US3158007A

US3158007A - Pressure exchangers

Info

Publication number: US3158007A
Application number: US145383A
Authority: US
Inventors: Kentfield John Alan Charles
Original assignee: Power Jets Research and Development Ltd
Current assignee: Power Jets Research and Development Ltd
Priority date: 1960-10-14
Filing date: 1961-10-16
Publication date: 1964-11-24
Anticipated expiration: 1981-11-24

Description

Nov. 24, 1964 J. A. C. KENTFIELD PRESSURE EXCHANGERS Filed Oct. 16, 1961 2 Sheets-Sheet l I M 5 2o 23' 1 I J l 1b H9 '24 7e Hal.

1964 J. A. c. KENTFIELD 3,

PRESSURE EXCHANGERS Filed Oct. 16, 1961 2 Sheets-Sheet 2 United States Patent Office 3,158,067 Patented Nov. 24, 1964 3,158,007 PRESSURE EXCHANGERS John Alan Charles Kentfieid, Worthing, England, assignor to Power Jets (Research 8: Deveioprnent) Limited, London, England, a British company Filed Oct. 16, 1961, Ser. No. 145,383 Claims priority, application Great Britain Oct. 14, 1960 12 Claims. (Cl. 62401) This invention relates to pressure exchangers.

The term pressure exchanger is used herein to mean apparatus comprising cells in which one fluid quantity expands, so compressing another fluid quantity with which it is in contact, ducting to lead fluid substantially steadily to and from the cells at different pressures and means to effect relative motion between the cells and the ducting.

The cells of a pressure exchanger are usually arranged in a circular array as a rotor and the rotor is customarily termed a cell ring. A pressure exchanger may have a low-pressure scavenging stage and a relatively higher-pressure scavenging stage,'each stage having inlet and outlet ports in end-plates at opposite ends of the cell ring.

In one proposed form of pressure exchanger, two streams of fluid, one at a high pressure and one at a lower pressure, are introduced into the cells and these streams are combined into a single stream of'fluid at an intermediate pressure issuing from an outlet of the'pressure exchanger. Such a pressure exchanger is hereinafter referred to as a pressure equalizer.

Alternatively, in another proposed form of a pressure exchanger a single stream of fluid at an intermediate pres sure is introduced into the cells and this stream is divided into two streams of fluid, one at a pressure higher and one at a pressure lower than the intermediate pressure, issuing from outlets of the pressure exchanger. Such a pressure exchanger is hereinafter referred to as a pressure divider.

To provide a flow of cold fluid which may be used for cooling purposes in an aircraft, it has been suggested previously that both a pressure divider and a pressure equalizer should be used in combination. According to this prior suggestion, the high-pressure outlet flow and the lower-pressure outlet flow of the pressure divider provide, respectively, the high-pressure inlet flow and the lowerpressure inlet flow of the pressure equalizer. Some of the fluid admitted to the pressure divider at a pressure intermediate the high and lower pressures is compressed in the cells of the pressure divider with the object only of expanding, and so cooling, the remainder of the intermediate-pressure inlet fluid. The high-pressure fluid so produced is then expanded in the pressure equalizer with the object only of compressing the lower-pressure fluid. Thus, some of the intermediate-pressure inlet fluid is subject to a compression process followed by an expansion process, whilst the remainder of the intermediate-pressure inlet fluid is subject to an expansion process followed by a compression process. v According to the present invention, a pressure exchanger incorporates a ring of open-ended cells, end-plates effective to close the ends of the cells but'having ports therein for the admission of fluid to and the extraction of fluid from the cells, means to eflect relative movement between the cells and the end-plates, an inlet port and an outlet port of the said ports serving as a low-pressure scavenging stage and a further inlet port and a further outlet port of the said ports serving as a higher-pressure scavenging stage, ducting interconnecting the low-pressure scavenging stage outlet and inlet ports, the opening edge of the low pressure scavenging stage inlet port being in advance, considered in the direction of relative movement, of the opening edge of the low-pressure scavenging stage outlet port and the low-pressure scavenging stage inlet port providing for a higher volumetric flow of fluid than the low-pressure scavenging stage outlet port.

The pressure exchanger as set out in the immediatelypreceding paragraph may be conveniently referred to as a depressurizer.

By the use of such a depressurizer, the compression process and consequent expansion process is eliminated, whilst the whole of the expansion and compression processes take place in the depressurizer and thus the fluid admitted to the cells through the inlet port of the higher-pressure scavenging stage is expanded in the cells at that stage to produce a supply of low-temperature, low-pressure fluid and is subsequently compressed in the cells before being exhausted from the cells through the outlet port of that stage.

