GB2586584A

GB2586584A - Fluid expulsion for hot environments

Info

Publication number: GB2586584A
Application number: GB1911647.4A
Authority: GB
Inventors: Podkolinski Thomas
Original assignee: Swedish Biomimetics 3000 Umist Tech Ltd
Current assignee: Swedish Biomimetics 3000 Umist Tech Ltd
Priority date: 2019-08-14
Filing date: 2019-08-14
Publication date: 2021-03-03
Anticipated expiration: 2039-08-14
Also published as: GB2586584B; GB201911647D0

Abstract

Disclosed is a valve apparatus used for high temperature fluid expulsion in conjunction with the following apparatus, a reservoir for storing a fluid, a chamber 1 for containing a fluid, an inlet orifice 2 to the chamber, an inlet valve 3 comprising an actuator 5 and seat 6 including, an outlet orifice 6 from the chamber, an outlet valve 9 comprising components actuator 10, a pintle 11 and outlet valve seat 12, where the components are arranged spaced from each other and the outlet orifice, there being a heating means 13 for fluid within the chamber, where the pressure and temperature of the fluid in the chamber are raised, such that at least part of the fluid may change state when the inlet and outlet valves are sealed and the fluid is then expelled from the chamber by a vapour explosion process, where the pintle separating the outlet actuator and the seat prevent damage to the actuator.

Description

FLUID EXPULSION DEVICE FOR HOT ENVIRONMENTS

Technical Field

The present invention is directed towards an apparatus and method for fluid expulsion. In particular, a device for fluid expulsion which is able to expel fluid quickly and over relatively long distances from a chamber, comprising an arrangement which can protect valve components from over-exposure to heat.

Background

Devices exist which are capable of expelling fluids, including vapour and liquid sprays, at high velocities. These devices can be used, for example, in fire extinguishing systems, ink jet printers, engines and medical devices.

Typically, they comprise a reservoir arranged to hold a liquid, an inlet valve arranged to transfer some of the liquid into a chamber and an exit or outlet valve arranged to control the expulsion of the material from the chamber. The chamber can be referred to as an ejection chamber. The speed of ejection and distance travelled (also referred to as the "throw") by the expelled material is influenced by a number of variables, including the fluid being expelled, the temperature and pressure in the chamber, the valve timing, the size of the chamber, the outlet valve orifice size and the viscosity of the fluid to be ejected.

EP2343104B1 to the University of Leeds describes an apparatus for ejecting material with improved speed of ejection and distance travelled by the ejected liquid and liquid vapour.

The material is heated within a chamber, past the saturation point of the liquid at ambient pressure. The inlet and exit valves are kept closed, during heating, such that the pressure within the chamber is increased. The liquid is then released via the exit valve, where the sudden drop in pressure causes rapid expansion of the liquid and a vapour explosion.

However, it was found that the known devices cannot reliably operate in environments where they are exposed to high temperatures, as the heat is damaging to the valves and interferes with valve actuation. With prolonged use in extreme conditions the valve components, particularly any electromagnetic components of the valve actuators and seals, are more likely to fail. The present invention aims to address this issue.

Summary

According to the present invention there is provided an apparatus for expelling a fluid comprising; a reservoir for storing a fluid; a chamber for containing a fluid; an inlet orifice to the chamber; an inlet valve comprising an inlet valve actuator and an inlet valve seat; an outlet orifice from the chamber; an outlet valve comprising an outlet valve actuator, a pintle and an outlet valve seat, which are arranged separately and spaced from the outlet orifice; at least one means of heating the fluid within the chamber, such that the temperature and pressure of the fluid are raised when the inlet and outlet valves are closed, causing at least a portion of the fluid within the chamber to change state; whereby in use, fluid is expelled from the outlet orifice of the chamber by a vapour explosion process.

The outlet orifice is provided at another location in the chamber from the inlet orifice. The outlet valve actuator is arranged separately and spaced from the outlet orifice, or in other words, located at a distance from the outlet orifice. The separation of the valve actuator from the orifice itself is made possible by the use of a pintle (rod, pin or bolt), or similar element, which connects the valve actuator to the seat of the valve. The valve seat can provide a sealing surface, thus enabling closure of the valve and enabling pressurisation of the chamber. The valve actuator may be connected to one end of the pintle, and the valve seat may form the other end of the pintle. The pintle, rod or pin, can be made from a metal, such as iron or steel, for example. The valve actuator can move the pintle, causing the pintle to act upon the valve seat to open or close the orifice.

