Two Phase Pressure Drops for Refrigerants: A Statistical Comparison Among Experimental Data and Correlations

2006 ◽  
Author(s):  
Adriana Greco ◽  
Rita Mastrullo ◽  
Alfonso W. Mauro ◽  
Giuseppe P. Vanoli
Keyword(s):  
Experimental Data ◽  
Horizontal Tube ◽  
Operating Conditions ◽  
Prediction Methods ◽  
Two Phase Flows ◽  
Two Phase ◽  
Pressure Drops ◽  
Statistical Comparison ◽  
Wide Range ◽  
Phase Pressure

A 962 points database for refrigerants two-phase flows by Greco A. and Vanoli G.P. was statistically compared to four widely used prediction methods by Lockhart and Martinelli, Chawla, Theissing and Mu¨ller-Steinhagen and Heck in order to determine the best one. The experimental points are in a wide range of operating conditions for six pure or mixed refrigerants (R134a, R22, R407C, R507A, R410A and R404A) during evaporation in a smooth horizontal tube of 6 m length and 6 mm ID.

Experimental Adiabatic Two-Phase Pressure Drops of R134a, R236fa and R245fa in Small Horizontal Circular Channels

2011 ◽  
Author(s):  
Chin L. Ong ◽  
John R. Thome
Keyword(s):  
Pressure Drop ◽  
Flow Boiling ◽  
Homogeneous Model ◽  
Prediction Methods ◽  
Two Phase ◽  
Pressure Drops ◽  
Wide Range ◽  
Small Channels ◽  
Experimental Pressure ◽  
Phase Pressure

Experimental adiabatic two-phase pressure drops data for refrigerants R134a, R236fa and R245fa during flow boiling in small channels with internal diameters of 1.03, 2.20 and 3.04 mm are presented. The main purpose was to investigate the effects of channel confinement on adiabatic two-phase pressure drops. Thus, the two-phase pressure drop trends were systematically investigated over a wide range of test conditions for all three refrigerants and channel sizes. Statistical comparisons have also been made by comparing the experimental pressure drop data database with various macroscale and microscale prediction methods from the literature. The comparison showed relatively moderate accuracy for three prediction methods developed for macroscale flows, i.e. Baroczy and Chisholm, Friedel and the homogeneous model with the Cicchitti et al. viscosity relation. As for microscale prediction methods, the Cioncolini et al. annular flow model worked best with 68.5% of the data within ± 30%, followed by the Sun and Mishima and the Zhang et al. methods. Combining this database with the LTCM lab’s earlier database for 0.509 and 0.790 mm channels, there appears to be no evidence of a macro-to-microscale transition, at least with respect to two-phase pressure drops.

scholarly journals DYNAMICS OF TWO-PHASE FLOW ACROSS HORIZONTAL TUBE BUNDLES - A REVIEW

2005 ◽  
Vol 4 (2) ◽  
Author(s):  
G. Ribatskia ◽  
J. R. Thome
Keyword(s):  
Void Fraction ◽  
Two Phase Flow ◽  
Experimental Studies ◽  
Horizontal Tube ◽  
Prediction Methods ◽  
Phase Flow ◽  
Two Phase ◽  
Pressure Drops ◽  
Frictional Pressure Drop ◽  
Tube Bundles

This paper presents a state-of-the-art review of the hydrodynamic aspects of two-phase flow across horizontal tube bundles. The review covers studies related to the evaluation of void fraction, two-phase flow behaviors and pressure drops on the shell side of staggered and in-line tube bundles for upward, downward and side-to-side flows. This study of the literature critically describes the proposed flow pattern maps and semi-empirical correlations for predicting void fraction and frictional pressure drop. These predicting methods are generally based on experimental results for adiabatic air-water flows. A limited number of experimental studies with R-11 and R-113 were also carried out in the past. The review shows noticeable discrepancies among the available prediction methods. Finally, this study suggests that further research focusing on the development of representative databanks and new prediction methods is still necessary.

