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Title: Field Testing and Modeling of Supermarket Refrigeration Systems as a Demand Response Resource

Abstract

Supermarkets offer a substantial demand response (DR) resource because of their high energy intensity and use patterns; however, refrigeration as the largest load has been challenging to access. Previous work has analyzed supermarket DR using heating, ventilating, and air conditioning; lighting; and anti-sweat heaters. This project evaluated and quantified the DR potential inherent in supermarket refrigeration systems in the Bonneville Power Administration service territory. DR events were carried out and results measured in an operational 45,590-ft2 supermarket located in Hillsboro, Oregon. Key results from the project include the rate of temperature increase in freezer reach-in cases and walk-ins when refrigeration is suspended, the load shed amount for DR tests, and the development of calibrated models to quantify available DR resources. Simulations showed that demand savings of 15 to 20 kilowatts (kW) are available for 1.5 hours for a typical store without precooling and for about 2.5 hours with precooling using only the low-temperature, non-ice cream cases. This represents an aggregated potential of 20 megawatts within BPA's service territory. Inability to shed loads for medium-temperature (MT) products because of the tighter temperature requirements is a significant barrier to realizing larger DR for supermarkets. Store owners are reluctant to allow MT casemore » set point changes, and laboratory tests of MT case DR strategies are needed so that owners become comfortable testing, and implementing, MT case DR. The next-largest barrier is the lack of proper controls in most supermarket displays over ancillary equipment, such as anti-sweat heaters, lights, and fans.« less

Authors:
; ; ;
Publication Date:
Research Org.:
National Renewable Energy Lab. (NREL), Golden, CO (United States)
Sponsoring Org.:
USDOE Office of Energy Efficiency and Renewable Energy (EERE)
OSTI Identifier:
1324385
Report Number(s):
NREL/CP-5500-67075
DOE Contract Number:
AC36-08GO28308
Resource Type:
Conference
Resource Relation:
Conference: Presented at the 2016 ACEEE Summer Study on Energy Efficiency in Buildings, 21-26 August 2016, Pacific Grove, California
Country of Publication:
United States
Language:
English
Subject:
32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATION; demand response; refrigeration; supermarkets

Citation Formats

Deru, Michael, Hirsch, Adam, Clark, Jordan, and Anthony, Jamie. Field Testing and Modeling of Supermarket Refrigeration Systems as a Demand Response Resource. United States: N. p., 2016. Web.
Deru, Michael, Hirsch, Adam, Clark, Jordan, & Anthony, Jamie. Field Testing and Modeling of Supermarket Refrigeration Systems as a Demand Response Resource. United States.
Deru, Michael, Hirsch, Adam, Clark, Jordan, and Anthony, Jamie. 2016. "Field Testing and Modeling of Supermarket Refrigeration Systems as a Demand Response Resource". United States. doi:.
@article{osti_1324385,
title = {Field Testing and Modeling of Supermarket Refrigeration Systems as a Demand Response Resource},
author = {Deru, Michael and Hirsch, Adam and Clark, Jordan and Anthony, Jamie},
abstractNote = {Supermarkets offer a substantial demand response (DR) resource because of their high energy intensity and use patterns; however, refrigeration as the largest load has been challenging to access. Previous work has analyzed supermarket DR using heating, ventilating, and air conditioning; lighting; and anti-sweat heaters. This project evaluated and quantified the DR potential inherent in supermarket refrigeration systems in the Bonneville Power Administration service territory. DR events were carried out and results measured in an operational 45,590-ft2 supermarket located in Hillsboro, Oregon. Key results from the project include the rate of temperature increase in freezer reach-in cases and walk-ins when refrigeration is suspended, the load shed amount for DR tests, and the development of calibrated models to quantify available DR resources. Simulations showed that demand savings of 15 to 20 kilowatts (kW) are available for 1.5 hours for a typical store without precooling and for about 2.5 hours with precooling using only the low-temperature, non-ice cream cases. This represents an aggregated potential of 20 megawatts within BPA's service territory. Inability to shed loads for medium-temperature (MT) products because of the tighter temperature requirements is a significant barrier to realizing larger DR for supermarkets. Store owners are reluctant to allow MT case set point changes, and laboratory tests of MT case DR strategies are needed so that owners become comfortable testing, and implementing, MT case DR. The next-largest barrier is the lack of proper controls in most supermarket displays over ancillary equipment, such as anti-sweat heaters, lights, and fans.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = 2016,
month = 8
}

