APPARATUS FOR VAPOURISING A LIQUID FOR SUPPLY TO AN ENVIRONMENT

Abstract

The invention is a vapourising device (10) for vapourising a volatile liquid for supply to an environment. The device has a housing 100 having an inlet (109) for receiving inlet air which is warmed by inlet heater (111) before being supplied to cartridge assembly (200). Cartridge assembly (200) has a reservoir (204) for containing the liquid to be vapourised and at least one wick (206), one end of which is located in the reservoir to receive and transport the liquid to the other, exposed end of the wick where the liquid evaporates and mixes with the supplied stream of heated inlet air. The wick may be heated by a wick heater (211). The device also includes an outlet duct section (217) between the wick (206) and the outlet (221) which is conical in shape and is configured to accelerate the flow of the mixture of inlet air and vapourised liquid away from the wick towards the outlet (221). The invention provides increased control of the vapourisation process and helps to reduce condensation of the volatile liquid back onto the apparatus or onto surrounding surfaces.

Claims

1. Apparatus for vapourising a liquid for supply to an environment, comprising: a housing having an inlet configured to receive inlet air and an outlet configured to supply a mixture of the inlet air and vapourised liquid to the environment; a reservoir configured to contain the liquid to be vapourised and a reservoir heater configured to heat the liquid to be vapourised; and at least one wick, one end of the wick being located in the reservoir to receive liquid in use and transport the liquid to the other, exposed end of the wick where the liquid evaporates in use and a wick heater for heating the wick at or adjacent to the exposed end of the wick; wherein the apparatus further includes a duct path between the inlet and the outlet configured to convey the inlet air past the exposed wick end such that the inlet air mixes with the vapourised liquid; wherein the duct path includes an inlet duct section between the inlet and the wick, and wherein the apparatus further includes an inlet heater in the inlet duct section configured to heat the inlet air and a fan in the inlet duct section configured to draw in the inlet air; and wherein the duct path includes an outlet duct section between the wick and the outlet, and wherein the outlet duct section includes a conical chamber which reduces in cross-sectional area in the direction of flow towards the outlet to accelerate the flow of the mixture of inlet air and vapourised liquid away from the wick towards the outlet.

2. The apparatus of claim 1, wherein the apparatus further includes an inlet plenum chamber external to or upstream of the inlet.

3. (canceled)

4. The apparatus of claim 1, wherein the outlet duct section includes a straight section downstream of the conical chamber.

5. (canceled)

6. The apparatus of claim 1, wherein the wick heater is mounted in an apertured wick heater plate.

7. The apparatus of claim 1, wherein the duct path has a wick duct section between the inlet duct section and the outlet duct section, the exposed end of the wick extending into the wick duct section.

8. The apparatus of claim 7, wherein the apertures in the wick heater plate form part of the wick duct section.

9. The apparatus of claim 1, further comprising a wick mounting plate for mounting the wick.

10. The apparatus of claim 9, wherein the wick mounting plate is spaced from the wick heater plate and wherein the space between the plates forms part of the wick duct section.

11. The apparatus of claim 1, further comprising a removable cartridge assembly which includes the reservoir and the wick.

12. The apparatus of claim 1, wherein the inlet and outlet are arranged on the same vertical axis with the outlet above the inlet.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0105] An embodiment of the invention will now be described by way of example only and with reference to the accompanying drawings, in which:

[0106] FIG. 1 shows a perspective exterior view of a vapourising device in accordance with the invention;

[0107] FIG. 2A shows a cross-sectional view through the device of FIG. 1;

[0108] FIG. 2B shows a cross-sectional view through the device of FIG. 1 at 90 degrees to FIG. 2A;

[0109] FIG. 3 shows a cartridge assembly for use in the device of FIG. 1;

[0110] FIG. 4 shows a cross-sectional view through the cartridge assembly of FIG. 3;

[0111] FIG. 5 shows a detailed view of the wicks and wick heater plate in the cartridge assembly;

[0112] FIG. 6 shows a cross-sectional view through the device indicating the airflow paths;

[0113] FIG. 7 shows detailed view of the airflow into the cartridge assembly and past the wicks and wick heater plate;

[0114] FIG. 8 shows a vapour plume profile without an outlet duct fitted; and

[0115] FIG. 9 shows a vapour plume profile with an outlet duct fitted.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT

[0116] With reference to FIG. 1, an external view of a vapourising device 10 in accordance with the invention is shown. The device has a housing 100 comprising a cylindrical body 101 and a circular lid 102. Housing 100 is mounted on a base 103 which is generally circular and has three equally-spaced feet 104.

[0117] Turning to FIGS. 2A and 2B, it can be seen that feet 104 project downwards further than the side wall 105 of the base so that three air gaps 106 are formed between the surface on which the device is standing and the side wall 105. Air gaps 106 lead to inlet plenum chamber 107 which is formed in the underside of the base, and is a generally concave, semi-spherical chamber. As discussed above, the plenum chamber reduces the local velocity of the air, to create a localised, slower-moving volume of air from which the inlet air is drawn into the device.

[0118] Plenum chamber 107 leads to inlet duct section 108 which is the first part of the duct path through the device and starts with inlet 109 and ends with the inlets 202 to the cartridge assembly 200 discussed below. An inlet fan 110 is provided at the inlet 109 to draw air in from the plenum chamber.