The closing edge of the low-pressure scavenging stage outlet port of the depres surizer may be in advance of the closing edge of the low-pressure scavenging stage inlet port.

The outlet port of the higher-pressure scavenging stage may lead to the inlet of a diifuser, the outlet of which leads to the inlet of a fan.

If the depressurizer is incorporated in the cooling system of an aircraft, during flight, ram air is supplied to the inlet port of the higher-pressure scavenging stage and the outlet port of that stage may lead to a duct exhausting to the rear of the aircraft.

if the low-pressure scavenging stage of the depressurizer is used to provide a flow of coolant fluid for the cold pass of a heat-exchanger, the cold pass may constitute a portion of the ducting interconnecting the inlet and outlet ports of that stage. Alternatively, if the depressurizer is used to provide a flow of low-pressure fluid in a drying plant, a drying chamber of the plant may constituted a portion of the said interconnecting ducting.

In order to enable-the depressurizer to operate at a higher pressure ratio, the outlet port of the higher-pressure scavenging stage may lead to the lower-pressure fluid inlet port of a pressure equalizer, the high-pressure inlet port of which is connected to a source of high-pressure fluid. This arrangement improves the scavenging of the cells of the depressurizer at the higher-pressure scavenging stage. The intermediate-pressure fluid outlet port of the pressure equalizer may lead to the inlet of a diffuser, the outlet of which may be open to atmosphere.

In order to further increase the pressure ratio of the depressurizer, the higher-pressure scavenging stage inlet port of the depressurizer may be supplied with fluid from the outlet of an expansion engine, the inlet of which expansion engine is open to atmosphere. The expansion engine may be coupled to drive the cell rings of the depressurizer and of the pressure equalizer. An electric motor-generator may also be coupled to the cell rings and the electric motor-generator controlled in accordance with the speed of the cell rings.

The following description relates to the accompanying diagrammatic drawings.

In the drawing, which are given by way of example:

FIGURE 1 is a developed view of a depressurizer for providing a flow of cooling air for a cooling system;

FIGURE 2 shows the circuit of a drying plant incorporati ng a depressurizer;

FIGURE '3 shows a modified form of the circuit shown in FIGURE 2;

FIGURE 4 shows a modified form of the circuit shown in FIGURES; and

FIGURE 5 shows a vapour compression refrigeration circuit incorporating a depressurizer.

In FIGURE 1, a depressurizer cell ring 1 is rotatable in a direction indicated by an arrow 2 between end-plates 3 and 4. The end-plate 3 has a low-pressure fluid outlet port and a higher-pressure fluid inlet port 6. The endplate 4 has a low-pressure fluid inlet port 7 and an intermediate-pressure fluid outlet port 8. The ports 5 and 7 serve as a low-pressure scavenging stage. The

ports

6 and 8 serve as a relatively higher-pressure scavenging stage. The port 5 leads via a duct 9 to a port 7. A heatexchanger has a cold pass 10 formed by part of the duct 9. A hot-pass 11 of the heat-exchanger carries the flow of fluid to be cooled.

The port 6 is open to atmosphere, whilst the port 8 leads to the inlet of a diffuser 12, the outlet of which leads to the inlet of a fan 13 coupled to an electric motor 14 by a shaft 15. The outlet of the fan 13 is open to atmosphere. An electric motor 16 is arranged to drive the cell ring 1 through a shaft 17. Compression waves are represented by single

full lines

18, 19, and 21, expansion waves by a fan of broken lines 22 and an ideal interface line between the fluids in the cells is represented by a chain line 23.

In operation, the cell ring 1 is rotated in the direction of the arrow 2 by the electric motor 16 and the fan 13 is driven by the electric motor 14. Immediately on starting, cells approaching the port 8 of the higher-pressure scavenging stage contain air at substantially atmospheric pressure and owing to the operation of the fan 13, a sub-atmospheric pressure obtains at the port 8. Owing to this pressure diiference, when each cell opens to the port 8, the fan of expansion waves 22 is set up and travels across the cell accelerating the contents of the cell out of the port 8. When the rotor has reached its operational speed, the waves 22 arrive at the endaplate 3 as each cell is closing to the port 6. The waves 22 are then reflected from the end-plate 3 and traverse the cell reaching the end-plate 4 as the cell is closing to the port 8. Cells leaving the higher-pressure scavenging stage and approaching the low-pressure scavenging stage therefore contain air at sub-atmospheric pressure. Each of these cells is then opened to the port 7 where air at a pressure higher than that in the cell exists and the compression wave 18 traverses the cell followed by air from the port 7. The wave 18 reaches the end-plate 3 as each cell is opening to the port 5.

