The invention relates to heat treatment apparatus for treating air, in particular but not exclusively for inactivation of pathogens such as a virus.

Background

It is known to inactivate pathogens such bacteria and viruses, for example by application of chemicals to a surface.

Some pathogens may be airborne or transmitted as temporarily airborne particles. In the context of the global pandemic of Sars-CoV-2 there is a desire to inhibit airborne transmission of pathogens.

Summary

According to a first aspect there is disclosed heat treatment apparatus for treating air, comprising in flow order: a pre-heating portion, a heating portion and a cooling portion for conveying an air flow therethrough; and a heater configured to heat air received in the heating portion; wherein the pre-heating portion is configured for heat exchange with the cooling portion in a heat exchanger stage of the apparatus, such that upon discharge from the heating portion into the cooling portion the airflow is cooled by transferring heat to upstream air in the pre-heating portion.

As the pre-heating portion, heating portion and cooling portion are arranged in flow order to convey the air flow, it is to be understood that in use the same air flow is conveyed from one to the other. The pre-heating portion, heating portion and cooling portion may be substantially contiguous with one another. The pre-heating portion and the cooling portion may form opposing sides of a heat exchanger.

It may be that the pre-heating portion comprises a plurality of pre-heating channels for heat exchange with the cooling portion, optionally fluidically coupled to an intake of the apparatus by an intake manifold, and optionally fluidically coupled to an inlet of the heater by a heater inlet manifold. Additionally or alternatively, it may be that the cooling portion comprises a plurality of cooling channels for heat exchange with the pre-heating portion, optionally fluidically coupled to an outlet of the heater by a heater outlet manifold, and optionally fluidically coupled to a discharge nozzle of the apparatus by a discharge manifold.

The heater inlet manifold and the heater outlet manifold may be considered part of the heating portion. It may be that the pre-heating portion and the cooling portion are in a shell and tube heat exchange relationship, optionally in a co-current, countercurrent, crossflow or hybrid (cross/counter flow) configuration.

It may be that the plurality of pre-heating channels and the plurality of cooling channels are interleaved in an alternating arrangement for counterflow heat exchange.

It may be that the pre-heating portion and the cooling portion are co-extensive along a longitudinal axis of the heat exchanger, and it may be that each of the plurality of pre heating channels and/or each of the plurality of cooling channels has a slender cross- sectional profile in a plane normal to the longitudinal axis.

In other words, in a cross-section normal to the longitudinal axis, each channel may have an extent along a first direction orthogonal to the longitudinal axis which is greater than its extent along a second direction orthogonal to the longitudinal axis and to the first direction, for example at least 5 times greater, at least 10 times greater, or at least 20 times greater. When the cross-section of each channel is rectangular, being slender may correspond to the length of its longest side being greater than the length of its shortest side, for example at least 5 times greater, at least 10 times greater, or at least 20 times greater. The cross-section may vary along the longitudinal axis, for example in shape or size, or orientation. For example, it may be that the channels are configured in a spiral or helix around the longitudinal axis, but nevertheless may be slender in any particular cross-section. A slender cross-sectional profile may correspond to efficient heat exchange for a given installed volume, since it may be that most heat exchange is conducted at walls separating adjacent interleaved channels, and thereby a slender configuration of the channels may relate to there being a relatively high surface area of the walls between adjacent channels relative to the installed volume for a given volumetric flow rate.

It may be that each of at least some of the channels is subdivided into two or more subchannels by one or more fins extending across the channel, between walls separating adjacent channels. It may be that all of the channels are subdivided into two or more subchannels by one or more such fins.

The heat treatment apparatus may comprise a plurality of heat exchange features provided on walls separating adjacent channels. Each heat exchange feature may be a heat exchange member extending from a wall or between walls separating adjacent channels. Each heat exchange member may extend obliquely between the walls, for example along a swept direction having an upstream or downstream component. In other words, the respective channel may extend (or be elongate) along a longitudinal axis, and the swept direction along which the heat exchange member extends may have a longitudinal component. By extending obliquely, a length of the heat exchange member may be greater than a local shortest distance of separation between the walls of the respective channel.

By extending obliquely between the walls, when the heat exchanger stage is manufactured by an additive manufacturing process (such as an additive layer manufacturing process), each heat exchange member may be formed progressively from a root portion adjacent to one of the walls to a tip portion adjacent another one of the walls, such that the respective heat exchange member is supported by the wall during additive manufacture along a build direction. For example, the build direction may be aligned with the longitudinal axis of the heat exchanger stage.

The heat treatment apparatus may comprise a compound port manifold extending from the intake and the discharge nozzle to the heat exchanger stage, the compound port manifold defining the intake manifold and the discharge manifold. The intake manifold may comprise an array of intake guide channels fluidically coupling the intake with the plurality of pre-heating channels. The discharge manifold may comprise an array of discharge guide channels fluidically coupling the cooling channels with the discharge nozzle. The array of intake guide channels and the array of discharge guide channels may be interleaved in an alternating arrangement.

The intake and the discharge nozzle may be offset along a port offset axis. Each intake guide channel may diverge from the intake along the compound port manifold to expand along the port offset axis and interleave with the discharge guide channels. Additionally or alternatively, each discharge guide channel may diverge from the discharge nozzle along the compound port manifold to expand along the port offset axis and interleave with the intake guide channels.

Each pair of adjacent guide channels of the compound port manifold may be separated by a septum wall. Downstream of the intake, each discharge guide channel may be isolated from the intake by an end wall extending between the respective septum walls. Additionally or alternatively, upstream of the discharge nozzle, each intake guide channel may be isolated from the discharge nozzle by an end wall extending between the respective septum walls.

It may be that the compound port manifold comprises a housing wall bounding the intake manifold and the discharge manifold, the housing wall defining one or more partitions between the respective manifolds upstream of the intake guide channels and downstream of the discharge guide channels. It may be that the intake guide channels, the discharge guide channels and the respective septum walls extend through a profile of the or each partition to interleave the respective guide channels.

It may be that the septum walls fan out along the compound port manifold (i.e. along a direction from the intake and discharge nozzle towards the heat exchanger stage), for example over an axis orthogonal to the port offset axis as defined above; and/or orthogonal to a longitudinal axis of the heater.

