The following description relates to chillers and, more particularly, to sorption-based subcoolers.
Currently, chillers typically include an ejector for pressure recovery. In an exemplary case, a compressor compresses a refrigerant and outputs the refrigerant in superheated form to a gas cooler and then, in some cases, to an ejector. When an ejector is provided, the ejector is used for work recovery or pressure recovery of the refrigerant and can outputs the refrigerant in cooled form to an evaporator and the compressor.
Until now, the refrigerant has often been a fluid with either a high greenhouse warming potential (GWP) characteristic or a high ozone depletion potential (ODP) characteristic. This is changing, however, and there is an increasing demand for the use of natural, non-toxic, low-GWP and ODP refrigerants leading to the use of carbon dioxide and other similar fluids as refrigerants in supermarket cooling systems.
These systems can, in certain cases, have low coefficients of performance (COP) at high ambient conditions in which the carbon dioxide moves into supercritical/transcritical fluid zones.
According to an aspect of the disclosure, a cooling system is provided and includes a compressor, an expansion valve, a gas cooler through which a refrigerant received from the compressor passes toward the expansion valve in a supercritical state, an evaporator interposed between the expansion valve and the compressor and a vapor sorption subcooling system. The vapor sorption subcooling system includes a desorber disposed to remove heat from refrigerant flowing from the gas cooler toward the expansion valve.
In accordance with additional or alternative embodiments, an ejector is downstream from the desorber.
In accordance with additional or alternative embodiments, the vapor sorption subcooling system includes a vapor absorption subcooling system.
In accordance with additional or alternative embodiments, a subcooling refrigerant of the vapor absorption subcooling system includes a natural, low greenhouse warming potential (GWP), low ozone depletion potential (ODP) and non-flammable refrigerant.
In accordance with additional or alternative embodiments, a subcooling refrigerant of the vapor absorption subcooling system includes carbon dioxide.
In accordance with additional or alternative embodiments, the vapor absorption subcooling system includes a subcooling compressor, which is receptive of subcooling refrigerant from the desorber, an absorber for subcooling refrigerant absorption by an absorbent, a subcooling gas cooler through which the subcooling refrigerant received from the subcooling compressor passes toward the absorber in a supercritical state and a pump configured to pump at least the absorbent from the desorber to the absorber.
In accordance with additional or alternative embodiments, the absorbent includes an ionic liquid.
In accordance with additional or alternative embodiments, the vapor sorption subcooling system includes a vapor adsorption subcooling system.
In accordance with additional or alternative embodiments, a subcooling refrigerant of the vapor adsorption subcooling system includes a natural, low greenhouse warming potential (GWP), low ozone depletion potential (ODP) and non-flammable refrigerant.
In accordance with additional or alternative embodiments, a subcooling refrigerant of the vapor adsorption subcooling system includes carbon dioxide.
In accordance with additional or alternative embodiments, the vapor adsorption subcooling system includes a subcooling compressor, which is receptive of subcooling refrigerant from the desorber, an adsorber disposed in parallel with the desorber for subcooling refrigerant adsorption by an adsorbent and a subcooling gas cooler through which the subcooling refrigerant received from the subcooling compressor passes toward the adsorber and the desorber in a supercritical state.
In accordance with additional or alternative embodiments, the adsorbent includes a solid adsorbent and the solid adsorbent includes activated carbon or a metal organic framework (MOF).
According to an aspect of the disclosure, a vapor absorption subcooling system is provided and includes a desorber in which a first refrigerant is cooled, a subcooling compressor, which is receptive of subcooling refrigerant from the desorber, an absorber for subcooling refrigerant absorption by an absorbent, a subcooling gas cooler through which the subcooling refrigerant received from the subcooling compressor passes toward the absorber in a supercritical state and a pump configured to pump at least the absorbent from the desorber to the absorber.
