TECHNICAL FIELD OF THE INVENTION [0001] The present invention relates to fluid heating.

BACKGROUND OF THE INVENTION

[0002] Fluid heating is known in the industry. Fluids may need to be heated for many different purposes. One such purpose is heating fluids for use in chemical processing. It is often required to raise the temperature of a fluid to make that fluid more effective during chemical processing. Although fluid heaters exist, they each have their own shortcomings. Accordingly, it is desired to provide an improved fluid heater.

SUMMARY OF THE INVENTION

[0003] According to a first aspect, there is provided an inline fluid heater having an inlet operable to receive a fluid to be heated; a substrate defining at least one conduit fluidly coupled with the inlet to receive the fluid; a positive thermal coefficient heater thermally coupled with the substrate and operable to heat the substrate to provide a heated fluid by heating the fluid within the at least one conduit; and an outlet fluidly coupled with the at least one conduit and operable to provide the heated fluid, wherein said substrate defines a plurality of said conduits fluidly coupled with said inlet and said outlet and wherein said plurality of conduits are intersecting.

[0004] The first aspect recognises that a problem with existing fluid heaters is that they tend to be spatially large, inefficient, lack cost-effectiveness and often require safety devices or circuits to ensure safe operation. Accordingly, a fluid heater is provided. The fluid heater may be configured as an inline device which heats a fluid as it flows from a source to a destination. The heater may comprise an inlet which receives a fluid for heating. The heater may also comprise a substrate or body which defines or provides one or more conduits or passages which are in fluid communication with the inlet so that the fluid can flow from the inlet to the conduits. The heater may also comprise a positive thermal coefficient heater. The positive thermal coefficient heater may be in thermal contact with the substrate. The positive thermal coefficient heater may heat the substrate in order to heat the fluid flowing within the conduits. The heater may also comprise an outlet. The outlet may be in fluid communication with the conduits in order that the heated fluid may flow from the conduits to the outlet. The substrate may define a plurality of the conduits. A plurality of the conduits may be fluidly coupled with said inlet and said outlet. A plurality of the conduits intersect, interconnect or criss-cross. Accordingly, some conduits may each carry fluid from the inlet to the outlet with the fluid flowing between conduits. In this way, a compact, cost-effective and efficient heater is provided which avoids the need for safety devices or safety circuits, as the positive thermal co-efficient heaters are self-limiting. Increasing the number of conduits helps to reduce the pressure drop between the inlet and outlet and improves heating efficiency.

[0005] In another embodiment, the conduits extend within the substrate. Providing conduits within or enclosed by the substrate helps to contain the fluid and enables a simplified external envelope of the substrate to be provided.

[0006] In a further embodiment, some conduits are parallel. Accordingly, some conduits may each carry fluid from the inlet to the outlet either independently of the other.

[0007] In yet another embodiment, the conduits are at least one of elongate and serpentine. Providing non-linear conduits between the inlet and the outlet extends the dwell or residence time of the fluid within the heater and provides for a more compact arrangement.

[0008] In a further embodiment, the substrate comprises at least one of a mesh and fibres defining the conduits and encapsulated within a substrate housing. Hence, the conduits may be provided by a mesh or fibres contained within a substrate housing. Again, this helps to maximise dwell time and increase heat transfer between the heaters and the fluid.

[0009] In one embodiment, said substrate defines a void with opposing major faces, said substrate having a plurality of pillars extending between said opposing major faces to define said plurality of conduits. Hence, the substrate may be formed with a void. Pillars, columns or protrusions may extend into the void. The presence of the pillars partitions the void to create intersecting conduits through which the fluid flow. The pillars provide an efficient way of conveying heat from the positive thermal coefficient heater to the fluid and helps with fluid mixing.

[0010] In one embodiment, said pillars have a cross-sectional shape which is at least one of circular, elliptical, crescent-shaped and polygonal. The shape of the pillars influences the interface areas with the fluid and helps direct fluid flow.

