Abstract:
A warewash machine for washing wares includes a chamber for receiving wares, the chamber having at least one wash zone with an associated spray system for spraying liquid onto wares passing therethrough, wherein a downstream drying zone includes a blower for blowing air onto wares passing therethrough. The blower includes an ambient intake operatively connected to an ambient air flow path, a machine intake operatively connected to an internal machine air flow path and an exhaust intake operatively connected to a machine exhaust air flow path.

Description:
TECHNICAL FIELD 
       [0001]    This application relates generally to warewashers such as those used in commercial applications such as cafeterias and restaurants and, more particularly, to a drying system for such warewashers. 
       BACKGROUND 
       [0002]    Commercial warewashers commonly include a housing area which defines washing and rinsing zones for dishes, pots pans and other wares. In conveyor-type machines wares are moved through multiple different spray zones within the housing for cleaning (e.g., pre-wash, wash, post-wash (aka power rinse) and rinse zones). One or more of the zones includes a tank in which liquid to be recirculated for spraying is heated in order to achieve desired cleaning. 
         [0003]    Machines may also include a drying zone at the end of the ware path for drying wares as they exit the machine using a flow of heated air from a blower dryer. Generally, the blower dryer air temperatures T should be above a minimum threshold temperature Tmin and below a maximum threshold Tmax, where at least Tmin is desired to have the right temperature for drying and no more than Tmax is desired to ensure the wares are not too hot for handling and to avoid putting too much heat into the room. Blowing sufficient air over the wares helps both drying and the sheeting action of the final rinse water with or without rinse aid. Maintaining the air at desired conditions for drying can be difficult, given that some wares require different temperature air and/or air flows and/or air moisture levels for proper drying, while at the same time assuring that the wares exiting the machine are not too hot to the touch and/or that the drying air exiting the machine does not add too much heat to the ambient environment. 
         [0004]    It would be desirable to provide a warewasher drying system that is adaptable to different conditions. 
       SUMMARY 
       [0005]    In one aspect, a warewash machine includes a blower dryer system with air intake paths from each of the room, within the machine and from a machine exhaust flow path. 
         [0006]    In another aspect, a warewash machine for washing wares includes a chamber for receiving wares, the chamber having at least one wash zone with an associated spray system for spraying liquid onto wares passing therethrough, wherein a downstream drying zone includes a blower for blowing air onto wares passing therethrough. The blower includes an ambient intake operatively connected to an ambient air flow path, a machine intake operatively connected to an internal machine air flow path and an exhaust intake operatively connected to a machine exhaust air flow path. 
         [0007]    In another aspect, a warewash machine for washing wares includes a chamber for receiving wares, the chamber having at least one wash zone with an associated spray system for spraying liquid onto wares passing therethrough. The machine also has a downstream drying zone including a blower for blowing air onto wares passing therethrough. The blower includes multiple air intake flow paths for air from respective sources, wherein at least one air intake flow path is connected to receive air from a hot air exhaust flow path of the machine. 
         [0008]    In another aspect, a method of operating a blower dryer of a warewash machine involves: selectively and automatically adjusting intake flows to the blower dryer from each of an ambient room air flow path, an internal machine air flow path and a machine exhaust air flow path so as to achieve one or more characteristics of blower dryer output air. 
         [0009]    The details of one or more embodiments are set forth in the accompanying drawings and the description below. Other features, objects, and advantages will be apparent from the description and drawings, and from the claims. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]      FIG. 1  is a schematic side elevation of one embodiment of a warewasher; and 
           [0011]      FIG. 2  is a schematic depiction of an exemplary heat recovery system; 
           [0012]      FIG. 3  is schematic depiction of a machine with a blower dryer having multiple input paths; and 
           [0013]      FIG. 4  is a schematic depiction of the multiple input flow paths. 
       