Heat damage can be caused by exposure of the valve components to the hot stream of fluid leaving the chamber. Normally, hot fluid leaving the chamber passes through the outlet valve and transfers heat to the valve components. The use of a pintle allows the valve to be positioned away from the hot fluid which leaves via the outlet orifice. Heat damage can also be caused by the valve being placed in a high temperature environment. The advantage of being able to separate the outlet valve actuator from the outlet orifice is that the valve actuator can be located in a cooler environment which minimises damage to the valve actuator components.

The outlet valve actuator may be electromechanical, such as a solenoid. The electromechanical components of a valve actuator can be damaged or degraded by repeated exposure to heat. In addition, when the temperature is high, the resistance in the actuator coils (e.g. solenoid coils) increases. The high temperatures can also cause warping and distortion of components within the valve. In accordance with the present invention, the longevity of electromechanical actuators can be increased by relocating the valve actuator. The valve actuator can be relocated to a cooler surrounding environment, or to a position where it is possible to cool the valve actuator. Cooling could be achieved via a cold stream passing through the valve itself, or alternatively, by passing a cold stream around the valve in a heat-exchanger type arrangement, i.e. in fluid isolation from the fluid passing through the valve. By relocating the outlet valve actuator, it can be ensured that the valve is protected from hot fluid streams at the outlet. The outlet valve actuator may be positioned far enough away from the valve orifice to ensure that it is no longer exposed to heat or extreme conditions. The same advantages apply to relocating the inlet valve actuator. It has been found that relocating the valve actuators has resulted in improved reliability of the valves and valve actuators over time.

The inlet valve actuator may also be electromechanical, such as a solenoid. Heat damage can also be caused by exposure of the valve components to a hot stream of fluid entering the chamber via the inlet orifice. Similarly, the inlet valve actuator may be arranged separately and spaced from the inlet orifice, or in other words, located at a distance from the inlet orifice. The inlet valve actuator can be protected from exposure to high temperatures by being located at a distance from the inlet orifice. The advantages mentioned above for relocation of the outlet valve actuator also apply to the relocation of the inlet valve actuator.

The fluid leaving the chamber via the outlet orifice is usually at a high temperature (after being heated past the saturation point), and therefore any outlet valve actuator located at the outlet orifice is vulnerable to heat damage from the hot fluid. By using the pintle arrangement of the present invention, the valve actuator can be relocated away from the outlet orifice to prevent damage to the actuator components. The outlet valve actuator may be positioned far enough away from the valve orifice to ensure that it is no longer exposed to heat or extreme conditions.

Optionally, the outlet and/or inlet valve actuators may be placed near to or adjacent to a cool fluid stream to provide additional cooling to the valve components. For example, the valve actuator can be placed near to or adjacent to a cooler inlet flow of fluid to the chamber. The inlet fluid is generally at a lower temperature than the fluid inside the chamber. By positioning the valve actuator near to a cold stream, it is possible to provide continual cooling to the valve actuator components. This results in less damage to the components.

In some cases, the inlet fluid stream may also be hot, and it may therefore also be desirable to relocate the inlet valve actuator to avoid damage to the actuator components. Once again, the use of a pintle allows the inlet valve actuator to be relocated to a cooler location.

The fluid entering the chamber can be a liquid, or a mixture of liquid and gas, such as a foam, but is preferably a liquid. Where the fluid is a liquid or foam, it could also include suspended entrained particulate solids. The fluid can be pumped towards the chamber, or it could be supplied under a pressure differential, or could be supplied using a gravity feed. The fluid could be a liquid such as water, or a hydrocarbon fuel (e.g. petrol, kerosene or gasoline), to provide some examples. The fluid could also be a solution comprising a solvent and solute. The fluid is supplied from the reservoir into the chamber, where it is heated and pressurised. At least a portion of the fluid within the chamber changes state as a result of the conditions within the chamber, namely being subject to a combination of heat and pressure.