The heat treatment apparatus may comprise a compound heater manifold extending from the heater inlet and the heater outlet to the heat exchanger stage, the compound heater manifold defining the heater inlet manifold and the heater outlet manifold. It may be that the heater inlet manifold comprises an array of heater inlet guide channels fluidically coupling the heater inlet with the plurality of pre-heating channels. It may be that the heater outlet manifold comprises an array of heater outlet guide channels fluidically coupling the heater outlet with the plurality of cooling channels. It may be that the array of heater inlet guide channels and the array of heater outlet guide channels are interleaved in an alternating arrangement.

The heater inlet and the heater outlet may be offset along a port offset axis. It may be that each heater inlet guide channel diverges from the heater inlet along the compound heater manifold to expand along the port offset axis and interleave with the heater outlet guide channels. Additionally or alternatively, it may be that each heater outlet guide channel diverges from the heater outlet along the compound heater manifold to expand along the port offset axis and interleave with the heater inlet guide channels.

Each pair of adjacent guide channels of the compound heater manifold may be separated by a septum wall. It may be that, upstream of the heater inlet, each heater outlet guide channel is isolated from the heater inlet by an end wall extending between the respective septum walls. Additionally or alternatively it may be that downstream of the heater outlet, each heater inlet guide channel is isolated from the heater outlet by an end wall extending between the respective septum walls.

It may be that the compound heater manifold comprises a housing wall bounding he heater inlet manifold and the heater outlet manifold, the housing wall defining one or more partitions between the respective manifolds downstream of the heater inlet guide channels and upstream of the heater outlet guide channels. It may be that the heater inlet guide channels, the heater outlet guide channels and the respective septum walls extend through a profile of the or each partition to interleave the respective guide channels.

It may be that the septum walls fan out along the compound heater manifold (i.e. along a direction from the heater inlet and the heater outlet towards the heat exchanger stage), for example over an axis orthogonal to the port offset axis as defined above; and/or orthogonal to a longitudinal axis of the heater.

It may be each guide channel of one or more of the manifolds is configured to fluidically couple with a plurality of subchannels of a respective channel of the heat exchanger stage. In other words, each guide channel may have a single opening which is configured to fluidically couple with a plurality of separated subchannels of a respective channel of the heat exchanger stage.

The heat treatment apparatus may have a modular arrangement by which the or each manifold is detachably attached to the heat exchanger stage.

Otherwise, it may be that the or each manifold (or at least one of a plurality of manifolds, including any compound port manifold or compound heater manifold) is integral with the heat exchange stage. For example, it may be that a unitary structure defining the or each such manifold and the heat exchanger stage is formed by an additive layer manufacturing process (e.g. to achieve the associated complex internal structure as a unitary component).

It may be that the heater is configured to heat the airflow to at least a target temperature of between 150-250 °C. The heat treatment apparatus may further comprise a sensor configured to monitor a flow rate or thermodynamic property of the air flow and a controller configured to control the heater based on a corresponding signal received from the sensor to heat the airflow to at least the target temperature.

The heat treatment apparatus may comprise a porous material or high contact area structure within the heating portion (e.g. installed in a duct of heating portion, or integrally formed with the heating portion). As compared with the heating portion consisting of a shell wall and a channel therethrough, the provision of a porous material or other high contact area structure increases the ratio of an area of a contact surface (e.g. the surface area of the internal walls of the heating portion including the surface of the porous material or high contact area structure that is adjacent the air flow in use) for heating and a volume of air within the heating portion. This is considered to promote heat transfer to the air. Further, this is considered to increase a probability of direct contact (e.g. by a pathogen) with the contact surface. For example, a pathogen that undergoes direct contact with the contact surface of the heating portion may be heated to an elevated temperature relative to a peak temperature of air through the heating portion. For example, thermal conductivity of the heating portion, porous wall or high contact area structure may be relatively higher than the thermal conductivity of air, and/or the temperature of the heating portion, porous wall or high contact area structure may be higher than that of the air, such that direct contact with the contact surface may promote inactivation of a pathogen.

For example, it may be that the porous material or high contact area structure is configured to provide a total internal surface area within the heating portion for heat exchange with the air flow that is greater than an external surface area of the heating portion. For example, the total internal surface area may be at least twice as great, or at least 5 times as great.

It may be that the porous material or high contact area structure comprises a lattice of heat exchange members extending into the heating portion, or a foam (e.g. a metal foam).

The heater may be mounted exteriorly of the heating portion. It may be that the heater is configured to heat the heating portion by conduction. For example, the heating portion may comprise a heating element clamped around the heating portion and configured to transfer heat to a wall of the heating portion and any porous material or high contact area structure therein by conduction, for further convective heat transfer to an air flow passing therethrough. Providing an externally-mounted heater may provide a particularly simple mode of manufacture and assembly which facilitates ease of maintenance, servicing and replacement. Where a porous material or high contact area structure is disposed within the heating portion, the provision of an externally-mounted heater may aide manufacture and assembly owing to a lack of any interference or interaction (other than thermal) between the heater and the porous material or high contact area structure. Further, whereas an internally-mounted heater may require any porous material or high contact area structure to interfit with or be specifically shaped to integrate with the heater, there may be no such requirement for an externally-mounted heater, such that a porous structure or high contact area structure can be easily inserted into the heating portion, or integrally manufactured with the heating portion (e.g. by an additive layer manufacturing process).

Otherwise, it may be that the heater extends into or is disposed entirely the heating portion. Providing a heater at least partly disposed in the heating portion may improve an efficiency of heat transfer to air passing through the heating portion, since to the extent that the heater is internally-mounted, heat from the heater is directly dissipated only into the heating portion itself with no opportunity for direct dissipation outside of the heating portion (to the extend that the heater is internally-mounted).

