HEAT EXCHANGER WATER HEATING SYSTEM FOR COMMERCIAL DISHWASHER

• US 20110048342A1
• Filed: 09/03/2009
• Published: 03/03/2011
• Est. Priority Date: 09/03/2009
• Status: Active Grant

• Current Assignee: Ali Group North America Corporation (Ali Holding Srl)
• Original Assignee: Champion Industries, Inc. (Bessemer Group Incorporated)
• Inventors: Vroom, Robert C.
• Granted Patent: US 8,770,154 B2
• Time in Patent Office: Days
• US Class Current: 122/367.1
• CPC Class Codes: A47L 15/241 the dishes moving in a horizontal plane
• CPC Class Codes: A47L 15/4285 Water-heater arrangements steam generating arrangements A47L15/4234
• CPC Class Codes: A47L 15/4291 Recovery arrangements, e.g. for the recovery of energy or water
• CPC Class Codes: A47L 2401/12 Water temperature
• CPC Class Codes: A47L 2501/01 Water supply, e.g. opening or closure of the water inlet valve
• CPC Class Codes: F22B 1/28 in boilers heated electrically superheating using an electrical heat source independent from heat supply of the steam boiler F22G1/165

Abstract

A multi-chamber conveyor type dishwasher uses a heat recovery unit (HRU) to heat water for a final rinse chamber during a preheat and/or dishwashing phase. The HRU heats water supplied by a low temperature water source using the dishwasher'"'"'s hot vapor exhaust. An input supply of water for a downstream booster heater is varied based on a sensed temperature of the HRU'"'"'s output water. If the temperature is acceptable, the HRU supplies input water to the booster heater for the rinse chamber. When the temperature drops below a threshold, the controller temporarily bypasses the HRU and supplies water to the booster heater from a high temperature water source. The HRU may be primed during a preheat phase using water from the high temperature water source. An amount of fan force used to pull the hot exhaust vapors through the HRU may vary based on the status of the dishwasher.

Claims

1. A method of heating water for a commercial dishwasher, the method comprising:

supplying water from a low temperature external water source to a heat recovery unit;

heating the water flowing through the heat recovery unit using heat recovered from hot vapors exhausted by the dishwasher routed into the heat recovery unit; and

selecting an input water supply for a booster heater downstream from the heat recovery unit based on a sensed temperature of the water at the output of the heat recovery unit;

wherein the heat recovery unit supplies the input water to the booster heater in response to the sensed temperature meeting or exceeding a threshold; and

wherein a high temperature external water source that meets or exceeds the threshold bypasses the heat recovery unit and supplies the input water to the booster heater in response to the sensed temperature being less than the threshold.

2. The method of claim 1 wherein heating the water flowing through the heat recovery unit comprises activating a plurality of fans to pull the hot vapors exhausted by the dishwasher across a heat exchanger in the heat recovery unit while flowing the water supplied by the low temperature external water source through the heat exchanger.

3. The method of claim 1 further comprising disconnecting the high temperature external water source from the booster heater and reconnecting the booster heater to the heat recovery unit and the low temperature external water source to supply the input water from the heat recovery unit to the booster heater upon expiration of a bypass timer.

4. The method of claim 1 further comprising conducting heat from the dishwasher to the heat recovery unit by disposing at least part of the heat recovery unit in direct contact with the dishwasher.

5. The method of claim 1 further comprising, priming the heat recovery unit during a preheat phase by activating a first number of fans to pull hot vapors exhausted by the dishwasher across the heat exchanger.

6. The method of claim 5 wherein heating the water flowing through the heat recovery unit comprises activating a second number of fans greater than the first number of fans upon completion of the preheat phase to pull the hot vapors exhausted by the dishwasher across the heat exchanger while flowing the water supplied by the low temperature external water source through the heat exchanger.

7. The method of claim 1 further comprising, during a preheat phase occurring prior to said supplying water from the low temperature external water source, routing water from the high temperature external water source through a heat exchanger of the heat recovery unit.

