Liquid chiller system

Abstract

A liquid chiller system utilizing a refrigerant capable of possessing a liquid state and a gas/vapor state, the refrigerant being cycled through a closed loop assembly of a compressor, an eccentric condenser and an eccentric evaporator. The eccentric compressor has a lower integrated reservoir and the eccentric evaporator has an upper dedicated reservoir such that separate, dedicated separator or receiver vessels are not required. The eccentric condenser is positioned above the eccentric evaporator such that liquid refrigerant flows by gravity from the eccentric condenser to the eccentric evaporator.

Claims

1. A method of operating a liquid chiller system, the method comprising: passing a refrigerant in a gaseous stage through a cooling conduit in an upper portion of an eccentric condenser unit; lowering a temperature of the refrigerant in a gaseous stage; based upon the lowering of the temperature of the refrigerant, converting at least some of the refrigerant from the gaseous stage into a liquid stage; storing the refrigerant in a liquid stage in an integrated liquid reservoir located within the eccentric condenser unit below the cooling conduit and containing at least 10% of refrigerant in a liquid stage; receiving the refrigerant in a liquid stage from the eccentric condenser via transport piping into an eccentric evaporator; flowing a process liquid through process liquid conduits in a lower half of the eccentric evaporator partially evaporating the refrigerant in a liquid stage into refrigerant in a gaseous stage within the eccentric evaporator based upon absorption of heat from the process liquid in the eccentric evaporator; cooling the process liquid based upon the evaporating the refrigerant in a liquid stage into refrigerant in a gaseous stage; containing at least 65% of the refrigerant in a gaseous stage in an integrated refrigerant in a gaseous stage reservoir located within an upper portion of the eccentric evaporator; compressing some of the refrigerant in a gaseous stage with a compressor; passing the compressed refrigerant in a gaseous stage to the eccentric condenser where the compressed refrigerant in a gaseous stage; converting the refrigerant in a gaseous stage into the refrigerant in a liquid stage; and storing an integrated refrigerant in a liquid stage reservoir comprising sufficient capacity to obviate a need for a separate, distinct reservoir vessel.

2. The method of claim 1 additionally comprising the step of storing the integrated refrigerant in a gaseous stage reservoir comprising sufficient capacity to obviate the need for a separate, distinct separator vessel.

3. The method of claim 2, wherein the eccentric condenser is positioned at a higher elevation than the eccentric evaporator such that refrigerant in a liquid stage is gravity fed from the eccentric condenser to the eccentric evaporator.

4. The method of claim 3 additionally comprising the step of controlling a flow of refrigerant between the eccentric condenser and the eccentric evaporator.

5. The method of claim 4, additionally comprising the step of operating a flow control device disposed between the eccentric condenser and the eccentric evaporator to control a flow of the process liquid in a process liquid flow circuit.

6. The method of claim 5, additionally comprising the step of retaining a portion of the refrigerant from the eccentric condenser in a liquid stage in the liquid reservoir.

7. The method of claim 5, additionally comprising the step of delivering the refrigerant in a liquid stage from the eccentric condenser to the eccentric evaporator without passage through a separate reservoir vessel.

8. The method of claim 5, additionally comprising the step of delivering the refrigerant in a gaseous stage from the eccentric condenser to the compressor without passage through a separate separator vessel.

9. The method of claim 5 wherein the cooling conduit comprises a plate.

10. The method of claim 5 wherein the cooling conduit comprises a coil.

11. The method of claim 5 wherein the cooling conduit comprises a tube.

12. The method of claim 5 wherein the process liquid flow circuit comprises a plate.

13. The method of claim 5 wherein the process liquid flow circuit comprises a coil.

14. The method of claim 5 wherein the process liquid flow circuit comprises a tube.

15. The method of claim 5 wherein the refrigerant in a liquid stage comprises ammonia and the process fluid comprises glycol.

16. The method of claim 14 additionally comprising the step of changing a temperature of 2,200 gallons per minute or more of the glycol process liquid from about 33 degrees Fahrenheit or more to 28 degrees Fahrenheit or less.

17. The method of claim 15 wherein the change in temperature of temperature of the 2,200 gallons per minute or more of the glycol process liquid from about 33 degrees Fahrenheit or more to 28 degrees Fahrenheit or less, is accomplished utilizing less than 500 pounds of ammonia as the refrigerant in a liquid stage.

