Patent Publication Number: US-2010117482-A1

Title: Valve apparatus

Description:
TECHNICAL FIELD OF THE INVENTION 
     The present invention generally relates to valve apparatuses. The invention is preferably, but not exclusively, intended for a generator system for converting thermal energy to electric energy. 
     DESCRIPTION OF RELATED ART AND BACKGROUND OF THE INVENTION 
     In known generator systems for converting thermal energy to electric energy there is provided a magnetic circuit of a suitable magnetic material and a coil arranged around the magnetic circuit. A temperature-varying arrangement varies the temperature of the magnetic circuit alternately above and below a phase transition temperature such as the Curie point to thereby vary the reluctance of the magnetic circuit and the magnetization of the magnetic circuit is modulated by the varying reluctance so as to induce electric energy in the coil arranged around the magnetic circuit. The temperature-varying arrangement passes alternately hot and cold fluid by the magnetic circuit and comprises typically one or several feed pumps, piping, and a valve manifold. 
     JP 7107764 discloses such generator system provided with a switch valve comprising a hot water inlet port, a cold water inlet port, and two outlet pipes. When the switch valve rotates the outlet pipes receive alternately water from the hot water inlet port and the cold water inlet port. The phase between the outlet pipes is 180°. 
     SUMMARY OF THE INVENTION 
     A problem of such arrangement is that energetically inefficient cycling of fluid is achieved and that disturbances during fluid switching occur. 
     Another limitation is that the frequency of the thermal cycling is limited. 
     Further, the switch valve of JP 7107764 may not be optimally designed for different kinds of thermomagnetic generator systems. The cost per net power produced by a generator system featuring the known switch valve may not be optimum. 
     It is therefore an object of the present invention to provide a valve apparatus, by which the above limitations can be overcome. 
     It is a particular object of the invention to provide such valve apparatus, which can provide for a smooth and energetically efficient cycling of fluid. 
     It is still a further object of the invention to provide such valve apparatus, which is reliable, flexible, and of reasonable cost. 
     It is yet a further object of the invention to provide such valve apparatus, which is optimally designed for use in a temperature-varying arrangement for a specified kind of generator system converting thermal energy to electric energy. 
     These objects, among others, are according to the present invention attained by valve apparatuses as specified in the appended patent claims. 
     According to a first aspect of the invention there is provided a valve apparatus comprising a cylindrical casing, a shaft arranged symmetrically in the casing, a member fixedly attached to the shaft and in close fit with the cylindrical casing, thereby defining separated chambers within the casing, a plurality of axially arranged inlets, each of which being constantly in fluid communication with a respective one of the separated chambers, and at least one outlet fixedly arranged along the circumference of the casing, wherein the separated chambers and thereby the axially arranged inlets are alternately in fluid connection with a circumferential reference point of the at least one outlet in response to rotation of the shaft and the member with respect to the casing. The member has an elliptically shaped cross section. 
     Preferably, the member is in close fit with the cylindrical casing in the plane of the elliptically shaped cross section. 
     The member may be realized as a thin plate or as a slantingly cut solid cylinder having a diameter slightly less than the inner diameter of the cylindrical casing. 
     The valve apparatus of the first aspect of the invention provides for energetically efficient cycling of fluid and disturbances during fluid switching are minimized. 
     The elliptically shaped member provides for a reliable and robust valve apparatus to a reasonable cost. 
     According to a second aspect of the invention there is provided a valve apparatus comprising a cylindrical casing, a shaft arranged symmetrically in the casing, a member fixedly attached to the shaft and in close fit with the cylindrical casing, thereby defining separated chambers within the casing, a plurality of axially arranged inlets, each of which being constantly in fluid communication with a respective one of the separated chambers, and at least one outlet fixedly arranged along the circumference of the casing, wherein the separated chambers and thereby the axially arranged inlets are alternately in fluid connection with a circumferential reference point of the at least one outlet in response to rotation of the shaft and the member with respect to the casing. The number of the chambers is at least four. 
