Patent Application
20190178540
The invention relates in general to liquid chiller or refrigeration systems for cooling a liquid processed through the system, the chilled process liquid being utilized for example to maintain a storage room at a temperature well below ambient. The invention relates to such systems that utilize an expansion valve external to an evaporator.
Refrigeration is the lowering of the temperature of air or liquid within an enclosed space (kitchen refrigerators, store coolers, freezers, storage rooms, living quarters, etc.) by removing heat from the space and transferring it elsewhere. A typical refrigeration or chiller system utilizes a compressible refrigerant, such as for example ammonia, circulated through a closed loop assembly of interconnected devices. Refrigerant stored in a separator vessel in the gaseous or saturated vapor phase is delivered to a compressor for compression, which raises the temperature of the refrigerant. The compressed refrigerant is then passed to a condenser. A coolant liquid, such as for example water, is passed through plates, coils or tubes within the condenser to lower the temperature of the refrigerant gas such that it is condensed into a liquid refrigerant phase, the heat from the liquid refrigerant having been transferred to and removed by the coolant liquid.
The condensed liquid refrigerant is stored in a receiver vessel and then delivered by a flow control mechanism through an expansion valve that is located within an evaporator. The liquid refrigerant undergoes an abrupt reduction in pressure, resulting in evaporation of part of the refrigerant to further lower the temperature of the refrigerant.
A process liquid to be chilled, may include for example an industrial inhibited glycol and water mixture, such as one of ethylene or propylene. The process liquid, is passed through plate, coils or tubes within the evaporator such that heat from the process liquid transfers to the liquid/vapor refrigerant, causing evaporation of the liquid phase of the refrigerant and lowering the temperature of the process liquid, which is then delivered back to provide the desired cooling effect. The refrigerant vapor is passed from the evaporator into the separator vessel and the cycle is repeated.
It is an object of this invention to provide an improved chiller or refrigeration system that eliminates the need for an, which allows for an expansion valve to be located outside of the evaporator.
Accordingly, the present invention provides a liquid chiller or refrigeration systems of the evaporator/compressor/condenser type with an expansion valve located external to an evaporator. In some embodiments, an included condenser may be an eccentric condenser wherein the plates, coils or tubes receiving the coolant liquid are positioned in the upper half of the condenser body such that the lower half of the condenser body acts as a reservoir for the condensed liquid refrigerant, and further wherein the internal volume of the condenser is sufficiently large so as to obviate the need for providing a separate, dedicated receiver vessel to retain the liquid refrigerant in line between the condenser and the evaporator.
Similarly, in some embodiments, an included evaporator may include an eccentric evaporator with plates, coils or tubes receiving a process liquid to be cooled located in a lower half of an evaporator body such that an upper half of the evaporator body acts as a reservoir for vaporized refrigerant. An internal volume of the evaporator may be sufficiently large so as to obviate a need for providing a separate, dedicated separator vessel to retain the vaporized refrigerant in line between the evaporator and the compressor. Preferably, the condenser is physically positioned above the evaporator such that liquid refrigerant may be gravity fed to the evaporator.
According to the present invention, an evaporator valve is located external to the evaporator and allows ease of access and additional efficiency.
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, an evaporator and an expansion valve external to the 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.
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
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.
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
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.
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 RL 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 RG 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.
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.
Liquid Chiller System Variations
There may be various system component and configuration modifications and enhancements that may be consistent with the examples as have been discussed. Referring to
A treated water supply 321 may flow into the condenser and elements that allow the segregated flow of heat from the refrigerant to the treated water. The treated water may exit the condenser and flow through the treated water return 322. Liquefied or partially liquefied refrigerant may flow from the condenser 320 towards the expansion valve 330 and may be stored in one or more accumulators 331 before the expansion valve 330. Accordingly, to the present invention, the expansion valve 330 is located external to the evaporator 340.
As has been described previously the refrigerant may flow in the evaporator and exchange heat with a chilled liquid such as glycol or other suitable thermal carrying liquids. A loop of the chilled liquid may deliver the chilled liquid to heat loads 342 of various types. The exchanger may also include an oil collection vessel or oil pot 341 to catch oil or other contaminants that settle out from the refrigerant. The refrigerant may then return back to the compressor 310 to be compressed and processed again as has been described. The entire system may include one or more autopurging devices 350 that may be used to remove dissolved gasses from the refrigerant in the various stages of processing. The various elements may be consistent with the eccentric components as have been described herein and their methods of operation.
