Patent Publication Number: US-6666038-B1

Title: Air conditioning system including liquid washdown dispenser and related methods

Description:
FIELD OF THE INVENTION 
     The present invention relates to the field of air conditioning systems, and, more particularly, to a system and method for removing salt, dirt, etc., from air conditioning components. 
     BACKGROUND OF THE INVENTION 
     Air conditioners have long been used to provide comfortable air temperatures inside buildings. One type of air conditioning system which enjoys widespread use is the central heating and air conditioning system. Such systems typically include an indoor unit inside a building including a heat exchanger which transfers heat from air in the building to a refrigerant inside the heat exchanger. The refrigerant is then pumped outside the building by a compressor to an outdoor heat exchanger located in an outdoor unit where the heat is then transferred to the outside air. 
     Central heating/air conditioning systems can also be operated in a reverse manner (i.e., as heat pumps) during colder months to bring heat from the outside air into the building. While heat pumps generally cannot provide large amounts of heat as efficiently as a furnace, for example, they typically are able to provide adequate heat in regions that have fairly mild winters. 
     As such, central heating/air conditioning systems are particularly well suited for warmer climates, including coastal environments. In such environments the high quantity of corrosive salts in the air often causes various components of air conditioning systems to corrode, particularly the outdoor unit components which are continuously exposed to salt air. For example, the copper tubing used to make heat exchanger assemblies is particularly susceptible to corrosion from salts, as may also be certain parts of the fan used to blow outside air through the outdoor heat exchanger. Moreover, in other environments where coils, fans, etc. tend to have a large amount of dirt or other debris accumulate thereon, this may also tend to decrease component lifespan in addition to reducing system performance. 
     Some prior art systems have attempted to address the effects of corrosive particles on certain air conditioning system components. By way of example, U.S. Pat. No. 6,182,741 to Yoshii et al. is directed to an air conditioner for preventing corrosion of an evaporator heat exchanger. The air conditioner includes a case and an evaporator therein having a core portion and a lower tank at a bottom of the core portion. The case has a recess portion at an upstream air side of the evaporator, and a covering wall extends upwardly from the bottom of the recess portion to cover only the lower tank at an immediately upstream air side. When air passes through the evaporator, corrosive substances in the air collide with the evaporator and fall in the recess portion. As such, the corrosive substances do not directly adhere to the lower tank of the evaporator, which reduces evaporator corrosion. 
     A somewhat similar air conditioner is described in Japanese Patent No. 63-150540 to Yasuhiro. This air conditioner includes a condensation chamber which is filled with humidified air to remove salt particles from air being taken into the system. This is done to reduce the accumulation of such particles on a filter, and thus premature pressure loss. Moreover, the reduction in salt particles in the air also helps to prevent corrosion of a blower downstream from the condensation chamber. 
     While the above systems may be helpful in reducing corrosion of central air conditioning system components inside a building (i.e., the evaporator and blower), they provide no such protection for outdoor components. As such, apart from persistent manual cleanings, there has heretofore been no convenient way to reduce the accumulation of corrosive or other particles on outdoor air conditioning system components. Thus, such components require replacement on a more frequent basis, and system performance may suffer, when used in corrosive or dirty environments. 
     SUMMARY OF THE INVENTION 
     In view of the foregoing background, it is therefore an object of the present invention to provide an air conditioning system and associated methods which reduce the accumulation of salts, dirt and other contaminants on outdoor system components which may lead to system performance degradation and/or premature component failure. 
     This and other objects, features, and advantages in accordance with the present invention are provided by an air conditioning system including an indoor heat exchanger to be positioned within a building and including a refrigerant for exchanging heat with air inside the building, and an outdoor unit to be positioned outside of the building. The outdoor unit may include a housing and an outdoor heat exchanger carried by the housing. Further, the outdoor heat exchanger may be connected in fluid communication with the indoor heat exchanger for exchanging heat between the refrigerant and air outside the building. The air conditioning system may also include a compressor for circulating the refrigerant between the indoor heat exchanger and the outdoor heat exchanger. 
     Additionally, the system may further include a liquid washdown dispenser carried by the housing adjacent the outdoor heat exchanger. In particular, the liquid washdown dispenser may be connected to a liquid dispensing source for dispensing liquid (e.g., fresh water) to wash down the outdoor heat exchanger. Further, a controller may also be included for controlling liquid flow to the liquid washdown dispenser. Accordingly, the controller and liquid washdown dispenser advantageously cooperate to remove potentially corrosive or harmful particles from the outdoor heat exchanger before significant component or system performance degradation results. 
