Patent Application
20120037185
A dish machine is a utility dishwasher used in many restaurants, healthcare facilities, and other locations to clean and sanitize cooking and eating articles, such as dishes, pots, pans, utensils and other cooking equipment. Articles are placed on a rack and provided to a wash chamber of the dish machine. In the chamber, cleaning products and/or rinse agents are applied to the articles during a cleaning process. The cleaning process may include one or more wash phases and one or more rinse phases. At the end of the cleaning process, the rack is removed from the wash chamber so that other racks carrying other articles to be cleaned may be moved into the wash chamber. The cleaning process is then repeated for each of these subsequent racks.
Dish machines that clean and disinfect dishes in industrial settings often consume large amounts of energy and resources to ensure the dishes are cleaned and sanitized to predetermined standards. However, demand for more energy-efficient products that offer savings on energy and other utility bills, without sacrificing performance or features, has been increasing.
In general, the disclosure is related to high efficiency dish machines and parameters for operation. The parameters may include, for example, wash water temperature, rinse water temperature, and/or rinse flow rate.
In one example, the disclosure is directed to a method of operating a dish machine, comprising storing a wash water temperature of between 160° F. and 164.5° F., storing a rinse water temperature of between 182° F. and 211° F., storing a rinse flow rate of between 0.4 gal/rack and 0.66 gal/rack, and operating the dish machine at the stored wash water temperature, the stored rinse water temperature, and the stored rinse flow rate. The stored wash water temperature may be approximately 162° F. The stored rinse water temperature may be approximately 187° F. The stored rinse flow rate may be approximately 0.57 gal/rack.
In another example, the disclosure is directed to a dish machine, comprising a wash tank sized to receive articles to be washed, a computer readable medium that stores one or more dish machine operating parameters, wherein the dish machine operating parameters include at least one of a wash water temperature of between 160° F. and 164.5° F., a rinse water temperature of between 182° F. and 211° F., and a rinse flow rate of between 0.4 gal/rack and 0.66 gal/rack, and a processor that controls operation of the dish machine based on the one or more dish machine operating parameters. The dish machine may be a single tank conveyer dish machine. The wash water temperature may be approximately 162° F. The rinse water temperature may be approximately 187° F. The rinse flow rate may be approximately 0.57 gal/rack.
In another example, the disclosure is directed to an apparatus comprising a single wash tank sized to receive articles to be washed during a cleaning process, a conveyor that moves articles through the single wash tank, a dispense module that applies one or more chemical products into the wash tank at appropriate times during the cleaning process, one or more wash arms that deliver water and/or one or more of the chemical products into the wash tank during the cleaning process, a sump positioned to capture and hold liquid drained from the wash tank during the cleaning process, a computer readable medium that stores one or more dish machine operating parameters, wherein the dish machine operating parameters include at least one of a wash water temperature of between 160° F. and 164.5° F., a rinse water temperature of between 182° F. and 211° F., and a rinse flow rate of between 0.4 gal/rack and 0.66 gal/rack, and a dish machine controller that monitors and controls the one or more dish machine operating parameters during the cleaning process.
The details of one or more examples are set forth in the accompanying drawings and the description below. Other features will be apparent from the description and drawings, and from the claims.
Systems and methods are described that provide optimized operation of a high efficiency dish machine. The dish machines described in this application are generally of the type referred to as a “single tank conveyor” machine. However, it shall be understood that the techniques described herein may also be applied to other types of high efficiency dish machines, such as under counter dish machines, stationary single tank door machines, multiple tank conveyor machines, or other type of dish machine, and that he disclosure is not limited in this respect.
The dish machine 100 includes a housing 110 defining a wash chamber 108. The housing includes an entry door 114 and an exit door 116. The wash chamber 108 may be supported above ground level by a plurality of legs 144. In operation, each article rack 104 carries one or more articles to be washed by the dish machine 100 into the wash chamber 108 through entry door 114. A conveyor 106 moves the article racks 104 through dish machine 100. Arrows 118 show the direction of article racks 104 through the wash chamber 108 in this example. Article racks 104 leave the dish machine 100 through exit door 116. Entry door 114 and exit door 116 may be uncovered openings, openings covered by curtain-type panels or may be hinged or sliding doors that fully or partially open and close, or other appropriate covering for doors 114 and/or 116.
