This disclosure relates generally to a refrigerated room. More specifically, this disclosure relates to a system and method of reducing moisture in a refrigerated room.
Generally, the temperature within a refrigerated room such as a walk-in freezer or walk-in cooler is maintained in part by one or more heat exchanger coils in the refrigerated room. The heat exchanger coils are configured to absorb heat from the refrigerated room and transfer the heat to refrigerant circulating through the heat exchanger coils. Over time however, moisture within the refrigerated room may accumulate on or around the heat exchanger coils thereby reducing the capability of the coils to transfer heat.
According to one embodiment, a system includes a desiccant wheel, a motor, a fan, and a heat exchanger. The desiccant wheel is configured to absorb, in a portion of the desiccant wheel, moisture from moisturized air received from a refrigerated room, wherein absorbing the moisture from the moisturized air produces dehumidified air. The motor is configured to continually turn the desiccant wheel when in operation and the fan is configured to bring in outdoor air. The heat exchanger is configured to heat the outdoor air using waste heat from a transcritical refrigeration system and dry the portion of the desiccant wheel using the heated outdoor air. The system is operable to discharge the dehumidified air to the refrigerated room, thereby dehumidifying one or more heat exchanger coils in the refrigerated room.
According to another embodiment, a method includes receiving moisturized air from a refrigerated room and absorbing, in a portion of a desiccant wheel, moisture from the moisturized air, wherein absorbing moisture from the moisturized air produces dehumidified air. The method further includes discharging the dehumidified air to the refrigerated room.
According to yet another embodiment, a controller for a refrigeration system is configured to operate a motor configured to turn a desiccant wheel, wherein the desiccant wheel is configured to absorb, in a portion of the desiccant wheel, moisture from moisturized air received from a refrigerated room, wherein absorbing the moisture from the moisturized air produces dehumidified air that is discharged to the refrigerated room.
Certain embodiments may provide one or more technical advantages. For example, an embodiment of the present disclosure may result in more efficient heat transfer of coils in a refrigerated room. As another example, an embodiment of the present invention may reduce the time required to defrost coils in a refrigerated room. As yet another example, an embodiment of the present disclosure may provide supplemental cooling to refrigerant circulating through the refrigeration system. Certain embodiments may include none, some, or all of the above technical advantages. One or more other technical advantages may be readily apparent to one skilled in the art from the figures, descriptions, and claims included herein.
For a more complete understanding of the present disclosure, reference is now made to the following description, taken in conjunction with the accompanying drawings, in which:
Embodiments of the present disclosure and its advantages are best understood by referring to
Moisture is commonly present in refrigerated rooms such as walk-in freezers or walk-in coolers used to store refrigerated food and beverages in grocery stores. Over time, moisture in a refrigerated room results in frost accumulation on or around one or more heat exchanger coils of the refrigerated room. The frost accumulation on or around the heat exchanger coils reduces the ability of the coils to transfer heat efficiently, thereby causing the temperature inside the refrigerated room to increase to undesirable temperatures. Increased temperatures inside a refrigerated room may lead to additional energy consumption and/or food and drink spoilage which may correspond to increased costs. In conventional refrigeration systems, this problem is solved by defrosting (e.g., melting) the coils using electrical energy. Because the coils cannot simultaneously provide heating and cooling, the refrigeration cycle is shut down during a defrost cycle and the refrigeration cycle is restarted once the coils have melted the accumulated frost. In some cases, this cycling occurs multiple times per day. For example, coils in a walk-in freezer may require defrosting six times a day. As another example, coils in a walk-in cooler may require defrosting three times a day. Accordingly, the traditional solution is not energy efficient and is costly. Additionally, the traditional solution may cause undesirable fluctuating in refrigeration and may cause harm to the refrigeration system. This disclosure recognizes a dehumidification system that removes moisture from a refrigerated room and provides dehumidified air to the refrigerated room. As will be explained in further detail below, the disclosed system comprises a desiccant wheel configured to absorb moisture from moisturized air which may be dried by heat reclaimed from a refrigeration system. In doing so, the system reduces the amount of energy and time required to defrost heat exchanger coils relative to conventional refrigeration systems.