[0011] In one embodiment, said pillars have an elongate cross-sectional shape. Elongate or linear cross-sectional pillar are particularly effective at directing the flow of the fluid.

[0012] In one embodiment, said pillars are tapered. Tapered pillars are particularly suited to additive manufacture.

[0013] In one embodiment, said pillars are at least one of located and orientated to direct a flow of said fluid within said void. The pillars may be position or rotated to influence the flow the fluid.

[0014] In one embodiment, said pillars are equispaced (evenly distributed) within said void. Accordingly, the pillars may be evenly distributed, having a constant inter-pillar spacing.

[0015] In another embodiment, the substrate defines at least one face which receives the positive thermal coefficient heater. Accordingly, the heaters may be provided on one or more faces of the substrate. Also, more than one heater may be provided on each face.

[0016] In yet another embodiment, the substrate defines a plurality of faces which receive a plurality of the positive thermal coefficient heaters. Hence, one or more heaters may be provided on multiple faces of the substrate.

[0017] In a further embodiment, the substrate is elongate and planar and received between a plurality of the positive thermal coefficient heaters. Accordingly, the substrate may be sandwiched between a number of heaters.

[0018] In one embodiment, the substrate is non-planar. Accordingly, the substrate may deviate from being planar and may be castellated, curved or even folded. The substrate may be sandwiched between a number of heaters.

[0019] In another embodiment, the substrate receives at least one the positive thermal coefficient heater between faces of the non-planar substrate. Accordingly, any one heater may contact with multiple faces of the non-planar substrate. Again, this helps to improve heat transfer between the heater and the substrate. [0020] In a further embodiment, the substrate is folded and receives at least one the positive thermal coefficient heater between folds.

[0021] In another embodiment, the at least one face is roughened to receive a thermal bonding material between the face and the positive thermal coefficient heater. Roughing the surface provides for improved heat transfer with the bonding material.

[0022] In yet another embodiment, the positive thermal coefficient heater comprises a positive thermal coefficient heater element housed within a thermally-conductive housing.

[0023] In a further embodiment, the inlet defines an inlet chamber fluidly coupling an inlet aperture operable to receive the fluid with the at least one conduit.

[0024] In another embodiment, the outlet defines an outlet chamber fluidly coupling the at least one conduit with an outlet aperture operable to provide the heated fluid.

[0025] In yet another embodiment, the substrate is at least partially one of 3D printed and extruded. Accordingly, portions may be either 3D printed, extruded or both.

[0026] In a further embodiment, the inline fluid heater comprises a plurality of said inlets, each inlet being fluidly coupled with an associated at least one conduit defined by said substrate, each associated at least one conduit being fluidly coupled with an associated outlet. Hence, the substrate may be provided with more than one inlet. Each inlet may be coupled with separate set of conduits. In other words, separate inlets may feed separate conduits so that the fluids provided by those separate inlets are isolated from each other and do not mix. Each of those separate sets of conduits may then be coupled with an associated outlet. Hence, different fluids may be provided to inlets, pass through their own conduits and the different heated fluids provided at the respective outlets. This enables a single inline fluid heater to heat multiple different fluids concurrently.

[0027] In another embodiment, each inlet is coupled with one of identical and differing at least one conduits. Hence, each set of conduits connected with an associated inlet may have its own configuration suited to the needs of the fluid to be heated. For example, fluids required to be heated less and/or having a lower flow rate may have fewer conduits in its set compared to fluids which need to be heated more and/or which have a higher flow rate; for those fluids, the more conduits may be provided and/or the conduits may be longer to increase their dwell time and/or the power of the heater in proximity may be higher.