Dish machine 100 includes a dispense module 102 that dispenses one or more chemical agents, such as one or more cleaning agent(s), one or more rinse agent(s), and/or other chemical products into wash tank 108 at appropriate times during the cleaning process. In this example, dispense module 102 is shown as being located near the top of the inside of the wash chamber 108. However, it shall be understood that dispense module 102 may be located above or below the wash chamber, or at the bottom or side of the wash chamber, and that the disclosure is not limited in this respect.
Dish machine 100 may include one or more sumps 146 positioned underneath the wash chamber 108 in a sump compartment 140. The sump(s) 146 capture and hold liquid drained from the wash chamber 108. A drain 154 is positioned adjacent to the wash sump 146. The height of the drain 154 is less than the height of the wash sump 146 such that the cleaning agent contained in the wash sump 146 overflows into the drain 154. The drain 154 is fluidly connected to a receptacle for communicating fluids to a chemical waste system, such as a septic tank or sewer.
Various operations of the dish machine 100 may be controlled and monitored by a dish machine controller 112. Dish machine controller 112 includes a processor, memory and appropriate programmed software or firmware modules that control and monitor various tasks administered by the dish machine 100 during operation. Dish machine controller monitors and controls dish machine operating parameters, such as wash water temperature, rinse water temperature, and rinse flow rate, during a cleaning process. Dish machine controller 112 may also include various sensors and/or may receive information from various sensors associated with the dish machine. For example, in response to detecting initiation of a wash phase for each rack 104 provided to the dish machine 100, controller 112 may control dispensing of chemical product(s) used during the wash phase(s). Similarly, in response to detecting initiation of a rinse phase, controller 112 may control dispensing of any chemical product(s) used during the rinse phase(s). Controller 112 may also control, for example, the times at which the various wash and/or rinse phases are to occur during a wash cycle; the length of the wash and/or rinse phases; the temperature of the water applied during the wash and/or rinse phases; the times at which chemical products and/or water are dispensed into wash chamber 108 or into sump(s) 146; the concentration of chemical product in the one or more sump(s) 146; periodic emptying of the sump(s) 146; operation of one or more wash arms 109 or other mechanism through which water and/or chemical product(s) are dispensed into the wash chamber or into sump(s) 146; operation of a conveyor; and any other processes in the wash machine that may be electronically controlled.
Dish machine 100 may include one or more display devices or modules, such as, first, second and third status indicators 124, 125 and 126, e.g., light emitting diodes (LED's), and/or a graphical user interface 122, for example. Interface 122 may be used to input commands into the controller 112. Interface 122 provides a computer-assisted means through which operators can set up and deploy the dish machine 100 into operation in an intended service environment, such as, for example, a restaurant, a hotel, etc.. It should be appreciated that any conventional interface (e.g., touch-screen interfaces, mouse-based interfaces, keyboard-based interfaces, etc.) may be used, and that the disclosure is not limited in this respect. Furthermore, the GUI 122 and the first, second and third status indicators 124, 125 and 126 may provide operators with functionality to monitor operation of the dish machine 100 by displaying information relating to the various tasks that are controlled and monitored by the controller 112.
For example, the first, second and third status indicators 124, 125 and 126 may indicate the current operational status of the dish machine 100 (e.g., wash phase, rinse phase, final rinse phase, etc.). However, it shall be appreciated that more or fewer status indicators, or other types of indicators, such as audible or visual alerts, may be used for any other purpose related to operation of the dish machine 100.
Controller 112 may also store optimized dish machine operating parameters that may result in increased energy efficiency and reduced utility costs. A dish machine 100 using such optimized dish machine parameters may meet the definition of a “high efficiency” dish machine. In general, the term “high efficiency” dish machine as used herein means a dish machine that meets the specifications required to achieve ENERGY STAR status. ENERGY STAR is a joint program of the U.S. Environmental Protection Agency (EPA) and the U.S. Department of Energy. Products can earn the ENERGY STAR label by meeting the energy efficiency requirements set forth in ENERGY STAR product specifications established by the EPA. These specifications may be revised from time to time. Currently, the requirements to achieve ENERGY STAR status for a single tank conveyor machine are shown in Table 1.
