Pressure exchanging ejector and refrigeration apparatus and method

• US 5,647,221 A
• Filed: 10/10/1995
• Issued: 07/15/1997
• Est. Priority Date: 10/10/1995
• Status: Expired due to Term

• Current Assignee: George Washington University
• Original Assignee: George Washington University
• Inventors: Garris, Charles A. Jr.
• Primary Examiner(s): WAYNER, WILLIAM E
• Application Number:
  US08/541,653
• Time in Patent Office: 644 Days
• Field of Search: 62/116, 62/500, 417/179, 417/180
• US Class Current: 62/116
• CPC Class Codes: F04F 5/18 for compressing
• CPC Class Codes: F04F 5/462 with provisions for cooling the fluid
• CPC Class Codes: F04F 5/465 with supersonic flow mixing of supersonic fluids B01F25/20
• CPC Class Codes: F04F 5/467 with a plurality of nozzles arranged in series
• CPC Class Codes: F25B 1/08 using vapour under pressure
• CPC Class Codes: F25B 11/00 Compression machines, plants or systems, using turbines, e.g. gas turbines
• CPC Class Codes: F25B 2341/0015 using two or more ejectors
• CPC Class Codes: F25B 2400/14 Power generation using energy from the expansion of the refrigerant
• CPC Class Codes: F25B 2500/01 Geometry problems, e.g. for reducing size
• CPC Class Codes: F25B 27/02 using waste heat, e.g. from internal-combustion engines

Abstract

A novel ejector, an ejector-refrigeration system, and a method of refrigeration are disclosed. The system is particularly well suited for the utilization of energy sources such as waste heat from automobile engines and solar collectors. Further, the system is compatible with the use of environmentally benign refrigerant such as water. Unlike conventional ejectors, the novel ejector disclosed in the present invention is designed to utilize the principal of "pressure exchange" and is therefore capable of attaining substantially higher levels of performance than conventional ejectors whose operating mechanism is based on the principal of "turbulent mixing". The pressure exchanging ejector with a compressible working fluid utilizes the oblique compression and expansion waves occurring within jets emanating from the discharges of a plurality of supersonic nozzles so as to impart energy to a secondary gaseous fluid wherein the said waves are caused to move relative to the housing of said ejector by virtue of a motion inducing means applied to said nozzles, said nozzles being incorporated in a rotor. In the disclosed invention, the pressure exchanging ejector is utilized as an ejector-compressor with a vapor-compression refrigeration system whereby said working fluid constitutes the refrigerant.

Claims

1. An ejector compressor for transporting a compressible secondary fluid from a lower stagnation pressure supply to an ejector discharge of higher stagnation pressure, said ejector compressor utilizing pressure-exchange to affect energy transfer from an energetic primary compressible fluid to said secondary fluid, said ejector compressor comprising:

(a) an ejector housing preventing communication of the primary and secondary fluids with the environment;

(b) a primary fluid inlet duct;

(c) a plurality of supersonic nozzles of converging-diverging cross-section in the direction of flow whose inlets are in communication with said primary fluid inlet duct and which are integrated into a rotor such that the axis of discharge of one or more nozzles is located at a radial distance from the rotor'"'"'s axis of rotation, said nozzles accelerate the primary fluid to supersonic speeds in such a manner as to produce compression and expansion waves in the region of the nozzle exit;

(d) said rotor being rotatably mounted in said ejector housing and provided with sealing means to minimize the communication of primary and secondary flows through flow paths other than the nozzles;

(e) rotation means so that the ratio of the peripheral speed of the nozzle to the speed of the primary fluid immediately after the compression waves is greater than 0.1.

(f) a secondary fluid inlet conduit;

(g) aerodynamic flow control surfaces interior to said housing and in the conduit of the secondary fluid placed upstream and in the vicinity of the nozzles to increase the speed of the secondary flow and to bring it into direct contact with the primary fluid in the vicinity of the nozzle exits;

(h) a pressure exchange zone in the interior of said housing and bounded by aerodynamic surfaces which may include the rotor, the housing, a center-body, or an after-body to insure the direct action of the rotating pressure wave structure on the secondary fluid;

(i) a discharge duct for the combined flow.

2. An ejector compressor according to claim 1 which includes aerodynamic surfaces interior to said housing and downstream of said pressure exchange zone for the purpose of controlling stagnation pressure loss in diffusing the high kinetic energy combined flow, said aerodynamic surfaces may be integral with the rotor, the housing, a centerbody, or an afterbody.

3. An ejector compressor according to claim 1 which includes aerodynamic surfaces downstream of said pressure exchange zone for the purpose of allowing mixing of said primary and secondary flows to achieve substantially complete energy equalization prior to diffusion, said aerodynamic surfaces may be integral with the rotor, the housing, a centerbody, or an afterbody.

4. An ejector compressor according to claim 1 whose rotation means for said rotor comprises integral nozzles whose central axes at the discharge plane are skewed tangentially relative to the axis of rotor rotation so as to generate axial angular momentum of the primary fluid when the rotor is at rest.