Experimental Validation and Design Simulations of a Passive Two-Phase Cooling System for Datacenters

2020 ◽  
Author(s):  
Jackson B. Marcinichen ◽  
John R. Thome ◽  
Raffaele L. Amalfi ◽  
Filippo Cataldo
Keyword(s):  
Thermal Performance ◽  
Experimental Validation ◽  
Cooling System ◽  
Electronics Cooling ◽  
Operating Conditions ◽  
Two Phase ◽  
Data Set ◽  
Pressure Drops ◽  
Wide Range ◽  
Important Challenge

Abstract Thermosyphon cooling systems represent the future of datacenter cooling, and electronics cooling in general, as they provide high thermal performance, reliability and energy efficiency, as well as capture the heat at high temperatures suitable for many heat reuse applications. On the other hand, the design of passive two-phase thermosyphons is extremely challenging because of the complex physics involved in the boiling and condensation processes; in particular, the most important challenge is to accurately predict the flow rate in the thermosyphon and thus the thermal performance. This paper presents an experimental validation to assess the predictive capabilities of JJ Cooling Innovation’s thermosyphon simulator against one independent data set that includes a wide range of operating conditions and system sizes, i.e. thermosyphon data for server-level cooling gathered at Nokia Bell Labs. Comparison between test data and simulated results show good agreement, confirming that the simulator accurately predicts heat transfer performance and pressure drops in each individual component of a thermosyphon cooling system (cold plate, riser, evaporator, downcomer (with no fitting parameters), and eventually a liquid accumulator) coupled with operational characteristics and flow regimes. In addition, the simulator is able to design a single loop thermosyphon (e.g. for cooling a single server’s processor), as shown in this study, but also able to model more complex cooling architectures, where many thermosyphons at server-level and rack-level have to operate in parallel (e.g. for cooling an entire server rack). This task will be performed as future work.

Void Fraction and Two-Phase Pressure Drops for Evaporating Flow over Horizontal Tube Bundles

2006 ◽  
Vol 27 (3) ◽  
pp. 5-21 ◽  
Author(s):  
Lorenzo Consolini ◽  
Douglas Robinson ◽  
John R. Thome
Keyword(s):  
Void Fraction ◽  
Horizontal Tube ◽  
Two Phase ◽  
Pressure Drops ◽  
Tube Bundles ◽  
Phase Pressure

Curvature Ratio Effect on Two-Phase Pressure Drops in Horizontal Return Bends: Experimental Data for R134a

2013 ◽  
Vol 34 (13) ◽  
pp. 1124-1132 ◽  
Author(s):  
Marcello Tammaro ◽  
William A. Mauro ◽  
Jocelyn Bonjour ◽  
Rita M. A. Mastrullo ◽  
Rémi Revellin
Keyword(s):  
Experimental Data ◽  
Two Phase ◽  
Curvature Ratio ◽  
Pressure Drops ◽  
Ratio Effect ◽  
Phase Pressure

Investigation on Hydraulic Resistance of Steam Generator Tube Support Plates

2014 ◽  
Author(s):  
Ting Xiong ◽  
Bo Wen ◽  
Yuanfeng Zan ◽  
Xiao Yan
Keyword(s):  
Experimental Data ◽  
Pressure Drop ◽  
Hydraulic Resistance ◽  
Steam Generator ◽  
Single Phase ◽  
Empirical Correlations ◽  
Two Phase ◽  
Flow Area ◽  
Pressure Drops ◽  
Phase Pressure

In order to obtain the hydraulic resistance characteristics of steam generator (SG) tube support plates (TSP), experimental as well as CFD studies have been carried out on both the single-phase and two-phase hydraulic resistances of various trefoil or quatrefoil orifice plates. Results show that with the increase of the Renylod number, the single-phase pressure drop coefficient decreases firstly and remains almost constant later. The single-phase pressure drop coefficient decreases with the increase of the chamfer radius of orifice or flow area. The two-phase pressure drops predicted by the empirical correlations are generally larger than the experimental results, while the pressure drops predicted by CFD software agree with the experimental data.

Estimation of Pressure Drop of Two-Phase Flow in Horizontal Long Pipes Using Artificial Neural Networks

2020 ◽  
Vol 142 (11) ◽  
Author(s):  
Mostafa Safdari Shadloo ◽  
Amin Rahmat ◽  
Arash Karimipour ◽  
Somchai Wongwises
Keyword(s):  
Experimental Data ◽  
Neural Networks ◽  
Artificial Neural Networks ◽  
Pressure Drop ◽  
Newtonian Liquid ◽  
Operating Conditions ◽  
Two Phase ◽  
Wide Range ◽  
Liquid Systems ◽  
Artificial Neural

Abstract Gas–liquid two-phase flows through long pipelines are one of the most common cases found in chemical, oil, and gas industries. In contrast to the gas/Newtonian liquid systems, the pressure drop has rarely been investigated for two-phase gas/non-Newtonian liquid systems in pipe flows. In this regard, an artificial neural networks (ANNs) model is presented by employing a large number of experimental data to predict the pressure drop for a wide range of operating conditions, pipe diameters, and fluid characteristics. Utilizing a multiple-layer perceptron neural network (MLPNN) model, the predicted pressure drop is in a good agreement with the experimental results. In most cases, the deviation of the predicted pressure drop from the experimental data does not exceed 5%. It is observed that the MLPNN provides more accurate results for horizontal pipelines in comparison with other empirical correlations that are commonly used in industrial applications.