The heat treatment apparatus may be sized for mounting on a body harness for portably heat treatment. For example, the heat treatment apparatus may have a maximum length of up to 600mm, a maximum width of up to 300mm, and a maximum depth of up to 300mm, for example a maximum length up to 500mm, a maximum width of up to 150mm and a maximum depth up to 150mm. The inventors have considered a suitable sizings in which the cross sectional profile of the heat treatment apparatus (i.e. its width and depth) is 60mm by 60mm. A minimum depth and a minimum width may be 50mm. A minimum length for combination may be 250mm. It may be that the heat treatment apparatus is provided on a body harness for portable wear by a human user, for example for treating air received from an environment and delivering a supply of treated air to the user.

According to a second aspect there is disclosed a heat treatment installation comprising: a heat treatment apparatus in accordance with the first aspect; wherein the intake is fluidically coupled to a controlled environment to receive an air flow for heat treatment; wherein the discharge nozzle is fluidically coupled to the controlled environment to return the air flow

The intake and/or the discharge nozzle may be indirectly fluidically coupled to the controlled environment via an HVAC system.

According to a third aspect there is provided a method of manufacturing at least one component for a heat treatment apparatus in accordance with any statement herein with respect to the first aspect, wherein the at least one component comprises a compound port manifold in accordance according to any statement above, and/or a compound heater manifold in accordance with any statement above; and optionally a heat exchanger stage in accordance with any statement above, the method comprising: providing model data for the at least one component; and progressively forming the at least one component by an additive layer manufacturing process, based on the model data, so that the respective guide channels are interleaved; optionally so that the pre-heating and cooling channels are interleaved. If may be that, when the at least one component comprises the heat exchanger stage, the heat exchanger stage is progressively formed by the additive layer manufacturing process along a build direction aligned with the longitudinal axis of the heat exchanger stage. Accordingly, when the heat exchanger stage comprises heat exchange members extending obliquely between walls separating adjacent channels, the heat exchange members are progressively formed from a root portion adjacent to one of the walls to a tip portion adjacent another one of the walls.

According to a fourth aspect there is provided a non-transitory computer-readable medium comprising instructions that, when executed by a processor, cause an additive layer manufacturing apparatus to perform a method in accordance with the third aspect, or comprising the model data as defined in the third aspect for providing to an additive layer manufacturing apparatus for performance of a method in accordance with the third aspect.

The controller(s) described herein may comprise a processor. The controller and/or the processor may comprise any suitable circuity to cause performance of the methods described herein and as illustrated in the drawings. The controller or processor may comprise: at least one application specific integrated circuit (ASIC); and/or at least one field programmable gate array (FPGA); and/or single or multi-processor architectures; and/or sequential (Von Neumann)/parallel architectures; and/or at least one programmable logic controllers (PLCs); and/or at least one microprocessor; and/or at least one microcontroller; and/or a central processing unit (CPU), to perform the methods and or stated functions for which the controller or processor is configured.

The controller may comprise or the processor may comprise or be in communication with one or more memories that store that data described herein, and/or that store machine readable instructions (e.g. software) for performing the processes and functions described herein (e.g. determinations of parameters and execution of control routines).

The memory may be any suitable non-transitory computer readable storage medium, data storage device or devices, and may comprise a hard disk and/or solid state memory (such as flash memory). In some examples, the computer readable instructions may be transferred to the memory via a wireless signal or via a wired signal. The memory may be permanent non-removable memory, or may be removable memory (such as a universal serial bus (USB) flash drive). The memory may store a computer program comprising computer readable instructions that, when read by a processor or controller, causes performance of the methods described herein, and/or as illustrated in the Figures. The computer program may be software or firmware, or be a combination of software and firmware.

Except where mutually exclusive, a feature described in relation to any one of the above aspects may be applied mutatis mutandis to any other aspect. Furthermore, except where mutually exclusive, any feature described herein may be applied to any aspect and/or combined with any other feature described herein.

Brief Description of the Drawings

The invention will be disclosed by reference to the accompanying drawings, in which:

Figure 1 schematically shows an example heat treatment apparatus;

Figure 2 shows an exploded perspective view of an example heat treatment apparatus;

Figures 3a, 3b, 4a, 4b show views of a heat exchanger stage of the example heat treatment apparatus normal to a longitudinal axis (3a, 4a), in a first cross-sectional plane parallel with the longitudinal axis (3b) and in a second cross-sectional plane parallel with the longitudinal axis (4b);

Figures 5a-5d show a compound port manifold of the heat treatment apparatus of Figure 2, variously in perspective cutaway, magnified perspective cutaway, and cross-sectional views;

Figures 6a and 6b show cross-sectional and perspective views of a heater portion of the heat treatment apparatus of Figure 2;

Figure 7 schematically shows a side view of the heat treatment apparatus of Figure 2 provided with a fan and controller;

Figures 8a and 8b schematically show arrangements of a heat treatment apparatus with a controlled environment;

Figure 9 is a flow diagram of a method of manufacturing a component of a heat treatment apparatus;

Figure 10 schematically shows a non-transitory computer readable medium and a processor; and

Figure 11 is a plot of temperature through a heat treatment apparatus.

Detailed Description

Figure 1 schematically shows flow paths through a heat treatment apparatus 100. The heat treatment apparatus comprises a heat exchanger stage 120 comprising interleaving channels that define a pre-heating portion 130 for conveying air received from an intake 102 to a heating portion 150, and a cooling portion 170 for conveying air received from the heating portion 150 to a discharge port 198. As shown in Figure 1, the channels of the pre-heating portion 130 and the cooling portion 170 are provided in counterflow arrangement and are configured for heat exchange between the respective channels, within the heat exchanger stage 120 of the heat treatment apparatus. In use, an air flow received in the heating portion from the pre-heating portion is heated (for example to an elevated treatment temperature). Upon discharge from the heating portion into the cooling portion, the air flow is cooled by heat transfer to upstream air in the pre-heating portion.

The heat treatment apparatus comprises ports for receiving and discharging air, namely the intake 102 and the discharge nozzle 198, for example for receiving air from a controlled environment and/or returning it to the controlled environment. There is a plurality of pre-heating channels 130 defining the pre-heating portion and a plurality of cooling channels defining the cooling portion. An intake manifold 110 is provided to fluidically couple the intake 102 with the plurality of pre-heating channels 130. A discharge manifold 180 is provided to fluidically couple the plurality of cooling channels 170 with the discharge nozzle 198. As is shown in Figure 1, each of the intake manifold 110 and the discharge manifold 180 comprises a plurality of guide channels configured to separately guide flow between the respective port and the respective channels of the heat exchanger stage 120.