The chamber will be formed from a material which is able to withstand substantial changes in temperature and differentials in pressure. It may have a generally cylindrical shape. The chamber may also be referred to as a pressure vessel. It may be formed from a metal such as steel, copper or aluminium, or a polymer. Alternatively, the chamber may be formed from a composite material wound around a metal liner, in the form of a composite overwrapped pressure vessel. The chamber may be lined with another metal, ceramic, or polymer. For large-scale applications, the chamber could be formed from concrete, lined with a steel thin membrane. The most appropriate choice of material for constructing the chamber will depend on the size of the chamber.

Before heating, the outlet and inlet valves are closed to prevent the escape of fluid. Heating the fluid in the chamber causes an increase in the pressure within the chamber and hence also a lowering of the boiling temperature of the fluid. In most cases, where the fluid is a foam, the saturation or boiling point of the fluid will be based upon the boiling temperature of the liquid phase. The fluid is heated to a temperature well above the boiling point/temperature at atmospheric pressure. Preferably, the fluid in the chamber is heated to a temperature equal to or above the saturation point of the fluid at atmospheric pressure, or equal to or above the saturation point of the fluid at a pressure which is the pressure downstream of the outlet valve of the chamber. The temperature can be monitored by one or more temperature sensors.

The means of heating the fluid can be arranged to raise the temperature of the fluid to a value equal to or greater than a saturation temperature of the fluid at ambient pressure.

A means of heating the fluid may be a heating element located in or near the chamber. The means of heating may be a heated jacket which surrounds or partially surrounds the chamber, for example. The chamber may be located in a warm surrounding environment, such that the environment itself becomes at least one of the means of heating (e.g. when the chamber is situated in a combustion engine).

Alternatively, the means of heating may be generated by chemical components. For example, two chemicals may be combined which undergo an exothermic reaction when mixed, where the heat generated is sufficient to heat the fluid to a temperature which exceeds the saturation temperature of the fluid.

The sudden release of pressure when the fluid exits the outlet orifice causes a vapour explosion due to the rapid expansion of liquid, foam and/or vapour. The vapour explosion has the effect that the material is blasted out from the chamber very rapidly and over further distances than would otherwise be obtainable. A mixture of vapour and fine spray is ejected from the outlet orifice, which can travel at high velocities and over considerable distances.

For example, the throw of a liquid and vapour explosion in accordance with embodiments of the present invention may be around 200 to 300 times or more of the corresponding chamber length. This is due to the high fluid pressures which are obtained the chamber, as well as the dynamics of the fluid within the chamber. The present invention is able to produce a vapour mist from a liquid feed to the chamber.

A further feature of the device is that it can continually emit bursts of vapour in very quick succession. The valve timing can be programmed such that the outlet valve opens every few milli-seconds.

The temperature at which the outlet valve is allowed to open can be referred to as the trigger temperature. The trigger temperature can be set above the boiling point of the liquid or liquids within the chamber to ensure maximum explosion of liquid from the chamber. The trigger temperature can be set in the range of 10°C to 200°C above the boiling point of the liquid. Preferably, the trigger temperature is set in the range of 20°C to 90°C above the boiling point of the liquid. The necessary trigger temperature is relative to the ambient pressure of the environment into which the expelled spray is being injected into, i.e. the ambient environment external to the chamber at the outlet orifice. If the ambient pressure is high, then it is necessary to increase the temperature and pressure within the chamber, and the trigger temperature value will be at the higher end of the scale. The ratio of liquid to vapour can be altered when higher trigger temperatures are selected. This can eliminate the liquid phase altogether, if desired. In this way, the proportion of liquid and vapour can be controlled by varying one or more parameters associated with the chamber. It has been found that if the trigger temperature is not at least 10°C higher than the boiling temperature of the liquid, then the resulting droplet size is large.

Alternatively, instead of monitoring the temperature, the pressure within the chamber could be monitored and the outlet valve could be opened when a predetermined pressure value is reached. Selectively varying one or more parameters such as temperature, pressure or viscosity of the liquid can be used to control the drop size achieved in the resulting spray.