The optimized dish machine operating parameters may include, for example, a wash water temperature (or “wash temperature”), a rinse water temperature (or “rinse temperature), and a rinse flow rate. Operation of a single tank conveyor machine, such as machine 100 shown in
For example, experiments (described below) indicate that the optimized parameters for a single tank conveyor type dish machine (such as that shown in
A series of experiments were designed to investigate and optimize three dish machine design parameters: wash water temperature, rinse water temperature, and rinse flow rate to achieve superior results at a set food soil and detergent concentration. The tests were executed as a designed experiment with three factors (wash water temperature, rinse water temperature, and rinse flow rate) and two levels (high and low). The levels for each factor are given in Table 2.
In this example and as described below, the overall results of the experiments showed the dish machine parameters that achieved the best cleaning performance include a wash water temperature of approximately 160°, a rinse water temperature of approximately 187° F., and a rinse flow rate of approximately 0.57 gal/rack. Follow up testing revealed that further increasing of the rinse water temperature improved results when a higher food soil concentration (4500 ppm) was present in the wash tank, but did not improve results at lower food soil concentrations (2000 ppm).
Glasses were tested to determine the impact of wash water temperature, rinse water temperature, and rinse flow rate. The glasses were prepared by first cleaning them. During the test, a concentration of 1200 ppm (8 T1 drops) detergent and a concentration of 2000 ppm food soil (⅔ beef stew, ⅓ potato buds) was maintained in the wash tank throughout the test. The results were analyzed by visual grading of coated (dipped in whole milk and allowed to dry) and redeposit (not coated) glasses. For the actual test, the glasses were run for one wash cycle. Following the wash cycle, the glasses that had been dipped in whole milk were redipped and allowed to dry and then returned to the dish machine and all glasses were then sent through the wash cycle again. This was repeated until a number of cycles were run. After a number of cycles, the wash water was retested to make sure the proper level of detergent was present. Then the entire process was repeated. The glasses were allowed to dry overnight and then visually graded for film accumulation and spotting. The film accumulation was caused by the presence of milk fat residue on the glasses and redeposition of the food soil on the glasses.
The glasses were given a film and spot score ranging from 1-5 (1 being the best score and 5 being the worst score). The average of the scores were compiled for each run. In general, relatively better cleaning performance is indicated by a relatively lower Total Score. Table 3 shows the test parameters and average score data for each run.
Coated Film—Low Rinse Water temperature
Based on the experimental results discussed above, optimized wash water temperature, rinse water temperature, and rinse flow rate may be determined. For example, a desirability score (right-most column of Table 4, below) may be used to indicate how near the desired output (that is minimized spot and film scores indicative of relatively better cleaning performance) the conditions are predicted to achieve. In this example, the desirability score is scaled from 0 to 1. In general, the nearer the desirability score is to 1, the better the conditions are able to produce the desired results (minimized film and spot scores).
In another example, the dish machine parameters may be optimized by weighting the film, spot, and redeposit scores, indicating a degree of importance for each response. For example, by giving spots an importance of 5 (highest importance), film scores an importance of 1 (lowest importance), and Total (the sum of all the average scores) an importance of 3 (medium importance), the optimized dish machine settings shown in Table 5 were generated.
In general, these tests determined that optimized parameters for operating a single tank conveyor type dish machine may include a wash temperature of 160° F., a rinse temperature of 187° F., and a rinse flow rate of 0.57 gal/rack.
Two additional experiments were run to follow up and confirm the results of the designed experiment described above. The first follow up experiment was a ten cycle using the example optimized wash temperature (160° F.) and rinse flow rate (0.57 gal/rack) with an increased rinse temperature of 195° F. The second follow up experiment was a ten cycle using the example optimized wash and rinse temperatures (160° F. and 187° F., respectively) with a decreased rinse flow rate of 0.5 gal/rack. The test conditions for the first experiment were 1200 ppm of detergent and 2000 ppm of food soil. The first follow up experiment was then repeated with higher food soil concentration (4500 ppm). The conditions for the second follow up experiment were 2550 ppm and 4500 ppm food soils. The results of these experiments are summarized in Table 6, along with the baseline experiments for comparison. The sum of the averages in the following table is the average total score of two runs.
