IE86771B1

IE86771B1 - A device for the passage of water

Info

Publication number: IE86771B1
Application number: IE20140194A
Authority: IE
Inventors: Qasim Hezar; Sakr Fadl Mohamed; Edward Brash Robin; Liu Shuli
Original assignee: Norcros Group (Holdings) Ltd
Priority date: 2013-08-08
Filing date: 2014-08-06
Publication date: 2016-12-14
Also published as: GB2516953A; IE20140194A1; GB201314203D0; GB2516953B; GB2516953B8; GB2516953A8

Abstract

A device (10) for the passage of a volume of fluid including: a housing (12) having a chamber (16) for receiving fluid; an inlet (24) in fluid communication with the chamber (16); an outlet (26) in fluid communication with the chamber (16); and a phase change material (PCM) material (30) for permitting the transfer of heat away from or to fluid contained in or passing through the chamber (16). <Figure 1>

Description

Description of Invention The invention relates to a device for the passage of a volume of fluid. In particular, though not exclusively, the invention relates to a device for the passage of water for use as a component part of an instantaneous water heater.

An electric shower is an example of an instantaneous water heater and typically includes a housing having a chamber in which the water is heated by an electrically operated element. Typically such an electrically operated heating element is in the form of a coil. Often two or more of said heating elements are provided within the chamber in order to provide the user with a selectable level of heating.

During shut down of an electric shower, after the user has finished showering, the flow of water into the chamber and the heating element(s) must be turned off. Once the flow of water into the chamber had stopped, the heating elements(s) will continue to heat the water therein. This can result in the volume of water in the chamber reaching unsafe temperatures (i.e. water temperatures which could potentially harm a user who next uses the electric shower). This is because, if the electric shower is turned on before the water in the chamber has had time to cool, the super-heated volume of hot water will be outputted immediately through the shower rose onto the user.

Prior art electric showers have addressed this issue by providing for a staged shutdown of the electric shower. In other words, when the user presses the “off’ button, the electric shower firstly turns off the electrical power supply to the heating element(s) and then, after a short period of time (a few seconds) closes the water inlet to the shower. The time delay ensures that any latent heat in the heating element(s) is dissipated to the water which continues to exit the shower. By the time the inlet has been closed, there is little or no latent heat in the heating element(s) so the water remaining in the chamber will be at the user-selected showering temperature (and then gradually cool). One problem with such prior art showers, however, is that in order to provide for a staged shutdown, relatively complex electric circuitry (e.g. a printed circuit board, or the like) is required which leads to increased manufacturing costs.

According to a first aspect of the invention we provide an instantaneous water heater including a device for the passage of a volume of fluid, the device including: a housing having a chamber for receiving fluid and a heating element positioned therein; an inlet in fluid communication with the chamber; an outlet in fluid communication with the chamber; and a phase change material (PCM) material for permitting the transfer of heat away from or to fluid contained in or passing through the chamber.

According to a second aspect of the invention we provide an electric shower including an instantaneous water heater according to the first aspect of the invention.

Further features of the first and second aspects of the invention are set out in the dependent claims appended hereto.

Embodiments of the invention will now be described by way of example only with reference to the accompanying drawings, of which: Figure 1 is a cross-section view of a first embodiment of a device according to the present invention; Figure 2 is a cross-section view of a second embodiment of a device according to the present invention; Figure 3 is a perspective view of a component part for use with the device of figure 1; and Figure 4 is a perspective view of a component part for use with the device of figure 1.

Referring to the figure 1, this shows a first embodiment of a device 10 for the passage of a volume of fluid according to the present invention. The device 10 is for use in an instantaneous water heater, such as a shower. The other component parts of the water heater/shower are not shown herein, but it will be obvious to one skilled in the art how the device 10 can be incorporated into such a water heater/shower.

The device 10 includes a housing 12 which in the present example is injection moulded from a suitable plastics material. The housing 12 is substantially tubular in shape and includes a thermally conductive member 14 that provides therein a cylindrical chamber 16. The housing 12 has first 18 and second 20 generally opposed end walls and a peripheral side wall 22 extending therebetween. In the present example the side wall 22 and end wall 20 are formed as a single component, with the second end wall 18 being removably connectable to the peripheral side wall 22. This is so that access can be gained to an interior of the chamber 16 for installing the internal components.

