surface of the jacket element 12 at the top of jacket element 12, and between an upper surface of the connector body 18b and a lower surface of the jacket element 12 and at the bottom of the jacket element 12. The fixation elements 24 securely hold each connector 18 in place and reduce the risk of the connectors 18 slipping out of their installation position. Additionally, the fixation elements 24 absorb forces and / or moments from the heating element sections 16 during operation and transfer those forces and / or moments to the jacket element 12.

[0092] According to embodiments, the, or each connector and / or the at least one fixation element comprise(s) or consist(s) of at least one of the following materials: metallic material and / or ceramic material, such as an iron-chromium-aluminium (Fe-Cr-AI) alloy, an iron- chromium-aluminium-molybdenum (Fe-Cr-AI-Mo) alloy, a nickel-chromium (Ni-Cr) alloy, a nickel-chromium-iron (Ni-Cr-Fe) alloy, tungsten (W), molybdenum (Mo), silicon carbide (SiC), a silicide, molybdenum disilicide (MoSi?), molybdenum disilicide alloyed with tungsten (W) or aluminium (Al) or chromium (Cr), molybdenum disilicide containing an oxide or AI2O3 particles.

[0093] The, or each connector 18 and / or the at least one fixation element 24 may be manufactured using any suitable method(s), such as three-dimensional printing, casting, stamping, metal injection moulding, machining, and / or forging.

[0094] Figure 2 schematically shows a cross-section of a fluid channel 14 of an electric heating arrangement 10 according to an embodiment of the invention through which a circular heating element section 16 extends. In the illustrated embodiment, the jacket element 12 comprises a plurality of fins 12f, namely four fins 12f, that each extend longitudinally along the fluid channel 14 and project radially inwards towards a central region of the fluid channel 14 to stabilise and centre the heating element section 16 extending therethrough and to ensure that the heating element section 16 is not displaced too far from the axial centre of each fluid channel 14. A heating element section 16 may have any suitable size, i.e. length and width or diameter, and any suitable cross-section, such as an elliptical or polygonal cross-section. A fluid channel 14 may also have any suitable size, i.e. length and width or diameter, and any suitable cross-section, including a polygonal cross-section with or without rounded corners, such as a square or rectangular cross-section with or without rounded corners.

[0095] The cross-sectional area AFS is the free channel area in a fluid channel 14 around the heating element section 16 through which a fluid flows during operation, measured in a plane that is perpendicular to a longitudinal axis of the fluid channel 14. The area, a is the cross-sectional area of the heating element section 16, measured in a plane that is perpendicular to a longitudinal axis of the heating element section 14.

[0096] According to embodiments, the diameter or width of the at least one heating element section 16 may be at least or equal to 0.5 mm, such as at least or equal to 1 mm, such as at least or equal to at least 2 mm, such as at least or equal to 3 mm, such as at least or equal to 4 mm, such as at least or equal to 5 mm. According to embodiment the diameter or width of the at least one heating element section 16 may be up to or equal to 1 mm, such as up to or equal to 2 mm, such as up to or equal to 3 mm, such as up to or equal to 4 mm, such as up to or equal to 5 mm, such as up to or equal to 6 mm, such as up to or equal to 7 mm, such as up to or equal to 8 mm, such as up to or equal to 9 mm, such as up to or equal to 10 mm, or greater than 10 mm.

[0097] Figure 3 schematically shows a perspective view of a connector 18 of an electric heating arrangement 10 according to an embodiment of the invention in which the at least one fixation element 24 that extends from a lower surface of the illustrated connector 18 is not visible. The connector 18 comprises a connector body 18b comprising a first bore 20 configured to receive a longitudinal end 16e of a first heating element section 16a and a second bore 22 configured to receive a longitudinal end 16f of a second heating element section 16b, and a central part 18c extending between the first bore 20 and the second bore 22. Each bore 20, 22 is sufficiently sized to accommodate a longitudinal end 16e, 16f of a second heating element section 16, 16a, 16b, with a slight clearance.