At this stage the relevant cell now contains air at a pressure slightly lower than the pressure at the port 5 and this pressure difference causes the compression wave 19 to traverse the cell against the flow of air therein. In so doing, the compression wave 19 converts some of the velocity of that air into pressure. The conversion of velocity into pressure gives a sufficient increase in pressure to enable the air to pass out of the cells. The air which has approached the low-pressure scavenging stage in the cells, passes out of the cells through the port 5 and so via the duct 9 through the cold pass 10 of the heat-exchanger, where it is heated by the fluid passing through the hot pass 11, and re-enters the cells via the port 7. Closure of each cell to the port 5 causes the compression wave 2% to traverse the cell, thus bringing the contents of the cell to a pressure just below atmospheric. The compression waves 19 and 20 reach the end-plate 4 as each cell is closing to the port 7.

The absence of incident expansion waves at the lowpressure scavenging stage, permits a more accurate selection to be made of the optimum positions of the opening edge, that is the radially extending edge of the port first encountered by a given cell and closing edge, that is the radially extending edge of the port last encountered by a given cell, of the ports. This follows from the fact that an expansion wave is not, in fact, a single wave, but a divergent fan of waves.

The compression wave 19 causes a sufficient pressure rise at the low-pressure scavenging stage to overcome the losses in the port 5, the duct 9, the port 7 and the cells located at the low-pressure scavenging stage.

The port 7 permits a higher volumetric flow of fluid to enter the cells than the volumetric flow of fluid which is allowed to leave the cells via the port 5. In the embodiment of the invention herein described, the higher volumetric flow is achieved by arranging that the opening edge 7A of the port 7 is in advance of the opening edge 5A of the port 5, and that the closing edge 58 of the port 5 is in advance of the closing edge 78 of the port 7.

Air which has entered the cells via the port 7 is conveyed from the low-pressure scavenging stage in the cells and is at a pressure lower than atmospheric pressure. As each cell is opened to the port 6, the compression wave 21 traverses the cell followed by air at the port 6. The compression wave 21 reaches the end-plate 4 as the cell is again opening to the port 8 and the cycle is recommenced.

If the cooling system of FIGURE 1 is used in an aircraft, during flight, ram air is supplied to the port 6 and the fan 13 is omitted. The flow through the port 8 is exhausted to the rear of the aircraft.

In the cooling system of FIGURE 1, the stream of fluid passing through the hot pass 11 of the heat-exchanger is indirectly cooled by the stream of air passing through the cold pass 10 of the low-pressure scavenging stage circuit 5, 9 and 7. However, the circuits of drying plants shown in FIGURES 2, 3 and 4, now to be described, a material to be dried is inserted in the low-pressure scavenging stage circuit of the depressurizer.

Referring to FIGURE 2, a depressurizer 24, having a cell ring (not shown), has inlet and outlet ports, diffuser, fan, electric motors and shafts similar to those described in the embodiment of FIGURE 1. The outlet port 5 leads via a duct 25 to the inlet port 7. The duct 25 thus replaces the

integers

9 and 10 of FIGURE 1 and with the ports 5 and 7 forms the low-pressure scavenging stage. An auxiliary inlet duct 26 leading into the duct 25 has a throttle valve 27.

In operation, the material to be dried is inserted in the duct 25, the electric motor 16 drives the cell ring of the depressurizer 24, which functions as described with reference to FIGURE 1 and the fan 13 is driven by the motor 14. The auxiliary inlet duct 26 conveys fluid (for example atmospheric air) into the duct 25 of the lowpressure scavenging stage and the quantity of the fluid is controlled by the throttle valve 27 so as to maintain the flow of fluid in the port 7 at a value consistent with satisfactory operation of the drying process.

In the circuit shown in FIGURE 3, a pressure equalizer 28 is also coupled to be driven by the electric motor 16. The pressure equalizer 28 has a high-pressure fluid inlet port 29 in communication with a source of high pressure fluid, a lower-pressure fluid inlet port 30 and an intermediate-pressure fluid outlet port 31. The outlet port 8 of the depressurizer 24 leads to the lower-pressure fluid inlet port 30 of the pressure equalizer 28.

