ZA200502970B - Fluid displacement device - Google Patents

Description

FLUID DISPLACEMENT DEVICE

, Field of the Invention

THIS invention relates to a fluid displacement device. More specifically, this invention relates to a fluid displacement device such as a pump or fan having a heat transfer mechanism incorporated into it.

Description _of Prior Art

Heat pumps and air conditioning systems are well known. Heat pumps and/or refrigeration units are used in an increasing variety of applications today. One of the limitations on their usage is lack of space. For the above reason there is currently an emphasis on the reduction in size of heat exchange systems, and also to reduce the amount of refrigeration gasses used, as stipulated by legislation following from international environmental agreements. However refrigeration and/ or heat pump systems are large and difficult to reduce in size for applications where the system is to be fitted into small spaces, or where the system is required to be very light. It is well understood by persons skilled in the art that refrigeration systems consist of a compressor, a condenser, an expansion valve, and an evaporator.

Object of the Invention

It is accordingly an object of the present invention to provide a fluid displacement device, which it is believed will have advantages in certain applications over the prior art described above.

Disclosure of the Invention

According to the invention there is provided a fluid displacement device comprising: a moveable fluid displacement member for moving fluid along a first fluid flow path; a second fluid flow path incorporated within the fluid displacement device and communicating with the first fluid flow path for purposes of heat transfer. : The fluid displacement device may be a fan or a pump. The second flow path may . operate as a condenser or an evaporator. The first or second flow paths may incorporate fins, vanes or any other heat transfer mechanisms to enhance the transfer ] of heat from one fluid to another.

The fluid displacement device may include a casing. The second fluid flow path may beincorporated into the casing of the fluid displacement device, incorporated into the fluid displacement member, or incorporated into any other part of the fluid displacement device.

The fluid displacement member may displace fluid by means of positive displacement, rotary motion, oscillating motion or any combination of these.

The fluid being displaced by the fluid displacement device may be a liquid, gas, vapour, gel or any other flowable fluid or product that can be pumped.

The fluid displacement device may be in the form of a rotary lobe pump. The rotary lobe pump may have a casing and a set of rotating lobes. The casing may include a ’ front and/or back cover, as well as a central casing portion. The second fluid flow ‘ path may be incorporated into the front and/or back cover, central casing portion or into a lobe. , Also included within the scope of the invention, is a thermo dynamic cycle including the fluid displacement device of the invention?

In one arrangement according to the above aspect, a pair of thermo dynamic cycles may be provided having an interface which is provided by the first fluid path or the second fluid path. Thus in one arrangement, a first cycle may comprise a Compressor, a condenser, an expansion valve and an evaporator; and a second cycle may comprise afluid displacement device for moving fluid through the cycle with the second flow path in the fluid displacement device forming the aforesaid condenser. In a similar arrangement, a thermo-dynamic cycle may comprise a compressor, a condenser, an expansion valve, and an evaporator; and a second cycle comprising a fluid displacement device of the invention for moving a cooling fluid having a second fluid flow path being constituted by the aforesaid evaporator. ’ Brief Description of the Drawings

In order to illustrate the invention an embodiment thereof is described hereunder purely as an example, without limiting the scope of the invention, wherein:

Figure 1 is a schematic perspective view of a fluid displacement device in 5 accordance with the invention in the form of a pump with a front cover removed, showing a second fluid flow path incorporated into the front cover;

Figure 2 is a schematic perspective view of the pump in Figure 1, with the second fluid flow path covered by a plate;

Figure 3 is a schematic perspective view of the pump in Figure 1, with the front cover replaced;

Figure 4 is a schematic perspective view of a lobe from a rotary lobe pump in accordance with the invention, showing a second fluid flow path : incorporated in the lobe;

Figure 5 is a schematic perspective view of the central portion of the casing of . a rotary lobe pump in accordance with the invention, showing a : second fluid flow path incorporated in the interior surface of the central casing portion thereof;

Figure 6 is a schematic sectioned elevation of a monotype positive displacement pump with refrigerant flowing in a counter flow configuration in the rotor and/or in the casing of the pump;

Figure 7 is aschematic illustration of an air source hot water heat pump having a heat exchange interface utilizing the pump of the invention; and

Figure 8 is a graphic representation of the temperature/entropy of the cycles shown in Figure 7.

Referring to the drawings, a fluid displacement device is illustrated in Figures I to 5.