The thermally conductive member 14 is, in this example, made of copper and forms a cylindrical tube with open ends which are closed by the end walls 18 and 20. A tube-shaped phase change material (PCM) 30 is provided between the side wall 22 of the housing 12 and the thermally conductive member 14. The PCM 30 thus surrounds the chamber 16 and is in thermal contact with the chamber 16 via the thermally conductive member 14. The chamber 16 is thus tubular and the PCM 30 is substantially contained with the tubular space between the thermally conductive member 14 and the housing 12.

It will be understood that, in alternative embodiments, any number of intermediate thermally conductive layers may be provided between the PCM 30 and the chamber 16 whilst retaining thermal contact between the PCM and the chamber 16.

The PCM 30 used in this embodiment is a paraffin wax compound having a molecular structure C n H 2n+2- Alternative PCMs may also be used which have a suitable activation temperature which is around or slightly above a generally maximal user showering temperature.

The device 10 includes an inlet 24, which provides for an inlet flow of fluid to the chamber 16. The device 10 includes an outlet 26 which is connected to an outlet fluid flow path member 28, which is generally tubular, and which extends into the chamber 16 through the wall 20 and towards the wall 18 where it terminates a short distance therefrom. Alternative forms of inlet and outlet may be provided without departing from the present invention.

As can be seen in figure 1, within the chamber 16 are a pair of heating elements 32a, 32b which are positioned end to end and substantially coaxially with an axis of the chamber 16. The heating elements 32a, 32b define a generally axially extending passage through which the outlet flow path member 28 extends.

During use, water flows through the inlet 24 and into the chamber 16. The water is heated as it comes into contact with the heating elements 32a, 32b and travels through the chamber 16 towards the free end of the member 28. The water eventually reaches the top of the chamber 16 and passes through the outlet fluid flow path member 28 to the outlet 26 for use downstream by the user.

Operation of the device 10 during shutdown of the shower will now be described. The flow of water through the inlet 24 is controlled by a user operable member, e.g. a rotatable knob / dial (not shown in the drawings, but well known in the art). The user can therefore control whether the shower is on / off and how much water is flowing therethrough. The latter directly affects the temperature of the water exiting the shower. The heating elements 32a and 32b are switched on also by rotation of the user operable member, but the shower is also provided with a pressure switch which ensures that electrical supply to the heating elements 32a, 32b only occurs when water is flowing through the shower.

When a user has finished showering, he/she rotates the knob so as to stop the flow of water through the inlet 24, which also cuts of the electrical power supply to the heating elements 32a, 32b. However, it will be appreciated that the volume of water within the chamber 16 will continue to be heated by the latent heat in the heating elements 32a, 32b (even though they have been switched “off’). The temperature of the water will begin to rise (from the userselected temperature) and this will, in turn, increase the temperature of the thermally conductive member 14. Advantageously, heat is conducted away from the water, through the thermally conductive member 14, and to the PCM 30. The temperature of the PCM 30 rises as it absorbs heat from the water.

The PCM of the present invention is advantageous as it is configured to have an activation temperature which is around or slightly above a generally maximal user showering temperature. PCMs with a slightly higher or lower activation temperature may also be used depending on the anticipated user requirements. A phase change material has the property that it absorbs heat at a relatively constant rate until it reaches its activation temperature. At the activation temperature the phase change material will undergo a phase change and absorb heat at an increased rate whilst remaining at a substantially constant temperature. The heat energy being absorbed is used for breaking chemical bonds within the phase change material but does not cause any substantial release of heat energy; in other words the process is endothermic.

Thus by configuring the PCM 30 to have an activation temperature at around or slightly above the generally maximal user showering temperature, the PCM 30 will absorb a large amount of heat away from the water when the water temperature rises by virtue of the latent heat in the heating elements 32a, 32b. The water therefore stays below a safe threshold temperature. This stops the water becoming super-heated, and removes the requirement for a phased shut down having additional circuitry and mechanical components which are more costly and complex.

When a subsequent user switches the shower on, the water immediately leaving the outlet 26 would be at or below the activation temperature of the PCM 30 and so would be safe immediately for use in showering until the new user-selected temperature is reached.

