Refrigeration – Processes – Exchanging heat between plural systems – e.g. – disparate
Reexamination Certificate
2000-08-25
2001-12-11
Doerrler, William (Department: 3744)
Refrigeration
Processes
Exchanging heat between plural systems, e.g., disparate
C062S114000, C062S512000, C062S503000, C062S502000
Reexamination Certificate
active
06327865
ABSTRACT:
TECHNICAL FIELD
This invention relates generally to refrigeration and is particularly useful for use with refrigeration applications having unsteady requirements.
BACKGROUND ART
Refrigeration is an important utility for chemical, food and pharmaceutical manufacturing as well as other material processing industries. Generally refrigeration is generated using a vapor compression refrigeration circuit wherein a refrigerant fluid is compressed, cooled, expanded to generate refrigeration and then warmed to supply refrigeration to a refrigeration load.
While some refrigeration loads have a relatively unvarying refrigeration requirement, many refrigeration loads have refrigeration requirements which increase and decrease with time. In the interest of efficiency, it is desirable to vary the amount of refrigeration supplied to the refrigeration load to match the refrigeration requirements of refrigeration loads which have unsteady refrigeration requirements.
One way of addressing this problem is to adjust the refrigeration output of the refrigeration circuit by modulating the circulation rate of the refrigerant fluid within the refrigeration circuit. Unfortunately, refrigeration circuits are most efficient when operated continuously and at or near their maximum capacity. Another way of addressing this problem is to use a cryogenic liquid such as liquid nitrogen or liquid carbon dioxide to augment, as needed, the refrigeration provided by the refrigeration circuit to the refrigeration load. However, this expedient is quite costly owing to the costs of the cryogen.
Accordingly, it is an object of this invention to provide a system for efficiently providing refrigeration to a refrigeration load which has varying refrigeration requirements.
SUMMARY OF THE INVENTION
The above and other objects, which will become apparent to those skilled in the art upon a reading of this disclosure, are attained by the present invention, one aspect of which is:
A method for providing refrigeration to a refrigeration load comprising:
(A) compressing a refrigerant fluid, cooling the compressed refrigerant fluid, and expanding the cooled refrigerant fluid to generate refrigeration;
(B) warming the cooled refrigerant fluid by indirect heat exchange with a coupling fluid to produce warmed refrigerant fluid and cooled coupling fluid;
(C) warming the cooled coupling fluid to provide refrigeration to a refrigeration load; and
(D) periodically passing some cooled coupling fluid into a stabilizing reservoir, and periodically passing some cooled coupling fluid from the stabilizing reservoir to the refrigeration load.
Another aspect of the invention is:
Apparatus for providing refrigeration to a refrigeration load comprising:
(A) a compressor, a refrigerant heat exchanger, an expansion device, means for passing refrigerant fluid from the compressor to the refrigerant heat exchanger, and means for passing refrigerant fluid from the refrigerant heat exchanger to the expansion device;
(B) a refrigeration load, a coupling fluid heat exchanger, and means for passing refrigerant fluid from the expansion device to the coupling fluid heat exchanger;
(C) means for passing coupling fluid from the coupling fluid heat exchanger to the refrigeration load, and means for passing coupling fluid from the refrigeration load to the coupling fluid heat exchanger; and
(D) a stabilizing reservoir, means for passing coupling fluid from the coupling fluid heat exchanger into the stabilizing reservoir, and means for passing coupling fluid from the stabilizing reservoir to the refrigeration load.
As used herein, the term “indirect heat exchange” means the bringing of two fluids into heat exchange relation without any physical contact or intermixing of the fluids with each other.
As used herein, the term “expansion” means to effect a reduction in pressure.
As used herein, the term “expansion device” means apparatus for effecting expansion of a fluid.
As used herein, the term “compressor” means apparatus for effecting compression of a fluid.
As used herein, the term “multicomponent refrigerant fluid” means a fluid comprising two or more species and capable of generating refrigeration.
As used herein, the term “refrigeration” means the capability to reject heat from a subambient temperature system.
As used herein, the terms “turboexpansion” and “turboexpander” mean respectively method and apparatus for the flow of high pressure fluid through a turbine to reduce the pressure and the temperature of the fluid thereby generating refrigeration.
As used herein, the term “refrigerant fluid” means a pure component or mixture used as a working fluid in a refrigeration process which undergoes changes in temperature, pressure and possibly phase to absorb heat at a lower temperature and reject it at a higher temperature.
As used herein, the term “variable load refrigerant” means a mixture of two or more components in proportions such that the liquid phase of those components undergoes a continuous and increasing temperature change between the bubble point and the dew point of the mixture. The bubble point of the mixture is the temperature, at a given pressure, wherein the mixture is all in the liquid phase but addition of heat will initiate formation of a vapor phase in equilibrium with the liquid phase. The dew point of the mixture is the temperature, at a given pressure, wherein the mixture is all in the vapor phase but extraction of heat will initiate formation of a liquid phase in equilibrium with the vapor phase. Hence, the temperature region between the bubble point and the dew point of the mixture is the region wherein both liquid and vapor phases coexist in equilibrium. In the preferred practice of this invention the temperature differences between the bubble point and the dew point for a variable load refrigerant generally is at least 10° C., preferably at least 20° C., and most preferably at least 50° C.
As used herein, the term “refrigeration load” means a stream or object that requires a reduction in energy, or removal of heat, to lower its temperature.
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Arman Bayram
Bonaquist Dante Patrick
Victor Richard Amory
Wong Kenneth Kai
Doerrler William
Ktorides Stanley
Praxair Technology Inc.
Shulman Mark
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