Two or more heaters may be used. For example, an internal heating element may be used in combination with external heating. The chamber may be located in a hot environment, and able to absorb heat from the surroundings. For example, if the device is used in a combustion chamber of an engine, the heat required to bring the fuel to the designated temperature can be partially or totally obtained from the heat produced by the engine. When in use, the engine will be very hot, and the chamber can be designed to absorb the required heat from the environment. The heat or thermal energy can be obtained through the chamber walls of the injector, through a heat exchanger going into the chamber, or a combination of the two techniques. Additionally, the inlet pipe can be arranged such that it goes through or passes adjacent to the hot parts of the engine body, such that the fluid entering the inlet valve is heated nearer to the designated temperature before entering the chamber. However, it is preferable to maintain the temperature of the fluid below the saturation temperature of the lightest component of the fuel to avoid unfavourable cavitation in the pipe lines.

The outlet orifice from the chamber may be connected to a nozzle (not shown) to alter the dispersion properties of the spray. The nozzle can be used to generate a spray which has a wider field of dispersion, or a narrower, more concentrated spray. A nozzle can also be used to further decrease the droplet size of the liquid in the spray, such that a finer spray is produced.

The apparatus may further comprise a pump for supplying fluid to the chamber from the reservoir.

The temperature can be monitored by one or more temperature sensors which may be fitted inside the chamber or near to the chamber, for example in the inlet stream, or on a wall of the chamber.

The apparatus can also comprise at least one pressure sensor inside the chamber. This may be a pressure transducer. As fluid is expelled from the chamber, the pressure within the chamber drops. The outlet valve can be arranged to close when the pressure has dropped back to an ambient or second predetermined pressure, which may be referred to as the closure pressure.

It is possible to include a recycle loop (not illustrated) from the chamber to the reservoir. The recycle loop would be designed to allow some of the fluid in the chamber to return to the reservoir when the inlet valve is open for replenishing the fluid in the chamber. The recycle line allows some fluid to pass from the chamber back to the reservoir. Fresh fluid is supplied to the chamber from the reservoir via the inlet valve. The recycled fluid will be warmer than the fluid in the reservoir; such that the recycled fluid helps to raise the temperature of the fluid in the reservoir. This can accelerate the heating of the fluid in the chamber.

Optionally, the apparatus can further comprise a means for directing and controlling the flow of fluid through the chamber from the inlet orifice to the outlet orifice along a non-linear path. The use of a non-linear path has been shown to improve the concentration of foam at the outlet orifice of the chamber. The fluid can be directed from the inlet orifice to the outlet orifice via at least one non-linear channel, or alternatively, via a plurality of non-linear channels. The means for directing and controlling the flow of fluid from the inlet orifice to the outlet orifice along a non-linear path could comprise one or more baffles.

The apparatus can comprise at least one controller connected to the inlet and outlet valve actuators, such that the opening and closing of the inlet valve and outlet valve is electronically controlled. The controller can be programmed such that it closes the outlet valve when the closure pressure or when a set temperature is reached and opens the inlet valve again to introduce new fluid into the chamber. The system can cycle between introducing new fluid into the chamber and expelling the fluid from the outlet orifice (e.g. 1:1 ratio of valve timing for the inlet and outlet valve opening). Alternatively, the valve timing may be offset, such that the chamber is filled with fluid, and the outlet valve then fires a series of short rapid bursts until the chamber is partially or fully emptied. The controller can be programmed to open the valves according to a timing sequence, where the valves are opened and closed for a predetermined time, provided that a set (predetermined) pressure or temperature within the chamber has been reached or exceeded. The predetermined temperature could correspond with the saturation temperature of the fluid within the chamber at atmospheric pressure.

The claimed apparatus for rapidly expelling a fluid can be used in fire extinguishing systems, ink jet printers, fuel injection systems for engines, gas igniters, and medical devices such as nebulisers, to name just a few examples.