     Preferably, the member comprises sidewalls extending axially and radially from the shaft to the casing, and end covers extending radially from the shaft to the casing and circumferentially between neighboring ones of the sidewalls. Each of the chambers is delimited by (i) two of the sidewalls, (ii) one of the end covers, and (iii) the cylindrical casing. 
     The valve apparatus of the second aspect of the invention provides for an increased frequency of the output fluid pulses for a given rotational speed. Alternatively, for a maintained pulse frequency, the requirements on the rotational speed can be relaxed. 
     The higher number of chambers that is provided for a given rotational speed, the higher pulse frequency is obtained. 
     According to a third aspect of the invention there is provided a valve apparatus comprising a cylindrical casing, a shaft arranged symmetrically in the casing, a member fixedly attached to the shaft and in close fit with the cylindrical casing, thereby defining separated chambers within the casing, a plurality of axially arranged inlets, each of which being constantly in fluid communication with a respective one of the separated chambers, and at least three outlets fixedly arranged along the circumference of the casing, wherein the separated chambers and thereby the axially arranged inlets are alternately in fluid connection with the at least three outlets in response to rotation of the shaft and the member with respect to the casing. The number of outlets may advantageously be higher and/or an even number such as four, six, or even higher. 
     The valve apparatus of the third aspect of the invention provides for energetically efficient cycling of fluid and disturbances during fluid switching can be minimized. 
     A valve apparatus that has N*3 outlets, where N is a positive integer, preferably an even integer, is particularly suited to be used in a three-phase magnetothermal generator system. 
     According to a fourth aspect of the invention there is provided a valve apparatus comprising a cylindrical casing, a shaft arranged symmetrically in the casing, a member fixedly attached to the shaft and in close fit with the cylindrical casing, thereby defining separated chambers within the casing, and a plurality of axially arranged inlets, each of which being constantly in fluid communication with a respective one of the separated chambers. The valve apparatus is provided with a single outlet fixedly arranged along the circumference of the casing, wherein the separated chambers and thereby the axially arranged inlets are alternately in fluid connection with a circumferential reference point of the single outlet in response to rotation of the shaft and the member with respect to the casing. The single outlet may extend along the entire circumference of the casing or at least along a major portion thereof. 
     The valve apparatus of the fourth aspect of the invention provides for energetically efficient cycling of fluid and disturbances during fluid switching are minimized. If the single outlet has large cross sectional area the losses are low. 
     The valve apparatus may be provided with an output wherein different portions across the cross section thereof have different fluid path lengths so that any introduced phase delays across the cross section of the outlet can be compensated for. The valve apparatus is particularly suited to be used in a single-phase magnetothermal generator system. 
     Embodiments of the invention are set out in the dependent claims and are disclosed in the detailed description. 
     The present invention features a valve apparatus, which is simple, reliable, and robust, and by which smooth and energetically efficient pumping and distribution of fluids are enabled. 
     The valve apparatus of the present invention can be used for the thermal cycling of fluid in various kinds of thermomagnetic generator systems or can be used in entirely different applications, in which fluids of different characteristics should be alternately output in a single outlet. 
     Further characteristics of the invention and advantages thereof, will be evident from the following detailed description of preferred embodiments of the present invention given hereinafter and the accompanying  FIGS. 1-5 , which are given by way of illustration only and thus, are not limitative of the present invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIGS. 1 and 2  display each schematically in a perspective view a rotating valve apparatus according to a respective embodiment of the invention. 
         FIG. 3  displays schematically in a diagrammatic view a thermomagnetic generator system according to a further embodiment of the present invention. 
         FIG. 4  displays schematically in a cross sectional view a rotating valve apparatus according to an embodiment of the invention. 
         FIG. 5  displays schematically in a perspective view a rotating valve apparatus according to an embodiment of the invention. 
