Intermittent absorption refrigeration system

• US 9,459,027 B2
• Filed: 04/22/2014
• Issued: 10/04/2016
• Est. Priority Date: 04/22/2014
• Status: Active Grant

• Current Assignee: King Fahd University Of Petroleum And Minerals
• Original Assignee: King Fahd University Of Petroleum And Minerals
• Inventors: Said, Syed A. M., Siddiqui, Muhammad Umar
• Primary Examiner(s): Norman, Marc
• Assistant Examiner(s): TEITELBAUM, DAVID J
• Application Number:
  US14/259,074
• Publication Number:
  US 20150300702A1
• Time in Patent Office: 896 Days
• Field of Search: 624/77
• US Class Current: 1/1
• CPC Class Codes: F25B 15/006 with cascade operation
• CPC Class Codes: F25B 17/00 Sorption machines, plants or systems, operating intermittently, e.g. absorption or adsorption type
• CPC Class Codes: F25B 17/02 the absorbent or adsorbent being a liquid, e.g. brine F25B17/10 takes precedence
• CPC Class Codes: F25B 27/00 Machines, plants or systems, using particular sources of energy F25B30/06 takes precedence
• CPC Class Codes: F25B 27/007 in sorption type systems
• CPC Class Codes: F25B 29/006 of the sorption type system
• CPC Class Codes: F25B 30/04 of the sorption type
• CPC Class Codes: F25B 35/02 using a liquid as sorbent, e.g. brine
• CPC Class Codes: F25B 41/00 Fluid-circulation arrangements
• CPC Class Codes: Y02A 30/27 Relating to heating, ventilation or air conditioning [HVAC] technologies
• CPC Class Codes: Y02B 30/62 Absorption based systems

Abstract

The intermittent absorption refrigeration system includes a primary circuit having a generator/absorber, a dephlegmator, a condenser, an evaporator, and solar collectors to provide heat to the generator. The system also includes an ejector-based secondary circuit having a generator/absorber, an ejector, a condenser, a refrigerant storage unit, and solar collectors. Both circuits are aqua-ammonia systems, using ammonia as the refrigerant and water as the absorber liquid. The ejector permits evaporation during the daytime and storage of liquid ammonia refrigerant that is used for cooling in the heat exchanger of the primary circuit condenser and in the primary circuit absorber, thus permitting the primary circuit evaporator to operate at lower temperatures for low temperature freezing applications in the daytime, even at high ambient temperature.

Claims

1. An intermittent absorption refrigeration system, comprising:

a primary circuit having;

primary circuit refrigeration components including a primary circuit combination generator/absorber unit, a dephlegmator, a primary circuit condenser, an evaporator, primary circuit solar collection panels, and a plurality of primary circuit heat exchangers;

a primary circuit conduit system connecting the primary circuit refrigeration components;

a plurality of primary circuit valves disposed in the primary circuit conduit system for controlling primary circuit coolant flow; and

a primary circuit aqua-ammonia coolant circulating in the primary circuit conduit system, the primary circuit aqua-ammonia coolant including ammonia refrigerant and water absorber; and

a secondary circuit having;

secondary circuit refrigeration components including a secondary circuit combination generator/absorber unit, an ejector unit, a secondary circuit condenser, a refrigerant storage unit, secondary circuit solar collection panels, and a plurality of secondary circuit heat exchangers;

a secondary circuit conduit system connecting the secondary circuit refrigeration components;

a plurality of secondary circuit valves disposed in the secondary circuit conduit system for controlling a secondary circuit coolant flow; and

a secondary circuit aqua-ammonia coolant circulating in the secondary circuit conduit system, the secondary circuit aqua-ammonia coolant including ammonia refrigerant and water absorber;

the secondary circuit defining an ejector-based refrigeration loop operable to chill to between 5°

C. and 10°

C. in the daytime; and

the primary conduit system and the secondary conduit system being interconnected so that the primary circuit condenser and the primary circuit combination generator/absorber unit are chilled by the ejector-based refrigeration loop to operate between 5°

C. and 10°

C., thereby permitting the primary circuit evaporator to produce refrigeration below the freezing point of water in the daytime, when ambient temperatures up to 45°

C.

