Exergy characteristics of R404A indirect refrigeration system using CO2 as a secondary refrigerant

Yi, Wen-Bin; Choi, Kwang-Hwan; Yoon, Jung-In; Son, Chang-Hyo; Ha, Soo-Jung; Jeon, Min-Ju

doi:10.1007/s00231-018-2497-x

Cited by 5 publications

(2 citation statements)

References 3 publications

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“…As a result, alternative refrigeration technologies, such as secondary loop refrigeration systems [23], are becoming more popular for physically separating hazardous refrigerants from the cooling chamber by adding an additional loop to the primary cooling cycle. Both single-phase (e.g., glycol mixtures and hybrid nanofluids [24]) and two-phase fluids (e.g., CO 2 [25], paraffin emulsion [26], and salt hydrates [27]) are used as secondary refrigerants. Advantages of this architecture are reduced primary refrigerant charge and leakage and the ability to use the secondary loop as a TES [23].…”

Section: Introductionmentioning

confidence: 99%

Simulation-Based Sizing of a Secondary Loop Cooling System for a Refrigerated Vehicle

Lösch,

Fallmann,

Poks

et al. 2023

Energies

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Refrigerated transport by road is essential for the food industry but also contributes significantly to global energy consumption. In particular, last-mile transport, where the doors of the cooling chamber are opened frequently, puts a strain on energy efficiency and temperature control due to the high heat ingress from outside into the cooling chamber. These difficulties can be reduced by thermal energy storage systems, such as secondary loop refrigeration systems, if combined with a sophisticated control scheme. Although the storage capacity of such systems is critical for the overall performance of the cooling system, little research was performed regarding the sizing of the secondary loop thermal storage capacity. Therefore, this article examines the effect of the secondary loop thermal storage capacity on energy consumption and controller performance utilizing closed-loop simulations of a refrigerated vehicle model. Both a mixed-integer model predictive control scheme that can anticipate door openings and a conventional temperature controller are analyzed. An optimal thermal storage capacity of the secondary loop is found with the model predictive controller, whereas the conventional controller cannot exploit the secondary loop and thus shows significantly inferior performance. By using a dimensionless parameter for the thermal storage capacity of the secondary loop, the optimum found can be easily applied to refrigerated vehicles with various cooling chamber dimensions.

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Section: Introductionmentioning

confidence: 99%

Simulation-Based Sizing of a Secondary Loop Cooling System for a Refrigerated Vehicle

Lösch,

Fallmann,

Poks

et al. 2023

Energies

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“…The R744 refrigeration system has a wide range of applications, and R744 has recently been used as the working fluid in micro-coolers (for CPUs). Moreover, R744 is used in low-temperature freezing and refrigeration systems, and its scope of application is being expanded to the R744/R404A cascade refrigeration system (CRS) [7][8][9] or indirect refrigeration system (IRS) [10][11][12][13][14] by using it as a secondary refrigerant in supermarkets. Furthermore, the evaporative heat transfer characteristics of R744 in the evaporators used in such refrigeration systems are being researched actively.…”

Section: Introductionmentioning

confidence: 99%

Investigation of Heat Transfer and Pressure Drop for R744 in a Horizontal Smooth Tube of R744/R404A Hybrid Cascade Refrigeration System—Part 2: Low-Temperature Region

Jeon

2023

Energies

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This paper studies the evaporative heat transfer characteristics of R744 at low temperatures in a horizontal smooth tube as a cascade refrigeration system (CRS) among hybrid cascade refrigeration systems (HCRSs). There is a lack of research on the low-temperature evaporative heat transfer characteristics of R744 under the operating conditions of evaporators used in actual CRSs used in supermarkets. Therefore, this study aims to provide basic data on the evaporative heat transfer characteristics of R744 in the evaporators of refrigerators used in supermarkets. The tube used in the evaporation experiment conducted herein was a smooth horizontal copper tube with an inner diameter and length of 11.46 mm and 8000 mm, respectively. The experimental parameters were as follows: heat fluxes of 11.8–21.3 kW/m2, mass fluxes of 76.3–175.1 kg/(m2·s), and saturation temperatures of −49.8–−30.2 °C. The main results are summarized as follows: the evaporative heat transfer coefficient of R744 can be predicted well by using the correlation formula of Chen at the evaporation temperature of −40 °C in the CRS.

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Fault detection and isolation for a secondary loop refrigeration system

Poks

Fallmann

Fink

et al. 2023

Applied Thermal Engineering

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Exergy characteristics of R404A indirect refrigeration system using CO2 as a secondary refrigerant

Cited by 5 publications

References 3 publications

Simulation-Based Sizing of a Secondary Loop Cooling System for a Refrigerated Vehicle

Simulation-Based Sizing of a Secondary Loop Cooling System for a Refrigerated Vehicle

Investigation of Heat Transfer and Pressure Drop for R744 in a Horizontal Smooth Tube of R744/R404A Hybrid Cascade Refrigeration System—Part 2: Low-Temperature Region

Fault detection and isolation for a secondary loop refrigeration system

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