Numerical Simulation on Pressure Drops for Air-Water Two-Phase Flow in Micro-Channels

2008 ◽  
Author(s):  
Hao Peng ◽  
Xiang Ling
Keyword(s):  
Experimental Data ◽  
Pressure Drop ◽  
Two Phase Flow ◽  
Vof Method ◽  
Phase Flow ◽  
Micro Channel ◽  
Two Phase ◽  
Pressure Drops ◽  
Micro Channels ◽  
Phase Pressure

Rigorous two-phase flow modeling is one of the great challenges in the thermal sciences. A two-dimensional computational fluid dynamics (CFD) simulation of air-water two-phase pressure drop characteristics in micro-channels by using volume of fluid (VOF) method was carried out in this paper. The simulations were performed in a horizontal micro-channel with a diameter of 1.1 mm and a length of 200 mm. Firstly, a variety of air-water two-phase flow patterns (including bubbly, slug, slug-annular and annular flow) were simulated in order to validate the feasibility and reliability of the VOF method. Next to that, the two-phase pressure drops in micro-channel were analyzed numerically by using the same CFD method. Also the comparison of pressure drop among the numerical simulations, experimental data and the results calculated by homogeneous equilibrium model was presented. The agreement between numerical results and the existing experimental data was found to be satisfactory. Based on this good agreement, it is finally found that the numerical analysis procedure proposed in this paper can be used to achieve a better prediction for micro-channel air-water flow characteristics.

scholarly journals DYNAMICS OF TWO-PHASE FLOW ACROSS HORIZONTAL TUBE BUNDLES - A REVIEW

2005 ◽  
Vol 4 (2) ◽  
pp. 122 ◽  
Author(s):  
G. Ribatskia ◽  
J. R. Thome
Keyword(s):  
Void Fraction ◽  
Two Phase Flow ◽  
Experimental Studies ◽  
Horizontal Tube ◽  
Prediction Methods ◽  
Phase Flow ◽  
Two Phase ◽  
Pressure Drops ◽  
Frictional Pressure Drop ◽  
Tube Bundles

This paper presents a state-of-the-art review of the hydrodynamic aspects of two-phase flow across horizontal tube bundles. The review covers studies related to the evaluation of void fraction, two-phase flow behaviors and pressure drops on the shell side of staggered and in-line tube bundles for upward, downward and side-to-side flows. This study of the literature critically describes the proposed flow pattern maps and semi-empirical correlations for predicting void fraction and frictional pressure drop. These predicting methods are generally based on experimental results for adiabatic air-water flows. A limited number of experimental studies with R-11 and R-113 were also carried out in the past. The review shows noticeable discrepancies among the available prediction methods. Finally, this study suggests that further research focusing on the development of representative databanks and new prediction methods is still necessary.

scholarly journals Study of Pressure Drops and Heat Transfer of Nonequilibrial Two-Phase Flows

Water ◽  
2021 ◽  
Vol 13 (16) ◽  
pp. 2275
Author(s):  
Aleksandr V. Belyaev ◽  
Alexey V. Dedov ◽  
Ilya I. Krapivin ◽  
Aleksander N. Varava ◽  
Peixue Jiang ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Flow Regime ◽  
Flow Boiling ◽  
Experimental Studies ◽  
High Mass ◽  
Calculation Methods ◽  
Two Phase Flows ◽  
Two Phase ◽  
Pressure Drops ◽  
Wide Range

Currently, there are no universal methods for calculating the heat transfer and pressure drop for a wide range of two-phase flow parameters in mini-channels due to changes in the void fraction and flow regime. Many experimental studies have been carried out, and narrow-range calculation methods have been developed. With increasing pressure, it becomes possible to expand the range of parameters for applying reliable calculation methods as a result of changes in the flow regime. This paper provides an overview of methods for calculating the pressure drops and heat transfer of two-phase flows in small-diameter channels and presents a comparison of calculation methods. For conditions of high reduced pressures pr = p/pcr ≈ 0.4 ÷ 0.6, the results of own experimental studies of pressure drops and flow boiling heat transfer of freons in the region of low and high mass flow rates (G = 200–2000 kg/m2 s) are presented. A description of the experimental stand is given, and a comparison of own experimental data with those obtained using the most reliable calculated relations is carried out.

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