The device comprises a rotary lobe pump 10 being an outer casing 13; two rotating } lobes 14 which are capable of displacing fluid along a first fluid flow path (indicated by arrows A) from an inlet 16 to an outlet 18; and a cover 15 which is bolted onto the casing by means of bolts or cap screws (not shown) through apertures 17. In addition,

S a second fluid flow path (indicated by arrows B) in the form of a groove 19 is machined into the cover 15 (shown in Figure 1). These grooves each have an inlet 20 and an outlet 22. The grooves 19 are covered by a covering plate 24 (as shown in

Figure 2) to form a separate flow path for a second fluid.

Thus in one application cold water could be moved along through the first fluid flow path A by the rotary lobes 14, and superheated steam caused to flow through the second flow path B. The superheated will be condensed after coming into contact with the surfaces of the pump, which have been cooled by the flow of the cold water along the first flow path A.

A different embodiment is shown in Figure 4 wherein grooves 119 are machined into rotary lobes 114. These grooves 119 will be enclosed by means of a cover plates : shown schematically at 25, to define a separate second pathway B1 under such cover plates 25. Asin Figures 1 to 3 a primary pathway will be defined on the outer surface of the covering plates 25 as with a normal twin rotary lobe pump.

The second separate pathway Bl is thus defined within the lobes and an inlet of such : 5 pathway is shown at 120 and an outlet therefrom at 122, both inlet 120 and outlet 122 being disposed in the zone of the rotational axis of the lobe 114. With such an arrangement also in one application of the invention cold water could be moved along the outside of the lobes 114 below path A1 by means of a pumping action while super heated steam could flow through the second pathway B1 to be condensed after coming into contact with the surfaces of the lobe 114. The steam will thus be cooled, while the cold water flowing over the lobes 114 will be heated.

A further alternative arrangement is shown in Figure 5 wherein grooves 219 are incorporated within the inner surface of the central casing 26 of a rotary lobe pump.

Only the central casing is illustrated and it is envisaged that the grooves 219 will be enclosed by means of one or more covering plates shown schematically at 27, to ‘ define a sealed, separate second flow passageway B2. An inlet to this second * pathway is shown at 220 and an outlet therefrom at 224. A first primary flow path

J . through the rotary lobe pump shown by arrows A2, is the same as that shown in

Figure 1 having an inlet 216 thereto and an outlet 218. In this instance also for example cold water could pass along the first or primary path A2 and the steam along the pathway B2. The steam will thus be condensed upon cooling and serve to heat the water flowing along the primary pathway A2.

Figure 8 is a schematic illustration of a monotype pump 30 wherein a spirally formed rotor 31 rotates in a casing 32 with a complimentary spiral configuration 33 to the rotor 31. In this arrangement the invention envisages that a secondary flow path B3 could be defined through the rotor 31 itself, and/or through the casing 32 adjacent the rotor 31 as indicated by the arrows B3. Such secondary flow path B3 could therefore act as a condenser or evaporator with a primary first flow path A3 being defined by the pump pathway of the pump along the spiral 33. The same configuration can be used with a centrifugal pump or other pump, although the manufacturing process will be more complicated because of the physical size of the centrifugal impellor blade.

Yet another embodiment of the invention is a fan-type fluid displacement member * (not shown). The rotation of a fan causes air to move through the blades of the fan forming a first flow path while channels are incorporated into the blades of the fan to form a second flow path. The channels have an inlet and an outlet and are covered to } form a tubular conduit defining a flow path. Thus for example water may be circulated through the channels in the fan blades, thus cooling the air flowing through the blades of the fan while heating the water flowing through the channels in the fan blades.

Figure 8 illustrates a practical application of a pump in accordance with the invention in an air source hot water heat pump with two cycles 30, 31, being involved. A first refrigeration cycle 30 comprises a compressor 32, a condenser 33, an expansion valve 34 and an evaporator 35. The latter 35 may include a fan 36 for driving cold air through the evaporator 35, constituting a third cycle if required. The second cycle 31

Interfaces with the refrigeration cycle 30 to produce hot water to be stored in a reservoir 39. The second heated water cycle 31 is characterised in that it utilises the pump 37 of the invention wherein the first flow path conducts the water through the pump and the second flow path is constituted by the condenser 33 of the refrigeration cycle 30 as shown in the dotted block 38. The pump 37 of the invention thus serves to circulate water which is heated in the pump 37 by the integral condenser 33 of the refrigeration cycle 30. The principle of the invention can also be applied to the evaporator 35 of the refrigeration cycle 30 as mentioned above. Thus, the evaporator 35 could be integrally formed with fan 36 constituting the second flow passage, for example in the blades of the fan as described previously. The primary flow passage of the fan will thus be constituted by the flow path of the air which is driven by the fan 36.

