TWO-PHASE PRESSURE LOSS ACROSS ABRUPT CONTRACTlONS AND EXPANSIONS, STEAM-WATER AT 600 TO 1400 PSIA

2019 ◽  
Author(s):  
Earl Janssen
Keyword(s):  
Pressure Loss ◽  
Two Phase ◽  
Phase Pressure

An Experimentally Validated Model for Two-Phase Sudden Contraction Pressure Drop in Microchannel Tube Headers

2003 ◽  
Author(s):  
John Wesley Coleman
Keyword(s):  
Pressure Loss ◽  
Accurate Determination ◽  
Time Data ◽  
Two Phase ◽  
Pressure Transducers ◽  
Pressure Losses ◽  
Mass Fluxes ◽  
Data Points ◽  
Minor Losses ◽  
Phase Pressure

This paper presents the results of an experimental investigation of two-phase pressure loss of R134a in microchannel headers using various end-cut techniques. Novel experimental techniques and test sections were developed to enable the accurate determination of the minor losses without obfuscating the problem with a lengthwise pressure gradient. This technique represents a departure from approaches used by other investigators that have extrapolated minor losses from air-water experiments and the combined effects of expansion, contraction, deceleration, and lengthwise pressure gradients. Pressure losses were recorded over the entire range of qualities from 100% vapor to 100% liquid. In addition, the tests were conducted for five different refrigerant mass fluxes between 185 kg/m2-s and 785 kg/m2-s using two differnt end-cut techniques. More than 790 data points were recorded to obtain a comprehensive understanding of the effects of mass flux and quality on minor pressure losses. High accuracy instrumentation such as coriolis mass flowmeters, RTDs, pressure transducers, and real-time data analyses were used to ensure accuracy in the results. The results show that many of the commonly used correlations for estimating two-phase pressure losses significantly underpredict the pressure losses found in compact microchannel tube headers. Furthermore, the results show that the end-cut technique can substantially affect the pressure losses in microchannel headers. A new model for estimating the pressure loss in microchannel headers is presented and a comparison of the end-cut techniques on the minor losses is reported.

A Review of Prediction Methods for Two-Phase Pressure Loss in Mini/Micro-Channels

2016 ◽  
Vol 24 (01) ◽  
pp. 1630002 ◽  
Author(s):  
Jung Hoon Yun ◽  
Ji Hwan Jeong
Keyword(s):  
Experimental Data ◽  
Pressure Drop ◽  
Pressure Loss ◽  
Separated Flow ◽  
Empirical Correlations ◽  
Two Phase ◽  
Flow Models ◽  
Micro Channels ◽  
Extensive Experimental Data ◽  
Phase Pressure

Previous methods and correlations for predicting two-phase frictional pressure loss in mini/micro-channels are reviewed and compared. The empirical correlations are classified into four groups of modeling approaches: Homogeneous equilibrium models (HEMs), separated flow models (SFMs), direct empirical correlations, and flow pattern specific correlations. In order to examine the characteristics of the predictive methods for two-phase pressure loss in mini-channels and to assess the accuracy of the previous models and correlations, extensive experimental data and correlations that are available in the open literature are collected. The 1175 and 1304 experimental data for the two-phase pressure drop for condensing and boiling flows, respectively, are gathered from 15 papers and reports. The results present that the size of the channel significantly influences the pressure drop. The comparison demonstrates that Cicchitti et al.’s two-phase viscosity model is recommended for predicting two-phase pressure loss when the HEM is used. In general, the SFM with the two-phase multipliers of Muller–Steinhagen and Heck and Kim and Mudawar outperforms others for channel diameters of less than 3[Formula: see text]mm.

Modeling and Experimental Study of Solid–Liquid Two-Phase Pressure Drop in Horizontal Wellbores With Pipe Rotation

2015 ◽  
Vol 138 (2) ◽  
Author(s):  
Mehmet Sorgun ◽  
Erman Ulker
Keyword(s):  
Pressure Drop ◽  
Pressure Loss ◽  
Liquid System ◽  
Two Phase ◽  
Eccentric Annulus ◽  
Cfd Models ◽  
Horizontal Wellbores ◽  
Solid Liquid ◽  
Pipe Rotation ◽  
Phase Pressure

Determining pressure loss for cuttings-liquid system is very complicated task since drillstring is usually rotating during drilling operations and cuttings are present inside wells. While pipe rotation is increasing the pressure loss of Newtonian fluids without cuttings in an eccentric annulus, a reduction in the pressure loss for cuttings-liquid system is observed due to the bed erosion. In this study, cuttings transport experiments for different flow rates, pipe rotation speeds, and rate of penetrations (ROPs) are conducted. Pressure loss within the test section and stationary and/or moving bed thickness are recorded. This study aims to predict frictional pressure loss for solid (cuttings)–liquid flow inside horizontal wells using computational fluid dynamics (CFD) and artificial neural networks (ANNs). For this purpose, numerous ANN structures and CFD models are developed and tested using experimental data. Among the ANN structures, TrainGdx–Tansig structure gave more accurate results. The results show that the ANN showed better performance than the CFD. However, both could be used to estimate solid–liquid two-phase pressure drop in horizontal wellbores with pipe rotation.

Two-Phase Frictional Pressure Loss in Horizontal Bubbly Flow with 90-Degree Bend

2006 ◽  
Author(s):  
Seungjin Kim ◽  
Jung Han Park ◽  
Gunol Kojasoy ◽  
Joseph Kelly
Keyword(s):  
Pressure Drop ◽  
Pressure Loss ◽  
Two Phase Flow ◽  
Bubbly Flow ◽  
Glass Tube ◽  
Axial Direction ◽  
Phase Flow ◽  
Local Pressure ◽  
Two Phase ◽  
Phase Pressure

The two-phase pressure drop due to the minor loss in horizontal bubbly two-phase flow is studied. In particular, geometric effects of a 90-degree elbow is of interest in the present study. Experiments are performed in air-water two-phase flow near atmospheric pressure condition in round glass tube with inner diameter of 50.3mm. Along the test section, 90-degee elbow is installed at L/D = 206.6 from the two-phase mixture inlet. Experiments are performed in 15 different flow conditions and the local static pressures are measured at five axial locations. Characteristic pressure drop due to the elbow is clearly demonstrated in the profiles of local pressure data along the axial direction. It is also found that the elbow effect propagates and is more significant further downstream than immediate downstream of the elbow. The overall two-phase frictional pressure loss between L/D = 0 and 329 can be predicted well with the Lockhart-Martinelli correlation with parameter C = 25, which is higher than the generally accepted value of C = 20. A correlation for the two-phase pressure loss, including the minor loss due to the 90-degree elbow is developed by employing the approach analogous to that of Lockhart-Martinelli’s. The newly developed correlation suggests that the modified parameter, C = 65 fits best with the experimental data. In addition, the two-phase minor loss factor for the 90-degree elbow is found to be k = 0.58, 50% higher than that recommended for single-phase flow.

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