18. The method of claim 15 wherein less than about 40 pounds of refrigerant in a liquid stage is present in the condenser.

19. The method of claim 1 additionally comprising the step of delivering refrigerant from the condenser in a liquid stage though an expansion valve thereby evaporating at least some of the refrigerant in a liquid stage into a liquid and vapor mixture.

20. The method of claim 1 additionally comprising the step of storing the liquid and vapor mixture in the evaporator.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a schematic representation of an embodiment of the chiller system.

(2) FIG. 2 is an alternative schematic of an embodiment of the chiller system, illustrating the eccentric evaporator and eccentric chiller.

DETAILED DESCRIPTION OF THE INVENTION

(3) With reference to the drawings, embodiments of the invention will now be described in detail. In general, the invention is a refrigeration or liquid chiller system utilizing a refrigerant capable of possessing a liquid state and a gas/vapor state, the refrigerant being cycled through a closed loop assembly comprising a compressor, a condenser and an evaporator. Suitable known refrigerants include, for example, ammonia, carbon dioxide or hydrocarbons such as propane. In order to chill a process liquid, which then may be used for example to lower the temperature of an enclosed space or other gases or liquids, the refrigerant is compressed while in the vapor state and delivered to the condenser. A liquid coolant is passed through plates, coils or tubes in the condenser to lower the temperature of the refrigerant to convert the refrigerant from a compressed gas into a liquid, and the liquid refrigerant is then delivered into the evaporator and allowed to partially evaporate to a combined liquid/vapor state. The process liquid to be chilled is passed through plates, coils or tubes in the evaporator such that heat is transferred from the process liquid into the refrigerant, thereby evaporating the liquid phase of the refrigerant. The gas refrigerant is then delivered back to the compressor, and the cycle is repeated. The system is sized and structured so as not to require separate, dedicated separator (often referred to as a surge drum) or receiver vessels.

(4) FIG. 1 shows a representative schematic of the chiller system. Compressor 40, such as for example a screw or reciprocating type compressor, of suitable size and power to compress the chosen refrigerant, is operatively positioned in line and in fluid communication between the evaporator 30 and the condenser 10. The system may utilize various known refrigerants suitable for the purpose, such as for example ammonia, CO.sub.2 or hydrocarbons, which are capable of being compressed while in the vapor or gas phase and condensed into the liquid phase within suitable temperature and pressure ranges, for application in various commercial or residential refrigeration systems. The compressor 40 receives refrigerant in the gas phase from the evaporator 30, compresses the gas refrigerant, and delivers the compressed gas refrigerant to the condenser 10.

(5) The condenser 10 is an eccentric condenser, such as for example a plate and shell type condenser wherein the shell is oversized to increase the internal volume. The term oversized is used herein to define a shell having a greater capacity than required to perform the condensing operation. In the embodiment represented in FIG. 2, it is seen that the portion of the coolant liquid flow circuit C located internally within the condenser 10, which portion consists of plates, coils or tubes that are conduits 12 for the coolant liquid into, through and from the condenser shell or body 11, are positioned in the upper half of the condenser shell 11. The conduits 12 segregate the coolant liquid from the refrigerant within the condenser 10 such that heat is transferred from the compressed gas refrigerant into the coolant liquid. The gas refrigerant thereupon condenses into its liquid phase and collects in the lower half of the condenser 10, the lower half of the condenser defining a sump or reservoir R.sub.L. The internal volume of the oversized condenser shell 11 is sized so as to be sufficient to retain the minimum volume of liquid refrigerant necessary for continuous operation of the chiller system while simultaneously leaving room to receive the gas refrigerant from the compressor 40. In this manner, a separate receiver vessel is not required downstream of the condenser 10 for storage of the liquid refrigerant after it has been condensed. The liquid refrigerant is then delivered from the condenser 10, most preferably by gravity, to the evaporator 30, the condenser 10 being positioned at a higher elevation than the evaporator 30, as represented in FIG. 2.

(6) A flow control mechanism 20, comprising for example a float valve or any other suitable mechanical valve, is disposed in line between the condenser 10 and the evaporator 30 to control the flow of liquid refrigerant.

