Ejectors and Methods of Use
An ejector has: a motive flow inlet (40); a secondary flow inlet (42); an outlet (44); a motive flow nozzle (242) having an outlet (110); a primary flowpath from the motive flow inlet through the motive flow nozzle to the ejector outlet; a secondary flowpath from the secondary flow inlet to the ejector outlet, merging with the primary flowpath at the motive nozzle outlet; a control needle (200; 300; 400) shiftable along a range of motion between a first condition and a second condition and seated against the motive nozzle in the second condition. The needle comprises: a main shaft (210); a tip (204); a first portion (220; 320) converging toward the tip; and a shoulder portion (214; 314; 422) between the first portion and the main shaft and seated against the motive nozzle in the second condition and converging toward the tip at a greater angle (?1; ?1 2) than an angle (?2; ?2 2) of the first portion.
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Benefit is claimed of U.S. Patent Application Ser. No. 61/933,777, filed Jan. 30, 2014, and entitled “Ejectors and Methods of Use”, the disclosure of which is incorporated by reference herein in its entirety as if set forth at length.
BACKGROUNDThe present disclosure relates to refrigeration. More particularly, it relates to ejector refrigeration systems.
Earlier proposals for ejector refrigeration systems are found in U.S. Pat. Nos. 1,836,318 and 3,277,660.
In the normal mode of operation, gaseous refrigerant is drawn by the compressor 22 through the suction line 56 and inlet 24 and compressed and discharged from the discharge port 26 into the discharge line 28. In the heat rejection heat exchanger, the refrigerant loses/rejects heat to a heat transfer fluid (e.g., fan-forced air or water or other fluid). Cooled refrigerant exits the heat rejection heat exchanger via the outlet 34 and enters the ejector primary inlet 40 via the line 36.
The exemplary ejector 38 (generically shown in
Use of an ejector serves to recover pressure/work. Work recovered from the expansion process is used to compress the gaseous refrigerant prior to entering the compressor. Accordingly, the pressure ratio of the compressor (and thus the power consumption) may be reduced for a given desired evaporator pressure. The quality of refrigerant entering the evaporator may also be reduced. Thus, the refrigeration effect per unit mass flow may be increased (relative to the non-ejector system). The distribution of fluid entering the evaporator is improved (thereby improving evaporator performance). Because the evaporator does not directly feed the compressor, the evaporator is not required to produce superheated refrigerant outflow. The use of an ejector cycle may thus allow reduction or elimination of the superheated zone of the evaporator. This may allow the evaporator to operate in a two-phase state which provides a higher heat transfer performance (e.g., facilitating reduction in the evaporator size for a given capability).
The
In yet further variations, additional expansion devices and heat exchangers may be added. In one example, an economizer heat exchanger 94 has a first leg 96 along the line 72 upstream of the expansion device 70 and a second leg 98 along the line 56 from the vapor outlet 54 upstream of the junction with the bypass 82. An expansion device 92 may be upstream of the second leg. An expansion valve 99 is also shown downstream of the heat rejection heat exchanger. Valve 92 is used to provide further cooling (sub-cooling) effect to the primary flow in the line 72. Valve 70 is the primary expansion valve at the inlet to the heat absorption heat exchanger 66 to control the heat exchanger 66 superheat. Expansion valve 99 could be used to do partial expansion before the flow enters the ejector in one mode and acts as the primary expansion valve on the high side for the basic cycle mode. Valve 84, 88, 90 are on/off valves.
There have been a number of prior art proposals wherein the ejector needle has a fully closed/seated condition blocking flow through the motive nozzle.
One aspect of the disclosure involves an ejector comprising: a motive flow inlet; a secondary flow inlet; an outlet; a motive flow nozzle having an outlet; a primary flowpath from the motive flow inlet through the motive flow nozzle to the ejector outlet; a secondary flowpath from the secondary flow inlet to the ejector outlet, merging with the primary flowpath at the motive nozzle outlet; a control needle shiftable along a range of motion between a first condition and a second condition and seated against the motive nozzle in the second condition. The needle comprises: a main shaft; a tip; a first portion converging toward the tip; and a shoulder portion between the first portion and the main shaft and seated against the motive nozzle in the second condition and converging toward the tip at a greater angle (θ1; θ1-2) than an angle (θ2; θ2-2) of the first portion.