    
    
     DETAILED DESCRIPTION 
       [0014]    Referring to  FIG. 1 , an exemplary conveyor-type warewash machine, generally designated  10 , is shown. Warewash machine  10  includes a housing  11  that can receive racks  12  of soiled wares  14  from an input side  16 . The wares are moved through tunnel-like chambers from the input side toward a blower dryer unit  18  at an opposite exit end  17  of the warewash system by a suitable conveyor mechanism  20 . Either continuously or intermittently moving conveyor mechanisms or combinations thereof may be used, depending, for example, on the style, model and size of the warewash system  10 . Flight-type conveyors in which racks are not used are also possible. In the illustrated example, the racks  12  of soiled wares  14  enter the warewash system  10  through a flexible curtain  22  into a pre-wash chamber or zone  24  where sprays of liquid from upper and lower pre-wash manifolds  26  and  28  above and below the racks, respectively, function to flush heavier soil from the wares. The liquid for this purpose comes from a tank  30  and is delivered to the manifolds via a pump  32  and supply conduit  34 . A drain structure  36  provides a single location where liquid is pumped from the tank  30  using the pump  32 . Via the same drain structure, liquid can also be drained from the tank and out of the machine via drain path  37 , for example, for a tank cleaning operation. 
         [0015]    The racks proceed to a next curtain  38  into a main wash chamber or zone  40 , where the wares are subject to sprays of cleansing wash liquid (e.g., typically water with detergent) from upper and lower wash manifolds  42  and  44  with spray nozzles  47  and  49 , respectively, these sprays being supplied through a supply conduit  46  by a pump  48 , which draws from a main tank  50 . A heater  58 , such as an electrical immersion heater provided with suitable thermostatic controls (not shown), maintains the temperature of the cleansing liquid in the tank  50  at a suitable level. Not shown, but which may be included, is a device for adding a cleansing detergent to the liquid in tank  50 . During normal operation, pumps  32  and  48  are continuously driven, usually by separate motors, once the warewash system  10  is started for a period of time. 
         [0016]    The warewash system  10  may optionally include a power rinse (also known as post-wash) chamber or zone (not shown) that is substantially identical to main wash chamber  40 . In such an instance, racks of wares proceed from the wash chamber  40  into the power rinse chamber, within which heated rinse water is sprayed onto the wares from upper and lower manifolds. 
         [0017]    The racks  12  of wares  14  exit the main wash chamber  40  through a curtain  52  into a final rinse chamber or zone  54 . The final rinse chamber  54  is provided with upper and lower spray heads  56 ,  57  that are supplied with a flow of fresh hot water via pipe  62  running from a hot water booster  70  under the control of a solenoid valve  60  (or alternatively any other suitable valve capable of automatic control). A rack detector  64  may be actuated when a rack  12  of wares  14  is positioned in the final rinse chamber  54  and through suitable electrical controls (e.g., the controller mentioned below), the detector causes actuation of the solenoid valve  60  to open and admit the hot rinse water to the spray heads  56 ,  57 . The water then drains from the wares and is directed into the tank  50  by gravity flow. The rinsed rack  12  of wares  14  then exits the final rinse chamber  54  through curtain  66 , moving into dryer unit  18 , before exiting the outlet end  17  of the machine. 
         [0018]    An exhaust system  80  for hot moist air may be provided. A cold water input  72  line may run through a waste heat recovery unit (not shown in  FIG. 1 ) associated with the exhaust to recover heat from the exhaust air. Other heat recovery components may also be employed. By way of example, the heat recovery system shown in  FIG. 2  may be employed.  FIG. 2  shows a machine using a refrigeration or heat pump system to constantly recover waste heat from exhaust for reuse. As shown, the cold water input  72  line may run through a waste heat recovery unit  82  (e.g., a fin-and-tube heat exchanger through which the incoming water flows, though other variations are possible) located in the exhaust air flow path to recover heat from the exhaust air flowing across and/or through the unit  82 . The water line or flow path  72  then runs through one or more condensers  84  (e.g., in the form of plate heat exchangers or shell-and-tube heat exchangers, though other variations are possible), before delivering the water to a booster (not shown) for final heating. Additional condensers  86  and  88  may be provided and could be in heat exchange relationship with other machine fluids (e.g., located in the wash tank of the machine). A second waste heat recovery unit  92  may also be provided in the exhaust path. Exhaust blower  81  drives air flow across the heat recovery units. 