In accordance with additional or alternative embodiments, the subcooling refrigerant includes a natural, low greenhouse warming potential (GWP), low ozone depletion potential (ODP) and non-flammable refrigerant.
In accordance with additional or alternative embodiments, the subcooling refrigerant includes carbon dioxide.
In accordance with additional or alternative embodiments, the absorbent includes an ionic liquid.
According to another aspect of the disclosure, a vapor adsorption subcooling system is provided and includes a desorber in which a first refrigerant is cooled, a subcooling compressor, which is receptive of subcooling refrigerant from the desorber, an adsorber disposed in parallel with the desorber for subcooling refrigerant adsorption by an adsorbent and a subcooling gas cooler through which the subcooling refrigerant received from the subcooling compressor passes toward the adsorber and the desorber in a supercritical state.
In accordance with additional or alternative embodiments, the subcooling refrigerant includes a natural, low greenhouse warming potential (GWP), low ozone depletion potential (ODP) and non-flammable refrigerant.
In accordance with additional or alternative embodiments, the subcooling refrigerant includes carbon dioxide.
In accordance with additional or alternative embodiments, the adsorbent includes a solid adsorbent and the solid adsorbent includes activated carbon or a metal organic framework (MOF).
In accordance with additional or alternative embodiments, the desorber includes multiple desorbers, the adsorber includes multiple adsorbers, each one of the multiple adsorbers is paired with a corresponding one of the multiple desorbers to form respective combined beds and each of the combined beds is independently operable at a different adsorption stage.
These and other advantages and features will become more apparent from the following description taken in conjunction with the drawings.
The subject matter, which is regarded as the disclosure, is particularly pointed out and distinctly claimed in the claims at the conclusion of the specification. The foregoing and other features, and advantages of the disclosure are apparent from the following detailed description taken in conjunction with the accompanying drawings in which:
These and other advantages and features will become more apparent from the following description taken in conjunction with the drawings.
As will be described below, a cooling system for use in a supermarket cooling system, for example, is provided and uses a natural, non-toxic, low-GWP and ODP refrigerant. This refrigerant can be carbon dioxide, which is paired with an absorbent, such as one or more ionic liquids, or a solid adsorbent. The cooling system includes a gas cooler, a vapor absorption/adsorption-based subcooler and a desorber component that provides subcooling to refrigerant exiting the gas cooler. In the particular case of the refrigerant being carbon dioxide and the absorbent being an ionic liquid, the ionic liquid absorbs the carbon dioxide in an exothermic process in which the heat of absorption is rejected to ambient in order to sustain absorption processes (this is similar to the heat of compression needing to be rejected to ambient in a conventional gas cooler).
With reference to
The cooling system 101 also includes a vapor sorption subcooling system 150. The vapor sorption subcooling system 150 can be provided as a vapor absorption subcooling system 151 and includes the desorber 160, which is disposed between the gas cooler 120 and the first and second expansion valves 131 and 132 and which is configured to remove heat from the refrigerant flowing from the gas cooler 120 toward the first and second expansion valves 131 and 132. A subcooling refrigerant of the vapor absorption subcooling system 151 can include a natural, low greenhouse warming potential (GWP), low ozone depletion potential (ODP) and non-flammable refrigerant. More particularly, the subcooling refrigerant of the vapor absorption subcooling system 151 can include carbon dioxide.
The cooling system 101 can further include the ejector 155 disposed downstream from the desorber 160. The cooling system 101 in such cases would have subcooling capability from the vapor sorption subcooling system 150 and pressure recovery using the ejector 155. This would result in the cooling system 101 having increased COPs. It is to be understood that the ejector 155 is optional and that embodiments exist in which the ejector 155 is not present in the cooling system 101.