Over an extended period of time after the shower has been switched off, the water in the chamber 16 will gradually cool down to atmospheric temperature. The water and PCM 30 will reach thermal equilibrium at the ambient temperature of the environment and stay in this state.

If the shower is switched on before the water and PCM 30 have reached thermal equilibrium with the environment, then the invention provides a further advantageous effect. During a period after the shower is switched off, the PCM 30 will be in thermal equilibrium with the water within the chamber 16 at around the activation temperature of the PCM 30. The length of this period will be dependant upon the insulation provided by the device 10 with respect to the environment. If the shower were used within this period, cold water will enter the chamber 16 via the inlet 24. The heat energy stored within the PCM 30 will then flow from the PCM 30 to the water via the thermally conductive member 14. The flow of heat energy causes the temperature of the water to increase and eventually a new thermal equilibrium temperature will be reached between the water contained or flowing through the container and the PCM 30. The PCM 30 thus permits the cold water to reach the user-selected operating temperature quicker than prior art showers, due to this pre-heating effect. The arrangement of the PCM thus optimizes the energy efficiency of the device 10 in bringing the water to the temperature required for showering more quickly allowing the user to commence and finish showering faster than with prior art showers, thus using less water.

It will be appreciated that the phase change material permits both a transfer of heat energy away from water contained in or passing through the chamber as well as a transfer of heat energy to any water contained in or passing through the chamber. Alternative designs of the arrangement between the PCM, chamber and thermally conductive member may be employed that retain this functionality. For example, a solid PCM may be used to form all or a substantial part of the housing without requiring the use of a separate thermally conductive member. In this case, the surface of the PCM will then provide part or substantially all of an interior surface of the chamber for contact with the water contained in or passing through the chamber.

The preferred choice and configuration of phase change material is dependent on a number of factors. One such factor is the amount of latent heat present within the heating element(s) within the chamber 16. If the heating elements retain a large amount of latent heat, due to the volume of the elements, for example, then the preferred phase change material must have a correspondingly large energy storage density to accommodate that latent heat. Another factor is the rate at which heat energy can be transferred towards (absorbed) or away (released) from the phase change material. If the rate of heat energy transfer is too slow then the water may not be cooled to the generally maximal user showering temperature in time for the next user of the shower. Similarly, the efficiency of the shower on restart will not be optimal if the phase change material does not release heat energy into the cold water quickly enough to sufficiently heat the water.

Referring to figure 2, this shows a second embodiment of a device 110 according to the present invention. Features in common with those of the first embodiment have been given the same reference number but with the addition of 100. The difference between the two embodiments is that the thermally conductive member 114 includes a plurality of thermally conductive extension members 134 formed on an outwardly facing surface of the thermally conductive member 114. Each of the thermally conductive extension members is in thermal contact with the PCM 130. The thermally conductive extension members 134 are annular in axial view and extend radially away from the elongate axis of the chamber 116 and into the PCM 130. The thermally conductive extension members 134 are substantially evenly spaced along the elongate axis of the chamber 116. In this embodiment the thermally conductive extension members 134 are formed as part of the thermally conductive member 114 but they could be made separately and connected thereto.

The provision of the thermally conductive extension members 134 increases the surface area of the thermally conductive member 114 in thermal contact with the PCM 130. This increases the rate of transfer of heat energy away from or to the PCM 130 from or to any water contained in or passing through the chamber 116. The thermally conductive extension members 134 thus act to distribute thermal energy away from or to the PCM 130.

Figures 3 and 4 show alternative embodiments of a thermally conductive member for use with the device 10. Common features of the thermally conductive member of the first embodiment have been given the same reference number but with the addition of 200 (figure 3) and 300 (figure 4).

Each of the thermally conductive extension members 234 is generally cylindrical in shape and the members 234 are substantially evenly distributed over the outwardly facing surface of the thermally conductive member 234. The ends of the thermally conductive extension members 234 have a relatively small area compared to the outwardly facing surface area of the thermally conductive member 214 to ensure a large number of members 234 can be accommodated. The configuration of thermally conductive extension members 216 increases the exterior surface of the thermally conductive member 214 to increase the rate of heat energy transfer between the water and the PCM 230. Furthermore, the uniform distribution of the thermally conductive extension members 234 within the PCM 230 ensures that heat energy is transferred substantially homogeneously to the PCM 230.