Referring now to
Such an exemplary liquid chiller system may include a compressor 410 with multiple stages such as a low stage compression ratio and a high stage compression ratio. The compressor may output to an oil separator 411 which allows the compressed refrigerant to separate from compressor oils or other contaminants. The output of the compressor 410 may be routed by one or multiple pipes that flow compressed refrigerant to a condenser 420.
Amongst various enhancements such as connections to purge systems and the like, a major connection to the unit may include treated water supply which may remove/exchange heat from the refrigerant while it is in the condenser 420. A treated water supply 421 may flow into the condenser and elements that allow the segregated flow of heat from the refrigerant to the treated water. The treated water may exit the condenser and flow through the treated water return 422. Liquefied or partially liquefied refrigerant may flow from the condenser 420 towards the expansion valve 430.
In
As has been described previously refrigerant may flow in an evaporator and exchange heat with a chilled liquid, such as glycol or other suitable thermal carrying liquids. Circulation of chilled liquid may deliver the chilled liquid to heat loads 442 of various types. An exchanger may also include an oil collection vessel such as an oil pot 441 to catch oil or other contaminants that settle out from the refrigerant. The refrigerant may be returned via additional piping back to compressor 410 where the refrigerant is compressed and processed again as described.
The system 400 may include one or more autopurging devices 450 that may be used to remove dissolved gasses from the refrigerant in the various stages of processing. Although the various elements may be consistent with the eccentric components as have been described herein and their methods of operation, the modified location of the expansion valve and the use of piping elements before the expansion valve in the dual purpose of storing refrigerant may also be utilized with non-eccentric components. When the expansion valve 430 is located in a location exterior to the evaporator 440, there may be numerous types of valves that could be used for the control of the refrigerant including by way of non-limiting example, sense motorized valves and float type valves. Furthermore, types of refrigerant consistent with this design may include ammonia, but also non-ammonia type refrigerants such as HFC R134a, HFO, CO2, Hydrofluorocarbons and hydrocarbon-based refrigerants.
Advanced Liquid Chiller Design Aspects
Referring to
In some examples, a stage of a refrigerant loop may be a high compression stage in relation to an output of a low or lower compression stage. Variations may include incorporation of multiple loops of refrigerant into different stages, and an output of disparate stages may be routed to selected components within the liquid chiller system. Compressor outputs may be routed to low temperature accumulators 530 and high temperature accumulators 531 which may provide segregated loops to low temperature loads 570 and high temperature loads 580 respectively. In some embodiments, a single vessel accumulator 532 may include multiple chambers. Although the single vessel accumulator 532 is illustrated with two chambers, additional chambers are also within the scope of invention. For example, as illustrated a first chamber may be a low temperature chamber (LTA Chamber) 530, and a second chamber may be a high temperature chamber (HTA chamber) 531. The single vessel accumulator 532 may be divided into separate chambers by a plate between the chamber regions. Typically, a temperature of an accumulator chamber such as the low temperature chamber 530 or the high temperature chamber 531 will be dependent upon an amount of compression of the refrigerant as well as other factors.
Specialized components may be configured to control the transfer of liquids between various components such as the liquid transfer unit 540. Secondary storage elements such as the high-pressure receiver 550 may give the system flexibility and ability to buffer various loading needs. In some examples, a heat exchanger 560, may be used to exchange heat between the fluids stored in the low temperature chamber 530 and the high temperature chamber 531. The system 500 may also include an autopurging system 590 to remove gasses from the refrigerant streams.
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.
This application claims priority to non-provisional patent application U.S. Ser. No. 15/832,813, entitled LIQUID CHILLER SYSTEM, filed Dec. 6, 2017 as a Continuation in Part Application and to the non-provisional patent application U.S. Ser. No. 14/837,128, which is now the U.S. Pat. No. 9,869,496, entitled LIQUID CHILLER SYSTEM, filed Aug. 27, 2015 as a Continuation Application, which is relied upon and incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| Parent | 14837128 | Aug 2015 | US |
| Child | 15832813 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 15832813 | Dec 2017 | US |
| Child | 16279635 | US |