Also provided is a method for expulsion of a fluid from a chamber comprising supplying fluid from a reservoir to the chamber via an inlet orifice by opening an inlet valve to the chamber; where the inlet valve comprises an inlet valve actuator and a valve seat; where the fluid inside the chamber flows to an outlet orifice via an outlet valve; whilst the fluid is inside the chamber and the inlet and outlet valves are closed, heating the fluid above the saturation point of the fluid at atmospheric pressure, such that at least a portion of the fluid changes state; opening the outlet valve such that fluid is expelled from the outlet orifice by a vapour explosion process; where the outlet valve comprises an outlet valve actuator; and where the outlet valve actuator is spaced from the valve seat and the outlet orifice by means of a pintle.

The description provided above relating to the apparatus applies equally to the method for expulsion. The valve actuator moves the pintle, causing the pintle to act upon the valve seat to open or close the orifice. The advantage of separating the valve actuator from the valve seat and the orifice itself, is that the valve actuators can be relocated to a cooler environment.

The preselected value of the temperature of the fluid in the chamber can be equal to or greater than a saturation temperature of the fluid at atmospheric or ambient pressure. The fluid can be heated by a means of heating arranged in or near the chamber.

The fluid can be directed along a non-linear path from the inlet orifice to the outlet orifice. Optionally, the fluid can be directed from the inlet orifice to the outlet orifice via at least one non-linear channel, or alternatively, via a plurality of non-linear channels, or by one or more baffles. The non-linear path could cause a minimum of 90° degrees of change.

Preferably, the fluid is pumped from the reservoir to the chamber. Optionally, a fraction of the fluid from the chamber can be returned to the reservoir via a recycle loop.

The opening and closing of the inlet valve and outlet valve can be electronically controlled by a controller. This may be performed based on the pressure in the chamber, where the pressure is measured by one or more pressure sensors. Alternatively, this may be performed based on the temperature in the chamber, where the temperature is measured by one or more temperature sensors.

When the desired temperature or pressure has been reached, or a predetermined time has passed, the outlet valve can be opened to expel fluid by means of a vapour explosion process. The fluid can be expelled through a nozzle connected to the outlet orifice. A nozzle can be used to alter and control the properties of the spray.

Brief Description of the Drawings

The invention will now be described by way of example, with reference to the accompanying drawings: Figure 1 is a cross-sectional view of an example of a fluid expulsion device according to the present invention.

Figure 2 is a schematic diagram of a second example of a fluid expulsion device according to the present invention.

Figure 3 is a schematic diagram of another example of a fluid expulsion device according to the present invention.

Figure 4 is a cross-sectional view of a further example of a fluid expulsion device according to the present invention.

A cross-sectional schematic view of an example of a fluid expulsion device is provided in Figure 1. The fluid flows in the direction of the arrow, towards the chamber 1 via inlet orifice 2, when the inlet valve 3 is opened by the inlet valve actuator 5. The chamber 1 is heated by an external heating jacket 13.

Another example of a fluid expulsion device of the invention is provided in Figure 2. In this arrangement heating is provided in the interior of the chamber 1 as well as to the exterior. In this example, the actuators 5,10 are separate from and spaced away from the inlet and outlet orifices, respectively.

Figure 3 provides another alternative configuration of the device according to the invention. In Figure 3, the inlet valve 3 is cooled by a heat exchanger 15.

Figure 4 provides a cross-sectional view of another example of a device according to the invention. In this example, the chamber comprises a means for directing and controlling 16 the flow of fluid from the inlet orifice 2 to the outlet orifice 8 along a non-linear path 17.

Detailed Description

An embodiment of a fluid expulsion device according to this invention is illustrated in Figure 1. A fluid is supplied from a reservoir (not illustrated) into a chamber 1 via an inlet orifice 2, in the direction indicated by the arrow. The fluid which is supplied through the inlet can be a liquid, or a mixture of liquid and gas, such as a foam, but is preferably a liquid. The liquid or foam could also include suspended entrained particulate solids. The liquid could be a solution comprising a solvent and a solute. Preferably, the fluid is pumped from the reservoir to the chamber 1.

