Heat transfer coefficient and pressure drop characteristics of R410A condensation during upward flow in vertical smooth and micro-fin tubes

2017 ◽  
Author(s):  
Yunxiao Yang ◽  
Li Jia ◽  
Qi Peng
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Pressure Drop ◽  
Transfer Coefficient ◽  
Upward Flow ◽  
Fin Tubes

Condensation Pressure Drop and Heat Transfer in 5-mm-OD Micro-Fin Tubes

2012 ◽  
Author(s):  
Wei Li ◽  
Dan Huang ◽  
Zan Wu ◽  
Hong-Xia Li ◽  
Zhao-Yan Zhang ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Pressure Drop ◽  
Transfer Coefficient ◽  
Heat Transfer Enhancement ◽  
Condensation Heat Transfer ◽  
Transfer Enhancement ◽  
Mass Fluxes ◽  
Fin Tubes ◽  
Condensation Heat Transfer Coefficient

An experimental investigation was performed for convective condensation of R410A inside four micro-fin tubes with the same outside diameter (OD) 5 mm and helix angle 18°. Data are for mass fluxes ranging from about 180 to 650 kg/m2s. The nominal saturation temperature is 320 K, with inlet and outlet qualities of 0.8 and 0.1, respectively. The results suggest that Tube 4 has the best thermal performance for its largest condensation heat transfer coefficient and relatively low pressure drop penalty. Condensation heat transfer coefficient decreases at first and then increases or flattens out gradually as G decreases. This complex mass-flux effect may be explained by the complex interactions between micro-fins and fluid. The heat transfer enhancement mechanism is mainly due to the surface area increase over the plain tube at large mass fluxes, while liquid drainage and interfacial turbulence play important roles in heat transfer enhancement at low mass fluxes. In addition, the experimental data was analyzed using seven existing pressure-drop and four heat-transfer models to verify their respective accuracies.

Experimental Heat Transfer Coefficient and Pressure Drop during Condensation of R-134a and R-410A in Horizontal Micro-fin Tubes

2018 ◽  
Vol 26 (03) ◽  
pp. 1850022 ◽  
Author(s):  
Sanjeev Singh ◽  
Rajeev Kukreja
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Pressure Drop ◽  
Transfer Coefficient ◽  
Outer Diameter ◽  
Transfer Coefficients ◽  
Pressure Drops ◽  
Heat Transfer Coefficients ◽  
R 134A ◽  
Fin Tubes

Condensation heat transfer coefficients and pressure drops of HFC refrigerants R-134a and R-410A have been investigated experimentally in smooth and micro-fin tubes (helix angles 18[Formula: see text] and 15[Formula: see text]) of outer diameter 9.52[Formula: see text]mm at mass fluxes from 200 to 600[Formula: see text]kg/m[Formula: see text]s, vapor qualities between 0.1 and 0.9 and at saturation temperatures of 35[Formula: see text]C and 40[Formula: see text]C. Results showed that the heat transfer coefficients of R-134a and R-410A inside micro-fin tubes were 1.21–1.82 and 1.15–1.47 times higher and frictional pressure drops were 2.11–2.56 and 1.62–2.12 times higher than those of smooth tubes. These experimental results are compared with the existing heat transfer and frictional pressure drop correlations proposed by different researchers. The comparison showed fairly good agreement with these existing correlations within [Formula: see text]30%. A new correlation has also been proposed for predicting heat transfer coefficient in micro-fin tubes. The oil concentrations measured for refrigerants R-134a and R-410A varied in the range of 1.3–1.5%, respectively.

scholarly journals Study on Heat Transfer Characteristics of the Whole Plate Fin Tube Cooler

2020 ◽  
Vol 7 (2) ◽  
Author(s):  
Y. Zhou ◽  
L. Zhang ◽  
S. Bu ◽  
C. Sun ◽  
W. Xu ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Pressure Drop ◽  
Transfer Coefficient ◽  
Heat Transfer Characteristics ◽  
Frictional Pressure Drop ◽  
Transfer Characteristics ◽  
Heat Transfer Efficiency ◽  
Fin Tube ◽  
Fin Tubes