     
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS 
     A rotating valve apparatus according to an embodiment of the invention is disclosed in  FIG. 1 . A hollow cylinder or cylindrical casing  41  houses a symmetrically arranged rotatable shaft  42 , to which a member  43  is fixedly attached. The member  43 , which preferably is thermally isolating, is provided in close fit with the cylindrical casing  41  and defines a first and a second identical compartment or chamber  44   a - b  of the apparatus. The member  43  is an elliptic disc fixedly mounted on the shaft  42  at an axial position and with an inclination angle such that each of the outlets  46   a - f  at the circumference of the cylindrical casing  41  is alternately in fluid connection with the chambers  44   a - b  as the shaft  42  and the elliptic disc  43  are rotated with respect to the cylindrical casing  41 . 
     The elliptic plate might be fabricated by cutting it from a solid cylinder having a diameter slightly less than the inner diameter of the cylindrical casing. 
     Alternatively, the member  43  has other shapes as long it provides the above functionality and has an elliptically shaped cross section. For instance, the surfaces of the member  43  may be curved. 
     One of the chambers  44   a  is constantly in fluid communication with a first axially arranged inlet  45   a , and is configured to receive or output fluid of a first characteristic, and one of the chambers  44   b  is constantly in fluid communication with a second axially arranged inlet  45   b , and is configured to receive or output fluid of a second characteristic. 
     Further, a number of outlets  46   a - f  is arranged circumferentially in the casing  41 , preferably with equal distances between one another. The circumferentially arranged outlets  46   a - f  can alternately be put in fluid communication with the respective chambers  44   a - b  by rotating the shaft  42  and the member  43 , thereby also rotating the chambers  44   a - b.    
     The shaft  42  is advantageously mounted in the cylindrical casing  41  by means of bearings and means, e.g. an electric motor (not illustrated), is provided to apply a driving torque on the shaft  42 . Alternatively, the rotating valve apparatus is self-propulsive in response to being exposed to fluids flowing through the inlets of the rotating valve apparatus by means of a pump arrangement). In yet an alternative version the valve apparatus has an integrated impeller arrangement for the circulation, i.e. pumping, of the fluids (in which instance any external pump arrangement may be dispensed with). Such impeller arrangement can be separated from the member  43  or it can be integrated with the member  43  into a single-piece device by means of suitably shaping the surfaces of the member  43  in the two axial directions to resemble the operation of impellers. Such combined pump and valve apparatus is described in our copending European patent application No. 07120950.6 filed on 19 Nov. 2007, the contents of which being hereby incorporated by reference. 
     During operation of the valve apparatus in a first operation mode, the shaft  42  and thereby the member  43  are steadily rotated with respect to the casing  41  and the outlets  46   a - f , thereby sucking a fluid of a first characteristic trough the first axially arranged inlet  45   a  and into the first chamber  44   a  constantly in fluid communication with the first axially arranged inlet  45   a , and sucking a fluid of a second characteristic trough the second axially arranged inlet  45   b  and into the second chamber  44   b  constantly in fluid communication with the second axially arranged inlet  45   b . As the member  43  and thus the chambers  44   a - b  thereof are rotated with respect to the casing the fluids of the first and second characteristics are alternately output through the circumferentially arranged outlets  46   a - f.    
     The circumferentially arranged outlets  46   a - f  alternately output pulses of fluids of the first and second characteristics. The rotational speed for a given number of chambers controls the wavelength and frequency of the train of fluid pulses and the angular separation of the outlets controls the phase shift between them. 
     The fluids of the first and second characteristics may be fluids, such as e.g. water or other heat exchange fluid, of different temperatures. Alternatively, different fluids or fluids having different properties are mixed by the valve apparatus. 