The inlet orifice 2 and inlet valve 3 are arranged to allow a portion of fluid into the chamber 1 via an associated inlet pipe, tube or channel 4 from the reservoir. The fluid passes through the inlet orifice 2 when the inlet valve 3 is in the open position. The inlet valve 3 of Figure 1 comprises an inlet valve actuator 5 and an inlet valve seat 6. The valve actuator 5 may be connected to a controller (not illustrated). In the embodiment illustrated in Figure 1, the inlet valve actuator 5 is spaced from the inlet orifice by the use of a pintle 7 or rod connecting the valve actuator 5 to the inlet valve seat 6. The inlet valve 3 is opened to allow fluid to enter the chamber 1 until the chamber 1 contains a predetermined quantity of liquid. When the predetermined quantity of fluid has entered the chamber, the inlet valve 3 is closed by the inlet valve actuator 5.

A separate outlet orifice 8 is provided at another location in the chamber 1. The outlet orifice 8 is opened or closed using outlet valve 9. Opening the outlet valve 9 allows fluid to be ejected from the chamber 1, whilst closing the outlet valve 9 allows fluid to be sealed in the chamber 1. The outlet valve 9 comprises an outlet valve actuator 10, a pintle 11 and an outlet valve seat 12. In accordance with the invention, the outlet actuator 10 is spaced from the outlet orifice 8 by the use of a pintle 11 which connects the valve actuator 10 to the valve seat 12. The outlet valve actuator is arranged to move the pintle 11, which acts upon the outlet valve seat 12 to open or close the outlet orifice 8.

In the embodiment of Figure 1, the inlet valve 3 is connected to a pintle or rod 7, which allows the inlet valve 3 to be spaced from the inlet orifice 2. The valve 3 moves the pintle 7 to open or close the inlet orifice 2. In Figure 1, both the inlet valve 3 and inlet valve actuator 5 are positioned at a distance from the inlet orifice 2. Due to the pintle 11, the outlet valve 9 and the outlet valve actuator 10 can be located away from, and at a distance from the outlet orifice 8 (as shown in Figure 1). As the valve actuators (5,10) can be located separately from the inlet/outlet orifices (respectively), they can be removed from extreme environments, and can instead be placed in the most suitable environment for reliable longterm operation.

The fluid is heated inside the chamber 1, with the inlet 3 and outlet valves 9 closed. In the embodiment demonstrated in Figure 1, the means of heating 13 is an external heating jacket, but as explained above, alternative means can also be used.

Closing the inlet 3 and outlet 9 valves prevents the escape of fluid. Heating the fluid in the chamber causes an increase in the pressure within the chamber 1 and hence also a further temperature increase. The temperature and/or pressure can be monitored by one or more temperature and/or pressure sensors (not shown) which may be fitted inside the chamber 1 or near to the chamber 1, for example in the inlet stream, or on a wall of the chamber 1. The

pressure sensors could be pressure transducers. The outlet valve 9 can be controlled by a controller (not shown) such that the outlet valve 9 will not open when the pressure is below a specific predetermined pressure or temperature. Alternatively, or additionally, the outlet valve 9 may be arranged to open or close after a specified amount of time.

The sudden release of pressure when the fluid exits the outlet orifice 8 causes a vapour explosion due to the rapid expansion of liquid, foam and/or vapour. The outlet orifice 8 may be optionally connected to a nozzle (not shown) which can be used to alter the dispersion properties of the spray and to further decrease the droplet size of the liquid in the spray.

The device is able to produce vapour or mist in short sharp bursts. As fluid is expelled from the chamber 1, the pressure within the chamber 1 drops. The outlet valve 9 can be arranged to close when the pressure has dropped back to an ambient or second predetermined pressure, which may be referred to as the closure pressure. Alternatively, the outlet valve can be arranged to close once the temperature has returned to a predetermined temperature, or after a specific amount of time has passed.

A controller can be programmed such that it closes the outlet valve 9 when a predetermined closure pressure is reached and opens the inlet valve 3 again to introduce new fluid into the chamber 1. The system can cycle between introducing new fluid into the chamber 1 and expelling the fluid from the outlet orifice 8. The controller can be used in combination with the valve actuators 5,10 to control a rapid cycle of expelling the fluid and admitting new fluid into the chamber 1, provided that there is sufficient time to heat the liquid in the chamber 1. Alternatively, the controller can be programmed to open the valves according to a timing sequence, where the valves 3,9 are opened and closed for a predetermined time, provided that a set (predetermined) pressure or temperature has been reached or exceeded. The valve timing can be offset, such that the inlet valve can remain open for longer, followed by several rapid openings of the outlet valve. The timing sequence chosen for the valve will depend on the specific application for the device.