[0119] Inlet duct section 108 initially expands to slow the inlet air down for heating by means of electric inlet heater 111 which is provided with a plurality of fins 112. Inlet duct section temperature sensor 113 downstream of the heater 111 provides temperature information to a controller (not shown) for controlling the inlet heater.

[0120] Downstream of the heater 111, inlet duct section 108 splits into two paths and passes either side of a central holder 114 for the cartridge assembly 200, discussed further below. Holder 114 is also referred to as a container or crucible and is located in the central core of housing 100, bisecting the inlet duct section 108. This part is therefore very well insulated from the external environment. Holder 114 is provided with a reservoir heater 115 to heat the liquid being vapourised.

[0121] In order to minimise heat loss from the device, particularly if it is to be used in a low-temperature environment, the body and lid are fitted with insulation material 116 (e.g. foam board or mineral wool insulation).

[0122] Cartridge assembly 200 is best described with reference to FIGS. 3-5. Cartridge assembly 200 has a main body 201 in which are formed a plurality of inlets 202 which lead to wick duct section 203, which is the second part of the duct path through the device. The wick duct section is the section of the duct path which passes through the main body 201.

[0123] Cartridge assembly 200 has a reservoir 204 which contains the liquid to be vapourised in use. A reservoir temperature sensor 205 (FIG. 4) provides liquid temperature information to a controller (not shown) for controlling the reservoir heater. Cartridge main body 201 is removable from the reservoir 204 so that the reservoir can be refilled or maintenance of the components carried out.

[0124] FIG. 4 shows the internal components of the cartridge assembly 200. Four cylindrical wicks 206 are provided. The wicks are mounted with their major axes in a vertical orientation in a wick mounting plate 207 which is a generally circular plate covering the top of the reservoir 204. The wick mounting plate is provided with a gripping insert 208 for each wick. Each insert 208 has an aperture for the wick to pass through and a gripping surface on the side of the aperture (which may be a pinch-point, an interference fit, or an angled or ridged surface) which holds the wick and maintains the correct vertical alignment. The electrical connection for the reservoir temperature sensor 205 also passes through the wick mounting plate 207 through guide 209 mounted into the mounting plate.

[0125] Spaced apart from the wick mounting plate, vertically above, is the wick heater plate 210. This can be seen in FIGS. 4 and 5. Wick heater plate 210 comprises four wick heaters 211. Each wick heater is a generally cylindrical structure with a central, circular passage 212 to receive a wick. The passage diameter is configured to be slightly larger than the diameter of the wick so that an annular aperture 213 is formed allowing air to pass through the wick heater plate, between the heater and the wick. Other apertures are also provided in the wick heater plate, including peripheral apertures 214 and central aperture 215. All three apertures combine to allow inlet air to pass through the wick duct section 203, from inlets 202 through the wick heater plate 210, so that the inlet air passes the exposed wick ends and mixes with the vapourised liquid.

[0126] A wick heater temperature sensor 216 provides temperature information to a controller (not shown) for controlling the wick heaters 211.

[0127] With reference to FIG. 4, once the inlet air has passed the wicks and becomes a mixture of inlet air and vapourised liquid, the gas stream enters the outlet duct section 217 which is also part of the cartridge assembly 200 and is the third part of the duct path through the device. Outlet duct section 217 is formed in outlet body 218 which is removable from the cartridge main body 201. Outlet body 218 includes conical chamber 219, straight section 220 and outlet 221.

[0128] The combination of the conical chamber 219 (which is an upturned truncated cone) and the straight section 220 acts as a chimney and serves to accelerate the flow of the gas mixture away from the wicks and to the outlet 221, as discussed further above and below.

[0129] As an example of the preferred geometry for the conical chamber 219, the cone may taper from a diameter of about 70 mm to about 17 mm, with an angle of approximately 45 degrees. The height of the cone is about 30 mm. The length of the chimney is about 15 mm. Different dimensions are of course possible depending on the scale of the device, which will still be within the scope of the invention.

[0130] The flow of inlet air and inlet air/vapourised liquid mixture through the duct path of the device is shown in FIGS. 6 and 7. In FIG. 6, it can be seen that the gas flow is generally vertically upwards from the inlet 109 to the outlet 221. In FIG. 7, the flow of the inlet air through the wick duct section 203 is shown, from inlets 202 (arrow A) and through apertures 213, 214 and 215 of the wick heater plate 210 (arrows B, C and D respectively), around the wicks 206.

[0131] FIGS. 8 and 9 illustrate schematically the effect of the outlet duct section 217 configuration on the shape of the vapour plume as it leaves the device, and particularly how far the plume is accelerated away from the device before it begins to disperse in the environment.

[0132] FIG. 8 shows a vapour plume profile P1 without an outlet duct fitted and it can be seen that the slower-moving vapour plume is more easily deflected by ambient air current (shown by the arrow) almost as soon as the plume leaves the outlet. The plume therefore passes close to the device and there is a high risk of the vapourised liquid condensing onto the exterior surface of the device or any other surrounding surfaces.

[0133] FIG. 9 shows a vapour plume profile P2 with outlet body 218 fitted, which forms outlet duct 217 in accordance with the invention. Due to the increase in speed with which the plume is ejected from the outlet, it moves further away from the device before being deflected by the ambient air current and dispersed in the environment. There is therefore a lower risk of the vapourised liquid condensing onto the exterior surface of the device and mixing of the vapourised material in the external environment is improved.