     In a second operation mode the valve apparatus operates in a reciprocal manner to divide up fluid pulses of the first and second characteristics received at the circumferentially arranged outlets  46   a - f , being inlets in this operation mode. The shaft  42  and thereby the member  43  are steadily rotated in the opposite direction with respect to the casing  41  and the outlets  46   a - f . Hereby, the fluid pulses of the first and second characteristic are sucked through the circumferentially arranged outlets  46   a - f  and alternately into the respective chambers  44   a - b  of the casing  41 . The fluid pulses that are collected in the first chamber  44   a  constantly in fluid communication with the first axially arranged inlet  45   a  is output there through, and the fluid pulses that are collected in the second chamber  44   b  constantly in fluid communication with the second axially arranged inlet  45   b  is output there through. Thus, the axially arranged inlets  45   a - b  are outlets in this operation mode. If the rotational speed of the shaft  42  is adapted to the frequency of the fluid pulses and the phase shift between the fluid pulses at the circumferentially arranged outlets  46   a - f  is adapted to the angular separation of the circumferentially arranged outlets  46   a - f , fluid of the first characteristic can be collected by the valve apparatus and output though the first axially arranged inlet  45   a  and fluid of the second characteristic can be collected by the valve apparatus and output though the second axially arranged inlet  45   b.    
     It should be understood by a person skilled in the art that even if the apparatus is described in the present text and in the appended patent claims as having axially arranged inlets and circumferentially arranged outlets, they can be operated as axially arranged outlets and circumferentially arranged inlets as described above. Thus, the wording used covers both operation modes. 
       FIG. 2  illustrates a valve apparatus, which differs from the one of  FIG. 1  in that only three outlets  46   a - f  are arranged circumferentially in the casing  41 , preferably with equal distances between one another. 
     The valve apparatus of  FIG. 2  can preferably be used in a three-phase thermomagnetic generator system as being illustrated in  FIG. 3  in order to provide the temperature variation above and below the phase transition temperature of the magnetic material of the magnetic circuits  1  thereof. 
     Three only schematically indicated magnetic circuits  1  are provided, each of which being operatively connected to a respective LC circuit  11  including a winding or coil  7  and a capacitor  9  connected in parallel. Advantageously, the ratio of the resonance frequency of the resonant electric circuit  11  and the frequency of the temperature variation above and below the phase transition temperature of the magnetic material is approximately ½ or n/2, where n is a positive integer. 
     A temperature-varying device  5  comprises an outer part, which includes a first external pipe arrangement  21 , in which hot fluid is circulated by a feed pump  22 , and a second external pipe arrangement  23 , in which cold fluid is circulated by a feed pump  24 . The hot and cold fluids of the outer part are entirely isolated from each other as well as from the material of the magnetic circuits  1 . 
     The hot fluid in the first external pipe arrangement  21  transfers heat to fluid in a first intermediate pipe arrangement  25  via a first heat exchanger  26  and the cold fluid in the second external pipe arrangement  23  transfers cold to fluid in a second intermediate pipe arrangement  27  via a second heat exchanger  28 . Each of the first and second intermediate pipe arrangements  25 ,  27  is connected between a first one of the valve apparatus of  FIG. 2 , denoted by reference numeral  29 , and a second one of the valve apparatus of  FIG. 2 , denoted by reference numeral  30 , to transport fluid from the first valve apparatus  29  to the second valve apparatus  30 . 
     It shall be appreciated that the outer part may be exchanged for any other kind of arrangement for transferring heat and cold in the heat exchangers  26  and  28 . For instance, heat may be transferred to fluid in the first intermediate pipe arrangement  25  in the first heat exchanger  26  via an incinerator, hot sand, a solar heating panel, or similar. 
     Finally, a first  31 , a second  32 , and a third  33  internal pipe arrangement are each connected between the second valve apparatus  30  and the first valve apparatus  29  via a respective one of the magnetic circuits  1 . 
     A single fluid is flowing in the inner part of the temperature-varying device  5 , which comprises the intermediate and internal pipe arrangements and the first and second valve apparatuses. The inner part thus provides a closed fluid loop. 
     The second valve apparatus  30  is provided for alternately switching hot fluid from the first intermediate pipe arrangement  25  and cold fluid from the second intermediate pipe arrangement  27  into each one of the first, second and third internal pipe arrangements  31 ,  32 ,  33 , preferably with a 120° phase shift there in between. Thus, the second valve apparatus “chops” the hot and cold fluids and forms trains of alternating hot and cold fluid pulses, which are fed into each of the internal pipe arrangements. As the hot and cold fluid pulses pass by, or through holes in, a magnetic material of the magnetic circuits  1 , the magnetic material will be alternately heated above and cooled below the phase transition temperature. 
