Emerging Technologies in the Dishroom: Exhaust-Air Heat Recovery. May 14 th, 2010 Presented by: Amin Delagah Project Engineer

Transcription

1 Emerging Technologies in the Dishroom: Exhaust-Air Heat Recovery May 14 th, 2010 Presented by: Amin Delagah Project Engineer

2 The Relationship of Hot Water Systems and Dishwashers Dishwashers consume 20% of the hot water used in a typical full-service restaurant. Operating cost of a dishwasher (water, energy, detergent) is approximately 50% of the total cost of the entire hot water system. Most dishwashers require: More complex distribution systems (recirc line) which reduces system efficiency Elevated outlet temperatures (+20 F) that increases the energy use of the hot water system Most high-temp dishwashers require exhaustventilation systems

3 Energy Flow Diagram Heater and distribution system: ¼ heat lost Exhaust air: ¼ heat lost Diagram is not accounting for the energy used to operate the exhaust ventilation system or dishwasher 140 F 180 F Heat lost to dishes 65 F Water heater: 2/3 energy input Electric booster and wash tank heater: 1/3 energy input Drain water: ½ heat lost

4 Utilizing Exhaust-Air Heat Recovery Exhaust-air heat recovery (EAHR) is the most accepted strategy used to preheat incoming cold water Heat pumps can be utilized as a second level of heat recovery to additionally increase the temperature of preheated water May eliminate the need for dedicated exhaust ventilation system Exhaust-Air Temperature without EAHR 110 to 130 F with EAHR and Heat Pump 70 to 80 F 60 to 70 F

5 Energy Savings of EAHR Dishwashers 75% energy savings over conventional low and high-temperature dishwashers. In the table below, energy savings was estimated of an EAHR dishwasher over a similar unit that is ENERGY STAR rated. ENERGY With STAR EAHR 300 Daily use (racks/d) Actual flow (gal/rack) Total water use (gal/d) Water heater gas load (therms/y) Booster heater temperature rise ( F) 55 7,950 Booster heater load (kwh/y) 10,900 1,520 Idle electricity load (kwh/y) 1,540 2,400 Exhaust fan (1/4 HP) motor (kwh/y) - 11,870 Total electricity load (kwh/y) 12,440 1,190 Operating energy load (therms/y) Energy savings from EAHR 60% Ventless

6 EAHR Dishwashers Available in the U.S. Door Type: Conveyor: Flight Conveyor:

7 Best-in-Class HR Models Available Overseas Door Type integrates exhaust air and drain water HR. It is ventless and requires only a cold water feed. Flight Conveyor integrates EAHR, drain water HR, and heat pump. It is ventless and requires only a cold water feed.

8 Energy Efficiency Trends Conventional Low + High Temperature Dishwashers 30-40% Energy Savings TIER I ENERGY-STAR Low + High Temperature Dishwashers (Low hot water use and Idle energy) 70-75% Energy Savings TIER II Beyond ENERGY-STAR High Temperature Dishwashers (Lowest hot water use, insulated, heat recovery technology) 80% Energy Savings TIER III Best-in-Class High Temperature Dishwashers (Lowest hot water use, several heat recovery technologies, cold water feed, heat pump, ventless)

9 Energy Efficiency Potential Door-Type Savings 1,400 Therms/y 7,300 kwh/y $5,000 annually Conveyor Savings 2,100 Therms/y 15,000 kwh/y $9,300 annually Cost savings based on the following: $1.10/therm, $0.15/kWh, $8.00 water + sewer/hcf, detergent $0.02/gal of water.

10 Energy and Cost Savings If 35% of California commercial kitchens installed EAHR dishwashers, they could: Conserve 26 million therms of gas Use an additional 66 million kwh Reduce energy costs by $19 million annually ($0.15/kWh, $1.10/therm) Thanks for Listening! Phone: (925)