8. A heating system for a commercial dishwasher, comprising:

a heat recovery unit comprising a heat exchanger disposed in a housing, said heat recovery unit configured to heat water supplied by a low temperature external water source to the heat recovery unit using hot vapors exhausted by the dishwasher into the heat recovery unit;

a temperature monitor to sense a temperature of the water at an output of the heat recovery unit;

a booster heater having an input selectively connected to one of the output of the heat recovery unit and a high temperature external water source that supplies water at a temperature that meets or exceeds a temperature threshold;

a controller configured to control the flow of the water supplied by the low temperature and high temperature water sources through the heating system, the controller configured to;

supply the water from the low temperature external water source to the heat recovery unit and supply the water output by the heat recovery unit to the booster heater in response to the sensed temperature of the water output by the heat recovery unit meeting or exceeding the threshold; and

bypass the heat recovery unit and supply water from the high temperature external water source to the booster heater in response to the sensed temperature of the water output by the heat recovery unit being less than the threshold.

9. The heating system of claim 8 wherein the heat recovery unit further comprises a plurality of fans configured to pull the hot vapors exhausted by the dishwasher across the heat exchanger while water supplied by the low temperature external water source flows through the heat exchanger.

10. The heating system of claim 8 wherein the controller is further configured to disconnect the booster heater from the high temperature external water source and reconnect the booster heater to the heat recovery unit and the low temperature external water source upon expiration of a bypass timer.

11. The heating system of claim 8 wherein the heat recovery unit further comprises a plurality of fans;

wherein the controller is further configured to prime the heat recovery unit during a preheat phase by activating a first number of the fans less than all the plurality of fans to pull the hot vapors exhausted by the dishwasher across the heat exchanger.

12. The heating system of claim 8 wherein the controller is further configured to prime the heat recovery unit during a preheat phase by routing water supplied by the high temperature external water source through the heat exchanger.

13. A method of heating water for a commercial dishwasher, the method comprising:

routing water supplied by a high temperature external water source through a heat recovery unit during a preheat phase; and

upon completion of the preheat phase, flowing water supplied by a low temperature external water source into a heat exchanger, and heating the water flowing through the heat exchanger using heat recovered from hot vapors exhausted by the dishwasher into the heat recovery unit.

14. The method of claim 13 further comprising activating at least one fan to pull hot vapors exhausted by the dishwasher across the heat exchanger to increase the temperature of the heat exchanger during the preheat phase.

15. The method of claim 14 further comprising activating additional fans upon completion of the preheat phase to pull the hot vapors exhausted by the dishwasher across the heat exchanger.

16. A heating system for heating water for a commercial dishwasher, comprising:

a heat recovery unit comprising a heat exchanger; and

a controller configured to;

route water supplied by a high temperature external water source through said heat exchanger during a preheat phase; and

upon completion of the preheat phase, flow water from a low temperature external water source into the heat exchanger to heat the water flowing through the heat exchanger using heat recovered from hot vapors exhausted by the dishwasher into the heat recovery unit.

17. The heating system of claim 16 wherein the heat recovery unit further comprises a plurality of fans, and wherein the controller is further configured to activate less than all of the fans during the preheat phase to pull hot vapors exhausted by the dishwasher across the heat exchanger.

18. The heating system of claim 17 wherein the controller is further configured to activate additional fans upon completion of the preheat phase to pull the hot vapors exhausted by the dishwasher across the heat exchanger.

19. A method of heating water for a commercial dishwasher, the method comprising:

pulling, by a first number of fans, hot vapors exhausted by the dishwasher across a heat exchanger in a heat recovery unit to increase the temperature of the heat exchanger during a preheat phase; and

upon completion of the preheat phase, heating water flowing through the heat exchanger using heat recovered from hot vapors exhausted by the dishwasher into the heat recovery unit by pulling, by a second larger number of fans, the hot vapors exhausted by the dishwasher across the heat exchanger.