Conference:
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  • A computer model has been developed that can predict the performance of supermarket refrigeration equipment to within 3% of field test measurements. The Supermarket Refrigeration Energy Use and Demand Model has been used to simulate currently available refrigerants R-12, R-502 and R-22, and is being further developed to address alternative refrigerants. This paper reports that the model is expected to be important in the design, selection and operation of cost-effective, high-efficiency refrigeration systems. It can profile the operation and performance of different types of compressors, condensors, refrigerants and display cases. It can also simulate the effects of store humidity andmore » temperature on display cases; the efficiency of various floating head pressure setpoints, defrost alternatives and subcooling methods; the efficiency and amount of heat reclaim from refrigeration systems; and the influence of other variables such as store lighting and building design. It can also be used to evaluate operational strategies such as variable-speed drive or cylinder unloading for capacity control. Development of the model began in 1986 as part of a major effort, sponsored by the U.S. electric utility industry, to evaluate energy performance of then conventional single compressor and state-of-the-art multiplex refrigeration systems, and to characterize the contribution of a variety of technology enhancement features on system energy use and demand.« less
  • The Supermarket Energy Systems Program was structured to investigate and develop new highly energy-efficient supermarket systems. A supermarket refrigeration system consisting of: unequal parallel compressors; condenser with floating head-pressure control; and micoprocessor-based electronic control system was analyzed, designed, and tested. The total system capacity is 35 hp and three compressors of 5, 10, and 20 hp capacity were determined to be the optimum number and capacity distribution. Compared to the conventional supermarket refrigeration systems, the three unequal parallel compressor systems with R-12 will demonstrate a maximum annual energy savings of 29,100 kWhr or 26% and with R-502 will demonstrate amore » maximum annual energy savings of 20,100 kWhr or 15%. A compressor capacity control algorithm was designed to select the optimum compressor combination for each operating condition to match compressor capacity to refrigeration load. A microprocessor system based on an Intel 8085 microprocessor was selected for system control and data acquisition. The economic analysis revealed that for a payback period of 3 years or less, an added microprocessor-based electronic controls cost between $500 to $1500 is acceptable. Testing was performed on the unequal parallel compressor system over a refrigeration load range of 78,000 to 160,000 Btu/h. For refrigerant R-12, the increase in the energy efficiency ratio (EER) for the microprocessor-based electronic control system as compared to the mechanical pressure control system ranged from 9.8 to 12.5%« less
  • International agreements have legislated the phaseout of many refrigerants, including R-502 and R-12, which are commonly used in supermarket refrigeration systems. R-22 and ammonia (R-717) are candidate replacement refrigerants having appropriate thermodynamic properties. The toxicity of ammonia at low concentrations required that it be confined to the equipment room, so a secondary fluid is needed to distribute cooling to the refrigerated cases. This paper investigates ammonia-secondary fluid systems and compares their performance with equivalent R-22 systems. Both R-22 and ammonia have high compressor discharge temperatures, necessitating staged compression. Three methods of staging the compression were compared for both refrigerants. Sixmore » secondary fluids were evaluated for use with ammonia in the supermarket system. The overall system performance of the ammonia-secondary fluid refrigeration system, including both compressor and secondary fluid pump power, is governed by a large set of design parameters. The influence of these parameters on the overall system performance was studied in a systematic manner. From this parametric study, design rules leading to optimal ammonia-secondary fluid systems were developed. The performance of well-designed ammonia-secondary fluid systems was found to be 4% to 10% lower than that of R-22 systems operating under similar conditions.« less
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