Patent Publication Number: US-8534083-B2

Title: Evaporative cooling condenser for household appliance

Description:
BACKGROUND 
     The present disclosure generally relates to appliances, and more particularly to an evaporative cooling condenser for a household appliance. 
     Government regulations and consumer demand strongly encourage the development of low energy use appliances. Cooling and air-conditioning systems for appliances such as refrigerators use a great deal of energy. Efforts to produce highly efficient appliances can be costly. For example, various approaches to energy-saving appliances have been developed that include the use of vacuum panels to decrease the heat entering the refrigerator. However, the use of vacuum panels requires the addition of expensive parts, thus increasing the total cost of the appliance for a consumer. Evaporative cooling is used in larger commercial refrigeration applications and systems to reduce the heat of the liquid refrigerant flowing from the condenser into the evaporator, thereby increasing heat absorption and decreasing the amount of energy use required. However, a practical method to apply an evaporative cooling process to a household appliance, such as a refrigerator, has not been developed. 
     Accordingly, it would be desirable to provide a system that addresses at least some of the problems identified. 
     BRIEF DESCRIPTION OF THE EMBODIMENTS 
     As described herein, the exemplary embodiments overcome one or more of the above or other disadvantages known in the art. 
     One aspect of the exemplary embodiments relates to an evaporator cooling condenser for a household appliance. In one embodiment, the evaporator cooling condenser includes a water source, a condenser coil, and a fluid heat transfer device. The fluid heat transfer device is configured to receive water from the water source and apply the water to the condenser coil to enable the condenser coil to reject heat. 
     In another aspect, the disclosed embodiments are directed to a cooling system for a household appliance. In one embodiment, the household appliance includes an evaporator stage, a compressor stage coupled to the evaporator stage, and a condenser stage coupled between the compressor stage and the evaporator stage. The condenser stage includes an evaporative cooling condenser. 
     These and other aspects and advantages of the exemplary embodiments will become apparent from the following detailed description considered in conjunction with the accompanying drawings. It is to be understood, however, that the drawings are designed solely for purposes of illustration and not as a definition of the limits of the invention, for which reference should be made to the appended claims. Moreover, the drawings are not necessarily drawn to scale and that, unless otherwise indicated, they are merely intended to conceptually illustrate the structures and procedures described herein. In addition, any suitable size, shape or type of elements or materials could be used. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In the drawings: 
         FIG. 1  is a perspective view of an exemplary appliance incorporating aspects of the disclosed embodiments. 
         FIG. 2  is a block diagram of one embodiment of a cooling system incorporating aspects of the present disclosure. 
         FIG. 3  is a schematic block diagram of an exemplary evaporative cooling condenser incorporating aspects of the disclosed embodiments. 
         FIG. 4  illustrates an exemplary heat transfer device for an evaporative cooling condenser incorporating aspects of the disclosed embodiments. 
         FIG. 5  illustrates an exemplary heat transfer device for an evaporative cooling condenser incorporating aspects of the disclosed embodiments. 
         FIG. 6  illustrates an exemplary heat transfer device for an evaporative cooling condenser incorporating aspects of the disclosed embodiments. 
         FIG. 7  illustrates an exemplary heat transfer device for an evaporative cooling condenser incorporating aspects of the disclosed embodiments. 
     
    
    
     DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENTS 
     Referring to  FIG. 1 , an exemplary household appliance, such as a refrigerator, incorporating aspects of the disclosed embodiments, is generally designated by reference numeral  100 . The aspects of the disclosed embodiments are generally directed to lowering the condenser temperature of a refrigerant based cooling system in a household appliance to allow the refrigerant to absorb more heat in the evaporator. An evaporative cooling condenser is used to lower the condenser temperature so that the refrigerant exiting the condenser and entering the capillary tube will be at a lower enthalpy. The lower enthalpy allows the refrigerant to absorb more heat when it reaches the evaporator, which increases the cooling capacity of the household appliance without increasing the energy usage or costs. The compressor discharge pressure will also be lowered, reducing the energy consumed by the compressor. Although the aspects of the disclosed embodiments will generally be described with a respect to a household appliance such as a refrigerator, in alternate embodiments the household appliance can comprise any suitable household appliance that includes a refrigerant based cooling system, such as for example, a freezer or air conditioning unit. 