In one or more embodiments of any of the foregoing embodiments: the shoulder portion angle (θ1) is 15° to 75°; and the first portion angle (θ2) is 5° to 60°.
In one or more embodiments of any of the foregoing embodiments: the shoulder portion angle (θ1-2) is 75° to 115°; and the first portion angle (θ2-2) is 5° to 60°.
In one or more embodiments of any of the foregoing embodiments, the shoulder portion angle (θ1) is 10° to 30° greater than the first portion angle (θ2).
In one or more embodiments of any of the foregoing embodiments, the shoulder portion angle (θ1-2) is 5° to 80° greater than the first portion angle (θ2-2).
In one or more embodiments of any of the foregoing embodiments, a throat of the motive nozzle has clearance relative to the needle in the second condition.
In one or more embodiments of any of the foregoing embodiments: the motive nozzle is made of stainless steel; and the needle is made of stainless steel.
In one or more embodiments of any of the foregoing embodiments, the needle comprises a transition section between the first portion and the second portion and being closer to cylindrical than the first portion and the second portion.
In one or more embodiments of any of the foregoing embodiments, the motive nozzle is a convergent-divergent nozzle.
In one or more embodiments of any of the foregoing embodiments, the ejector further comprises: a mixer comprising a convergent portion at least partially downstream of the motive nozzle; and a divergent diffuser portion downstream of the convergent portion.
In one or more embodiments of any of the foregoing embodiments, a vapor compression system comprises: a compressor; a heat rejection heat exchanger coupled to the compressor to receive refrigerant compressed by the compressor; the ejector; a heat absorption heat exchanger; and a separator having: an inlet coupled to the outlet of the ejector to receive refrigerant from the ejector; a gas outlet; and a liquid outlet.
In one or more embodiments of any of the foregoing embodiments, a method for operating the system comprises: compressing the refrigerant in the compressor; rejecting heat from the compressed refrigerant in the heat rejection heat exchanger; passing a flow of the refrigerant through the primary ejector inlet; and passing a secondary flow of the refrigerant through the secondary inlet to merge with the primary flow.
In one or more embodiments of any of the foregoing embodiments, a method for operating the ejector comprises: driving a motive flow along the primary flowpath; and shifting the needle to the second condition so as to stop the motive flow.
The details of one or more embodiments are set forth in the accompanying drawings and the description below. Other features, objects, and advantages will be apparent from the description and drawings, and from the claims.
Like reference numbers and designations in the various drawings indicate like elements.
DETAILED DESCRIPTIONIn use, the closing of the ejector may serve the role of the solenoid valve 88 of the
Exemplary θ1 is 40°, more broadly, 30° to 50° or 15° to 75°. Exemplary θ2 is 24°, more broadly, 20° to 30° or 5° to 60°. An exemplary difference between θ1 and θ2 is at least 2°, more particularly at least 5°, more particularly, 10° to 30° or 10° to 20°. Exemplary θ3 is the same as θ1 (e.g., within 1° thereof). Relative to the
A second illustrated difference is the presence of a step discontinuity 315 (e.g., shallower than either adjacent section) between the surface 322 of the section 320 and the surface 316 when compared with the intersection of the surface 222 and the surface 216. The exemplary discontinuity in the form of a straight section 330 having a circular cylindrical outer surface 332 and respective junctions 334 and 336 with the surfaces 316 and 322. An exemplary length LS of the surface 332 is at least 0.01 inches (0.25 mm), more particularly, an exemplary 0.04 inches to 0.2 inches (1 mm to 5 mm) or 0.5 mm to 10 mm.
Exemplary values for θ2-2 are similar to those given above for θ2. An exemplary value for θ1-2 is 90°, more broadly, 75° to 115° or 15° to 145° or 45° to 120°. An exemplary difference between θ2-2 and θ1-2 is at least 2°, more particularly at least 5°, or 40°-70°, more broadly, 5°-80°.