[0098] According to embodiments, the minimum distance between the first bore 20 and the second bore 22 is at least or equal to 2 mm, such as at least or equal to 3 mm, such as at least or equal to 4 mm, such as at least or equal to 5 mm. According to embodiments, the minimum distance between the first bore 20 and the second bore 22 is up to or equal to 1 mm, such as up to or equal to 2 mm, such as up to or equal to 3 mm, such as up to or equal to 4 mm, such as up to or equal to 5 mm, such as up to or equal to 6 mm, such as up to or equal to 7 mm, such as up to or equal to 8 mm, such as up to or equal to 9 mm, such as up to or equal to 10 mm, or greater than 10 mm.

[0099] Figure 4 schematically shows a plan view of the connector 18 shown in Figure 3, and indicates the length, L, and the width, b, of the connector body 18b. The connector 18 is configured to maintain the desired alignment and position of the heating element sections 16, 16a, 16b within the electric heating arrangement 10.

[0100] Figure 5 schematically shows a plan view of the connector 18 shown in Figures 3 and 4 connected between the longitudinal ends 16e, 16f ends of two heating elements 16a and 16b which extend along a longitudinal axis through fluid channels 14 which each have the cross-sectional shape shown in Figure 2.

[0101] Figure 6 shows a perspective view of one half of a connector 18 of an electric heating arrangement 10 according to another embodiment of the invention in which a fixation element 24 having a height, h, is visible. The area, A, is the cross-sectional area of the central part 18c of the connector 18, through which electric current flows during operation, measured in a plane that is perpendicular to the longitudinal axis of the connector body 18b. In the illustrated embodiment, area, A, has a rectangular shape. The area, A, may have any suitable shape.

[0102] The connector 18, half of which is shown in Figure 6, comprises a connector body 18b having a first external end comprising the first bore 20, and a second external end comprising the second bore 22, whereby the width, b, of the central part 18c of the connector body 18b is smaller than the width, w, of the first external end and the width of the second external end of the connector body 18b, measured along an axis perpendicular to the longitudinal axis of the connector body. Such a connector 18 thereby has a "dog bone shape".

[0103] One or more fixation elements 24 may be integrally formed with the connector body 18b of the connector 18. At least one jacket element 12 may comprise one or more recesses configured to receive the one or more fixation elements 24.

[0104] A connector 18 according to any of the embodiments of the invention has a compact design, which means that less material may be used to produce the connector 18, which may in turn decrease the cost and / or size of an electric heating arrangement 10 or a fluid flow heater containing comprising such connectors 18. At least one of the following ratios is / are met in all of the electric heating arrangements 10 according to the present invention: 0.7 - 1.5 0.3 to 0.9 where:

[0105] - h is the height of the at least one fixation element 24 which protrudes from the, or each connector body 18b,

[0106] - L is the length of the connector body 18b, measured along a longitudinal axis of the connector body 18b,

[0107] - AFS is the free channel area in a fluid channel 14 around a heating element section 16, 16a, 16b through which a fluid flows during operation, measured in a plane that is perpendicular to a longitudinal axis of the fluid channel 14, and

[0108] - Ac is the cross-sectional area of the, or each connector 18, measured in a plane that is perpendicular to the longitudinal axis of the fluid channel 14. The surface Ac is shown in Figure 11.

[0109] In addition to meeting ratios R.1 and / or R.2, an electric heating arrangement 10 may also meet at least one of the following ratios: w

[0110] R3 = - = 1.7 - 2.3 h 1.6 where:

[0111] - w is the maximum width of the, or each connector body, measured along an axis perpendicular to the longitudinal axis of the, or each connector body 18b,

[0112] - h is the height of the at least one fixation element 24 which protrudes from the, or each connector body 18b,

[0113] - A is the cross-sectional area of the central part 18c of the, or each connector 18, through which electric current flows during operation, measured in a plane that is perpendicular to the longitudinal axis of the connector body 18b, and - a is the cross-sectional area of a heating element section 16, 16a, 16b, measured in a plane that is perpendicular to a longitudinal axis of the heating element section 16, 16a, 16b.