The heat treatment apparatus comprises heater ports for conveying air to and from the heater, in particular a heater inlet and a heater outlet. A heater inlet manifold 140 is provided to fluidically couple the plurality of pre-heating channels 130 with the heater inlet. A heater outlet manifold 160 is provided to fluidically couple the heater outlet with the plurality of cooling channels 170. While the examples discussed herein envisaged both a plurality of pre-heating channels and a plurality of cooling channels, with respective manifolds, the broadest concepts of the disclosure may be implemented with other arrangements, for example a shell and tube heat exchanger which may only require a manifold (e.g. a header) for the tubes.

The heating portion 150 extends between the heater inlet and the heater outlet and is provided with a heater (not shown) for heating air received from the pre-heating portion as will be described in further detail below.

Figure 2 shows an exploded perspective view of an example implementation of the heat treatment apparatus 100. In the following description of drawings 2-11 , elements introduced with reference to earlier drawings will generally retain the same reference numeral (unless for example the respective element is presented in an alternative form).

The heat treatment apparatus 100 as shown in Figure 2 is generally elongated along a longitudinal axis 121 of the heat exchanger stage 120, but may take other forms in other implementations.

The heat exchanger stage 120 as shown in this example is generally cuboidal (e.g. square) in cross-section, but again may take other forms. The heat exchanger 120 extends from a port interface 222 to a heater interface 224, both of which are rectangular in this example.

The intake manifold and the discharge manifold are provided in a compound port manifold 210 configured to connect to the port interface 222 of the heat exchanger stage 120. For example, the port interface 222 of the heat exchanger stage and a heat exchanger interface 212 of the compound port manifold 210 may be configured to push- fit together and/or be fastened together by a mechanical fastener such as a bolt.

As shown in Figure 2, in this example the compound port manifold 210 has a housing wall which is blended from the intake 102 and discharge nozzle 198 toward the heat exchanger interface 212. While a compound port manifold may take other forms, in this example the intake 102 and the discharge nozzle 198 are spaced apart along a port axis 211 which is orthogonal to the longitudinal axis 121 of the heat exchanger stage 120 (when the compound port manifold and heat exchanger stage are assembled). The housing wall has a blended shape from the respective ports (the intake and the discharge nozzle) to the heat exchanger interface.

The heater inlet manifold and the heater outlet manifold are similarly provided by a compound heater manifold 240 configured to connect to the heater interface 224 of the heat exchanger stage. For example, the heater interface 224 of the heat exchanger stage and a heat exchanger interface 244 of the compound heater manifold 240 may be configured to push-fit together and/or be fastened together by a mechanical fastener such as a bold, as discussed above.

As shown in Figure 2, in this example the compound heater manifold 240 has a housing wall which is blended from a heater inlet 242 and a heater outlet 262 toward the heat exchanger interface 244. While a compound heater manifold may take other forms, in this example the heater inlet 242 and the heater outlet 244 are spaced apart along the port axis 211 which is orthogonal to the longitudinal axis 121 of the heat exchanger stage 120 (when the compound port manifold and heat exchanger stage are assembled). The housing wall has a blended shape from the respective ports (the heater inlet and the heater outlet) to the heat exchanger interface.

While the compound port manifold 210 and the compound heater manifold 240 may take different forms and have different combinations of features as disclosed herein, in the particular example described with reference to Figure 2 they have substantially the same configuration, both coupling two ports with respective interleaving channels of the heat exchanger stage. Accordingly, while the following further description is with reference to the compound port manifold 210, it applies equally to the compound heater manifold.

The heating portion 150 is configured to couple with the heater inlet 242 and the heater outlet 262 of the compound heater manifold 240. In this example the heater inlet 242 and the heater outlet 262 have a circular cross-section and the heating portion 150 is provided in the form of a duct having a corresponding circular cross section, although it will be appreciated that in other examples the heating portion may take any suitable form. As shown in Figure 2, in this example the heating portion 150 is provided in the form of a duct that is configured to turn the air flow received from the heater inlet 242 for re supply to the heater outlet 262, and in particular adapts a "horseshoe" or "hairpin bend" configuration, having inlet and outlet regions (e.g. longitudinally extending), and a hairpin region that turns the direction of the airflow and/or a centroidal line of the heating portion through an angle of approximately 180°. Further features of the heating portion will be discussed below with reference to Figure 6.

Figure 3a shows a view of the heat exchanger stage 120 normal to the longitudinal axis, the view corresponding to the port interface 222 of the heat exchanger stage 120 (as shown in Figure 2).

The heat exchanger stage 120 is bounded by a wall 321 which in this example is substantially in the form of a rectangular (e.g. square) cross section duct, having shoulder portions at the port interface and the heater interface for coupling with the respective compound manifolds.

As shown in Figure 3a, the heat exchanger stage 120 defines a plurality of channels 322, each of which forms part of either the pre-heating portion or the cooling portion of the apparatus. The channels 322 have a height along a first direction orthogonal to the longitudinal axis and a width along a second direction orthogonal to the first direction and the longitudinal axis. In this example, the channels are considered to be slender channels having a height greater than their width, with the height substantially corresponding to the extent of the heat exchanger stage 120 along the first axis (aside for the bounding wall of the heat exchanger stage), noting that the channels may nevertheless be subdivided by fins as will be described below.

As indicated by the four adjacent regions of hatching over four channels 322, each channel 322 forms part of either the pre-heating portion (pre-heating channels 332) or of the cooling portion (cooling channels 372), with the pre-heating channels 332 and the cooling channels 372 being interleaved in an alternating arrangement, for example side- by-side with each other as shown in Figure 3a.