As discussed above, in certain embodiments, a dehumidification system may be configured to reclaim waste heat from a refrigeration system in order to perform dehumidification using a desiccant wheel. In certain embodiments, the desiccant wheel may be positioned within a duct above the refrigerated room. The duct may be open on both ends such that a first end is configured to receive outdoor air (e.g., from an outdoor environment) and the second end is configured to direct moisturized heated outdoor air to the outdoor environment. As will be explained in more detail below, the first end of the duct may be configured to receive outdoor air that has been heated using reclaimed waste heat from a refrigeration system. The heated outdoor air may then be directed, within the duct, to dry a moisturized portion of a desiccant wheel. As the heated outdoor air is applied to the moisturized portion of the desiccant wheel, the heated outdoor air passing through the desiccant wheel becomes moisturized (e.g., moisture from the moisturized portion of the wheel is transferred into the heated outdoor air). This moisturized, heated outdoor air is then directed to the outdoor environment. In some embodiments, discharging the moisturized, heated outdoor air yields various benefits over other dehumidification systems. As an example, conventional dehumidification systems may reuse moisturized, heated outdoor air and apply separate processes (which may require additional energy) to dehumidify the moisturized, heated outdoor air. This disclosure recognizes simply removing this air from the duct, thereby eliminating the need for a separate dehumidification step.
In addition to being a component of refrigeration system 100, heat exchanger 110 may be a component of dehumidification system 200. In some embodiments, heat exchanger 110 may apply waste heat from refrigeration system 100 to dehumidification system 200, which in turn provides supplemental cooling to refrigerant circulating through refrigeration system 100. As depicted in
As described above, refrigeration system 100 includes one or more compressors 105. Refrigeration system 100 may include any suitable number of compressors 105. For example, as depicted in
In some embodiments, refrigeration system 100 comprises one or more heat exchangers. As depicted in
Refrigeration system 100 may also comprise an expansion valve 120. In some embodiments, expansion valve 120 is configured to receive liquid refrigerant from gas cooler 115 and to reduce the pressure of received refrigerant. For example, gas cooler 115 may discharge liquid refrigerant having a pressure of 90 bar to expansion valve 120, and the refrigerant may be discharged from expansion valve 120 having a pressure of 40 bar. In some embodiments, this reduction in pressure causes some of the liquid refrigerant to vaporize. As a result, mixed-state refrigerant (e.g., refrigerant vapor and liquid refrigerant) is discharged from expansion valve 120. In some embodiments, this mixed-state refrigerant is discharged to flash tank 125.
Refrigeration system 100 may include a flash tank 150 in some embodiments. Flash tank 150 may be configured to receive mixed-state refrigerant (e.g., from expansion valve 120) and separate the received refrigerant into flash gas and liquid refrigerant. Typically, the flash gas collects near the top of flash tank 125 and the liquid refrigerant is collected in the bottom of flash tank 125. In some embodiments, the liquid refrigerant flows from flash tank 125 and provides cooling to one or more evaporators (cases) 135 and the flash gas flows to one or more compressors (e.g., compressor 105b) for compression before being discharged to heat exchanger 110 and/or gas cooler 115 cooling.
Refrigeration system 100 may include one or more evaporators 135 in some embodiments. As depicted in
(“MT case” 170b). LT case 135a may be configured to receive liquid refrigerant of a first temperature and MT case 135b may be configured to receive liquid refrigerant of a second temperature, wherein the first temperature (e.g., −30° C.) is lower in temperature than the second temperature (e.g., −6° C.). As an example, LT case 135a may be a freezer in a grocery store and MT case 170b may be a cooler in a grocery store. In some embodiments, the liquid refrigerant leaving flash tank 125 is the same temperature and pressure (e.g., 4° C. and 38 bar) as the refrigerant discharged from expansion valve 120. Before reaching cases 135, the liquid refrigerant may be directed through one or more evaporator valves 130 (e.g., 130a and 130b of
System 100 may also include a flash gas valve 140 in some embodiments. Flash gas valve 140 may be configured to open and close to permit or restrict the flow through of flash gas discharged from flash tank 125. In some embodiments, controller 170 controls the opening and closing of flash gas valve 140. As depicted in
Although this disclosure describes and depicts refrigeration system 100 including certain components, this disclosure recognizes that refrigeration system 100 may include any suitable components. As described above, refrigeration system 100 may include controller 170 operable to communicate with one or more components of refrigeration system 100. For example, controller 170 may be configured to control the operation of valves 120, 130a, 130b, 140. As was also described above, refrigeration system 100 may include an oil separator (not depicted) operable to separate compressor oil from the refrigerant. As another example, refrigeration system 100 may include one or more sensors configured to detect information about refrigeration system 100 (e.g., temperature and/or pressure information). One of ordinary skill in the art will appreciate that refrigeration system 100 may include other components not mentioned herein.
In addition to controlling operations of one or more components of refrigeration system 100, controller 170 may also be configured to operate components of dehumidification system 200. As an example, controller 170 may be configured to power fan 145 on or off and/or increase or decrease the speed of fan 145. As another example, controller 170 may be configured to operate a motor (e.g., motor 225) configured to turn desiccant wheel 165. As yet another example, controller 170 may be configured to receive information about humidity status within refrigerated room 150 via one or more sensors (not depicted) in refrigerated room 150.