         [0019]    The flow configuration for both incoming fresh cold water and for refrigerant are shown in  FIG. 2 . Cold fresh water delivered via a variable flow control pump  60 ′ (or alternatively by the valve  60  of  FIG. 1 ) is first heated by the hot air passing through the waste heat recovery unit  82  (e.g., per arrows  83 ,  85 ), then heated further by refrigerant when passing through condenser  84 . The refrigerant medium circuit  100  includes a thermal expansion valve  101 , which leads to waste heat recovery unit  92  to recover heat from warm waste air (e.g., the exhaust air flow indicated by arrows  85 ,  87 ) after some heat has already been removed from the exhaust air flow by unit  82 . A compressor  102  compresses the refrigerant to produce superheated refrigerant, which then flows sequentially through the condensers  86 ,  88 , and  84 . 
         [0020]    In practice, when the energy requirement in one or more of the condensers  84 ,  86 ,  88  is satisfied, the system requires the other condensers to utilize the recovered energy, which is almost constant. In the situation of one or more condensers being energy satisfied during operation, excess heat results in the refrigeration circuit, which in turn results in high blower dryer air temperatures (e.g., because waste heat recovery unit  92  does not remove a desired level of heat from the exhaust air stream, which air stream contributes to the blower dryer air flow). In such cases operators may be undesirably exposed to hot blower dryer air and handling of very hot ware at the unloading side of the machine during and after drying. 
         [0021]    In addition to excessive heat conditions, as a general rule different wares require different blower air temperatures and flowrates for effective drying. Thus, the blower dryer system described herein can be used in both warewashers including heat recovery systems such as that of  FIG. 2 , and warewashers that do not include heat recovery systems. 
         [0022]    Referring to  FIGS. 3 and 4 , the blower dryer system  18  includes an ambient air intake  120  from the room and an air intake  122  from internal of the machine. Portions of the exhaust air may also be blended in via intake  124  in order to make use of the heat in the exhaust air. The air from the machine (e.g., from within the tunnel defined by the machine housing) in most cases has higher temperature and humidity compared with the ambient air of the surrounding room. If a constant blower heater system were employed, the lower the blower dryer intake air temperature the lower the blower output air temperature and vice versa. However, the higher the humidity the increased chance of wet wares exiting the machine. Blending of the blower air intakes  120 ,  122  and/or  124  can be used to achieve desired objectives for the blower output  126  to meet ware dryness and ware temperature (e.g., the blower air temperature, humidity and air flow rate for the ware type and size). Although a variable blower heater could be used to maintain or control the blower air output condition, the inventive blending of the various available intakes leads to energy savings given the various air intake and output conditions desired for different wares. 
         [0023]    The blower dryer system  18  can blend room air, hot air from within the machine and machine exhaust from the various intakes  120 ,  122  and  124  based at least in part upon one or more output characteristics of the blower dryer output air  126 . Such characteristics may include blower output air temperature (T), airflow rate (M), humidity (H) and energy (Q) (e.g., as detected by one or more output air sensors  146 ) and ware dryness or temperature (Tw of ware rack  12 ). The blower intakes (i.e., room intake air, machine intake air, and machine exhaust) can be controlled manually (e.g., where intake flow control valves  130 ,  132  and  134  are manual) or automatically (e.g., where intake flow control valves  130 ,  132  and  134  are automated under control of a controller  200 ) to achieve the right blower output using manual or automatic baffles or valves. The machine exhaust at intake  124  may be colder or hotter depending on the type of warewash machine (e.g., with our without energy recovery, respectively). In some cases all the exhaust may be channeled to blower intake depending on the ware type or material, or during startup or machine operation to balance the machine to achieve the right blower air temperature and airflow for the necessary ware dryness. 
         [0024]      FIG. 4  shows individual blower air intakes with respective air flow temperatures T 1 , T 2 , T 3 , humidity or air quality H 1 , H 2 , H 3  and energy Q 1 , Q 2 , Q 3  available to be blended in different proportions (e.g., controllable flow rates M 1 , M 2 , M 3 ), all of which may be detected by one or more respective intake air sensors  140 ,  142 ,  144 , to achieve a desired blower output air characteristic of M, T, H and/or Q. Controlling blower output temperature and energy to desired levels could mean lower or higher intake air temperature is required to assure that the blower output temperature T is within and acceptable range of the desired temperature (e.g., as set by minimum and maximum thresholds of Tmin and Tmax, such that Tmin≦T≦Tmax). Both Tmin and Tmax at a constant blower fan rate are associated with an energy range (e.g., Qmin≦Q≦Qmax). Qmin pertains to wares that require minimal heat or energy for drying while Qmax pertains to wares that require more heat or energy for drying. 
         [0025]    From  FIG. 4  the following relationships between the individual blower intakes and the blower output hold: 
         [0000]    
       