In operation, corresponding parts of this circuit func tion in the same manner as described with reference to FIGURE 2. The pressure equalizer 28, however, is supplied with a high-pressure fluid through the inlet port 29 and the inlet port 30 is supplied with fluid from the outlet port 8 of the depressurizer 24. Fluid at a pressure intermediate the high and lower pressures of the fluid supplied to the pressure equalizer is discharged from the pressure equalizer via the outlet port 31 and the difiuser 12.

The addition of the pressure equalizer 28 to the circuit as shown in FIGURE 2 enables the depressurizer 24 to operate at a higher pressure ratio by improving scavenging of the cells via the port 8. This improved scavenging results in the cells that are leaving the higher-pressure scavenging stage containing fluid at a lower pressure than is the case in the arrangement shown in FIGURE 1 and consequently, the low-pressure scavenging stage operates at a lower fluid pressure.

To obtain an even lower fluid pressure in the lowpressure scavenging stage, the fluid entering the port 6 of the depressurizer 24 may first be passed through an expansion engine. A circuit including such an expansion engine in the form of a turbine 32 is shown in FIGURE 4. In this figure, the turbine 32 is coupled to the cell rings of the depressurizer and the pressure equalizer by the shafts 1'7 and the electric motor 16 shown in FIG- URES 2 and 3 is replaced by an electric motor-generator 33. This replacement allows power to be taken from the shafts 17 when the amount of Work available at the turbine 32 exceeds that which is required to drive the cell rings. With this arrangement, it is advantageous to control the motor-generator 33 in accordance with the speed of the shafts 17 and thus provide shaft speed-governing means. In other respects, a system having a circuit as shown in FIGURE 4 functions as described with reference to FIGURE 3.

In FIGURE 5, the depressurizer 24 and a rotary compressor 34 are coupled to be driven by an electric motor 35 via shafts 36. The ports 5 and 7 of the depressurizer 24 are interconnected by a duct 37 including an evaporator having a cold pass 38. The port 8 leads via a duct 39 to the inlet of the compressor 34, the outlet of which leads, via a duct 40 including a hot pass 41 of a condenser, to the port 6. The circuit is filled with a suitable quantity of a refrigerant such as ammonia.

In operation, the rotor of the compressor and the cell ring of the depressurizer are driven by the electric motor 35. The refrigerant is compressed in the compressor 34 and passes, via the duct 40, through the hot pass 41 Where it is cooled and condensed to a wet vapour. The refrigerant then enters the cell ring of the depressurizer 24 via the port 6 where it is further cooled in passing through the fan of expansion waves 22, FIGURE 1. The refrigerant leaves the cell ring via the port 5 and passes through the duct 37, a part of which constitutes the cold pass 38, where it is heated and vaporised, to re-enter the cell ring via the port 7 and leave the cell ring via the port 8. The cycle is then recommenced.

A vapour compression refrigeration plant incorporating a depressurizer as described, offers the advantage of increased capacity over the conventional compressor-restrictor vapour compression plants. Furthermore, the cell ring of the depressurizer will sufler less erosion damage due to impingement of the refrigerant liquid on the inter-cell walls than would turbine blades if a turbine were used as an expander in place of the depressurizer.

I claim:

1. A pressure exchanger incorporating a ring of openended cells, end-plates effective to close the ends of the cells but having ports therein for the admission of fluid to and the extraction of fluid from the cells, means to elfect relative movement between the cells and the endplates, an inlet port and an outlet port of the said ports serving as a low-pressure scavenging stage and a further inlet port and a further outlet port of the said ports serving as a higher-pressure scavenging stage, ducting interconnecting the low-pressure scavenging stage outlet and inlet ports, the opening edge of the low-pressure scavenging stage inlet port being in advance, considered in the direction of relative movement, of. the opening edge of the low-pressure scavenging stage outlet port and the low-pressure scavenging stage inlet port providing for a higher volumetric flow of fluid than the low-pressure scavenging stage outlet port.

2. A pressure exchanger as claimed in claim 1, in which the closing edge of the low-pressure scavenging stage outlet port is in advance, considered in the direction of relative movement, of the closing edge of the low-pressure scavenging stage inlet port. I

3. A pressure exchanger as claimed in claim 1 including a heat-exchanger, a hot pass and a cold'pass of the heat exchanger, the cold pass of which constitutes a portion of the interconnecting ducting.

4. A pressure exchanger as claimed in claim 1 including a diffuser and a fan, the outlet port of the higherpressure scavenging stage leading to the inlet of the diffuser, the outlet of which leads to the inlet of the fan.

