Evaporation heat transfer of carbon dioxide at low temperature inside a horizontal smooth tube

Yoon, Jung-In; Son, Chang-Hyo; Jeon, Min-Ju; Yang, Dong-Il

doi:10.1007/s00231-016-1922-2

Cited by 5 publications

(3 citation statements)

References 18 publications

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“…Yoon et al [21] experimentally investigated the evaporative heat transfer coefficient of R744 at the low-temperatures of −30-−20 °C in a horizontal smooth tube. The inner and outer diameters of the test section were 8 mm and 9.52 mm, respectively, and the experiment was conducted at the mass fluxes of 100-300 kg/(m 2 •s) and saturation temperatures of −30-−20 °C.…”

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

Jeon¹

2023

Preprint

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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 pa-rameters were as follows: heat fluxes of 12–21.5 kW/m2, mass fluxes of 75–225 kg/(m2·s), and saturation temperatures of −50–−30 °C. The main results are summarized as follows. (1) When designing the R744 evaporator, the mass and heat fluxes must be maximized within the operating conditions, and the saturation temperature must be designed to be as low as possible. (2) 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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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

Jeon¹

2023

Preprint

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“…In total, 34 correlations were analyzed and evaluated using 2956 experimental data points related to the flow boiling heat transfer of R744 obtained from 10 independent laboratories. Yoon et al [21] experimentally investigated the evaporative heat transfer coefficient of R744 at the low temperatures of −30-−20 • C in a horizontal smooth tube. The inner and outer diameters of the test section were 8 mm and 9.52 mm, respectively, and the experiment was conducted at the mass fluxes of 100-300 kg/(m 2 •s) and saturation temperatures of −30-−20 • C. Liang et al [22] studied the heat transfer properties of boiling R744 streams in horizontal microtubes.…”

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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“…When compared to theoretical and experimental data, 5% difference was seen. Yoon et al [11] investigated the evaporation heat transfer coefficient of CO 2 at low temperature of -30 to -20°C in a horizontal smooth tube. When results were examined, it was seen that heat transfer coefficient was stable depending on vapor quality when the mass flux was 100 kg/ 2 s; heat transfer coefficient increased depending on increasing of vapor quality when the mass flux was 200 kg/ 2 s and 300 kg/ 2 s. Diani et al [12] experimentally investigated the heat transfer coefficient of refrigerants in inside a mini microfin tube, with an inner diameter at the fin tip of 2.4 mm.…”

Section: Introductionmentioning

confidence: 99%

A Theoretical Investigation on the Evaporative Heat Transfer of Co2 in Smooth and Microfin Tube

Alataş

Özkan

2021

Journal of Thermal Engineering

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Nowadays, global environmental events such as thinning of the ozone layer and climate changes are increasing. These types of events are not only affecting all creatures living on the Earth, but also decreasing the quality of life. For this reason, natural refrigerants which are not harmful to environment, have been preferred in cooling systems. In this study, heat transfer coefficient of CO 2 was investigated during the evaporation process in smooth tube and designed microfin tube. Features of the tube used in evaporator of these cooling systems directly affect to the heat transfer coefficient. The geometric parameters of the microfin tubes are an outer diameter of 9.52 mm, number of fins 50, apex angle of 38°, helix angle of 20° and fin height of 0.12 mm. Theoretical model was created on MATLAB environment. The heat transfer coefficient was investigated based on vapor quality. When theoretical results obtained for microfin tube were compared with experimental results, 6% approach was seen. A theoretical model was created for smooth and microfin tube by selecting heat flux as 10 kw/ 2 and mass flux as 380 kg/m 2 s and heat transfer coefficients in different evaporation temperatures were compared based on vapor quality. It has been concluded that heat transfer coefficients of microfin tube at 5°C, 0°C and -8°C were 52%, 44% and 34% higher than that of smooth tube, respectively.

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Evaporation heat transfer of carbon dioxide at low temperature inside a horizontal smooth tube

Cited by 5 publications

References 18 publications

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

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

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

A Theoretical Investigation on the Evaporative Heat Transfer of Co2 in Smooth and Microfin Tube

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