         
           
             
               
                 
                   M 
                   = 
                   
                     
                       M 
                        
                       
                           
                       
                        
                       1 
                     
                     + 
                     
                       M 
                        
                       
                           
                       
                        
                       2 
                     
                     + 
                     
                       M 
                        
                       
                           
                       
                        
                       3 
                     
                   
                 
               
               
                 
                   ( 
                   1 
                   ) 
                 
               
             
             
               
                 
                   Q 
                   = 
                   
                     
                       M 
                        
                       
                           
                       
                        
                       1 
                        
                       T 
                        
                       
                           
                       
                        
                       1 
                     
                     + 
                     
                       M 
                        
                       
                           
                       
                        
                       2 
                        
                       T 
                        
                       
                           
                       
                        
                       2 
                     
                     + 
                     
                       M 
                        
                       
                           
                       
                        
                       3 
                        
                       T 
                        
                       
                           
                       
                        
                       3 
                     
                   
                 
               
               
                 
                   ( 
                   2 
                   ) 
                 
               
             
             
               
                 
                   
                     Q 
                     = 
                     
                       
                         Q 
                          
                         
                             
                         
                          
                         1 
                       
                       + 
                       
                         Q 
                          
                         
                             
                         
                          
                         2 
                       
                       + 
                       
                         Q 
                          
                         
                             
                         
                          
                         3 
                       
                     
                   
                   , 
                   
                     
 
                   
                    
                   
                     
                       where 
                        
                       
                           
                       
                        
                       Qi 
                     
                     = 
                     
                       
                         MiTi 
                          
                         
                             
                         
                          
                         and 
                          
                         
                             
                         
                          
                         Q 
                       
                       = 
                       
                         
                           ∑ 
                           1 
                           n 
                         
                          
                         MiTi 
                       
                     
                   
                   , 
                 
               
               
                 
                   ( 
                   3 
                   ) 
                 
               
             
           
         
       
     