[0028] According to a second aspect, there is provided an inline fluid heater having an inlet operable to receive a fluid to be heated; a substrate defining at least one conduit fluidly coupled with the inlet to receive the fluid; a positive thermal coefficient heater thermally coupled with the substrate and operable to heat the substrate to provide a heated fluid by heating the fluid within the at least one conduit; and an outlet fluidly coupled with the at least one conduit and operable to provide the heated fluid.

[0029] In embodiments, the inline fluid heater of the second aspect comprises the features of the first aspect set out above.

[0030] Further particular and preferred aspects are set out in the accompanying independent and dependent claims. Features of the dependent claims may be combined with features of the independent claims as appropriate, and in combinations other than those explicitly set out in the claims.

[0031] Where an apparatus feature is described as being operable to provide a function, it will be appreciated that this includes an apparatus feature which provides that function or which is adapted or configured to provide that function.

[0032] Other preferred and/or optional aspects of the invention are defined in the accompanying claims.

BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order that the present invention may be well understood, an embodiment thereof, which is given by way of example only, will now be described with reference to the accompanying drawing, in which:

[0034] Figures 1 A and IB illustrate an inline fluid heater according to one embodiment of the present invention;

[0035] Figures 2A to 2F illustrate an inline fluid heater according to a related technique;

[0036] Figures 3A and 3B illustrate an inline fluid heater according to a related technique;

[0037] Figure 4 illustrates an inline fluid heater according to another embodiment of the present invention; and

[0038] Figure 5 illustrates an inline fluid heater according to yet another embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0039] Before discussing the embodiments in any more detail, first an overview will be provided. Embodiments provide a fluid heater. Typically, the fluid heater is placed inline, between a fluid inlet and a fluid outlet in order to heat the fluid as it flows from a source or supply to a destination. Such fluid heaters can be used to heat a variety of fluids, both liquids and gases, as may be used in, for example, the heating of gases used in the exhaust management of semi-conductor processes. The fluid heater has an inlet which receives the fluid to be heated and an outlet which provides the heated fluid. A substrate, body or member is provided with one or more conduits, channels or apertures which fluidly couple the inlet with the outlet. A heater such as, for example, a positive thermal coefficient heater, thermally couples with the member and heats the member in order to heat the fluid as it flows through the conduits within the member. More than one inlet may be provided which is coupled with its own set of conduits within the substrate in order to provide for heating of separate fluids within a single substrate. The sets of conduits may share or have different configuration. The sets of conduits may also share or have separate heaters. This provides for a safe, efficient and compact way of conveniently heating fluids.

Fluid Heater

[0040] Figures 1A and IB show an inline fluid heater, generally 10, according to one embodiment. The inline fluid heater 10 has an inlet port 20 provided on a body 30 and an outlet port 40. In this embodiment, the body 30 has a generally box-like, planar configuration. The body 30 is thin and elongate with both rectangular faces and cross- section. The body 30 has a first major face 30A and a second major face 30B, joined by minor faces 30C, 30D. The inlet port 20 has a coupling 20A which is coaxially-located and surrounds a tube 20B. The tube 20B defines a blind cylindrical void extending from the coupling 20A and terminating within the tube 20B. A similar arrangement exists on the outlet port 40 - the cylindrical void 40C can be seen in Figure 1 A.

[0041] A plurality of open cylindrical voids (not shown) extend along the elongate length of the body 30, between the inlet port 20 and the outlet port 40. The conduits fluidly couple the cylindrical void within the tube 20B with the cylindrical void 40C within the tube 40B. [0042] Heater elements 50A, 50B are thermally coupled with major faces 30A, 30B, respectively. The heater elements 50A, 50B have a metal shell 55A, 55B, each of which retains a positive thermal coefficient heater (not shown). Each heater element 50A, 50B has a heater coupling 60A which couples with a pair of electrical feed wires 65 A, 66A and 65B, 66B respectively which supply power to the heater elements 50A, 50B.

[0043] In operation, the gas to be heated is provided at the inlet port 20 and passes through the cylindrical void within the tube 20B. The gas within the cylindrical void is then free to enter each of the conduits extending through the body 30.