In yet alternative embodiments, θ2 or θ2-2 may go to an exemplary 180° with the associated surface portions being radial. The angels may even go beyond radial. In alternative implementations with such a radial surface or of the shallower surfaces, one or both exemplary surfaces may be formed by separate members carried by the needle or by a main portion of the motive nozzle.
Exemplary ejector materials and manufacture techniques may be those conventionally known in the art (e.g., casting and/or machining from various metals and alloys, typically stainless steels). Use may similarly mirror use in the art with, in particular, use including actuating the ejector to fully close off flow therethrough in the absence of a separate valve.
Although an embodiment is described above in detail, such description is not intended for limiting the scope of the present disclosure. It will be understood that various modifications may be made without departing from the spirit and scope of the disclosure. For example, details of the particular refrigeration system in which the ejector is to be used may influence details of any particular implementation. Accordingly, other embodiments are within the scope of the following claims.
Claims
1. An ejector comprising: wherein the needle comprises:
- a motive flow inlet (40);
- a secondary flow inlet (42);
- an outlet (44);
- a motive flow nozzle (242) having an outlet (110);
- a primary flowpath from the motive flow inlet through the motive flow nozzle to the ejector outlet;
- a secondary flowpath from the secondary flow inlet to the ejector outlet, merging with the primary flowpath at the motive nozzle outlet;
- a control needle (200; 300; 400) shiftable along a range of motion between a first condition and a second condition and seated against the motive nozzle in the second condition,
- a main shaft (210);
- a tip (204);
- a first portion (220; 320) converging toward the tip; and
- a shoulder portion (214; 314; 422) between the first portion and the main shaft and seated against the motive nozzle in the second condition and converging toward the tip at a greater angle (θ1; θ1-2) than an angle (θ2; θ2-2) of the first portion.
2. The ejector of claim 1 wherein:
- the shoulder portion angle (θ1) is 15° to 75°; and
- the first portion angle (θ2) is 5° to 60°.
3. The ejector of claim 1 wherein:
- the shoulder portion angle (θ1-2) is 75° to 115°; and
- the first portion angle (θ2-2) is 5° to 60°.
4. The ejector of claim 1 wherein:
- the shoulder portion angle (Of) is 10° to 30° greater than the first portion angle (θ2).
5. The ejector of claim 1 wherein:
- the shoulder portion angle (θ1-2) is 5° to 80° greater than the first portion angle (θ2-2).
6. The ejector of claim 1 wherein:
- a throat of the motive nozzle has clearance relative to the needle in the second condition.
7. The ejector of claim 1 wherein:
- the motive nozzle is made of stainless steel; and
- the needle is made of stainless steel.
8. The ejector of claim 1 wherein:
- the needle comprises a transition section (330) between the first portion and the second portion and being closer to cylindrical than the first portion and the second portion.
9. The ejector of claim 1 wherein:
- the motive nozzle is a convergent-divergent nozzle.
10. The ejector of claim 1 further comprising:
- a mixer comprising a convergent portion at least partially downstream of the motive nozzle; and
- a divergent diffuser portion downstream of the convergent portion.
11. A vapor compression system comprising:
- a compressor (22);
- a heat rejection heat exchanger (30) coupled to the compressor to receive refrigerant compressed by the compressor;
- the ejector of claim 1;
- a heat absorption heat exchanger (64); and
- a separator (48) having: an inlet (50) coupled to the outlet of the ejector to receive refrigerant from the ejector; a gas outlet (54); and a liquid outlet (52).
12. A method for operating the system of claim 11, the method comprising:
- compressing the refrigerant in the compressor;
- rejecting heat from the compressed refrigerant in the heat rejection heat exchanger;
- passing a flow of the refrigerant through the primary ejector inlet; and
- passing a secondary flow of the refrigerant through the secondary inlet to merge with the primary flow.
13. A method for operating the ejector of claim 1, the method comprising:
- driving a motive flow along the primary flowpath; and
- shifting the needle to the second condition so as to stop the motive flow.
Type: Application
Filed: Jan 23, 2015
Publication Date: Apr 20, 2017
Applicant: Carrier Corporation (Jupiter, FL)
Inventors: Parmesh Verma (South Windsor, CT), Larry D. Burns (Avon, IN), Alexander Lifson (Manlius, NY)
Application Number: 15/115,753