[0114] Figure 7 schematically shows a cross-sectional view of the connector 18 shown in Figures 3, 4 and 5. The connector 18 comprises a first bore wall 26 that extends around the first bore 20 and a second bore wall 28 that extends around the second bore 22. Each bore wall 26, 28 comprises an inner chamfered edge 30 having a first depth DI and an inner chamfer angle Cl, at the central part 18c of the connector body 18b, and an outer chamfered edge 32 having a second depth D2 and an outer chamfer angle C2 located at an external end of the connector body 18b. The inner chamfered edge 30 and the outer chamfered edge 32 are tapered inwards towards the respective bore 20, 22, and the first depth DI and the first chamfer angle Cl differ from the second depth D2 and the second chamfer angle C2.

[0115] The chamfered edges 30, 32, or asymmetrical chamfered edges 30, 32 facilitate a directional flow of molten material towards the central part 18c of the connector body 18b during a connection process, such as welding, brazing or soldering, rather than towards neighbouring heating element sections 16.

[0116] According to embodiments, a connector 18 may comprise a first bore wall 26 that extends around the first bore 20 and a second bore wall 28 that extends around the second bore 22, whereby the following ratio is met: where:

[0117] - Av / is the cross-sectional area of the bore wall both surrounding the conductor measured in a plane along an axis perpendicular to the longitudinal axis and the conductor center axis;

[0118] - a is the cross-sectional area of the first and second electrical conductors measured in a plane that is perpendicular to a longitudinal axis of the first or second electrical conductor.

[0119] In one example the Rw ratio may be calculated as:

[0120] - H is the height of the electrical conductor along which each bore wall extends, measured along a longitudinal axis of the electrical conductor,

[0121] - t is the thickness of each bore wall, measured along the longitudinal axis of the connector body 18b,

[0122] - a is the cross-sectional area of the first and second electrical conductor and is measured in a plane that is perpendicular to a longitudinal axis of the first or second electrical conductor.

[0123] In some examples a, i.e. for a circular cross-sectional area of the conductor, can be calculated by the following expression: where

[0124] - d is the diameter of the electrical conductor.

[0125] Figure 8 schematically shows a plan view of the connector 18 shown in Figures 3-5 and 7. The central part 18c of the connector body 18b comprises a ridge 34 extending between the first bore 20 and the second bore 22 and an inclined surface 36 sloping downwards from the ridge 34 on each side of the ridge 34 (which can be seen more clearly in Figures 3 and 9).

[0126] A connector 18 according to any embodiment described herein may namely have a central part 18c comprising a ridge 34, i.e. a raised or elevated section that extends between the first bore 20 and the second bore 22, and at least one inclined surface 36 sloping downwards from the ridge 34. Alternatively, a connector 18 according to any embodiment described herein may have a central part 18c comprising a bridge, i.e. a non-elevated or flat structural connection that extends between the first bore 20 and the second bore 22 without any inclined surface.

[0127] According to embodiments, a connector 18 may be connected to a longitudinal end 16e, 16f of a heating element section 16a, 16b around at least 40% of the circumference of the longitudinal end 16e, 16f of the heating element section 16a, 16b. The connector does not necessarily have to fully enclose the end of the conductor and may have a recess of the same circumference. Figure 8 shows an embodiment in which a longitudinal end 16e, 16f of a heating element section 16a, 16b is connected to the connector 18 around an angle of 199°, i.e. around about 55% of the circumference of the heating element section 16a, 16b. Thus, showing the area where the electrical conductor may not be connected the connector 18.

