Monday, June 26, 2017: 9:45 AM-10:45 AM
Refrigeration
Chair:
Xiwang Li, Drexel University
Refrigeration is often the largest single energy use in supermarkets. This session examines three widely different topics related to the refrigeration systems used in retail food establishments. The first examines the potential for use of a water-cooled condenser that rejects heat to soil via an intermediate water circuit. It then moves on to examine issues related to the use of HCF 245fa and HCF 124a blowing agents in insulation that is widely used in refrigerated structures. The final paper examines design procedures used to reduce the risk of fire when using flammable refrigerants.
1 Defining Room Area for Connected Spaces for Flammable Refrigerants (LB-17-C023)
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William Hansen, P.E., Trane, Ingersoll Rand |
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Stephen Kujak, Trane, Ingersoll Rand |
Flammability risk, in the event of a leak, can be lowered by reducing the potential for forming a refrigerant/air mixture that can reach the lower flammability limit (LFL) in the event of a leak into a confined space. The determination of effective room area and space volume has become critical to safety. This paper will describe an approach for determination effective room area, including methods to utilize adjacent connected spaces. Computational fluid dynamic (CFD) analysis was performed to support the justification for the methodology. An approach, utilizing the principles of natural convection and forced convection will be described for determining the effective room area and volume for individual rooms and connected rooms for unventilated spaces.
2 Long-Term Thermal Performance of Polyurethane Insulation within Cold Storage Panel Systems Used in U.S. Retail Grocery Environments (LB-17-C024)
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James M Costanza, KPS Global LLC |
This paper presents details of a study which investigates the long-term thermal resistance (LTTR) performance of polyurethane insulation within discrete cold storage panels used in the US retail grocery environment. The research seeks to better define the potential benefit of extending the productive life of the insulation through longer cold storage service or through recycling into another insulative material. A total of ten U.S. retail chain grocery store sites were semi-randomly selected for the extraction of polyurethane panel specimens from decommissioned cold storage structures. Thermal performance of the cold storage panel specimens was determined by using the ASTM C518-10 Standard Test Method.
3 Analysis of Water-Cooled Refrigeration Systems for the Food Retail Industry (LB-17-C025)
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Maria-Aliki Efstratiadi, M.D., Imperial College London |
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Salvador Acha, Ph.D., Imperial College London |
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Nilah Shah, Ph.D., Imperial College London |
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Christos N. Markides, Ph.D., Imperial College London |
The need for refrigeration in the retail industry and specifically in supermarkets, currently accounts for around 30% to 60% of the total energy consumed in stores. A key characteristic of this consumption, is the high amount of low-grade (i.e., low-temperature) heat rejected by the condensation units to the ambient air. This paper focuses on the transcritical CO2 (R744) refrigeration cycles and aims to assess whether the use of a water-cooled condenser rejecting heat to the soil via an intermediate closed water-circuit, can reduce the energy consumption, while also considering the economic implications of this modification.