     More particularly, the outdoor unit may also include a fan carried by the housing for circulating outside air through the outdoor heat exchanger, and the liquid washdown dispenser may also dispense liquid to wash down the fan. The outdoor unit may also be switchable between on and off states, and the controller may prohibit liquid flow to the liquid washdown dispenser when the outdoor unit is in the on state. As such, the liquid will not be sprayed outside of the outdoor unit by the fan, for example. 
     Furthermore, the controller may also include a timer for periodically causing the liquid flow to be turned on and off. Thus, the timer may be set to provide liquid dispensing at desired intervals and for a predetermined duration so that wash downs are performed frequently enough to adequately reduce corrosion, yet while not wasting liquid/fresh water. In particular, the controller may further include a valve connecting the liquid washdown dispenser to the liquid dispensing source, and a solenoid connected between the timer and the valve. 
     The liquid washdown dispenser may include a plurality of nozzles adjacent the outdoor heat exchanger and tubing connecting the nozzles to the liquid dispensing source. In addition, the housing may have openings therein to permit air flow, and the outdoor heat exchanger may be positioned adjacent the at least one side. 
     A method aspect of the invention is for retrofitting an outdoor unit of an air conditioning system to be positioned outside of a building, such as the one described briefly above. The method may include mounting a liquid washdown dispenser in the housing adjacent the outdoor heat exchanger, and connecting the liquid washdown dispenser to a liquid dispensing source for dispensing liquid to wash down the outdoor heat exchanger. In addition, the method may also include connecting a controller to the liquid dispensing source for controlling liquid flow to the liquid washdown dispenser. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a schematic block diagram of an air conditioning system in accordance with the present invention. 
     FIG. 2 is a schematic block diagram illustrating in greater detail the controller of FIG.  1 . 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The present invention will now be described more fully hereinafter with reference to the accompanying drawings, in which preferred embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. Like numbers refer to like elements throughout, and prime notation is used to indicate similar elements in alternate embodiments. 
     Turning now to FIGS. 1-2, an air conditioning system  10  in accordance with the present invention illustratively includes an indoor unit  11  that is positioned within a building  12 . As previously described above, the indoor unit  11  includes an indoor heat exchanger  13  which exchanges heat between air in the building  12  and a refrigerant being circulated in the indoor heat exchanger. That is, a fan or blower (not shown) blows air from within the building  12  through the indoor heat exchanger  13 , which is typically constructed of copper tubing configured in coils which have metal (e.g., aluminum) fins mounted thereon to increase the amount of surface area over which heat exchange takes place. 
     Thus, when cooling within the building  12  is required, warm air from within the building is blown across the indoor heat exchanger  13 , which draws heat from the air into the refrigerant. When heating is required, the air conditioning system  10  is operated in reverse as a heat pump in that the refrigerant circulating through the indoor heat exchanger  13  is warmer than the indoor air, and thus heat is draw from the refrigerant to heat the indoor air. The air conditioning system  10  may include a reversing valve (not shown) for changing the refrigerant flow direction based upon which mode of operation is being used, as will be appreciated by those of skill in the art. 
     To cool (or, in the case of heat pump operation, heat) the refrigerant after it passes through the indoor heat exchanger  13 , the air conditioning system  10  includes an outdoor unit  14  positioned outside of the building  12 . The outdoor unit  14  includes a housing  15  and an outdoor heat exchanger  29  carried by the housing which illustratively includes coils  16  and metal fins  17  mounted thereon to improve thermal transfer. Of course, other suitable types of heat exchangers may also be used, as will be appreciated by those of skill in the art. 
     The housing  15  may have openings  19  therein to permit air flow, and the outdoor heat exchanger  29  is preferably positioned adjacent the openings for this reason. While the outdoor heat exchanger  29  is shown as being adjacent only a single side of the housing  15 , it will be appreciated that the outdoor heat exchanger may extend around to other sides of the housing as well, which may similarly have openings  19  therein. 
     Moreover, various shapes of housings  15  are contemplated by the present invention, such as square housings, circular or rounded housings, etc. Further, in some embodiments, the housing  15  may have sides made of panels (e.g., metal panels), as illustratively shown, but in other embodiments the sides may resemble a “cage” made of relatively thick metal wires or rods. Numerous other housing  15  configurations will also be appreciated by those skilled in the art. 
     More particularly, the outdoor heat exchanger  29  is connected in fluid communication by tubing  18  with the indoor heat exchanger  13  for exchanging heat between the refrigerant and air outside the building  12 . To this end, the air conditioning system  10  also includes a compressor  20  for circulating the refrigerant between the indoor heat exchanger  13  and the outdoor heat exchanger  29 , and the outdoor unit  14  includes a fan  21  carried by the housing  15  for circulating outside air through the outdoor heat exchanger. The compressor  20  is illustratively shown as being located within in the outdoor unit  14 , but it will be appreciated that the compressor may be located elsewhere in some embodiments. 