[0128] A connection process, such as arc welding, may be used to join a longitudinal end 16e, 16f of a heating element section 16a, 16b to a connector 18. A power supply may be used to create an electric arc between the components that are to be connected. The welding area may be protected by a shielding gas. Optionally, filler materials may be used. The area indicated by the circle in Figure 9, is where the electrical conductor may be connected to the connector 18. During welding a molten pool of material will be formed and will then be guided towards the central part 18c of the connector 18 and forms a proper joint with the ridge 34 and the inclined surfaces 36. As more of the longitudinal end 16e, 16f of the heating element section 16a, 16b is welded to the connector 18, the rest of the molten material will be guided in the same manner due to the geometry of the connector 18.

[0129] In the embodiment illustrated in Figure 9, the angle between the inclined surfaces 36 is about 75°. Any suitable angle may however be selected, such as an angle of at least 50°, or at least 60°, or at least 70°, or at least 80°, or at least 90°, or at least 100°, or at least 110°, or at least 120°.

[0130] Figure 10 is a cross-sectional side view of a fluid flow heater 38 for electrically heating a flow of fluid according to an embodiment of the invention. The fluid flow heater 38 comprises a fluid inlet 40, such as a gas feed tube, and a fluid outlet 42, such as a gas outlet nozzle. The fluid outlet 40 opens into a cavity containing at least one electric heating arrangement 10 according to any embodiment of the present invention.

[0131] The at least one electric heating arrangement 10 comprises a plurality of elongated or tubular jacket elements 12, each of which comprises an internal fluid channel 14 extending along the full length of each jacket element 12. Each jacket element 12 is open at both ends. The connectors 18 connect the longitudinal ends of heating element sections 16 that extend through each fluid channel 14 to provide a heating element as described herein.

[0132] Figure 11 is a cross-section view of the connector body 18b of a connector 18 illustrating the surface Ac. The surface Ac is thus an imaginary surface of the cross-section of the connector as if there were no bore holes in the connector body 18b, that is including the cross-sectional area of the at least two conductors 16a, 16b, i.e. 2*a. Figure 12 schematically shows a perspective view of a connector 18 according to an embodiment of the invention. The connector 18 is configured to connect a longitudinal end of a first electrical conductor to a longitudinal end of a second electrical conductor. The connector 18 comprises a connector body 18b comprising a first bore 20 configured to receive a longitudinal end of a first electrical conductor and a second bore 22 configured to receive a longitudinal end of a second electrical conductor, and a central part 18c extending between the first bore 20 and the second bore 22. Each bore 20, 22 may be sufficiently sized to accommodate a longitudinal end of an electrical conductor, with a slight clearance.

[0133] The central part 18c of the connector body 18b comprises a bridge portion 35, i.e. a section of the connector body 18b having a concave longitudinal profile, wherein the central part 18c exhibits a reduced height relative to the end portions, forming a continuous curvature along the longitudinal axis, which extends between the first bore 20 and the second bore 22. The connector 18 also comprises a first bore wall 26 that extends around the first bore 20 and a second bore wall 28 that extends around the second bore 22, whereby both the first bore wall 26 and the second bore wall 28 may comprise a chamfered edge that is tapered inwards towards the respective bore 20, 22.

[0134] Figure 13 schematically shows a perspective view of one half of a connector 18, as shown in Figure 11 but which also includes a fixation element 24 that extends outwards from a side or surface of the connector body 18b, such as a lower side or lower surface of the connector body 18b. The fixation element 24 may be integrally formed with the connector body 18b of the connector 18 or be attached thereto using any suitable method. In Figure 12, the surface A is also defined. The area, A, is the cross-sectional area of the central part 18c of the connector 18, through which electric current flows during operation, measured in a plane that is perpendicular to the longitudinal axis of the connector body 18b. In the illustrated embodiment, area, A, has a rectangular shape. The area, A, may have any suitable shape. As shown in Figure 12, the width w of the connector body 18b may be equal to the width b of the central portion 18c of the connector 18.