     An exemplary refrigerator  100  is shown in  FIG. 1 . The refrigerator  100  shown in  FIG. 1  is a multi-compartment refrigerator  100  that includes at least two compartments within a cabinet structure  102 , including, for example, a fresh food compartment  104  and a freezer compartment  106 . In alternate embodiments, the refrigerator  100  of the present disclosure can include any suitable number of compartments. The refrigerator  100  includes doors  108  and  110  for the fresh food compartment  104 , and door  112  for the freezer compartment  106 . A divider or mullion  114  separates the fresh food compartment  104  from the freezer compartment  106 . 
       FIG. 2  illustrates one embodiment of a cooling system  200  for a refrigerator  100  incorporating aspects of the disclosed embodiments. In one embodiment, the cooling system  200  includes a compressor stage  202 , a condenser stage  204 , and an evaporator stage  206 . In one embodiment the condenser stage  204  includes an evaporative cooling condenser  210 . 
     The compressor stage  202  is generally configured to compress a low, ambient temperature and low-pressure refrigerant received from the evaporator stage  206  into a high-temperature and high-pressure gaseous refrigerant. The condenser stage  204  is connected to the compressor stage  202  and is configured to condense the compressed gaseous refrigerant into a liquid refrigerant. The evaporator stage  206  is connected between the condenser stage  204  and the compressor stage  202  and is generally configured to evaporate the expanded refrigerant, absorb heat and generate cool air. Each of the compressor stage  202 , the condenser stage  204  and evaporator stage  206  can include other suitable components for providing the general functionalities described herein. 
     The evaporative cooling condenser  210  of the disclosed embodiments is generally configured to lower the condenser stage temperature by cooling the air entering the condenser stage  204  from the ambient thy bulb temperature to a point that is closer to the wet bulb temperature, or by causing the condenser stage  204  to reject heat to a pool of water. In one embodiment, referring to  FIG. 3 , a fluid, such as water or water vapor, is introduced into a fluid heat transfer device  312 , where the fluid is passed over, or brought in contact with, a condensing coil  302 . The condensing coil  302  generally comprises a heat exchanger containing refrigerant, and is located after the compressor stage  202  and before the evaporator stage  206 . In one embodiment, the fluid can be introduced by the fluid heat transfer device  312  into an airflow path  310  passing through the condenser coil  302 , or the condenser coil  302  can be continually wetted by the fluid. A heat convection process will cause the condenser coil  302  to reject heat to the fluid, thus lowering the temperature of the condenser stage  204 . 
     For example, when water or water vapor is introduced into the airflow path  310  and the air is pulled through the condensing coil  302 , such as by a fan  308 , the water will evaporate. The evaporation removes heat from the refrigerant vapor in the condenser coil  302 , thus reducing the temperature of the condensed refrigerant. When the condenser coil  302  is brought in contact with water, such as by wetting the coil  302  with water or immersing the condenser coil  302  into a pool of water that is lowered to an ambient temperature or below by evaporative cooling, the condensing temperature will be lowered by rejecting heat to this water. The reduced condensing temperature allow the refrigerant to absorb more heat in the evaporator stage  206 , reduce compressor power, and thus lower energy use and costs. Generally, a one-degree Fahrenheit reduction in the temperature of the condenser stage can reduce refrigerator energy use by one percent or more. 
     In one embodiment, the system  200  can include a humidity sensor  212 . The humidity sensor  212  can be part of the condenser stage  204 , or can be separately included in the system  200 , as a stand-alone device or part of a system controller  216 . The humidity sensor  212  is generally configured to detect a humidity level in an area of the appliance and enable or disable the evaporative cooling condenser  210  depending upon the humidity level. In one embodiment, a signal corresponding to the detected humidity level is sent to a controller  216 , where the controller  216  is configured to enable or disable the evaporative cooling condenser  210 . The aspects of the disclosed embodiments are generally applicable in environments where the relative humidity levels are below a pre-determined values, such as for example, approximately 40-50% relative humidity, and are less effective at humidity levels that are higher than approximately 70%. 