     The terms hot fluid and cold fluid as used in the description of this and next embodiment are intended to indicate fluid having a temperature above the phase transition temperature of the magnetic material of the portion  3  of the magnetic circuit and fluid having a temperature below the phase transition temperature of the magnetic material of the portion  3  of the magnetic circuit, respectively. 
     The variation of temperature above and below the phase transition temperature causes drastic changes of the permeability of the magnetic material and thus a rapid variation of the magnetic resistance or reluctance of the magnetic circuit  1 . In other words, the magnetization is varied rapidly when a constant magnetic field is applied. 
     Provided that a magnetic flux is provided in the magnetic circuit  1 , the rapid variation of the reluctance will modulate the magnetic flux, thereby obtaining a rapidly varying magnetic flux in the magnetic circuit  1 . As a result a magnetomotive force and an alternating current are obtained in the coil  7 . 
     The magnetic material can be provided as parallel sheets or plates preferably arranged in parallel to one another, granulates, small spheres, wires, fabrics or similar allowing the fluid, in a laminar or turbulent flow, to exchange heat with the magnetic material with large contact surface. 
     After having passed the magnetic material the temperature variation between the hot and cold fluid pulses is smaller and smoother. The trains of hot and cold fluid pulses are then returned in the respective internal pipe arrangements  31 ,  32 ,  33  to the first valve apparatus  29 , which is synchronized with the trains of hot and cold fluid pulses. 
     The first valve apparatus  29  is thus provided for alternately switching the hotter fluid pulses from the first, second and third internal pipe arrangements  31 ,  32 ,  33  into the first intermediate pipe arrangement  25  and the colder fluid pulses from the first, second and third internal pipe arrangements  31 ,  32 ,  33  into the second intermediate pipe arrangement  27 . Hereby, the hotter and colder fluid pulses are returned to the respective intermediate pipe arrangement, from which they were originating. The fluid in the first intermediate pipe arrangement  25  is then returned to the first heat exchanger  26  in order to be heated again and the fluid in the second intermediate pipe arrangement  27  is then returned to the second heat exchanger  28  in order to be cooled again. 
     The fluid in the inner part is driven in a single direction by feed pumps  34 ,  35 . 
     The rotating valves  29 ,  30  of  FIG. 2  are advantageously mounted on a single shaft to be rotated simultaneously/synchronously with a suitable phase shift there in between. 
     In an alternative embodiment the first valve apparatus  29 , particularly where the temperature difference between the hotter and colder fluid pulses is low, the hotter and colder fluid pulses from the first, second and third internal pipe arrangements may not have to be switched back into the second and first intermediate pipe arrangements. Thus, the first valve apparatus  29  may be dispensed with and another kind of passive distribution or mixing arrangement may be used instead in order to return the fluids to the second and first intermediate pipe arrangement. If an open circuit is used the fluids do not have to be returned. 
     The three-phase generator system of  FIG. 3  comprises further advantageously a power conversion device connected to the capacitors  9  of the three generator units or phases at the output. The coils  7  and the power conversion device are controlled to match the cycle of the thermal variation and to thereby enable optimum energy to be tapped from the circuit. The power conversion device may comprise an AC/DC or AC/AC frequency converter or a power electronic converter including a current or voltage source converter  36 , which encompasses a rectifier and an inverter at the DC side of the rectifier. 
     Additionally, or alternatively, a battery is connected at the DC side. This is particularly advantageous if the power output from the generator is very fluctuating. 
     A transformer  37  is connected to the output of the voltage source converter  36  to transform the output voltage and frequency of about 1 kV and 1 Hz from the multiphase generator to a frequency and a voltage (50 Hz, 10 kV) suitable for normal grid connection. The rating of the equipment is typically larger than 1 kW. 