         [0000]    with i representing the various individual blower intake and “n” the number of intakes. 
         [0026]    Equation (2) provides the relation between the various blower intake airflow Mi and intake airflow temperatures Ti to achieve the right blower output energy Q. This equation assures that the various ratios of the air intake flow maintain Q within an acceptable range of a desired level (e.g., per Qmin and Qmax, where Qmin≦Q≦Qmax). Generally, it is desired that the air intake  122  from the machine area in  FIG. 4  be used, when possible, in the minimum needed to conserve energy in the machine. 
         [0027]    To maintain the blower dryer output air energy Q, either the blower output air M increases with low T to maintain Q, which means more of the colder air intake needs to be used, or M is decreased with high T to maintain Q, which means less of the hot air intake needs to be used. 
         [0028]    However, there are special cases where Q may need to be below Qmin (Q&lt;Qmin) for drying thermally liable or sensitive wares and/or materials or Q may need to be above Qmax (Q max) for drying some ware types, sizes and/or materials; in these cases either both M and T could be increased or M increased at constant T or T increased at constant M. In most cases, the heating source  160  for the blower dryer is operated at a constant level. The various relations involving temperature T, airflow M, humidity or air quality H, energy Q, etc. and combinations such as heat index in addition to Equation (1), (2) and (3) are applicable. 
         [0029]    In an exemplary automatic drying system, all the individual intake blower air conditions (temperature Ti, airflow Mi, humidity Hi) as well as the blower output conditions temperature T, airflow M, humidity H may be sensed for decision making Qi corresponds to the energy of the various intake air sources and Q corresponds to the blower output air calculated using Equation (2). The ware will be sensed (e.g., type and size) and the size used to regulate the blower output conditions such as temperature T, airflow M, humidity H to meet the need including, dryness of the ware; light ware vs heavy wares which require less or more blower output air, respectively; thermally liable ware or heavy wares which require less or more heat, respectively; situations where the blower has to be in a range to satisfy Qmin&lt;Q&lt;Qmax or outside the range to meet the requirement of Q&lt;Qmin and Q&gt;Qmax. The ware size and/or type, and the detected blower output temperature T, airflow M, humidity H, can be used to control the individual intakes  120 ,  122 ,  124  to keep the outputs within specified ranges or levels. This means that various intake combinations may be used. 
         [0030]    Components  130 ,  132   134  (e.g., in the form automatic valves as suggested above, or controllable baffles or other flow control structure) are used to control the individual intake air flowrates, e.g., as controlled by a controller  200  that is also connected to sensors  140 ,  142 ,  144  and  146 . As used herein, the term controller is intended to broadly encompass any circuit (e.g., solid state, application specific integrated circuit (ASIC), an electronic circuit, a combinational logic circuit, a field programmable gate array (FPGA)), processor (e.g., shared, dedicated, or group—including hardware or software that executes code) or other component, or a combination of some or all of the above, that carries out the control functions of the machine or the control functions of any component thereof. 
         [0031]    In an alternative embodiment, manual controlling or adjusting of the baffles/valves to achieve the blower output requirement given the type of ware, balancing machine, etc. may be implemented. In this case, components  130 ,  132 ,  134  represent manual valves or baffles used to control the individual airflow rates. 
         [0032]    Dryer systems according to the above concept(s) may provide one or more of: (1) variable air intake conditions with constant or fixed blower dryer heater energy to meet the need; constant or fixed air intake conditions with variable blower dryer heater energy to meet the need; (2) sensing individual blower intake air conditions (temperatures T 1 , T 2 , T 3 , airflows M 1 , M 2 , M 3 , humidity levels H 1 , H 2 , H 3 ) corresponding to energies Q 1 , Q 2 , Q 3 , as well as the blower output temperature T, airflow M, humidity H corresponding to energy Q for decision making to control the individual blower air intakes to achieve any of: Qmin≦Q≦Qmax (normal range), Q&lt;Qmin (for thermally liable ware or material), Q&gt;Qmax (for heavier ware), comparing the various individual intake air conditions to make decisions on what intake proportions to use to meet the objectives (e.g., including dryness, light ware wanting less blower output air, heavy wares which could handle higher blower air output for dryness, thermally liable ware or material wanting low blower output temperature, heavy ware wanting less blower output air and the combinations); (3) sensing ware type and size (e.g., per ware type and/or size sensor  150 ) for decisions that establish whether to control the intakes according to Qmin≦Q≦Qmax, Q&lt;Qmin or Q&gt;Qmax; (4) variable blower output based on lightness of the ware; (5) sensing humidity of the blower output to increase the airflow of the hottest intake to result in drier ware or increase the blower heater energy to dry the air; and/or (6) system use to enhance machine adaptation to the various operational phases (e.g., initial start-up, continuous operation and start-up from idling). 
         [0033]    It is to be clearly understood that the above description is intended by way of illustration and example only and is not intended to be taken by way of limitation, and that changes and modifications are possible. Accordingly, other embodiments are contemplated and modifications and changes could be made without departing from the scope of this application.