An efficiency of heat transfer between the cooling channels 372 and the pre-heating channels 332 can be increased by minimizing a thickness of walls 323 separating adjacent channels, and by providing a relatively greater number of channels (of either type) of lower width rather than a relatively lower number of channels (of either type) of greater width. In the design of the heat exchanger portion, analysis may be performed to define a wall thickness that is sufficient for the anticipated structural loads of the heat exchanger portion and which can be reliably manufactured. For example, this may be a thickness of approximately 0.2mm to 3mm, for example 0.5mm to 2mm or 0.5-1 mm, or approximately 0.5mm as in the example arrangement of Figure 3a. A channel width may be selected based on a trade-off between heat exchange efficiency (which may favour relatively narrow channels), manufacturing complexity and weight (which may favour relatively wide channels, to minimise a number of walls and their associated weight). A suitable width may be between 0.5mm to 5mm, for example 1 mm-3mm, or approximately 1mm, as in the example arrangement of Figure 3a.

As shown in Figure 3a, optionally there may be fins 326 extending laterally through the channels (i.e. along a width direction or the second direction as defined above). The fins 326 may be provided in the form of continuous (i.e. unperforated) sheets of material that subdivide each channel 322 to evenly distribute the flow through the heat exchanger. Alternatively, the fins 326 may comprise openings or be perforated. In the example of Figure 3a, there are 5 fins 326 equally spaced along a height direction of the heat exchanger stage (or along the first direction, as defined above), and extending the full width of the heat exchanger. As will be appreciated, when manufactured as an integral structure (e.g. when manufactured by additive layer manufacturing), each fin effectively comprises a plurality of fin elements within each respective channel 332, and it may be that fin elements are provided at different heights between different channels, rather than as a continuous fin at the same height throughout the heat exchanger stage.

The fins may guide and subdivide the air flow, and also enhance heat transfer. In particular, the fins provide additional surface area within the heat exchanger stage for convective heat transfer between the air and the material of the heat exchanger stage, which is then conducted to an opposing side of the heat exchanger. The expression "side" as used herein in the context of a heat exchanger or heat exchanger stage relates to the conventional concept that a heat exchanger can be configured to transfers heat from a first fluid provided on a first side to a second fluid provided on a second side. The expression "side" is not used to indicate a location of the respective fluid, but merely that there are respective portions of the heat exchanger stage which contain the respective fluids, namely the pre-heating portion and the cooling portion, which form opposing sides of the heat exchanger.

As shown in Figure 3a, but best shown in Figure 3b, the heat exchanger stage 120 optionally further comprises a plurality of heat exchange features 324 on each wall separating adjacent channels 322. In the example of Figure 3b, the heat exchange features 324 are spaced apart from each other and distributed throughout the respective channel, for example at different longitudinal locations and at different heights. In the particular example of Figure 3b, the heat exchange features 324 are provided in a regular staggered arrangement with longitudinally-offset rows of heat exchange members at multiple heights within each subchannel. A heat exchange feature as envisaged by the present disclosure may be a recess such as a dimple, or may be a heat exchange member extending into the respective channel from a wall and optionally extending across the channel to engage an opposing wall. In the particular example of Figure 3b, the heat exchange features 324 are heat exchange members extending across respective channels 322 between the walls 323 separating adjacent channels 322. Figure 3b shows a cross-sectional view of the heat exchanger stage 120 along a plane parallel with the longitudinal axis 121 and a width direction (or first direction) of the heat exchanger stage. The heat exchange members 324 are provided to enhance heat transfer in the heat exchanger stage, each heat exchanger member providing additional surface area for convective heat transfer between the air and the material of the heat exchanger stage, which is then conducted along the heat exchange member to the walls to which it is attached. The heat exchanger members may be provided in the form of rods or pins (e.g. having a circular cross-section), plates, fins, vortex generators (e.g. vortex generator vanes or fences), dimples or other protrusions. Such members may be coupled to one or both walls of a channel in which they are provided.

As shown in Figure 3b, the heat exchange members 324 may extend obliquely between the respective walls 323 such that they are inclined with respect to the longitudinal axis 121 and optionally inclined relative to a width direction of the heat exchanger stage. By providing the heat exchange members in the oblique arrangement, they may be progressively formed during an additive layer manufacturing process from a root portion attached to one of the respective walls to a tip portion attached to another of the respective walls, for support of the heat exchange member during manufacture.

Figures 4b shows a cross-sectional cutaway view of the heat exchanger stage 120 along a cross-section parallel with the longitudinal axis 121 and parallel with a height direction (or second direction) of the heat exchanger stage 120 (i.e. along a plane normal to the width direction, or first direction). The cross-sectional view is along a cross-section B-B indicated in Figure 4a, which is a reproduction of Figure 3a oriented with respect to the view of Figure 4b to show corresponding alignment of the bounding wall 321 and the fins 326.

Figure 4b shows the fins 326 subdividing the respective channel 322 into six sub channels, with a staggered arrangement of heat exchange members 324 extending obliquely from the wall defining the channel 322 (i.e. a wall separating adjacent channels), but it will be appreciated that there may be fewer or more fins and/or sub channels in other examples.

Figure 5a shows a perspective cutaway view of the compound port manifold 210, with an upper portion (as oriented in the drawing) of the manifold 210 cutaway at a height to bisect the intake 102. As mentioned above, while the description relates to the compound port manifold 210 it may be equally applied to the compound heater manifold in the context of the respective ports (heater inlet and heater outlet), manifolds and guide channels.

Figure 5a shows the housing wall 516 of the compound port manifold 210 blending from the intake 102 and the discharge nozzle 198 towards the heat exchanger interface 212 as described above. The housing wall 516 may be considered to define two geometric halves including an intake region downstream of the intake 102 and a nozzle region upstream of the discharge nozzle 198, the housing wall defining partitions extending from the intake 102 and the nozzle 198 to fluidically separate the intake from the nozzle. However, as shown in Figure 5a, intake guide channels and discharge guide channels extend from the intake 102 the discharge nozzle respectively into an opposing geometric half of the compound port manifold.

As partially shown in Figure 5a and shown in magnified view in Figure 5b, septum walls 323 define and separate the intake guide channels 314 and the discharge guide channels 384. The septum walls are disposed in both geometric halves of the compound port manifold as discussed above, such that the guide channels are interleaved with each other.