[0135] Figure 14 is a side view of a connector 18, as shown in Figure 11, but which also includes a fixation element 24 that extends downwards from the central portion 18c. The fixation element 24 may be integrally formed with the connector body 18b of the connector 18 or be attached thereto using any suitable method. As shown in Figure 13 the length L refers to the entire length of the connector body 18b and the height h of the fixation element is the portion of the fixation element 24 that protrudes beneath the central portion 18c. As seen in the side view the central portion 18c has a bridge like profile. Figure 15 illustrates a connector 18 where a portion of a bore hole 22 is cut-out, showing the surface where the area Aw of the wall 28 of the bore hole 22 is to be calculated or determined from regardless of the shape of the wall 26, 28 of the bore hole 20, 22.

[0136] Options and examples for a given aspect, feature or parameter of the invention should, unless the context indicates otherwise, be regarded as having been disclosed in combination with any and all options and examples for all other aspects, features and parameters of the invention. For example, any feature disclosed with respect to an electric heating arrangement 10 may be regarded as having been disclosed in a fluid flow heater 38, and vice versa.

Claims

Claims1. An electric heating arrangement (10) for heating a flow of fluid, the electric heating arrangement (10) comprising:- at least one jacket element (12),- a plurality of fluid channels (14), whereby each fluid channel (14) extends along a longitudinal axis through, or each jacket element (12), and has an opening at one or both longitudinal ends,- at least one heating element comprising:- a plurality of heating element sections (16, 16a, 16b), each extending along a longitudinal axis through a fluid channel (14) and having at least one longitudinal end that is positioned at at least one open longitudinal end of the fluid channel (14), and- at least one connector (18) connecting a longitudinal end (16e) of a first heating element section (16a) to a longitudinal end of a second heating element section (16b), characterized in that the, or each connector (18) comprises:- a connector body (18b) comprising a first bore (20) configured to receive a longitudinal end (16e) of the first heating element section (16a), and a second bore (22) configured to receive a longitudinal end (16f) of the second heating element section (16b),- a central part (18c) extending between the first bore (20) and the second bore (22), and- at least one fixation element (24) that extends between the connector body (18b) and a jacket element (12), whereby at least one of the following ratios is / are met: 0.6 - 1.60.3 to 0.9where:- h is the height of the at least one fixation element (24) which protrudes from the, or each connector body (18b),- L is the length of the connector body (18b), measured along a longitudinal axis of the connector body (18b),- AFS is the free channel area in a fluid channel (14) around a heating element section (16, 16a, 16b) through which a fluid flows during operation, measured in a plane that is perpendicular to a longitudinal axis of the fluid channel (14), and23- Ac is the cross-sectional area of the, or each connector (18), measured in a plane that is perpendicular to the longitudinal axis of the fluid channel (14).

2. The electric heating arrangement (10) according to claim 1, characterized in that at least one of the following ratios is / are also met: wR3 = - = 1.7 - 2.3 h 0.7 — 1.6where:- w is the maximum width of the, or each connector body (18b), measured along an axis perpendicular to the longitudinal axis of the, or each connector body (18b),- h is the height of the at least one fixation element (24) which protrudes from the, or each connector body (18b),- A is the cross-sectional area of the central part (18c) of the, or each connector (18), through which electric current flows during operation, measured in a plane that is perpendicular to the longitudinal axis of the connector body (18b), and- a is the cross-sectional area of a heating element section (16, 16a, 16b), measured in a plane that is perpendicular to a longitudinal axis of the heating element section (16, 16a, 16b).

3. The electric heating arrangement (10) according to claim 1 or 2, characterized in that the, or each connector (18) comprises a first bore wall (26) that extends at least partly around the first bore (20) and / or a second bore wall (28) that extends at least partly around the second bore (22).