Figure 2 shows an alternative configuration of the claimed device. In Figure 2, the outlet valve actuator 10 is spaced from the outlet valve orifice 8. The outlet valve comprises an outlet valve actuator 10, a pintle 11 and an outlet valve seat 12. The inlet valve 3 comprises an inlet valve actuator 5 and an inlet valve seat 6. In the embodiment illustrated in Figure 2, only the outlet valve actuator is relocated to a cooler environment. In the embodiment demonstrated in Figure 2, the means of heating 13 is an external heating jacket, and this is further supplemented by a heating element 14 located within the chamber 1.

Figure 3 shows an alternative configuration of the device. In Figure 3, the inlet valve actuator 5 is cooled by a colder fluid stream, which may be achieved by means of a heat exchanger 15, for example. In Figure 3, the inlet and outlet valve actuators (5,10) are spaced from the inlet and outlet orifices (2,8), respectively.

In Figure 4, the chamber 1 further comprises an optional means of directing and controlling 16 the flow of fluid from the inlet orifice 2 to the outlet orifice 8 along a non-linear path 17. The means of directing and controlling 16 the flow of fluid is a component arranged to redirect the flow of the fluid within the chamber 1, such that the fluid is forced to change direction several times when travelling between the inlet orifice 2 and the outlet orifice 8.

The means of directing and controlling 16 the flow of fluid acts to increase the foam concentration in the vicinity of the outlet orifice 8.

Experimental results In this test, the influence of moving the electrotechnical components of the outlet valve away from heat sources (both within and outside of the system) on the reliability of the system in was tested in high temperature environments.

Running the system in a horizontal orientation, a constant flow rate (1g/s) and a constant power setting (600W), the system was operated in an increasingly hot environment until system failure was experienced. Contained within a metal box, the outlet valve was arranged such that the resulting spray was issued from one side of the box. To the same side a heat source was applied. The set-up was designed to replicate the environment the system would experience when attached to the exhaust pipe of a combustion engine. The system was operated for 5 minutes and then the temperature of the heat source (to the metal box) was increased by 10°C. The system was held at this temperature for another 5 minutes and then the temperature of the heat source was increased again by 10°C. This was continued until the system failed.

All conditions other than the temperature applied to the metal box were kept the same between the experiments. The chamber was kept in one position, and the flow rate was kept constant. The fluid used was water. The lowest temperature of the box wall at which the valves were tested was ambient, 20°C.

The test was conducted for two arrangements of the system. Firstly, a traditional valve arrangement was tested, where the outlet valve actuator is situated at or near the outlet valve orifice. In this arrangement, if the fluids exiting the outlet valve orifice are at high temperatures, or if the outlet valve orifice is located in a heated environment, then the outlet valve actuator is exposed to the same temperatures. The second test was conducted on the new valve arrangement, as described in this application. The outlet valve actuator is not positioned at or near the outlet valve orifice, and therefore the temperature of the exiting fluid and the temperature of the ambient environment at the outlet valve orifice does not damage the valve actuator. The components in each arrangement (as the fluid flows through the system) were as follows: Traditional valve arrangement Inlet Valve (IV) Actuator, IV Orifice, Chamber + Heater, Outlet Valve (OV) Actuator, OV Orifice, Hot Environment New valve arrangement IV Actuator, IV Orifice, OV Actuator, Chamber + Heater, OV Orifice, Hot Environment The failure temperature for each of these systems were as follows: Valve arrangement Failure temperature (°C) Traditional 180 New The system ran at the max temp: 300 On analysis of the failure modes of the "Traditional" arrangement, two areas were highlighted. The first was a drop off in magnetic power (due to increased heat and electronic resistance) and its ability to move the valve pintle for optimal spraying. The second and eventual catastrophic failure mode was the degradation of solenoid winding coatings leading to electrical shorts and total loss of magnetic power. Neither of these failure modes were observed in the 'New' arrangement therefore showing, as claimed in the present application, it is more resilient against high temperatures at the outlet orifice than the "Traditional" valve arrangement. This means that the valve can operate reliably even when the temperatures in the chamber or near the outlet orifice are high.