6. A refrigeration system operating in a closed cycle comprising:

(a) An ejector compressor according to claim 1 utilizing pressure-exchange from an energized primary driving refrigerant vapor to a secondary driven refrigerant vapor;

(b) a vapor generator;

(c) a liquid refrigerant pump;

(d) a condenser/separator;

(e) an evaporator;

(f) an expansion means;

(g) a refrigerant;

(h) a driver-fluid;

where the driver fluid is of a substantially lower molecular weight than the refrigerant fluid and where the two fluids are immiscible and both of which are liquefied in the condenser/separator. The lighter driver liquid is drawn separately from the condenser/separator and pumped into the vapor generator which discharges vapor to the primary of said ejector. The higher molecular weight refrigerant liquid is conducted to the expansion means and thence, as a colder liquid-vapor mixture, to the evaporator where said liquid refrigerant is vaporized as a result of heat extracted from the cooling space. The refrigerant vapor discharge of said evaporator is connected to the secondary flow inlet passage of said ejector-compressor. The combined driver fluid vapor and refrigerant vapor discharging from the ejector outlet is conducted to the condenser where both fluids are liquefied, and where heat rejection to an external thermal sink takes place.

7. A refrigeration system operating in a closed cycle comprising:

(a) a vapor generator;

(b) a liquid refrigerant pump;

(c) a condenser;

(d) an evaporator;

(e) an expansion means;

(f) a refrigerant;

(g) An ejector compressor according to claim 1 utilizing pressure-exchange from an energized primary driving refrigerant vapor to a secondary driven refrigerant vapor

and, where the liquid refrigerant discharging from said condenser is divided into two parts, one part being drawn into the pump which discharges liquid refrigerant to said vapor generator which energizes and vaporizes said refrigerant prior to entering said ejector-compressor as the primary fluid; and

, where the other part of said liquid refrigerant from the condenser discharge passes through said expansion means and into said evaporator where said liquid refrigerant is vaporized as a result of heat extracted from the cooling space. The vapor discharge of said evaporator is connected to the secondary flow inlet passage of said ejector-compressor. The vapor discharging from the ejector outlet is conducted to the condenser where it is liquefied, and where heat rejection to an external thermal sink takes place.

8. A refrigeration system according to claim 7 whereby said vapor generator includes a boiler followed by a superheater so as to produce superheated vapor.

9. A refrigeration system according to claim 7 with the improvement of including any one or more of the following heat exchangers:

recuperator, a precooler, or a regenerator.

10. A refrigeration system according to claim 7 wherein said refrigeration system stages a multiplicity of ejectors in series, whereby, the vapor discharged from the first ejector is introduced as the secondary flow for the second ejector in the series, while the primary flow for the second ejector is obtained directly from the vapor generator. At each successive stage, said ejector discharges into the secondary of the following stage, and the said primary flows of all ejectors are obtained directly from the vapor generator. The last ejector in the series is discharged into the condenser.

11. A refrigeration system according to claim 7 with said refrigerant selected from the group consisting of water, chlorofluorocarbons (CFC'"'"'s), hydrochlorofluorcarbons (HCFC'"'"'s), ammonia, hydrocarbons, and carbon dioxide.

12. A refrigeration system according to claim 7 which is used as a space air conditioner for human comfort.

13. A refrigeration system according to claim 7 where the vapor generator is a heat exchanger placed in the path of exhaust gases in an internal combustion engine.

14. A refrigeration system according to claim 7 where the vapor generator includes a heat exchanger placed in thermal communication with the engine coolant in an internal combustion engine.

15. A refrigeration system according to claim 7 where the vapor generator includes a heat exchanger placed in thermal communication with the products of combustion of a fueled furnace.

16. A refrigeration system according to claim 7 whereby said vapor generator consists of a boiler producing substantially saturated vapor.

17. A refrigeration system according to claim 7 where the vapor generator includes a heat exchanger placed in thermal communication with a solar collector.

18. In a method of refrigeration, the steps of:

(a) extracting a liquid refrigerant from a condenser and dividing it into two conduits;

(b) from one conduit, draw liquid refrigerant by means of a pump and discharge it into a boiler;

(c) adding thermal energy from an external source to the liquid refrigerant and causing the refrigerant to boil into a vapor;

(d) discharge the vapor from the boiler to the primary of a pressure-exchanging ejector according to claim 1.;

(e) from the second conduit emanating from the condenser, direct the liquid refrigerant to an expansion means to partially vaporize the refrigerant;

(f) direct the discharge from the expansion means to an evaporator which extracts heat from the cooling space and applies it to substantially completely vaporize the refrigerant;

(g) draw the vapor from the evaporator into the secondary of said pressure-exchanging ejector;

(h) causing pressure exchange to occur inside said pressure-exchanging ejector by passing the primary vapor through a plurality of supersonic nozzles so as to produce compression and expansion waves at the nozzle discharges, and integrating said nozzles into a rotor, and providing means to produce rotation at a peripheral speed which is a substantial fraction of the primary vapor nozzle exit speed, and directing said secondary vapor into direct contact with said compression and expansion waves so as to affect pressure exchange between said primary and secondary fluids;

(i) directing the discharge of the combined primary and secondary vapor into the condenser where liquification takes place and heat is rejected to an external heat sink.

19. The method of claim 18 whereby the refrigerant is superheated after discharging from the boiler but before entering the primary of the pressure-exchange ejector.

20. The method of claim 18 whereby the pressure exchange ejector incorporates aerodynamic surfaces downstream of said pressure exchange zone for the purpose of controlling stagnation pressure loss in diffusing the high kinetic energy combined flow. Said aerodynamic surfaces may include the rotor, the housing, a centerbody, or an afterbody.

21. The method of claim 18 whereby the pressure exchange ejector incorporates aerodynamic surfaces downstream of said pressure exchange zone for the purpose of allowing mixing of said primary and secondary flows to achieve substantially complete energy equalization prior to diffusion said aerodynamic surfaces may be integral with the rotor, the housing, a centerbody, or an afterbody.

5. An ejector as claimed in 1 where both primary fluid and secondary fluid are of the same substance.