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Title: Evaluation of a Transcritical CO2 Supermarket Refrigeration System for the USA Market

 [1];  [1];  [1]
  1. ORNL
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Building Technologies Research and Integration Center (BTRIC)
Sponsoring Org.:
USDOE Office of Energy Efficiency and Renewable Energy (EERE)
OSTI Identifier:
DOE Contract Number:
Resource Type:
Resource Relation:
Conference: IIR Ammonia and CO2 Refrigeration Technology Conference, Ohrid, Macedonia, 20150415, 20150418
Country of Publication:
United States

Citation Formats

Sharma, Vishaldeep, Fricke, Brian A, and Bansal, Pradeep. Evaluation of a Transcritical CO2 Supermarket Refrigeration System for the USA Market. United States: N. p., 2015. Web.
Sharma, Vishaldeep, Fricke, Brian A, & Bansal, Pradeep. Evaluation of a Transcritical CO2 Supermarket Refrigeration System for the USA Market. United States.
Sharma, Vishaldeep, Fricke, Brian A, and Bansal, Pradeep. 2015. "Evaluation of a Transcritical CO2 Supermarket Refrigeration System for the USA Market". United States. doi:.
title = {Evaluation of a Transcritical CO2 Supermarket Refrigeration System for the USA Market},
author = {Sharma, Vishaldeep and Fricke, Brian A and Bansal, Pradeep},
abstractNote = {},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = 2015,
month = 1

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  • This report covers in detail the engineering evaluation of a highly energy-efficient supermarket refrigeration system. The primary components of this system were a set of three unequal parallel compressors, a microprocessor-based compressor controller, and floating head pressure for condenser operation. For this evaluation, such a system - referred to here as the test system - was designed, fabricated, installed and instrumented in a supermarket operated by the H.E. Butt Grocery Co., in San Antonio, TX. A second refrigeration system - referred to here as the reference system and located in another HEB supermarket in San Antonio - was also instrumentedmore » so that comparative measurements between the two systems could be made. The major components of the reference system were two equal parallel compressors, a solid state compressor controller, and conventional head pressure control. The two systems were monitored for a period of approximately one year. The results showed that the test system produced a system EER (energy efficiency ratio) that was on the average 15.9% higher than that of the reference system. Further analysis of the performance data showed that the following parameters (presented in descending order of importance) contributed to this improvement: Operation of the test system at higher suction pressure; cycling control strategy for the test system condenser fans; fewer defrosts experienced by the test system; and operation of the test system at lower condenser pressure. Similar analyses were carried out for the power consumptions and refrigeration loads of both the test and reference systems. 9 figures, 10 tables.« less
  • Commercial refrigeration systems consumed 1.21 Quads of primary energy in 2010 and are known to be a major source for refrigerant charge leakage into the environment. Thus, it is important to study the environmental impact of commercial supermarket refrigeration systems and improve their design to minimize any adverse impacts. The system s Life Cycle Climate Performance (LCCP) was presented as a comprehensive metric with the aim of calculating the equivalent mass of carbon dioxide released into the atmosphere throughout its lifetime, from construction to operation and destruction. In this paper, an open source tool for the evaluation of the LCCPmore » of different air-conditioning and refrigeration systems is presented and used to compare the environmental impact of a typical multiplex direct expansion (DX) supermarket refrigeration systems based on three different refrigerants as follows: two hydrofluorocarbon (HFC) refrigerants (R-404A, and R-407F), and a low global warming potential (GWP) refrigerant (N-40). The comparison is performed in 8 US cities representing different climates. The hourly energy consumption of the refrigeration system, required for the calculation of the indirect emissions, is calculated using a widely used building energy modeling tool (EnergyPlus). A sensitivity analysis is performed to determine the impact of system charge and power plant emission factor on the LCCP results. Finally, we performed an uncertainty analysis to determine the uncertainty in total emissions for both R-404A and N-40 operated systems. We found that using low GWP refrigerants causes a considerable drop in the impact of uncertainty in the inputs related to direct emissions on the uncertainty of the total emissions of the system.« 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