[0044] Power is supplied via the power cables 65A, 66A and 65B, 66B via the heater couplings 60A and the temperature of the heater elements 50A, 50B rises. The heater elements 50A, 50B are thermally coupled with the metal shells 55A, 55B and so the temperature of the metal shells 55A, 55B also rises. This in turn heats the major faces 30A, 30B, which heats the body 30. Fluid passing through the conduits within the body is therefore heated as it passes along the elongate length of the body from the inlet port 20 to the outlet port 40. Heated fluid then exits the outlet port 40.

[0045] It will be appreciated that thermal pastes, surface finishes and/or thermal epoxy may be used to enhance the thermal coupling between components of the inline fluid heater 10. Also, it will be appreciated that heating can occur in both directions and that fluid may be supplied to the outlet port 40 and heated fluid exit the inlet port 20.

3D Printed Heater

[0046] Figures 2A to 2F show an inline fluid heater, generally 10', according to a related technique (the heater elements have been omitted to improve clarity). Figure 2A is a side view. Figure 2B is an end view. Figure 2C is a sectional view along the line A-A of Figure 2B. Figure 2D is a sectional view along the line B-B of Figure 2B. Figure 2E is an enlarged view of detail C of Figure 2C. Figure 2F is an enlarged view of detail D of Figure 2C. The body 30' is formed from 3D printed aluminium and has conduits 35' extending in parallel along its elongate length. The tubes 20B', 40B' are elongate and are formed with the body 30' . The body 30' has a roughened surface which is machined in the vicinity of the couplings (not shown). Heater Configuration

[0047] Figures 3A and 3B (which is a section B-B through Figure 3A) show an inline fluid heater, generally 10"', according to a related technique (the heater elements have been omitted to improve clarity). The body 30"' has conduits 35"' extending in parallel along its elongate length. The tubes 20B' ", 40B' " are elongate and are formed with the body 30" ' .

[0048] In testing, an inline heater having an elongate length of around 115 mm, a width between minor faces of around 16 mm and a distance between major faces of around 1.8 mm, with 13 parallel conduits extending along the elongate length of the body of diameter of around 1 mm with a 200W positive thermal coefficient heater on each major face heated a flow of gas from ambient, when flowing at 10 standard litres per minute (SLM) to 210°C, 50 standard litres per minute to 180°C and 90 standard litres per minute to 155°C. When no flow occurred, the heating elements settled at 240°C.

Multi-fluid heater

[0049] Figure 4 illustrates an inline heater according to one embodiment. In this embodiment, the inline heater, generally 10" ', is provided as part of a head assembly for an abatement apparatus. Multiple inlet ports 20"' A - 20" 'C are provided, each of which is coupled with a source of fluid to be heated. In this embodiment, the body 30" ' is formed as part of the head assembly from 3D printed aluminium and has conduits (not shown) extending therethrough. Each inlet ports 20" ' A - 20" 'C is coupled with its own set of conduits. The size, number and configuration of the conduits is selected based on the heating requirements for each fluid. Multiple outlet ports 40" ' A - 40" 'C are provided which provide the respective heated fluids. In this embodiment, separate heating elements are provided for each set of conduits, however, it will be appreciated that shared heating elements may be provided.

Pillar heater

[0050] Figure 5 is a plan cross-section illustrating an inline heater, generally 10" ", according to one embodiment (the heater elements have been omitted to improve clarity). A body 30" " is formed from 3D printed aluminium and has a chamber 100" " formed therewithin. The chamber 100" " fluidly couples an inlet port 20"" with an outlet port 30"" . The chamber 100"' has side-walls 110" ", 120" " extending between major faces which receive the heater elements in a similar manner to that illustrated in Figure 1. Pillars 130"", 140" " extend between the major faces across the chamber 100" " . The pillars 130"" are distributed within chamber 100"" . In this example, the pillars 130"" are arranged in rows and have offset or staggered columns to provide equal spacing between the pillars 130" " . The pillars 130"" are cylindrical (typically conical) with a circular cross-section. The pillars 140" " are elongate and are located at positions within the chamber 100" " where blocking or redirecting of fluid flow is required. The orientation of the pillars 140" " is selected to provide the required direction of fluid flow. The pillars 130"", 140" " define a plurality of intersecting conduits 35" " extending through the chamber 1000"" .