Thus a prime objection of the invention is to improve the heat transfer efficiencyin a condenser and evaporator whereby the components. can be made smaller and therefore cheaper. The cost of the heat pump in Figure 8 can be reduced and made smaller by combining different components of the heat pump. As mentioned above, such proposed combinations could be the condenser 33 and the water pump 37 and/or the fan 36 and the evaporator 35.

The theoretical cycle of the air source hot water heat pump shown in Figure 8 and is described in the illustration.

Doubtless variations of the invention in detail are possible without departing from the principles set out in the consistory clauses.

For instance, various types of pumps may be used, and other means of incorporating fluid flow paths into fluid displacement devices may be used, such as the use of piping within the fluid displacement device.

Claims (18)

Claims

1. A thermodynamic apparatus, adapted to perform a thermodynamic cycle, the apparatus including a fluid displacement device comprising: a moveable fluid displacement member for moving fluid along a first fluid flow path; and a second fluid flow path incorporated within the fluid displacement device and communicating with the first fluid flow path for purposes of heat transfer, wherein the second fluid flow path operates as a condenser or an evaporator.

2. The thermodynamic apparatus according to claim 1 wherein the fluid displacement device is in the form of a pump or a fan.

3. The thermodynamic apparatus according to claim 1 or claim 2 wherein the fluid displacement device includes heat transfer mechanisms such as fins, coils or ribs to enhance the transfer of heat from the first fluid flow path to the second fluid flow path or vice versa. AMENDED SHEET

4. The thermodynamic apparatus according to any one of claims 1 to 3 wherein the fluid displacement device includes a casing with the second fluid flow path incorporated in such casing. 5S

5. The thermodynamic apparatus according to any one of claims | to 3 wherein the second fluid flow path of the fluid displacement device is incorporated in the fluid displacement member.

6. The thermodynamic apparatus according to any one of claims I to 5 wherein the fluid displacement device is in the form of a rotary lobe pump having a casing within which a pair of rotating lobes are adapted to rotate, and a front and/or rear cover plate, with the second fluid flow path being incorporated into the front and/or rear cover plate, the central casing portion, or in a lobe, or in a combination of the aforegoing.

7. The thermodynamic apparatus according to claim 1 substantially as herein described and exemplified, and/or described with reference to the accompanying drawings. AMENDED SHEET

8. A thermodynamic apparatus adapted to perform a pair of thermodynamic cycles, the apparatus including a fluid displacement device, comprising a moveable fluid displacement member for moving fluid along a first fluid flow path; and a second fluid flow path incorporated within the fluid displacement device and communicating with the first fluid flow path for purposes of heat transfer, the pair of thermodynamic cycles having an interface which is provided by the first fluid flow path and the second fluid flow path of the fluid displacement device.

9. The thermodynamic apparatus according to claim 8 wherein the second flow path of the fluid displacement device operates as a condenser.

10. The thermodynamic apparatus according to claim 8 wherein the second flow path of the fluid displacement device operates as an evaporator.

['1. The thermodynamic apparatus according to any one of claims 8 to 10 wherein the AMENDED SHEET fluid displacement device is in the form of a pump or a fan.

12. The thermodynamic apparatus according to any one of claims 8 to 11 wherein the fluid displacement device includes heat transfer mechanisms such as fins, coils or ribs to enhance the transfer of heat from the first fluid flow path to the second fluid flow path or vice versa.

13. The thermodynamic apparatus according to any one of claims 8 to 12 wherein the fluid displacement device includes a casing with the second fluid flow path incorporated in such casing.

14. The thermodynamic apparatus according to any one of claims 8 to 12 wherein the second fluid flow path of the fluid displacement device is incorporated in the fluid displacement member.

15. The thermodynamic apparatus according to any one of claims 8 to 14 wherein the fluid displacement device is in the form of a rotary lobe pump having a casing within which a pair of rotating lobes are adapted to rotate, and a front and/or rear cover plate, with the second fluid flow path being incorporated into the front AMENDED SHEET and/or rear cover plate, the central casing portion, or in a lobe, or in a combination of the aforegoing.

16. The thermodynamic apparatus according to any one of claims 8 to 15 wherein a first cycle comprises a compressor, a condenser, an expansion valve and an evaporator; and a second cycle comprises the fluid displacement device for moving fluid through such cycle, with the second fluid flow path of the fluid displacement device constituting the condenser of the first cycle.

17. The thermodynamic apparatus according to any one of claims 8 to 15 wherein a first cycle comprises a compressor, a condenser, an expansion valve and an evaporator, and a second cycle comprises the fluid displacement device for moving fluid through the second cycle, with the second flow path of the fluid displacement device constituting the evaporator of the first cycle.

18. A thermodynamic apparatus according to claim 8, substantially as herein described and exemplified, and/or described with reference to the accompanying drawings. AMENDED SHEET