As shown in
The absorber 180 includes an enclosure 181 and the absorbent 182, which is contained within the enclosure 181. In accordance with embodiments, the absorbent 182 may include an ionic liquid (see below for example of ionic liquids). While this absorbent 182 (i.e., ionic liquid) is contained within the enclosure 181, it can be used to dissolve the subcooling refrigerant (i.e., carbon dioxide).
xCO2
xCO2
xCO2
Where the absorbent 182 includes an ionic liquid, the ionic liquid can be immobilized in an adsorbent. In such cases, the vapor absorption subcooling system 151 is similar to an adsorption system (to be discussed below) where pores of an adsorbent are filled with the ionic liquid (sometimes referred to as an immobilized ionic liquid).
During an operation of the vapor absorption subcooling system 151, the desorber 160 provides subcooling to the refrigerant exiting the gas cooler 120. This is accomplished as follows.
Within the absorber 180, the subcooling refrigerant flowing into the absorber 180 from the subcooling gas cooler 190 is absorbed into the absorbent 182 (i.e., absorption by the subcooling refrigerant being dissolved into the absorbent 182 within the enclosure 182) as part of an exothermic process. The heat of absorption gets rejected to ambient. The absorbent 182 with the subcooling refrigerant absorbed therein flows through the second valve 211 to the desorber 160, which is at a lower pressure than the absorber 180. Within the desorber 160, the subcooling refrigerant desorbs from the absorbent 182 in an endothermic process and provides cooling through a heat transfer surface to the refrigerant flowing from the gas cooler 120. The subcooling refrigerant that desorbs is recompressed by the subcooling compressor 170. At least the absorbent 182 or a mixture of the absorbent 182 and a portion of the subcooling refrigerant is pumped back into the absorber 180 in order to complete the cycle by the pump 200.
In accordance with embodiments, the absorber 180 and the desorber 160 can be operated in a cyclic mode.
As shown in
With reference to
As shown in
Within the adsorber 310, the subcooling refrigerant flowing into the adsorber 310 from the subcooling gas cooler 190 is adsorbed into the adsorbent 312 as part of an exothermic process. The heat of adsorption gets rejected to ambient.
In accordance with embodiments, adsorption and desorption beds of the adsorber 310 and the desorber 160, respectively, can be operated in a cyclic mode. In addition, the adsorber 310 can include two or more adsorbent beds.
The adsorber 310 includes an enclosure 311 and a solid adsorbent 312 contained within the enclosure 311. In accordance with some embodiments, the solid adsorbent 312 can include or be provided as activated carbon and metal organic frameworks (MOFs).
With reference to
The respective desorber/adsorber beds 4101, 4102 and 4103 are operable at different stages of adsorption and desorption to mitigate a potential issue of intermittency in which the desorber 160 switches from desorption mode to adsorption mode. With the presence of the multiple desorbers 160, cooling loads can be maintained by having the different multiple desorbers 160 at different stages of desorption. As one of the multiple desorbers 160 switches from desorption mode to adsorption mode, the other of the multiple desorbers 160 are available to provide cooling effects to satisfy extra cooling requirements.
With reference to
Technical effects and benefits of the features described herein are the provision of a vapor sorption subcooling system that uses a natural, low ODP, low GWP, non-flammable refrigerant like carbon dioxide for the subcooler system that, when combined with a current cooling system, shows 10% increase in COP.
While the disclosure is provided in detail in connection with only a limited number of embodiments, it should be readily understood that the disclosure is not limited to such disclosed embodiments. Rather, the disclosure can be modified to incorporate any number of variations, alterations, substitutions or equivalent arrangements not heretofore described, but which are commensurate with the spirit and scope of the disclosure. Additionally, while various embodiments of the disclosure have been described, it is to be understood that the exemplary embodiment(s) may include only some of the described exemplary aspects. Accordingly, the disclosure is not to be seen as limited by the foregoing description, but is only limited by the scope of the appended claims.
This application claims the benefit of Provisional Application No. 62/830,924 filed Apr. 8, 2019, the disclosure of which is incorporated herein by reference in its entirety.
Number | Date | Country | |
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62830924 | Apr 2019 | US |