(7) The evaporator 30 is an eccentric evaporator, such as for example a plate and shell type evaporator wherein the shell 31 is oversized to increase the internal volume. The term oversized is used herein to define a shell having a greater capacity than required to perform the evaporating operation. The liquid refrigerant is delivered from the condenser 10 through an expansion valve such that a portion of the refrigerant evaporates and creates a liquid/vapor mixture. In the embodiment represented in FIG. 2, it is seen that the portion of the process liquid flow circuit P located internally within the evaporator 30, which portion consists of plates, coils or tubes that are conduits 32 for the process liquid into, through and from the evaporator shell or body 31, are positioned in the lower half of the evaporator shell 31. The conduits 32 segregate the process liquid from the refrigerant within the evaporator 30 such that heat is transferred from the process liquid into the liquid refrigerant, thereby lowering the temperature of the process liquid and converting the refrigerant from the liquid phase to the gas phase, which collects in the upper half of the evaporator 30, the upper half of the condenser defining a reservoir R.sub.G. The internal volume of the oversized evaporator shell 31 is sized so as to be sufficient, if necessary, to retain the entire volume of liquid refrigerant from the condenser 10 below a high level cut-out point to insure that no liquid refrigerant passes to the compressor 20, i.e., the evaporator shell 31 can handle a full surge volume of liquid refrigerant without allowing any liquid refrigerant to enter the conduits transporting the gas refrigerant to the compressor 20. In this manner, a separate, dedicated separator vessel downstream from the evaporator 30 is not required for storage of the gas refrigerant after it has been evaporated. The gas refrigerant is then delivered from the evaporator 30 directly to the compressor 20 to complete the cycle.

(8) With this structure the eccentric condenser 10 can be defined as having an integrated receiver vessel and the eccentric evaporator 30 can be defined as having an integrated separator vessel. Preferably, the capacity of the oversize shell 31 of the eccentric evaporator 30 is at least approximately 65% of the total volume of liquid refrigerant in the system and the capacity of the oversize shell of the eccentric condenser 10 is a least 10% of the total volume of liquid refrigerant in the system, the remaining volume of liquid refrigerant being retained in the condenser or transport piping or conduits.

(9) In operation the gas refrigerant is compressed by the compressor 40 and delivered to the eccentric condenser 10. A liquid coolant in the coolant liquid flow circuit C is passed through the plates, coils or tubes of conduits 12 in the eccentric condenser 10 to lower the temperature of the gas refrigerant to convert the refrigerant from a compressed gas into a liquid, which is retained in the liquid reservoir R.sub.L within the eccentric condenser 10. The liquid refrigerant is then delivered to the eccentric evaporator 30 without passage through or storage in a separate and distinct reservoir vessel. The liquid refrigerant is allowed to partially evaporate into a combined liquid/vapor state. The process liquid resident in the process liquid flow circuit P, i.e., the liquid to be chilled, is passed through the plates, coils or tubes of conduits 32 in the eccentric evaporator 30 such that heat is transferred from the process liquid into the liquid refrigerant, thereby evaporating the liquid phase of the refrigerant and cooling the process liquid. The gas refrigerant is retained in the gas reservoir R.sub.G within the eccentric evaporator 30, then delivered from the eccentric evaporator 30 back to the compressor 40 without passing through or storage in a separate and distinct separator vessel, and the cycle is repeated.

(10) As a representative example not intending to limit the scope of the invention, the liquid chiller system may utilize ammonia as the refrigerant and glycol as the process liquid, a 529 horsepower screw compressor, an eccentric plate and shell condenser such as a Vahterus model PSHE 7/6HH-406, an eccentric evaporator such as a Vahterus model PSHE 8/6HH-438. Cooling water is provided at 82 degrees F. Such a system will cool 2,230 gpm of glycol from 33 degrees F. to 28 degrees F. while utilizing only 485 pounds of ammonia as liquid refrigerant for 446 TR (1.08 pounds/TR). During operation approximately 39 pounds (about 8% of the total volume) of the liquid refrigerant will be present in the condenser and approximately 281 pounds (about 58% of the total volume), with the remaining approximately 165 pounds (about 34% of the total volume) distributed elsewhere in the system. Such a system produces a cooling efficiency equal to or better than typical systems utilizing greater amounts of refrigerant and additional system operational components.

(11) It is contemplated that equivalents and substitutions for elements and structures set forth, described and illustrated above may be obvious to those of ordinary skill in the art, and therefore the true scope and definition of the invention is to be as set forth in the following claims.