In order to enhance the cooling efficiency of plate-fin motor cooler, two kinds of plate-fin-tubes were proposed, which named triangle-wing and convex fin-tube. The heat transfer characteristics of fin-tubes are investigated via numerical simulation and experiment. The result showed that the k-ε turbulence model is highly accurate in simulation of cooler, and the deviation of average heat transfer coefficient and frictional pressure drop between experiment and simulation is within 10% and 8%, respectively. Both of the triangle-wing and convex fin-tube can increase the heat transfer efficiency of plate-fin cooler. The frictional pressure drop also has an approximate variation trend. In addition, the pressure drop of convex-fin-tube is smaller than triangle-wing-fin-tube on the premise of the same heat transfer coefficient, so the heat transfer performance of convex-fin-tube is the best.

scholarly journals Effect of Tube Expansion on Heat Transfer and Pressure Drop Characteristics During Condensation in Micro-Fin Tubes

2021 ◽  
Vol 9 ◽  
Author(s):  
Na Liu ◽  
Qian Zhao ◽  
Zhixiang Lan
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Pressure Drop ◽  
Transfer Coefficient ◽  
Mass Flux ◽  
Condensation Heat Transfer ◽  
Mass Fluxes ◽  
Fin Tubes ◽  
Tube Expansion ◽  
The Heat Transfer Coefficient

Despite of the large number of research dedicated to condensation heat transfer and pressure drop characteristics in pristine micro-fin tubes, experimental investigation on effects of tube expansion have not been reported in the open literature. The paper reports measured cross-sectional dimensions, condensation heat transfer and pressure drop data of R1234ze(E) in pristine (5.10 mm OD) and expanded (5.26 mm OD) micro-fin tubes with mass fluxes from 100 to 300 kg/(m2·s). Effects of mass flux, vapor quality and tube expansion on the heat transfer coefficients and friction pressure gradients were investigated in the study. When the mass flux is 100 kg/(m2·s), the heat transfer coefficient and pressure drop of R1234ze(E) decrease after tube expansion. However, when the mass fluxes are 200 and 300 kg/(m2·s), tube expansion effects on the heat transfer coefficient and pressure drop are not notable. In addition, the experimental results are analyzed based on the existing condensation heat transfer and pressure drop correlations.

Development of a New Correlation and Post Processing of Heat Transfer Coefficient and Pressure Drop of Functionalized COOH MWCNT Nanofluid by Artificial Neural Network

2018 ◽  
Vol 14 (2) ◽  
pp. 104-112 ◽  
Author(s):  
Mohammad Hemmat Esfe ◽  
Somchai Wongwises ◽  
Saeed Esfandeh ◽  
Ali Alirezaie
Keyword(s):  
Neural Network ◽  
Heat Transfer ◽  
Thermal Conductivity ◽  
Artificial Neural Network ◽  
Heat Transfer Coefficient ◽  
Pressure Drop ◽  
Transfer Coefficient ◽  
Regression Coefficient ◽  
New Correlation ◽  
The Neural Network

Background: Because of nanofluids applications in improvement of heat transfer rate in heating and cooling systems, many researchers have conducted various experiments to investigate nanofluid's characteristics more accurate. Thermal conductivity, electrical conductivity, and heat transfer are examples of these characteristics. Method: This paper presents a modeling and validation method of heat transfer coefficient and pressure drop of functionalized aqueous COOH MWCNT nanofluids by artificial neural network and proposing a new correlation. In the current experiment, the ANN input data has included the volume fraction and the Reynolds number and heat transfer coefficient and pressure drop considered as ANN outputs. Results: Comparing modeling results with proposed correlation proves that the empirical correlation is not able to accurately predict the experimental output results, and this is performed with a lot more accuracy by the neural network. The regression coefficient of neural network outputs was equal to 99.94% and 99.84%, respectively, for the data of relative heat transfer coefficient and relative pressure drop. The regression coefficient for the provided equation was also equal to 97.02% and 77.90%, respectively, for these two parameters, which indicates this equation operates much less precisely than the neural network. Conclusion: So, relative heat transfer coefficient and pressure drop of nanofluids can also be modeled and estimated by the neural network, in addition to the modeling of nanofluid’s thermal conductivity and viscosity executed by different scholars via neural networks.