In this example, the results of the follow up testing revealed that increasing the temperature of the rinse beyond 187° F. did not improve performance when using lower food soil concentration. However, it did improve performance when the food soil concentration was increased.
Additionally, the results of the follow up testing showed that further lowering of the rinse flow rate improved ten cycle test results. One possible explanation for this result is that the lower rinse flow rate may have left more residual detergent on the glassware, which may have reduced spotting due to the residual surfactant. Follow up tests on the detergent carryover were run, but did not appear to reveal any more detergent carryover than was seen with the 0.57 gal/rack flow rate. This study suggests that optimized parameters for a single tank conveyor type dish machine (such as that shown in
In another example, optimized ranges for one or more of the operating parameters (wash water temperature, rinse water temperature, and/or rinse flow rate) may be determined. For example, optimized ranges (listed below in Table 7) for each of the three operating parameters (wash water temperature, rinse water temperature, and rinse flow rate) were compiled using a statistical model based on the designed experiments discussed above. In this example, the model predicted the results based on all the input variables. The model was reiterated until a decrease in performance by 10% was reached (so essentially, at the maximum and minimum in Table 6 the results will be 10% worse than the optimal conditions.
The data of Table 7 indicates that optimized parameters for a single tank conveyor type dish machine (such as that shown in
Processor 220 controls operation of the dish machine by opening valves at predetermined times, heating water to predetermined temperatures, applying water to the wash tank at predetermined times and at predetermined wash and/or rinse flow rates, causing chemical product to be dispensed at predetermined times during the wash or rinse cycles, etc. To do so, processor 220 controls the various pumps, valves, chemical dispensers, dish machine arms, and other components of the dish machine via input/output lines, indicated generally by I/O line 228.
User interface 122 may be used to input commands into the controller 112, or to display data, text, or other instructions to a service technician or other user. First, second, and third status indicators 124, 125, and 126, respectively, may indicate the current operational status of the dish machine (e.g., wash phase, rinse phase, final rinse phase, etc.), for example.
In some examples, one or more of the parameters may be set by a service technician via a user interface such as user interface 122 shown in
Referring again to
In some examples, control of a dish machine may encompass one or more computer-readable media comprising instructions that cause a processor, such as microcontroller 30, to carry out the methods described above. A “computer-readable medium” includes but is not limited to read-only memory (ROM), random access memory (RAM), non-volatile random access memory (NVRAM), electrically erasable programmable read-only memory (EEPROM), flash memory a magnetic hard drive, a magnetic disk or a magnetic tape, a optical disk or magneto-optic disk, a holographic medium, or the like. The instructions may be implemented as one or more software modules, which may be executed by themselves or in combination with other software. A “computer-readable medium” may also comprise a carrier wave modulated or encoded to transfer the instructions over a transmission line or a wireless communication channel.
The instructions and the media are not necessarily associated with any particular computer or other apparatus, but may be carried out by various general-purpose or specialized machines. The instructions may be distributed among two or more media and may be executed by two or more machines. The machines may be coupled to one another directly, or may be coupled through a network, such as a local access network (LAN), or a global network such as the Internet.
Control of a dish machine may also be embodied as one or more devices that include logic circuitry to carry out the functions or methods as described herein. The logic circuitry may include a processor that may be programmable for a general purpose or may be dedicated, such as microcontroller, a microprocessor, a Digital Signal Processor (DSP), an Application Specific Integrated Circuit (ASIC), a field programmable gate array (FPGA), and the like.
One or more of the techniques described herein may be partially or wholly executed in software. For example, a computer-readable medium may store or otherwise comprise computer-readable instructions, i.e., program code that can be executed by a processor to carry out one of more of the techniques described above.
Various examples have been described. These and other examples are within the scope of the following claims.
This application claims the benefit of U.S. provisional Application Ser. No. 61/373,668 filed Aug. 13, 2010, the entire contents of which is incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| 61373668 | Aug 2010 | US |