2. The intermittent absorption refrigeration system according to claim 1, wherein said ejector unit comprises a nozzle, a mixing chamber, and a diffuser section.

3. The intermittent absorption refrigeration system according to claim 2, wherein said dephlegmator comprises a dephlegmator heat exchanger and a dephlegmator condenser, the dephlegmator being configured to remove substantially all water from a primary circuit aqua-ammonia vapor generated by said primary circuit combination generator/absorber unit from said primary circuit aqua-ammonia coolant, the water being returned to said primary circuit combination generator/absorber unit, whereby pure ammonia refrigerant is left to circulate to said primary circuit condenser and said evaporator to produce temperatures below the freezing point of water by evaporation of the ammonia refrigerant.

4. The intermittent absorption refrigeration system according to claim 3, wherein said primary circuit conduit system and secondary circuit conduit system are interconnected such that said primary circuit condenser is connected to the mixing chamber of said ejector unit, whereby a pressure drop in the mixing chamber resulting from accelerated flow of secondary circuit aqua-ammonia vapor from said secondary circuit combination generator/absorber unit induces secondary circuit saturated liquid ammonia refrigerant in said primary circuit condenser to flow into the mixing chamber to mix with the secondary circuit aqua-ammonia vapor, said secondary circuit conduit system connecting said ejector unit to said secondary system condenser and said secondary system condenser to said refrigerant storage unit, whereby a condensed mixture of the secondary circuit aqua-ammonia vapor and the secondary circuit saturated liquid ammonia refrigerant produced in the primary circuit is stored until needed.

5. The intermittent absorption refrigeration system according to claim 4, wherein said primary circuit conduit system and said secondary circuit conduit system are interconnected such that said refrigerant storage unit is connected to said primary system condenser, said plurality of secondary circuit valves disposed in the secondary circuit conduit system include a throttling valve and a ball valve in a conduit connecting said refrigerant storage unit to both of said primary circuit condenser and primary circuit combination generator/absorber unit so that the throttling valve and the ball valve may be opened in the daytime to use the stored condensed mixture to operate said primary circuit condenser at between 5°

C. and 10°

C. in the daytime, as well as to operate said primary circuit combination generator/absorber unit at between 5°

C. and 10°

C. in the nighttime.

6. The intermittent absorption refrigeration system according to claim 5, wherein said secondary circuit combination generator/absorber unit includes a first secondary circuit heat exchanger connected to said secondary circuit solar collection panels for heating said secondary circuit aqua-ammonia coolant to produce the secondary circuit aqua-ammonia vapor circulating to the nozzle of said ejector unit.

7. The intermittent absorption refrigeration system according to claim 6, wherein said primary circuit combination generator/absorber unit includes:

a primary circuit first heat exchanger connected to said primary circuit solar collection panels for heating said primary circuit aqua-ammonia coolant to produce the primary circuit aqua-ammonia vapor circulating to the dephlegmator; and

a second secondary circuit heat exchanger connected to said refrigerant storage unit by interconnecting said primary circuit conduit system and said secondary circuit conduit system, said plurality of secondary circuit valves disposed in the secondary circuit conduit system including a ball valve in the conduit connecting said throttling valve to the second secondary circuit heat exchanger in said primary circuit combination generator/absorber unit, whereby the ball valve in the conduit connecting said throttling valve to the second secondary circuit heat exchanger in said primary circuit combination generator/absorber unit may be opened at nighttime after depressurization of said primary circuit combination generator/absorber unit, the stored condensed mixture of secondary circuit aqua-ammonia vapor from the secondary circuit and the secondary circuit saturated liquid ammonia refrigerant produced in the primary circuit evaporates in the second secondary circuit heat exchanger in said primary circuit combination generator/absorber unit, whereby absorption of ammonia refrigerant into said primary circuit aqua-ammonia coolant occurs at between 5°

C. and 10°

C.