Generally,
As depicted in
Turning now to
In some embodiments, desiccant wheel 165 is rotated by motor 225. Motor 225 may be controlled by one or more controllers. As an example, motor 225 may be controlled by controller 170. In some embodiments, controller 170 may operate motor, which in turn rotates desiccant wheel 165, based on a humidity of refrigerated room 150. As an example, controller 170 may be configured to operate motor 225 when the humidity in refrigerated room 150 reaches 70%. In some embodiments, the humidity in refrigerated room 150 is determined by one or more sensors in refrigerated room 150. In other embodiments, controller 170 operates motor 225 based on a temperature and/or a power status of refrigerated room 150. For example, controller 170 may operate motor 225 only when refrigerated room 150 is being cooled (e.g., not when refrigerated room 150 is not in operation). Controller 170 may cause motor 225 to turn desiccant wheel 165 continuously or periodically.
As motor 225 turns desiccant wheel 165, different portions of desiccant material may be exposed to one or more of moisturized air from refrigerated room 150 (e.g., in QIII) and heated outdoor air directed into duct 160 by heat exchanger 110 (e.g., in QI). As described above, fan 145 may pull in outdoor air which is heated by heat exchanger 110 using the waste heat of refrigeration system 100. As an example, heat exchanger 110 may apply a heating stage to outdoor air and increase the temperature of outdoor air from 30° C. to 90° C. Heat exchanger 110 may then direct the heated air into QI of duct 160a where it is applied to a moisturized portion of desiccant wheel 165 (e.g., portion of desiccant material that absorbed moisture from the moisturized air from refrigerated room 150). In some embodiments, the heated outdoor air is applied to the portion of desiccant wheel in QI (e.g., first surface 230 of desiccant wheel in top portion 160a of duct 160). In some embodiments, applying the heated outdoor air to the moisturized portion of desiccant wheel 165 dries the portion of desiccant wheel 165. As a result, the moisture from desiccant wheel 165 passes into the heated outdoor air (e.g., in QII) which is directed to an outdoor environment.
Bottom portion 160b of duct 160 may be configured to receive moisturized air from refrigerated room 150 which is then dehumidified and discharged to refrigerated room 150. In some embodiments, moisturized air exits refrigerated room via refrigerated room outlet 205 and enters QIII of duct 160 via inlet 210. Upon entering QIII, the moisturized air contacts second surface 235 of desiccant wheel 165. Accordingly, the portion of desiccant wheel 165 exposed to the moisturized air (e.g., the portion of desiccant wheel 165 in QIII) will absorb moisture from the moisturized air, thereby producing dehumidified air that passes through first surface 230 of desiccant wheel 165 into QIV of duct 160. The dehumidified air may then be directed out from QIV via outlet 215 to refrigerated room 150 via refrigerated room inlet 220.
The following is a description of a cycle of operation for dehumidifying refrigerated room 150 using the system described above. In operation, moisturized air from refrigerated room 150 is directed to QIII where it contacts a first surface of a portion of desiccant wheel 165. The portion of desiccant material absorbs moisture from the moisturized air, thereby producing dehumidified air, and the dehumidified air passes through the second surface of the portion of desiccant wheel 165 (e.g., into QIV) and is directed to refrigerated room 150. In some embodiments, the moisturized air exits refrigerated room 150 through refrigerated room outlet 205 and enters the duct through an inlet (e.g., inlet 210). In some embodiments, the dehumidified air exits duct 160 through an outlet (e.g., outlet 215) and enters refrigerated room 150 via refrigerated room inlet 220. In some embodiments, desiccant wheel 165 is continuously turned by motor 225 such that the portion of desiccant wheel 165 that absorbed the moisture is exposed to outdoor air that has been heated by waste heat from refrigeration system 100 by heat exchanger 110. The heated outdoor air may be applied to the portion of desiccant wheel 165 that absorbed the moisture, thereby drying the portion of desiccant wheel 165 and forcing the moisture into air that is discharged to the outdoor environment. The now-dried portion of desiccant wheel 165 may subsequently be exposed to moisturized air (e.g., by turning desiccant wheel 165 with motor 225) from refrigerated room 150 and the process can begin anew.
At step 310, the system 200 receives moisturized air from a refrigerated room 150. As explained above, moisture develops within refrigerated room 150 over time and can lead to frost accumulation on/around coils 155. In some embodiments, the moisturized air is directed out of refrigerated room 150 via refrigerated room outlet 205 and directed into QIII of duct 160 via inlet 210. In some embodiments, the method 300 continues to a step 320.