5. Refrigeration plant, incorporating a pressure exchanger as claimed in claim 1, including an evaporator which constitutes a portion of the interconnecting ducting, a compressor, the outlet port of the higher-pressure scavenging stage leading to the inlet of the compressor, a duct communicating with the outlet of the compressor and a condenser interposed in said duct, the duct terminating at the inlet port of the higher-pressure scavenging stage.

6. Aircraft plant, incorporating a pressure exchanger as claimed in claim 3, including means to compress air by ram effect, ducting between the said means and the inlet port of the higher-pressure scavenging stage, a nozzle facing rearwardly of the aircraft and a ducting through which the fluid flow in the outlet port of the higher-pressure scavenging stage can be exhausted to atmosphere via said nozzle.

7. Plant as claimed in claim 6, including a pressure equalizer having a higher pressure inlet port, a lower pressure inlet port and an intermediate pressure outlet port, and a source of high pressure fluid the higher-pressure scavenging stage outlet port of the pressure exchanger being connected to the lower-pressure fluid inlet port of the pressure equalizer, the intermediate-pressure fluid outlet port of the pressure equalizer being connected to the inlet of the rearwardly-facing nozzle, and the highpressure fluid inlet port of the pressure equalizer being connected to the source of high-pressure fluid.

8. Plant as claimed in claim 6, including an expansion engine, through which ram air can be supplied from the means to compress air to the higher-pressure scaveng ing stage inlet port of the pressure exchanger.

9. Plant incorporating a pressure exchanger as claimed in claim 1, including a drying chamber which constitutes a portion of the said interconnecting ducting of the lowpressure scavenging stage.

10. Plant as claimed in claim 9, including a source of high pressure fluid and a diffuser the outlet of which is open to atmosphere, the higher-pressure scavenging stage outlet port of the pressure exchanger leading to the lower-pressure fluid inlet port of a pressure equalizer and the intermediate-pressure fluid outlet port of the pressure equalizer leading to the inlet of the diffuser, the highpressure fluid inlet port of the pressure equalizer'communicating with the source of high-pressure fluid.

11. Plant as claimed in claim 9, including an expansion engine, the outlet of which communicates with the higher-pressure scavenging stage inlet port of the pressure exchanger, the inlet of the expansion engine being open to atmosphere.

12. Plant as claimed in claim 9, including a source of high-pressure fluid, a diffuser the outlet of which is open to atmosphere, a pressure equalizer having a higher pressure inlet port, a lower pressure inlet port and an intermediate pressure outlet port, ducting forming a communication between the-higher-pressure scavenging stage outlet port of the pressure exchanger and the lower-pressure fluid inlet port of the pressure equalizer, ducting forming a communication between the source of high-pressure fluid and the higher-pressure fluid inlet port of the pressure equalizer and ducting forming a communication between the intermediate-pressure fluid outlet port of the pressure equalizer and the inlet of the diffuser.

References Cited in the file of this patent UNITED STATES PATENTS 2,848,871 Jendrassik Aug. 26, 1958 2,952,982 Spalding Sept. 20, 1960 FOREIGN PATENTS 159,112 Australia Sept. 29, 1954

Claims

1. A PRESSURE EXCHANGER INCORPORATING A RING OF OPENENDED CELLS, END-PLATES EFFECTIVE TO CLOSE THE ENDS OF THE CELLS BUT HAVING PORTS THEREIN FOR THE ADMISSION OF FLUID TO AND THE EXTRACTION OF FLUID FROM THE CELLS, MEANS TO EFFECT RELATIVE MOVEMENT BETWEEN THE CELLS AND THE ENDPLATES, AN INLET PORT AND AN OUTLET PORT OF THE SAID PORTS SERVING AS A LOW-PRESSURE SCAVENGING STAGE AND A FURTHER INLET PORT AND A FURTHER OUTLET PORT OF THE SAID PORTS SERVING AS A HIGHER-PRESSURE SCAVENGING STAGE, DUCTING INTERCONNECTING THE LOW-PRESSURE SCAVENGING STAGE OUTLET AND INLET PORTS, THE OPENING EDGE OF THE LOW-PRESSURE SCAVENGING STAGE INLET PORT BEING IN ADVANCE, CONSIDERED IN THE DIRECTION OF RELATIVE MOVEMENT, OF THE OPENING EDGE OF THE LOW-PRESSURE SCAVENGING STAGE OUTLET PORT AND THE LOW-PRESSURE SCAVENGING STAGE INLET PORT PROVIDING FOR A HIGHER VOLUMETRIC FLOW OF FLUID THAN THE LOW-PRESSURE SCAVENGING STAGE OUTLET PORT.