     Preferably, the generator system of the present invention is provided for electric power generation in the range of 100 kW to 50 MW, and more preferably in the range of 1-5 MW. Several generator systems may be arranged together as modules to generate electric powers of about 10-50 MW. 
     Further details regarding magnetothermal generator systems in which the rotating valve apparatus of the present invention can be implemented are found in our copending Swedish patent applications Nos. 0700779-2, 0700780-0, and 0700781-8 filed on Mar. 28, 2007, the contents of which being hereby incorporated by reference. 
     It shall be appreciated that for a three-phase generator system the valve apparatus may comprise 3*N outlets fixedly arranged along the circumference of the casing of the valve apparatus, where N is an integer, preferably an even integer. 
     If a single-phase thermomagnetic generator system including a rotating valve apparatus of the present invention should be provided, the rotating valve apparatus can preferably be provided with a single output. 
       FIG. 4  displays schematically such a rotating valve apparatus. 
     The rotating valve apparatus is similar to the ones displayed in  FIGS. 1 and 2 , but has a single outlet  71 , which extends around the entire circumference of the rotating valve apparatus. The single outlet  71  includes eight sub-outlets  72 , which are laterally separated portions of the single outlet  71 . The sub-outlets  72  may be separated by fluid guiding walls (not illustrated). The cold fluid pulses are white and the hot fluid pulses are grey. 
     The single outlet  71  is preferably designed with phase delayed sub-outlets  72  as realized through tailor suited fluid paths. The single outlet  71  has preferably a fluid path length that varies along the circumference of the casing of the rotating valve apparatus depending on the rotational speed of the shaft and the member such that the interfaces between fluids originating from different ones of the axially arranged inlets will be essentially vertical to the flow direction of the fluids in a downstream end of the single outlet  71  as being illustrated in  FIG. 4 . In other words, the fluid pulses in the different sub-outlets  72  are in phase with one another. 
     A rotating valve apparatus according to a further embodiment of the invention is disclosed in  FIG. 5 . A hollow cylinder or cylindrical casing  41  houses a symmetrically arranged rotatable shaft  42 , to which a member  43  is fixedly attached. The member  43 , which preferably is thermally isolating, is provided in close fit with the cylindrical casing  41  and defines four essentially separated and identical compartments or chambers  44   a - d  of the apparatus. Each of the chambers  44   a - d  is defined by (i) two sidewalls that extend axially and radially from the shaft  42  to the casing  1 , (ii) an end cover that extends radially from the shaft  42  to the casing  1  and circumferentially between the two sidewalls, and (iii) the casing  1 . Two of the chambers  44   a ,  44   c  are constantly in fluid communication with a first axially arranged inlet  45   a , and is configured to receive or output fluid of a first characteristic, and two of the chambers  44   b ,  44   d  are constantly in fluid communication with a second axially arranged inlet  45   b , and is configured to receive or output fluid of a second characteristic. 
     Further, a number of outlets  46   a - f  is arranged circumferentially in the casing  41 , preferably with equal distances between one another. The circumferentially arranged outlets  46   a - f  can alternately be put in fluid communication with the respective chambers  44   a - d  by rotating the shaft  42  and the member  43 , thereby also rotating the chambers  44   a - d.    
     The shaft  42  is advantageously mounted in the cylindrical casing  41  by means of bearings and means, e.g. an electric motor (not illustrated), is provided to apply a driving torque on the shaft  42 . Alternatively, the rotating valve apparatus is self-propulsive in response to being exposed to fluids flowing through the inlets of the rotating valve apparatus by means of a pump arrangement). In yet an alternative version the valve device has an integrated impeller arrangement for the circulation, i.e. pumping, of the fluids (in which instance any external pump arrangement may be dispensed with). Such impeller arrangement can be separated from the member  43  or it can be integrated with the member  43  into a single-piece device by means of suitably shaping the surfaces of the member  43  in the two axial directions to resemble the operation of impellers. Such combined pump and valve apparatus is described in our copending European patent application No. 07120950.6 filed on 19 Nov. 2007, the contents of which being hereby incorporated by reference. 