4. The electric heating arrangement (10) according to claim 3, characterized in that at least one bore wall comprises:- an inner chamfered edge (30) having a first depth (DI), and an inner chamfer angle (Cl) at the central part (18c) of the connector body (18b), and- an outer chamfered edge (32) having a second depth (D2), and an outer chamfer angle (C2) located at an external end of the connector body (18b), whereby the inner chamfered edge (30) and the outer chamfered edge (32) are tapered inwards towards the respective bore, and: the inner chamfer angle (Cl) is the same as the outer chamfer angle (C2), or the inner chamfer angle (Cl) differs from the outer chamfer angle (C2), and / orthe first depth (DI) is the same as the second depth (D2), or the first depth (DI) differs from the second depth (D2).

5. The electric heating arrangement (10) according to claim 4, characterized in that the inner chamfer angle (Cl) is greater than the outer chamfer angle (C2), and / or the first depth (DI) is greater than the second depth (D2).

6. The electric heating arrangement (10) according to any of claims 3-5, characterized in that the following ratio is met:where:- Aw is the cross-sectional area of a bore wall (26, 28) both surrounding a conductor (16a, 16b) and is measured in a plane along an axis perpendicular to the longitudinal axis and the conductor (16a, 16b) center axis, and- a is the cross-sectional area of the first and second electrical conductor (16a, 16b) and is measured in a plane that is perpendicular to a longitudinal axis of the first or second electrical conductor (16a, 16b).

7. The electric heating arrangement (10) according to any preceding claim, characterized in that the central part (18c) of the connector body (18b) comprises a ridge (34) extending between the first bore (20) and the second bore (22) and at least one inclined surface (36) sloping downwards from the ridge (34).

8. An electric heating arrangement (10) according to any preceding claim, characterized in that the, or each connector (18) is connected to the longitudinal end of the first heating element section (16a) around at least 40% of the circumference of the longitudinal end (16e) of the first heating element section (16a), and / or to the longitudinal end (16f) of the second heating element section (16b) around at least 40% of the circumference of the longitudinal end (16f) of the second heating element section (16b).

9. The electric heating arrangement (10) according to any preceding claim, characterized in that the, or each connector (18) and / or the at least one fixation element (24) metallic material and / or ceramic material, such as an iron-chromium- aluminium (Fe-Cr-AI) alloy, an iron-chromium-aluminium-molybdenum (Fe-Cr-AI-Mo) alloy, a nickel-chromium (Ni-Cr) alloy, a nickel-chromium-iron (Ni-Cr-Fe) alloy, tungsten (W), molybdenum (Mo), silicon carbide (SiC), a silicide, molybdenum disilicide (MoSi?), molybdenum disilicide alloyed with tungsten (W) or aluminium (Al) or chromium (Cr), molybdenum disilicide containing an oxide or AI2O3 particles.

10. The electric heating arrangement (10) according to any preceding claim, characterized in that the at least one jacket element (12) comprises ceramic material.

11. The electric heating arrangement (10) according to any preceding claim, characterized in that the, or each connector (18) is connected to the longitudinal end (16e) of the first heating element section (16a) and / or to the longitudinal end (16f) of the second heating element section (16b) by one of the following: a welded joint, a brazed joint, a soldered joint, an adhesive joint, a co-fired joint, a mechanical joint.

12. The electric heating arrangement (10) according to any preceding claim, characterized in that the, or each connector (18) comprises a connector body (18b) having a first external end comprising the first bore (20), and a second external end comprising the second bore (22), whereby the width, b, of the central part of the connector body (18b) is the same as, or smaller than the width, w, of first external end and the width of the second external end of the connector body, measured along an axis perpendicular to the longitudinal axis of the connector body (18b).

13. The electric heating arrangement (10) according to any preceding claim, characterized in that the at least one fixation element (24) is integrally formed with the connector body (18b) of the, or each connector (18).

14. The electric heating arrangement (10) according to any preceding claim, characterized in that the, or each jacket element (12) comprises at least one recess configured to receive the at least one fixation element (24).

15. A fluid flow heater (38) for electrically heating a flow of fluid, characterized in that the fluid flow heater comprises at least one electric heating arrangement (10) according to any preceding claim.26

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