     As is shown in  FIG. 2 , in one embodiment, the cooling system  200  can also include a temperature sensor  214 . The temperature sensor  214  can be configured to monitor one or more of the ambient temperature, or the temperature of the system components such as the compressor stage  202  or the condenser stage  204 . The temperature sensor  214  can provide temperature indications to the controller  216 , where the controller  216  can interpret the data for the purpose of determining whether or not to activate the evaporative cooling condenser  210 . For example, if the ambient temperature is not high enough to provide adequate evaporation of the water, under certain humidity conditions, the controller  216  can interrupt or disable the operation of the evaporative cooling condenser  210 . The humidity and temperature readings from the sensors  212 ,  214 , can also be used by the controller  216  to increase or decrease the flow of fluid to the fluid heat transfer device  312  shown in  FIG. 3 . For example, in high ambient temperature conditions, it may be desirable to increase the fluid flow to the fluid heat transfer device  312 , while in low ambient temperature conditions, where fluid evaporation is not favorable, the flow of fluid to the fluid heat transfer device  312  can be decreased. 
     As is shown in  FIG. 3 , the aspects of the disclosed embodiments utilize both defrost drain water and make-up water as sources of water for the fluid heat transfer device  312 . In one embodiment, the defrost drain water can also include water or condensation that may form on the interior or exterior surfaces of the cabinet structure  102  and is collected. A first source is the defrost drain water  304  that is generated as a result of a defrosting cycle or process in the cooling system  200 . The second source of water is the make-up water  306 , which can be an external water source. Each source  304 ,  306  can be suitably coupled to the fluid heat transfer device  312 , by for example, a valve, where each source  304 ,  306  can be individually controlled to provide water to the fluid heat transfer device  312 . By using both defrost drain water  304  and make-up water  306 , the defrost drain water  304  can be recycled, allowing water to be supplied to the evaporative cooling condenser  210  in a practical and energy efficient manner. 
       FIG. 4  illustrates one example of an evaporative cooling condenser  210  incorporating aspects of the disclosed embodiments. In this embodiment, the evaporative cooling condenser  210  shown in  FIG. 4  is generally configured to use water in the form of vapor or steam, generally referred to herein as water vapor, to remove heat from the condenser coil  302 . The fluid heat transfer device  312  in this example is configured to release water vapor into an inner portion or area of the condenser coil  302  where the water vapor can mix with the air stream  310  flowing through the condenser coil  302 . The evaporative cooling process will lower the condensing temperature. 
     In the embodiment shown in  FIG. 4 , the fluid heat transfer device  312  comprises a water vapor generating device  402 . The water vapor generating device  402  generally comprises a water fill device  404 , tubing  406  and water vapor jet  408 . The condenser coil  302  generally comprises tubing  410  and heat conductive fins  412 . 
     As shown in  FIG. 4 , the condenser coil  302  is generally circular in nature, in the form of a cylinder. In alternate embodiments, the condenser coil  302  can be configured in any suitable geometric shape. In the embodiment shown in  FIG. 4 , the airflow path  310  generally flows into and through the inner area  418  of the condenser coil  302  in the direction A from end  414 . Air can also be drawn into the inner area  418  from the sides of the condenser coil  302 , across the tube  410  and fins  412 . In one embodiment, a fan  308  can be used to assist and direct the airflow path  310  through the condenser coil  302 . In this fashion, heat is removed or transferred from the condenser coil  302  in a convection heat transfer process. 
     The water vapor generating device  402  receives water from water dispensing device or source  404 . The water dispensing device  404  is configured to receive water from both the defrost water supply  304  and the make-up water supply  306 . In one embodiment, the water dispensing device  404  comprises a reservoir for storing water. In alternate embodiments, the water dispensing device  404  can comprise a pump or valve that is cycled between an open and closed state to allow water to enter the tube  406  from the dispensing device  404 . Where the water dispensing device  404  is a reservoir, a water level sensor  416  can be provided that allows the water to fill in the reservoir to a certain level. In one embodiment the water level sensor  416  can comprise a float mechanism. In alternate embodiments, any suitable water level sensor device can be used, other than including a float. 
     In one embodiment, the flow of water into the tubing  406  from the water dispensing device  404  can be regulated. The rate of the flow of water will be such that the water in the tube  406  can evaporate without overflowing from the tube  406 . In one embodiment, the flow rate will be at a slow rate, such as for example a drip rate. The water dispensing device  404  can include a suitable valve mechanism can be used to regulate the flow of water, which in one embodiment can also be a time-release valve mechanism. 