In particular, as best shown in Figures 5c and 5d, the guide channels diverge along the extent of the compound port manifold from the ports (the intake 102 and discharge nozzle 198) to the heat exchanger interface 212, for example by having an increasing extent along the height direction from the ports to the heat exchanger interface. As shown in Figure 3c, a representative discharge guide channel 384 expands along the direction of the block arrow, as bounded by the housing wall 516 of the compound port manifold, by an end wall 386 which isolates the intake 102 from the respective discharge guide channel, and by laterally adjacent septum walls 323. The end wall 386 extends between the respective septum walls 323 to isolate the intake 102 from the discharge guide channel, and in particular extends between the septum walls 323 along an extent from a partition 518 of the housing wall 516 (which separates the intake from the discharge nozzle) and a location where the septum walls 323 terminate at the housing wall 516. Further, as shown in Figure 3d, a representative intake guide channel 314 expands along the direction of the block arrow, as bounded by the housing wall 516 of the compound port manifold, by an end wall 316 which isolates the discharge nozzle 198 from the respective cooling guide channel, and by laterally adjacent septum walls 323. The end wall 316 extends between the respective septum walls 323 to isolate the discharge nozzle 198 from the cooling guide channel, and in particular extends between the septum walls 323 along an extent from the partition 518 and a location where the septum walls 323 terminate at the housing wall 516. As can be seen in Figures 5c and 5d, the end walls 316, 384 define a diverging profile of the respective guide channels so that the guide channels are interleaved with each other in an alternating arrangement.

The compound port manifold 210 is configured so that the septum walls 323 and the guide channels defined therebetween engage and align with the respective separating walls of the heat exchanger stage and the respective pre-heating and cooling channels, to retain air from the intake within the intake guide channels and pre-heating channels, and to retain air discharged from the heater within the cooling channels and the discharge guide channels (i.e. without cross-contamination. As discussed elsewhere herein, it may be that the manifolds are integrally formed with the heat exchanger stage, which may provide for a particularly simple mode of ensuring alignment between the respective channels.

Figure 6a shows the heating portion 150 as described above with respect to Figure 2, in a cross-sectional view along a plane parallel with the longitudinal axis of the heat exchanger stage 121 and parallel to a height direction of the heat exchanger stage (i.e. normal to the width direction). The cross-section is of a central plane substantially bisecting the heating portion 150 into two geometric halves. As shown in Figure 6a and also in the perspective view of the heating portion 150 in Figure 6b, a conductive heating element 654 (or "heater") is provided externally around the heating portion to transfer heat to walls of the heating portion 150. For example, the heating element may be an electrical heating element (e.g. for resistive heating) that is configured to slide over or open and close around the heating element. The heating element may be coupled to an electrical power source and a controller, as will be described in further detail below.

As shown in Figure 6a, the heating portion 150 defines a duct within which a porous material or high contact area structure is disposed (e.g. installed or integrally provided) to provide a relatively high internal surface area for heat transfer between the heating portion and/or the porous material or high contact area structure, and an airflow passing therethrough. For example, the porous material or high contact area structure may be configured so that a total internal surface area within the heating portion for heat exchange with the air flow that is greater than an external surface area of the heating portion 150.

Merely by way of example, a suitable porous material may comprise a metal foam, for example having a porosity of between 75-90%, and an open cell structure. A suitable material for such a metal foam is any metal having a relatively high thermal conductivity, such as copper, titanium, aluminium nickel or alloys of such components (such as AlsiMglO and Inconel® alloys). A metal foam may be conformable for insertion into a separate a duct defined by the heating portion, or the duct may be assembled around the metal foam. The metal foam may be manufactured separately to the heating portion (for example provided as an off-the-shelf product), and shaped (e.g. machined) to size to fit the heating portion. Alternatively, a metal foam and the surrounding wall of the heating portion may be integrally formed, with the surrounding wall having a non-foamed structure and the interior portion having a foamed structure. An example manufacturer of metal foam structures is Alantum Corporation of South Korea, which manufactures a variety of metal foam structures, with a disclosure of a manufacturing process in "A review on manufacturing and application of open-cell metal foam", Sooho Kim, Chang- Woo Lee, Alantum Corporation, Procedia Materials Science 4 (2014) 305-309.

A suitable high contact area structure may include a latticework structure having a relatively high dimensional ratio of surface area to volume. For example, such a latticework structure may be formed by an additive layer manufacturing process, for example in an integral manner with the external wall of the heating portion, or separately (e.g. with the wall of the heating portion being assembled around the structure).

By providing the porous material or high contact area structure, heat from the heating element may be efficiently conducted throughout the heating portion for convective heat transfer with the air flow through the heater.

Figure 7 schematically shows the example heat treatment apparatus of Figures 2-6 as provided with a controller 702 and various control equipment. The heat treatment apparatus optionally comprises a temperature sensor 704 positioned and configured to monitor a temperature of an air flow through the heat treatment apparatus. In this particular example, the temperature sensor 704 is disposed within the heating portion at a location that may correspond peak or near-peak temperature of air flow. For example, analysis may be performed to determine a minimum peak temperature to which every streamline of air flow through the heat treatment apparatus is achieved, and the temperature sensor may be provided at a location corresponding to the minimum peak temperature or marginally below it, such that a temperature monitored by the temperature sensor is representative of a minimum temperature to which each streamline of air flow is likely to have been heated. The temperature sensor 704 is coupled to the controller 702, which is also coupled to the heater 654.

The heat treatment apparatus optionally comprises an air mover assembly comprising a duct 706 in fluid communication with one of the ports (i.e. with either the intake or the discharge nozzle) and an air mover 708 (e.g. a pump or fan) provided within the duct 706 to convey an air flow through the heat treatment apparatus.

In some implementations, the air mover assembly may be integral with the heat treatment apparatus, and in other implementations it may be attached to the respective port. The air mover 708 may be coupled to the controller 702.

The controller may be configured to control the heater 654 and/or the air mover 708 based on an output of the temperature 704, for example to target heating of the air flow to a target temperature, which may be a temperature range.

In some implementations, the controller may not be in control of a rate at which an air flow is provided to the heat treatment apparatus, and so it may be configured to heat the air flow to the target temperature by varying a parameter of the heater alone, such as a heating power.

