Refrigerated display case demand defrost controller: Field demonstration results. Final report
- Encore/Johnson Controls, Marietta, GA (United States)
- CDH Energy Corp., Cazenovia, NY (United States)
EPRI in partnership with Johnson Controls/Encore has developed a new demand defrost controller for use in refrigerated display cases in supermarkets. This ``sensorless`` defrost system uses a control algorithm -- currently being patented by EPRI -- that uses the microprocessor power of the energy management system to learn from the defrost pattern to automatically create a new defrost schedule. This algorithm offers a significant advantage over conventional demand defrost technology, which typically requires additional sensors to be installed in the cases. Demand defrost sensors are usually expensive, difficult to install, and not as reliable as existing defrost termination sensors. The algorithm was implemented on three low-temperature reach-in frozen food cases with electric defrost in the Grand Union supermarket. The defrost algorithm increased the time between defrost cycles from the nominal value of one day to the maximum limit of three days. This maximum limit is programmed in the software, and can be changed. Less frequent defrost operation reduced electric heater consumption by an average of 63%. Applying the algorithm to all 15 cases with electric defrost at the store would save 38,000 kWh on an annual basis. The measured results have also confirmed that demand defrost can reduce the impact of defrost operation on average case temperatures.
- Research Organization:
- Electric Power Research Inst., Palo Alto, CA (United States); Encore/Johnson Controls, Marietta, GA (United States); CDH Energy Corp., Cazenovia, NY (United States)
- Sponsoring Organization:
- Electric Power Research Inst., Palo Alto, CA (United States)
- OSTI ID:
- 355090
- Report Number(s):
- EPRI-TR--112121
- Country of Publication:
- United States
- Language:
- English
Similar Records
Defrost Temperature Termination in Supermarket Refrigeration Systems
Measured impacts of supermarket humidity level on defrost performance and refrigerating system energy use