     The tubing  406  is generally in thermal or physical contact with the condenser  302  and is suitably arranged on the condenser  302 . In the example shown in  FIG. 4 , the tubing  406  is arranged in a substantially serpentine pattern along or around an outer surface of the condenser  302 . In alternate embodiments, the tubing  406  can be arranged in any suitable configuration or pattern that promotes the transformation of the liquid water into vapor as it moves from the water dispensing device  404  through tube  406  to the water vapor jet  408  end. In one embodiment, the tubing  406  is a thermally conductive material such as metal. This allows the tubing  406  to remove heat from the condenser  302  and heat the water inside the tube  406 . Generally, the water exiting the evaporator stage  206  into the defrost water supply  304  will be at a temperature level of approximately 32 degrees Fahrenheit. The water in the tube  406  will heat to a level approximating an evaporation point, and can be released from the water vapor jet  408  as liquid vapor or steam. In one embodiment, the water dispensing device  404  can include a valve to prevent the release of water vapor or steam from the water dispensing device  404  end of the tubing  406 . 
       FIG. 5  illustrates another example of an evaporative cooling condenser  210  incorporating aspects of the disclosed embodiments. In this example, water is collected in a water reservoir or vessel  502 , such as a pan or tub, to form a water bath  510 . In this example, the water bath  510  generally comprises the fluid heat transfer device  312 . As shown in  FIG. 5 , the condenser coil  302  is placed near or in the vessel  502 . The water for the vessel  502  is delivered by the water dispensing device  404 , which as noted above supplies water from one or both of the defrost water supply  304  and the make-up water supply  306 . The vessel  504  can include a water level sensor  504 , such as for example a float valve, that can be used to regulate the level of water in the vessel  502 . The water level sensor  504  can be coupled to a valve  506  that can be used to regulate the flow of water and fill level. 
     Although the embodiment in  FIG. 5  shows a portion of the condenser coil  302  submerged in the water bath  510 , the condenser coil  302  does not have to be submerged for the evaporative cooling condenser  210  to have effective results. In one embodiment, the vessel  502  can be placed in front of, or in the path of the air flow  310 . When the condenser coil  302  is submerged in the water bath  510 , the amount of submersion can be approximately one-half of the condenser coil  302 . In high humidity levels, the humidity sensor  212  can be configured to prevent water from filling the vessel  502 . 
       FIG. 6  illustrates another example of an evaporative cooling condenser  210  incorporating aspects of the disclosed embodiments. In this example, the fluid heat transfer device  312  comprises an evaporative pad or other suitable device that is configured to absorb fluid such as water. In one embodiment the evaporative pad  602  is a sponge. In alternate embodiments, the evaporative pad can comprise any suitable water retaining device, other than including a sponge. The evaporative pad  602  is generally configured to absorb the water, and provide an evaporative effect as the airflow  310  passes over the evaporative pad  602 . 
     As shown in  FIG. 6 , the evaporative pad  602  is retained in an interior or central section of the condenser coil  302 . The evaporative pad  602  is generally configured to be dampened with, or absorb water. As the ambient air moves across the evaporative pad  602 , the heat in the air evaporates the water from the pad  602 . The pad  602  is continually re-dampened to continue the cooling process. The use of the pad  602  increases the evaporation rate of the water used in conjunction with the evaporative cooling condenser  210 . 
     The water dispensing device  404  is configured to provide water to, and/or wet the evaporative cooling pad  602 . In one embodiment, a timed fill water delivery method can be used, where the water dispensing device  404  is activated or opened for a pre-determined time according to a pre-determined schedule to provide a flow of water. The schedule or fill cycle could also be based on, or affected by factors such as, the ambient temperature of the area of the appliance  100 , the relative humidity of the area or the defrost cycle of the cooling system  200 . The delivery or fill rate of the water to the evaporative pad  602  can be based on a size or configuration of the pad  602 , the number of evaporative pads  602  being used, and should be sufficient to maintain the evaporative pad  602  in a moist, dampened or saturated state. A base plate or other suitable water collection device can be placed underneath the condenser  302  to collect any water that is not evaporated from or drips or flows from the evaporative pad  602 . 
     In one embodiment, the evaporative pad  602  is secured within the central portion  604  of the condenser coil  302  and in the airflow path  310 . The evaporative pad  602  can be supported within the central portion  604  of the condenser coil  302  in any suitable manner, using for example, a supporting bracket. In one embodiment, portions of the evaporative pad  602  can be in physical or thermal contact with the condenser coil  302 . As air flows into and through the central portion  604  of the condenser coil  302 , the airflow  310  will flow across the evaporative pad  602 . The water that is absorbed or retained in the evaporative pad  602  will cool the air and allow the air to absorb more heat from the condenser coil  302 . Similarly, if any portions of the evaporative pad  602  are in physical or thermal contact with any portions of the condenser coil  302 , water in the evaporative pad  602  at those portions will also absorb heat and cool the condenser coil  302  through the convection process. 