Where the controller is configured to operate the air mover 708, the controller may be configured to vary an operating speed of the air mover 708 to target the target temperature, in particular to maintain heating to the target temperature when the heater is operating at a maximum heating power.

In further examples, the controller may operate the air mover 708 and/or heater 654 to maintain heating the air flow to the target temperature based on other signal inputs, for example based on temperature data relating to the air flow or source of air upstream of the heat treatment apparatus.

The target temperature may be set at a suitable level for inactivation of one or more respective pathogens. It should be noted that different pathogens may be inactivated at different temperatures, and/or durations (e.g. residence time) held at respective temperatures. Concepts of the disclosure relate to arrangements for providing efficiently providing such heating (in particular with heat transfer from the cooling portion to the pre heating portion) which apply irrespective of the selected temperature range. Nevertheless, it may be that a suitable temperature for heat treatment is 150°C-250°C, for example 175°C - 225°C, for example at least 200° such as 200°C-250°C, 200°C - 225°C, or approximately 210°C.

Figure 8a schematically shows an example heat treatment installation comprising a controlled environment 800 and a heat treatment apparatus, for example a heat treatment apparatus 100 as described with reference to the examples above. As schematically shown by block arrows, an air flow may be provided from the controlled environment 800 to the heat treatment apparatus 100 (e.g. via an intake of the heat treatment apparatus) for heat treatment, and then returned from the heat treatment apparatus 100 to the controlled environment.

The controlled environment 800 may be any space from which air is to be extracted for heat treatment. For example, the controlled environment may be an interior public or private space, such as an interior space of a building (e.g. an office building, industrial plant, public transport infrastructure such as an airport or rail station) or of a vehicle (e.g. an aircraft, train, bus or coach, car, truck, boat or other vehicle).

It may be that air is received from a different source location or controlled environment than that to which the air is returned via the discharge nozzle.

Figure 8b schematically shows a further example heat treatment installation comprising a controlled environment 800 (such as described above with reference to Figure 8a), a heat treatment apparatus, and an auxiliary air treatment system 802. For example, the auxiliary air treatment system may be an HVAC system, filter system or other system for treating air. It may be that an air flow to the heat treatment apparatus is received from the controlled environment 800 directly and/or indirectly via the auxiliary air treatment system 802, and it may be that the air flow is provided from the heat treatment apparatus to the controlled environment directly and/or via the auxiliary air treatment system 802. Each and every permutation of such direct/indirect supply and direct/indirect return is envisaged by the present disclosure.

Figure 9 is a flow diagram of a method of manufacturing at least one component for heat transport apparatus as described herein, in particular at least one of (i) a compound port manifold; (ii) a compound heater manifold; and (iii) a heat exchanger station.

In block 902, model data for the at least one component is provided, for example to an additive layer manufacturing apparatus or a controller for additive layer manufacturing apparatus. The model data may be a digital design model for the respective component which can be processed to provide instructions for the additive layer manufacturing apparatus (e.g. model data defining a shape of the component by a generic format which is not adapted for a specific additive layer manufacturing apparatus), or may comprise data defining instructions adapted for the additive layer manufacturing apparatus.

In block 904, the at least one component is progressively formed by an additive layer manufacturing process based on the model data, for example by progressively and selectively sintering or fusing a bed of build material provided on a platform in a layer- by-layer manner, with intermittent re-application of build material for each successive layer. A suitable additive layer manufacturing process may be selective laser sintering, or metal binder jetting.

The model data and additive manufacturing process may be such that the respective component has any of the features described above with respect to the examples.

Figure 10 schematically shows a non-transitory computer readable medium 1002 (such as a memory) comprising computer-readable data and/or instructions 1004. The data and/or instructions 1004 may comprise model data for at least one component to be manufactured according to an additive manufacturing method as described above with reference to Figure 9, and/or computer-readable instructions for controlling an additive manufacturing apparatus to progressively form the at least one component based on such model data.

In another example, the non-transitory computer readable medium 1002 may store instructions for operating a controller of a heat treatment apparatus as disclosed herein, to control a heater and/or an air mover based on data received from a temperature sensor to target heating an air flow to a target temperature, as disclosed herein. Figure 11 is a plot of air temperature along an air flow pathway through a heat treatment apparatus as envisaged in the present disclosure, for example a heat treatment apparatus as described above with reference to Figures 2-7. The plot shows temperature against longitudinal position,. As can be seen from the plot, air entering the heat exchanger at the inlet is heated in the pre-heating portion by heat transfer from the same stream of (downstream) air within the cooling portion, thereby raising the temperature of the air (in this particular example by approximately 160 °C from 20 °C at the intake 102 to 180 °C at the heater inlet 242). In the heating portion, the temperature of the air rises further (in this particular example, to approximately 200 °C), before it is cooled in the cooling portion by heat transfer to an upstream portion of the same airflow within the pre-heating portion. In this example, the heat transfer between the cooling and pre-heating portion reduces the exit temperature to a temperature higher than the temperature of air at the intake, for example approximately 10 °C higher (e.g. to 30 °C in the example of Figure 11). Such cooling enables practical return of the air to a controlled environment at a relatively moderate temperature, while passively raising a temperature of the inlet air in the pre-heating portion (i.e. without requiring heater power for that phase of heating). Further cooling of the discharged air may be performed, for example by providing the air to an HVAC system prior to resupply to a controlled environment.

The disclosure extends to the subject-matter of the following numbered clauses:

Clause 1. Heat treatment apparatus for treating air, comprising in flow order: a pre heating portion, a heating portion and a cooling portion for conveying an air flow therethrough; a heater configured to heat air received in the heating portion; wherein the pre-heating portion is configured for heat exchange with the cooling portion in a heat exchanger stage of the apparatus, such that upon discharge from the heating portion into the cooling portion the air flow is cooled by transferring heat to upstream air in the pre-heating portion.