At step 320, the system 200 absorbs moisture from the moisturized air in a portion of desiccant wheel 165. In some embodiments, the component of system 200 that absorbs moisture from the moisturized air is desiccant wheel 165. As described above, desiccant wheel 165 may be located within duct 160 and may comprise desiccant material configured to absorb moisture. As such, the desiccant material of desiccant wheel 165 in QIII of duct 160 may absorb the moisture from the moisturized air received at step 310. In some embodiments, the moisturized air becomes dehumidified air as it passes through desiccant wheel 165 from QIII to QIV. In some embodiments, the method 300 continues to a step 330.
At step 330, the system 200 discharges the dehumidified air to refrigerated room 150. As explained above, the moisture from the moisturized air is absorbed by the desiccant material of desiccant wheel 165 at step 320, thereby producing dehumidified air. The system 200 may discharge the dehumidified air from QIV to refrigerated room 150 via outlet 215 and refrigerated room inlet 220. In some embodiments, the method 300 continues to an end step 335.
The method 300 may include one or more additional steps in some embodiments. As an example, the method 300 includes steps that may occur in top portion 160b of duct 160. Thus, in some embodiments, the method 300 may include one or more of the following steps: bringing in outdoor air from an outdoor environment; heating the outdoor air using waste heat from a transcritical refrigeration system; and drying the portion of the desiccant wheel using the heated outdoor air to produce moisturized outdoor air. In some embodiments, the component of system 200 that brings in outdoor air from an outdoor environment may be fan 145 and the component of system 200 that heats the outdoor air using waste heat from a transcritical refrigeration system may be heat exchanger 110. Although this disclosure describes and depicts certain steps of method 300, this disclosure recognizes that method 400 may comprise any suitable step.
Memory (or memory unit) 420 stores information. As an example, memory 420 may store method 300. Memory 420 may comprise one or more non-transitory, tangible, computer-readable, and/or computer-executable storage media. Examples of memory 420 include computer memory (for example, Random Access Memory (RAM) or Read Only Memory (ROM)), mass storage media (for example, a hard disk), removable storage media (for example, a Compact Disk (CD) or a Digital Video Disk (DVD)), database and/or network storage (for example, a server), and/or other computer-readable medium.
Processor 430 may include any suitable combination of hardware and software implemented in one or more modules to execute instructions and manipulate data to perform some or all of the described functions of controller 400. In some embodiments, processor 430 may include, for example, one or more computers, one or more central processing units (CPUs), one or more microprocessors, one or more applications, one or more application specific integrated circuits (ASICs), one or more field programmable gate arrays (FPGAs), and/or other logic.
Embodiments of the present disclosure may have one or more technical advantages. In certain embodiments, a heat exchanger downstream the gas cooler provides supplemental cooling to refrigerant, thereby reducing the amount of power of other refrigeration system components configured to cool the refrigerant. Additionally, the waste heat produced by the downstream heat exchanger may be reclaimed by other facility systems (e.g., floor heating system, water heating system), thereby reducing the amount of power of compressors 105.
Although this disclosure describes and depicts a configuration of a transcritical refrigeration system including a heat exchanger downstream from the gas cooler, this disclosure recognizes other similar applications. For example, this disclosure recognizes a configuration of a conventional refrigeration system comprising a heat exchanger downstream from a condenser. The downstream heat exchanger would provide supplemental cooling to refrigerant circulating through the conventional refrigeration system, thereby reducing the power consumption of compressors 105. Additionally, the waste heat produced as a result of operation of the downstream heat exchanger could be reclaimed and used by other facility systems.
This disclosure also recognizes dehydrating food in a similar manner. Taking
Modifications, additions, or omissions may be made to the systems, apparatuses, and methods described herein without departing from the scope of the disclosure. The components of the systems and apparatuses may be integrated or separated. Moreover, the operations of the systems and apparatuses may be performed by more, fewer, or other components. For example, refrigeration system 100 may include any suitable number of compressors, condensers, condenser fans, evaporators, valves, sensors, controllers, and so on, as performance demands dictate. One skilled in the art will also understand that refrigeration system 100 can include other components that are not illustrated but are typically included with refrigeration systems. Additionally, operations of the systems and apparatuses may be performed using any suitable logic comprising software, hardware, and/or other logic. As used in this document, “each” refers to each member of a set or each member of a subset of a set.
Modifications, additions, or omissions may be made to the methods described herein without departing from the scope of the disclosure. The methods may include more, fewer, or other steps. Additionally, steps may be performed in any suitable order.
Although this disclosure has been described in terms of certain embodiments, alterations and permutations of the embodiments will be apparent to those skilled in the art. Accordingly, the above description of the embodiments does not constrain this disclosure. Other changes, substitutions, and alterations are possible without departing from the spirit and scope of this disclosure.