     In another embodiment, the evaporative pad  602  of  FIG. 6  can be placed in a water containing device, such as for example, the water vessel  502  shown in  FIG. 5 . In this example, the evaporative pad  602  can sit in, or be partially submerged in the water in the water vessel  502 . The amount to which the evaporative pad  602  is submerged should be sufficient to allow the evaporative pad  602  to remain wet or moist in those areas that are above the water line. A float and valve assembly can be used to maintain a sufficient level of water in the water vessel  502 . 
     Another example of an evaporative cooling condenser  210  incorporating aspects of the disclosed embodiments is shown in  FIG. 7 . In this example, the fluid heat transfer device  312  comprises a fluid misting device  702 . The misting device  702  is generally configured to convert the water from the water dispensing device  404  into a spray of water in the form of a mist and direct the mist onto the condenser coil  302 . The water, in the form of the mist, will evaporate when it comes in contact with the condenser coil  302 . As shown in  FIG. 7 , the misting device  702  generally comprises water dispensing device or valve  404  that supplies water to the misting jet  706  through tube  704 . The misting jet  706  delivers the water to the condenser coil  302  in the form of a spray, sufficient to allow the water to evaporate when it contacts the condenser coil  302 . A pan or other water collection device (not shown) positioned underneath or below the condenser coil  302  can be used to collect any excess water that is not evaporated. The timing or cycling of the delivery of the water mist, which in one embodiment is not continuous, can be controlled by parameters such as the ambient heat in the area of the appliance  100  or the relative humidity in the area, as supplied by humidity sensor  212  and temperature sensor  214 . For example, the cycle of the timing of the water delivery to the misting device  702  can be controlled by an algorithm that takes into account the relative humidity and/or temperature, as measured by the humidity and temperature sensors  212 ,  214 . If the relative humidity exceeds a pre-determined level, the misting device  702  can be disabled. 
     The aspects of the disclosed embodiments may also include software and computer programs incorporating the process steps and instructions described above that are executed in one or more computers. In one embodiment, one or more computing devices, such as a computer or controller  216  of  FIG. 2 , are generally adapted to utilize program storage devices embodying machine-readable program source code, which is adapted to cause the computing devices to perform the method steps of the present disclosure. The program storage devices incorporating features of the present disclosure may be devised, made and used as a component of a machine utilizing optics, magnetic properties and/or electronics to perform the procedures and methods of the present disclosure. In alternate embodiments, the program storage devices may include magnetic media such as a diskette or computer hard drive, which is readable and executable by a computer. In other alternate embodiments, the program storage devices could include optical disks, read-only-memory (“ROM”) floppy disks and semiconductor materials and chips. 
     The computing devices may also include one or more processors or microprocessors for executing stored programs. The computing device may include a data storage device for the storage of information and data. The computer program or software incorporating the processes and method steps incorporating features of the present disclosure may be stored in one or more computers on an otherwise conventional program storage device. 
     The aspects of the disclosed embodiments are generally directed to an evaporative cooling condenser for a household appliance that utilizes a fluid heat transfer device to bring defrost drain water and/or make-up water in contact with the coils of a condenser in order to remove heat from the condenser and lower the enthalpy of the refrigerant traveling through the condenser into the evaporator. This allows the evaporator to remove more heat from the appliance in an energy efficient and cost effective manner. 
     Thus, while there have been shown and described and pointed out fundamental novel features of the invention as applied to the exemplary embodiments thereof, it will be understood that various omissions and substitutions and changes in the form and details of devices illustrated, and in their operation, may be made by those skilled in the art without departing from the spirit of the invention. For example, it is expressly intended that all combinations of those elements and/or method steps which perform substantially the same function in substantially the same way to achieve the same results are within the scope of the invention. Moreover, it should be recognized that structures and/or elements and/or method steps shown and/or described in connection with any disclosed form or embodiment of the invention may be incorporated in any other disclosed or described or suggested form or embodiment as a general matter of design choice. It is the intention, therefore, to be limited only as indicated by the scope of the claims appended hereto.