Clause 2. Heat treatment apparatus according to Clause 1, wherein the pre-heating portion comprises a plurality of pre-heating channels for heat exchange with the cooling portion, optionally fluidically coupled to an intake of the apparatus by an intake manifold, and optionally fluidically coupled to an inlet of the heater by a heater inlet manifold; and/or wherein the cooling portion comprises a plurality of cooling channels for heat exchange with the pre-heating portion, optionally fluidically coupled to an outlet of the heater by a heater outlet manifold, and optionally fluidically coupled to a discharge of the apparatus by a discharge manifold.

Clause 3. Heat treatment apparatus according to according to Clause 2, wherein the plurality of pre-heating channels and the plurality of cooling channels are interleaved in an alternating arrangement for counterflow heat exchange.

Clause 4. Heat treatment apparatus according to Clause 3, wherein the pre-heating portion and the cooling portion are co-extensive along a longitudinal axis of the heat exchanger, and wherein each of the plurality of pre-heating channels and/or each of the plurality of cooling channels has a slender cross-sectional profile in a plane normal to the longitudinal axis.

Clause 5. Heat treatment apparatus according to Clause 3 or 4, wherein each of at least some of the channels is subdivided into two or more subchannels by one or more fins extending across the channel, between walls separating adjacent channels.

Clause 6. Heat treatment apparatus according to any of Clauses 3 to 5, comprising a plurality of heat exchange features provided on walls separating adjacent channels; optionally wherein each heat exchange feature is a heat exchange member extending from a wall or between walls separating adjacent channels; optionally wherein each heat exchange member extends obliquely between the walls, for example along a swept direction having an upstream or downstream component.

Clause 7. Heat treatment apparatus according to any of Clauses 3-6, comprising a compound port manifold extending from the intake and the discharge nozzle to the heat exchanger stage, the compound port manifold defining the intake manifold and the discharge manifold; wherein the intake manifold comprises an array of intake guide channels fluidically coupling the intake with the plurality of pre-heating channels; wherein the discharge manifold comprises an array of discharge guide channels fluidically coupling the cooling channels with the discharge nozzle; wherein the array of intake guide channels and the array of discharge guide channels are interleaved in an alternating arrangement. Clause 8. Heat treatment apparatus according to Clause 7, wherein the intake and the discharge nozzle are offset along a port offset axis; wherein each intake guide channel diverges from the intake along the compound port manifold to expand along the port offset axis and interleave with the discharge guide channels; and/or wherein each discharge guide channel diverges from the discharge nozzle along the compound port manifold to expand along the port offset axis and interleave with the intake guide channels.

Clause 9. Heat treatment apparatus according to Clause 7 or 8, wherein each pair of adjacent guide channels of the compound port manifold are separated by a septum wall; wherein downstream of the intake, each discharge guide channel is isolated from the intake by an end wall extending between the respective septum walls; and/or wherein upstream of the discharge nozzle, each intake guide channel is isolated from the discharge nozzle by an end wall extending between the respective septum walls.

Clause 10. Heat treatment apparatus according to any of Clauses 3-9, comprising a compound heater manifold extending from the heater inlet and the heater outlet to the heat exchanger stage, the compound heater manifold defining the heater inlet manifold and the heater outlet manifold; wherein the heater inlet manifold comprises an array of heater inlet guide channels fluidically coupling the heater inlet with the plurality of pre-heating channels; wherein the heater outlet manifold comprises an array of heater outlet guide channels fluidically coupling the heater outlet with the plurality of cooling channels; wherein the array of heater inlet guide channels and the array of heater outlet guide channels are interleaved in an alternating arrangement.

Clause 11. Heat treatment apparatus according to Clause 10, wherein the heater inlet and the heater outlet are offset along a port offset axis; wherein each heater inlet guide channel diverges from the heater inlet along the compound heater manifold to expand along the port offset axis and interleave with the heater outlet guide channels; and/or wherein each heater outlet guide channel diverges from the heater outlet along the compound heater manifold to expand along the port offset axis and interleave with the heater inlet guide channels. Clause 12. Heat treatment apparatus according to Clause 10 or 11, wherein each pair of adjacent guide channels of the compound heater manifold are separated by a septum wall; wherein upstream of the heater inlet, each heater outlet guide channel is isolated from the heater inlet by an end wall extending between the respective septum walls; and/or wherein downstream of the heater outlet, each heater inlet guide channel is isolated from the heater outlet by an end wall extending between the respective septum walls.

Clause 13. Heat treatment apparatus according to any of Clauses 2-12, having a modular arrangement by which the or each manifold is detachably attached to the heat exchanger stage.

Clause 14. Heat treatment apparatus according to any preceding Clause, wherein the heater is configured to heat the airflow to at least a target temperature of between 150- 250 °C; optionally further comprising a sensor configured to monitor a flow rate or thermodynamic property of the air flow and a controller configured to control the heater based on a corresponding signal received from the sensor to heat the airflow to at least the target temperature.

Clause 15. Heat treatment apparatus according to any preceding Clause, comprising a porous material or high contact area structure within the heating portion, the porous material or high contact area structure.

Clause 16. Heat treatment apparatus according to any preceding Clause, wherein the heater is mounted exteriorly of the heating portion.

Clause 17. A heat treatment installation comprising: a heat treatment apparatus in accordance with any preceding Clause; wherein the intake is fluidically coupled to a controlled environment to receive an air flow for heat treatment; wherein the discharge nozzle is fluidically coupled to the controlled environment to return the air flow. Clause 18. A heat treatment installation according to Clause 17, wherein the intake and/or the discharge nozzle is indirectly fluidically coupled to the controlled environment via an HVAC system.

Clause 19. A heat treatment apparatus according to any of Clauses 1-16, wherein the heat treatment apparatus is sized for mounting on a body harness for portable heat treatment. Clause 20. A method of manufacturing at least one component for a heat treatment apparatus in accordance with any preceding Clause, wherein the at least one component comprises: a compound port manifold in accordance with any of Clauses 7-9, and/or a compound heater manifold in accordance with any of Clauses 10-12; and optionally a heat exchanger stage in accordance with any of Clauses 1-6, the method comprising: providing model data for the at least one component; and progressively forming the at least one component by an additive layer manufacturing process, based on the model data, so that the respective guide channels are interleaved; optionally so that the pre-heating and cooling channels are interleaved.