Numerical simulation of the effect of baffle cut and baffle spacing on shell side heat exchanger performance using CFD

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Swanand Gaikwad ◽  
Ashish Parmar
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Heat Exchanger ◽  
Pressure Drop ◽  
Transfer Coefficient ◽  
Numerical Results ◽  
Shell Side ◽  
Tube Heat Exchanger ◽  
Shell And Tube ◽  
Two Parameters

AbstractHeat exchangers possess a significant role in energy transmission and energy generation in most industries. In this work, a three-dimensional simulation has been carried out of a shell and tube heat exchanger (STHX) consisting of segmental baffles. The investigation involves using the commercial code of ANSYS CFX, which incorporates the modeling, meshing, and usage of the Finite Element Method to yield numerical results. Much work is available in the literature regarding the effect of baffle cut and baffle spacing as two different entities, but some uncertainty pertains when we discuss the combination of these two parameters. This study aims to find an appropriate mix of baffle cut and baffle spacing for the efficient functioning of a shell and tube heat exchanger. Two parameters are tested: the baffle cuts at 30, 35, 40% of the shell-inside diameter, and the baffle spacing’s to fit 6,8,10 baffles within the heat exchanger. The numerical results showed the role of the studied parameters on the shell side heat transfer coefficient and the pressure drop in the shell and tube heat exchanger. The investigation shows an increase in the shell side heat transfer coefficient of 13.13% when going from 6 to 8 baffle configuration and a 23.10% acclivity for the change of six baffles to 10, for a specific baffle cut. Evidence also shows a rise in the pressure drop with an increase in the baffle spacing from the ranges of 44–46.79%, which can be controlled by managing the baffle cut provided.

Heat Transfer Performance of Different Nanofluids Flows in a Helically Coiled Heat Exchanger

2013 ◽  
Vol 832 ◽  
pp. 160-165 ◽  
Author(s):  
Mohammad Alam Khairul ◽  
Rahman Saidur ◽  
Altab Hossain ◽  
Mohammad Abdul Alim ◽  
Islam Mohammed Mahbubul
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Heat Exchanger ◽  
Pressure Drop ◽  
Transfer Coefficient ◽  
Friction Factor ◽  
Heat Exchangers ◽  
Heat Transfer Performance ◽  
Volume Concentration ◽  
Transfer Performance

Helically coiled heat exchangers are globally used in various industrial applications for their high heat transfer performance and compact size. Nanofluids can provide excellent thermal performance of this type of heat exchangers. In the present study, the effect of different nanofluids on the heat transfer performance in a helically coiled heat exchanger is examined. Four different types of nanofluids CuO/water, Al2O3/water, SiO2/water, and ZnO/water with volume fractions 1 vol.% to 4 vol.% was used throughout this analysis and volume flow rate was remained constant at 3 LPM. Results show that the heat transfer coefficient is high for higher particle volume concentration of CuO/water, Al2O3/water and ZnO/water nanofluids, while the values of the friction factor and pressure drop significantly increase with the increase of nanoparticle volume concentration. On the contrary, low heat transfer coefficient was found in higher concentration of SiO2/water nanofluids. The highest enhancement of heat transfer coefficient and lowest friction factor occurred for CuO/water nanofluids among the four nanofluids. However, highest friction factor and lowest heat transfer coefficient were found for SiO2/water nanofluids. The results reveal that, CuO/water nanofluids indicate significant heat transfer performance for helically coiled heat exchanger systems though this nanofluids exhibits higher pressure drop.

Experimental Study of Evaporation Heat Transfer Characteristics and Pressure Drops of R410A and R134a in a Multiport Mini-Channel

2009 ◽  
Author(s):  
Jatuporn Kaew-On ◽  
Somchai Wongwises
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Pressure Drop ◽  
Transfer Coefficient ◽  
Transfer Coefficients ◽  
Pressure Drops ◽  
Heat Transfer Coefficients ◽  
Evaporation Heat ◽  
Evaporation Heat Transfer ◽  
R 134A

The evaporation heat transfer coefficients and pressure drops of R-410A and R-134a flowing through a horizontal-aluminium rectangular multiport mini-channel having a hydraulic diameter of 3.48 mm are experimentally investigated. The test runs are done at refrigerant mass fluxes ranging between 200 and 400 kg/m2s. The heat fluxes are between 5 and 14.25 kW/m2, and refrigerant saturation temperatures are between 10 and 30 °C. The effects of the refrigerant vapour quality, mass flux, saturation temperature and imposed heat flux on the measured heat transfer coefficient and pressure drop are investigated. The experimental data show that in the same conditions, the heat transfer coefficients of R-410A are about 20–50% higher than those of R-134a, whereas the pressure drops of R-410A are around 50–100% lower than those of R-134a. The new correlations for the evaporation heat transfer coefficient and pressure drop of R-410A and R-134a in a multiport mini-channel are proposed for practical applications.

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