Claims

CLAI M S: 1) 2) 3) 4) 5) 6) 7) Apparatus for expelling a fluid comprising; - a reservoir for storing a fluid; a chamber (1) for containing a fluid; an inlet orifice (2) to the chamber; - an inlet valve (3) comprising an inlet valve actuator (5) and an inlet valve seat (6); an outlet orifice (8) from the chamber; an outlet valve (9) comprising an outlet valve actuator (10), a pintle (11) and an outlet valve seat (12), which are arranged separately and spaced from the outlet orifice (8); at least one means of heating (13) the fluid within the chamber (1), such that the temperature and pressure of the fluid are raised when the inlet and outlet valves (3,9) are closed, causing at least a portion of the fluid within the chamber (1) to change state; - whereby in use, fluid is expelled from the outlet orifice (8) of the chamber (1) by a vapour explosion process.
The apparatus according to Claim 1, where the inlet valve (3) further comprises a pintle (7).
The apparatus according to any preceding claim, where the inlet valve actuator (5) is arranged separately and spaced from the inlet orifice (2).
The apparatus according to any preceding claim, further comprising a means of cooling (15) the inlet or outlet valve (3,9).
The apparatus according to any preceding claim, where the inlet valve (3) and/or the outlet valve (9) is a solenoid valve.
The apparatus according to any preceding claim, where the inlet valve (3) is connected to the inlet orifice (2) by means of a pintle (7).
The apparatus according to any preceding claim, where the outlet valve (9) is connected to the outlet orifice (8) by means of a pintle (11).
8) The apparatus according to any preceding claim, where at least one means of heating (13) the fluid is external to the chamber (1).
9) The apparatus according to any preceding claim, where at least one means of heating (14) the fluid is internal to the chamber (1).
10) The apparatus according to any preceding claim, where the means of heating (13,14) the fluid is arranged to raise the temperature of the fluid to a value equal to or greater than a saturation temperature of the fluid at ambient pressure.
11) The apparatus according to any preceding claim, further comprising a means for directing and controlling (16) the flow of fluid from the inlet orifice (2) to the outlet orifice (8) along a non-linear path (17).
12) The apparatus according to any preceding claim, further comprising at least one controller connected to the inlet and outlet valve actuators (5,10), such that the opening and closing of the inlet valve (3) and outlet valve (9) is electronically controlled.
13) A method for expulsion of a fluid from a chamber (1), comprising: supplying fluid from a reservoir to the chamber (1) via an inlet orifice (2) by opening an inlet valve (3) to the chamber (1); where the inlet valve (3) comprises an inlet valve actuator (5); where the fluid inside the chamber (1) flows to an outlet orifice (6) via an outlet valve (9); - whilst the fluid is inside the chamber (1) and the inlet and outlet valves (3,9) are closed, heating the fluid above the saturation point of the fluid at atmospheric pressure, such that at least a portion of the fluid changes state; - opening the outlet valve (9) such that fluid is expelled from the outlet orifice (6) by a vapour explosion process; where the outlet valve (9) comprises an outlet valve actuator (10); and - where the outlet valve actuator (10) is spaced from the valve seat (12) and the outlet orifice (8) by means of a pintle (11).
14) The method according to Claim 13, where the inlet valve (3) further comprises a pintle (7).
15) The method according to Claim 13 or 14, where the inlet valve actuator (5) is arranged separately and spaced from the inlet orifice (2).
16) The method according to any of Claims 13 to 15, further comprising cooling the inlet or outlet valve (3,9).
17) The method according to any of Claims 13 to 16, where the inlet valve actuator (5) and/or the outlet valve actuator (11) is a solenoid valve.
18) The method according to any of Claims 13 to 17, where the fluid is heated by a means of heating (13,14) arranged in or near the chamber (1).
19) The method according to any of Claims 13 to 18, where the fluid inside the chamber (1) is directed to flow via a non-linear path (15) from the inlet orifice (2) to the outlet orifice (8).