Referring to figure 4, the thermally conductive member 314 has thermally conductive extension members 334 which are substantially cuboidal, e.g. a rectangular parallelipiped. The thermally conductive extension members 334 are substantially evenly spaced along an elongate axis of the chamber 316 and the circumference of the chamber 316. Other shapes and configurations of thermally conductive extension members could be employed. The thermally conductive extension members may be arranged to be curved as they extend away from the thermally conductive member and form a generally spiral arrangement.

It will be appreciated that the second (figure 2), third (figure 3) and fourth (figure 4) embodiments relate to optimizing the use of the phase change material within the device 10 by configuring the thermally conductive member 14 to increase the rate of heat energy transfer between it and the phase change material. This has been achieved by increasing the surface area of the thermally conductive member 114, 214, 314 in thermal contact with the phase change material. The thermally conductive member 114, 214, 314 has also been configured so that the thermal contact with the phase change material is substantially uniform. This prevents or at least reduces local hot or cold spots occurring and thus assists in ensuring the rate of heat energy transfer is optimal and efficient. A wide variety of configurations of the thermally conductive member, the thermally conductive extension members and phase change material may be used to provide this effect.

When used in this specification and claims, the terms comprises and comprising and variations thereof mean that the specified features, steps or integers are included. The terms are not to be interpreted to exclude the presence of other features, steps or components.

The features disclosed in the foregoing description, or the following claims, or the accompanying drawings, expressed in their specific forms or in terms of a means for performing the disclosed function, or a method or process for attaining the disclosed result, as appropriate, may, separately, or in any combination of such features, be utilised for realising the invention in diverse forms thereof.

Claims

1. An instantaneous water heater including a device for the passage of a volume of fluid, the device including: a housing having a chamber for receiving fluid and a heating element positioned therein; an inlet in fluid communication with the chamber; an outlet in fluid communication with the chamber; and a phase change material (PCM) material for permitting the transfer of heat away from or to fluid contained in or passing through the chamber.

2. A device according to claim 1 wherein all or a substantial part of the housing is formed from the PCM.

3. A device according to claim 1 or 2 wherein the PCM surrounds the whole or a part of the chamber.

4. A device according to claim 1, 2 or 3 wherein the chamber is substantially tubular.

5. A device according to any preceding claim wherein the PCM is substantially tubular or contained within a tubular body.

6. A device according to any preceding wherein a surface of the PCM provides part or substantially all of an interior surface of the chamber.

7. A device according to any preceding claim wherein a thermally conductive member is positioned in between the chamber and the PCM.

8. A device according to claim 7 wherein the thermally conductive member includes a plurality of thermally conductive extension members, each of which is in thermal contact with the PCM.

9. A device according to claim 8 wherein the thermally conductive extension members extend into the PCM or are surrounded by the PCM.

10. A device according to claim 8 or 9 wherein the thermally conductive extension members extend outwardly away from the chamber.

11. A device according to claim 8, 9, or 10 wherein each thermally conductive extension member extends circumferentially around the chamber.

12. A device according to any one of claims 8 to 11 wherein each thermally conductive extension member is annular.

13. A device according to claim 8, 9 or 10 wherein each thermally conductive extension member is cylindrical.

14. A device according to claim 8, 9 or 10 wherein each thermally conductive extension member is a parallelepiped.

15. A device according to claim 14 wherein each thermally conductive extension member is a rectangular parallelipiped.

16. A device according to claim 13,14 or 15 wherein the thermally conductive extension members are substantially evenly spaced around the circumference of the chamber.

17. A device according to any one of claims 10 to 16 wherein the thermally conductive extension members are substantially evenly spaced along an elongate axis of the chamber. 5

18. A device according to any one of claims 10 to 17 wherein the thermally conductive extension members are substantially evenly distributed over an outwardly facing surface of the thermally conductive member.

19. An electric shower including an instantaneous water heater according to 10 any preceding claim.

20. A device substantially as hereinbefore described with reference to and/or as shown in the accompanying drawings.