     In accordance with the invention, the air conditioning system  10  also includes a liquid washdown dispenser  22  carried by the housing  15  adjacent the outdoor heat exchanger  29 . The liquid washdown dispenser  22  illustratively includes a plurality of nozzles  23  adjacent the outdoor heat exchanger  29  and, optionally, the fan  21  and/or other components of the outdoor unit  14 . Tubing  24  connects the nozzles  23  to a liquid dispensing source  25 , such as the fresh water supply line in the illustrated example, via a controller  26  which controls liquid flow to the nozzles. Of course, other liquid dispensing sources  25  may also be used, such as a tank for fresh water or other liquid suitable for washing down the outdoor unit  15  components. Such liquids may include anti-corrosive agents as well. A manual shutoff valve  27  may optionally be included in some embodiments to override the flow of liquid to the outdoor unit  14 , if desired, as illustratively shown. 
     The controller  23  and liquid washdown dispenser  22  advantageously cooperate to remove salt or other unwanted material from the coils  16 , fins  17  and/or fan  21  (and, optionally, other components) to reduce corrosion and/or premature component failure, and thus prolong the life of such components. Not only is the air conditioning system  10  thus well suited for use in environments where there is a high percentage of salts in the air (e.g., in coastal regions), but it may also be used for removing dirt, grass, and other debris which can build up on the coils  16 , fins  17 , and/or fan  21  which can reduce heat exchange efficiency and even cause damage to such components. 
     In accordance with one exemplary embodiment illustrated in FIG. 2, the controller  26  includes a valve  30  connecting the liquid washdown dispenser  22  to the liquid dispensing source  25 , and a solenoid  31  for opening and closing the valve. The solenoid  31  is in turn connected to control circuitry  32  which determines when liquid is to be dispensed and supplies the requisite current to the solenoid for causing the value  30  to be opened. To this end, the control circuitry  32  may include a microprocessor, power amplifiers, etc., for example, as will be appreciated by those of skill in the art. 
     The control circuitry  32  may determine when liquid is to be dispensed based upon several different factors. For example, the controller  26  may also include a timer  33  for periodically causing the liquid flow to be turned on and off. That is, based upon the timer  33 , the valve  30  may be opened for desired intervals at a desired frequency, such as one-minute intervals three times a day, for example. Thus, wash downs may advantageously be performed frequently enough to adequately reduce corrosion while not wasting liquid/fresh water. Of course, any frequency and/or duration of waterings may be used in accordance with the present invention depending upon the particular environment or equipment being used. 
     It should be noted that while the control circuitry  32  and timer  33  have been illustrated as separate components for clarity of illustration, they may well be implemented in a single device. In fact, in some embodiments the controller  26  could be a controller for a sprinkler system in which the liquid washdown dispenser  22  is connected as one zone of the sprinkler system, as will be understood by those of skill in the art. It will also be appreciated that various types of timing devices (e.g., mechanical, electronic, etc.) may be used for the timer  33 . 
     Another factor which may be used for determining when to dispense liquid is whether the outdoor unit  14  is turned on. That is, the air conditioning system  10 , and thus the outdoor unit  14 , preferably cycles on and off as cooling/heating is required within the building  12 . This determination is generally made by a thermostat (not shown) within the building  12  that measures when the inside air has exceeded or fallen below a desired temperature. The thermostat then causes the system  10  to be operational until the temperature reaches the desired temperature. 
     As such, in some embodiments the controller  26  may advantageously receive an input indicating whether the outdoor unit  14  is on or off. That is, when the outdoor unit  14  is in the on state, the fan  21  blows heated (or cooled, in the case of heat pump operation) air away from the outdoor unit  14 . Accordingly, to avoid having the liquid sprayed outside of the outdoor unit  14  and onto the building  12 , passersby, etc., the controller  26  may prohibit liquid flow to the liquid washdown dispenser  22  when the outdoor unit  14  is in the on state. 
     A method aspect of the invention is for retrofitting the outdoor unit  14 . The method may include mounting a liquid washdown dispenser  22  in the housing  15  adjacent the outdoor heat exchanger  29 , and connecting the liquid washdown dispenser  22  to the liquid dispensing source  25  for dispensing liquid to wash down the outdoor heat exchanger. In addition, the method may also include connecting the controller  26  to the liquid dispensing source  25  for controlling liquid flow to the liquid washdown dispenser  22 . Other method aspects of the present invention will be apparent to those skilled in the art based upon the foregoing description and will therefore not be discussed further herein. 
     Many modifications and other embodiments of the invention will come to the mind of one skilled in the art having the benefit of the teachings presented in the foregoing descriptions and the associated drawings. Therefore, it is understood that the invention is not to be limited to the specific embodiments disclosed, and that modifications and embodiments are intended to be included within the scope of the appended claims.