     During operation of the valve apparatus in a first operation mode, the shaft  42  and thereby the member  43  are steadily rotated with respect to the casing  41  and the outlets  46   a - f , thereby sucking a fluid of a first characteristic trough the first axially arranged inlet  45   a  and into the two chambers  44   a ,  44   c  constantly in fluid communication with the first axially arranged inlet  45   a , and sucking a fluid of a second characteristic trough the second axially arranged inlet  45   b  and into the two chambers  44   b ,  44   d  constantly in fluid communication with the second axially arranged inlet  45   b . As the member  43  and thus the chambers  44   a - d  thereof are rotated with respect to the casing the fluids of the first and second characteristics are alternately output through the circumferentially arranged outlets  46   a - f.    
     The circumferentially arranged outlets  46   a - f  alternately output pulses of fluids of the first and second characteristics. The rotational speed for a given number of chambers controls the wavelength and frequency of the train of fluid pulses and the angular separation of the outlets controls the phase shift between them. 
     The fluids of the first and second characteristics may be fluids, such as e.g. water or other heat exchange fluid, of different temperatures. Alternatively, different fluids or fluids having different properties are mixed by the valve apparatus. 
     In a second operation mode the valve apparatus operates in a reciprocal manner to divide up fluid pulses of the first and second characteristics received at the circumferentially arranged outlets  46   a - f , being inlets in this operation mode. The shaft  42  and thereby the member  43  are steadily rotated in the opposite direction with respect to the casing  41  and the outlets  46   a - f . Hereby, the fluid pulses of the first and second characteristic are sucked through the circumferentially arranged outlets  46   a - f  and alternately into the respective chambers  44   a - d  of the casing  41 . The fluid pulses that are collected in the two chambers  44   a ,  44   c  constantly in fluid communication with the first axially arranged inlet  45   a  is output there through, and the fluid pulses that are collected in the two chambers  44   b ,  44   d  constantly in fluid communication with the second axially arranged inlet  45   b  is output there through. Thus, the axially arranged inlets  45   a - b  are outlets in this operation mode. If the rotational speed of the shaft  42  is adapted to the frequency of the fluid pulses and the phase shift between the fluid pulses at the circumferentially arranged outlets  46   a - f  is adapted to the angular separation of the circumferentially arranged outlets  46   a - f , fluid of the first characteristic can be collected by the valve apparatus and output though the first axially arranged inlet  45   a  and fluid of the second characteristic can be collected by the valve apparatus and output though the second axially arranged inlet  45   b.    
     While the rotating valve apparatus of  FIG. 5  has four separated chambers, the invention is not limited in this respect. There may be provided more than four separated chambers, such as six or eight chambers, in order to increase the frequency of the fluid pulses. 
     In the valve apparatuses of the present invention, a small separation between the chamber-dividing and rotating member and the wall of the cylindrical casing may advantageously be allowed, reducing or eliminating solid-to-solid contact forces with only negligible amounts of fluid being mixed. 
     The rotating valve apparatuses are capable of distributing industrial scale amounts of fluids with different characteristics to a common outlet (or several common outlets) with minimal mixing on a sub-second scale. The valve apparatus allows for a steady fluid flow with minimal disturbance from switching, minimal switching power demand, and a long lifetime with the ability to switch millions of cycles. Conventional valve arrangements either are too slow, too disruptive (flow stop, pressure waves), power demanding and/or wear out after rather short a number of cycles. 
     The rotating valve apparatus is applicable for industrial processes which involve alternating distribution of fluid with different characteristics into a common outlet, keeping the fluids separated with minimal mixing at a rate of a few cycles per second, continuously for e.g. several years. The fluids have preferably roughly similar fluid properties concerning e.g. density, viscosity, etc. They may consist of different substances, like water and ethanol, or of the same substance in different property states, like hot and cold water or other heat exchange fluid.