[0051] In operation, fluid is introduced through the inlet port 20"" . The fluid enters the chamber 100" " and is directed along the intersecting conduits 35" " by the pillars 130" ", 140"". Heat is conveyed from the heater elements, through the major faces, into the pillars 130"", 140" " to heat the fluid. The dwell time of the fluid within the chamber 100"" is influenced by the shape, size, location and orientation of the pillars 130" ", 140"". In one embodiment, just one type of pillar is used within the chamber. In other embodiments, more than one type of pillar is used within the chamber. A heated fluid exits through the outlet port 30" " . It will be appreciated that the location and orientation of the inlet port 20" " and the outlet port 30" " can be selected to suit requirements. This embodiment has been found to have significantly reduced pressure loss and significantly increased heat transfer. It will be appreciated that hybrid approaches are possible which combine the separate conduits illustrated in Figures 2 and 3 with the intersecting conduit illustrated in Figure 5.

[0052] In embodiments, the inline heater is 3D metal-printed. Other embodiments have non-linear conduits such as serpentine conduits. Also, the conduits need not be parallel but may intersect. Furthermore, the body may not be provided with distinct conduits, but may have a porous component such as a mesh or fibres sealed within a non-porous shell. In embodiments, the body itself may be non-planar and may be folded or deviate, with heating elements sandwiched or retained by the changes in direction of the body. [0053] Embodiments use of multiport extrusions (MPE) to maximize heat transfer area and provide a low-cost heat transfer device to heat gases/fluids using a positive thermal coefficient (PTC) heater.

[0054] Existing heating solutions tend to be too big, require many safety devices/circuits and are overly expensive. Embodiments provide a small, compact and inherently safe device to heat gases. Embodiments are a fraction of the cost and with very substantial safety increases over existing resistive heater element inline devices.

[0055] Embodiments use a MPE attached to a manifold to which tubing or pipework can be attached to flow gas and/or liquid through the ports and heating the gas/fluid as it passes through. Thermal epoxy or other methods are used to affix the PTC heater on either side or one side of the MPE to act as a heat source to heat the said gases/fluids. An example would be a device to heat 50 SLM of N ₂ . This is achieved in one embodiment by a device with 12 ports all at 1mm diameter extruded or 3D printed, running in parallel, with ¼" aluminium tubes on either end with a slot and the MPE brazed/welded/affixed into the slots to allow for easy manifolding in and out of the gas/fluid.

[0056] The use of MPEs from the HVAC industry coupled with PTCs provide an inherently safe and efficient means to heat gas/fluids. Unexpectedly, the devices are low cost, with a very low pressure drop.

[0057] Embodiments can be used in a controlled or non-controlled manner for any gas/fluid heating needs. Embodiments may be utilised in laboratories and any industry that needs or might need inline heating solutions. Some material changes to multiport tubes may be necessary depending on fluid or gas used, but the approach would still work.

[0058] Embodiments are particularly useful for abatement as space constraints are often very tight. Also embodiments may be utilised in pumps for heated seal purges and other such scenarios. Embodiments can be utilised in any place that a heated gas or fluid is needed.

[0059] Although illustrative embodiments of the invention have been disclosed in detail herein, with reference to the accompanying drawings, it is understood that the invention is not limited to the precise embodiment and that various changes and modifications can be effected therein by one skilled in the art without departing from the scope of the invention as defined by the appended claims and their equivalents.