The effect of spacer grid critical component on pressure drop under both single and two phase flow conditions

Kerntechnik ◽  
2016 ◽  
Vol 81 (3) ◽  
pp. 257-267 ◽  
Author(s):  
B. Han ◽  
B.-W. Yang ◽  
H. Zhang ◽  
H. Mao ◽  
Y. Zha
Keyword(s):  
Pressure Drop ◽  
Two Phase Flow ◽  
Phase Flow ◽  
Critical Component ◽  
Flow Conditions ◽  
Spacer Grid ◽  
Two Phase

Development of a new spacer grid pressure drop model in rod bundle for the post-dryout two-phase flow regime during reflood transients

2020 ◽  
Vol 368 ◽  
pp. 110815
Author(s):  
Yue Jin ◽  
Fan-Bill Cheung ◽  
Koroush Shirvan ◽  
Stephen M. Bajorek ◽  
Kirk Tien ◽  
...  
Keyword(s):  
Pressure Drop ◽  
Flow Regime ◽  
Two Phase Flow ◽  
Phase Flow ◽  
Spacer Grid ◽  
Two Phase ◽  
Rod Bundle

scholarly journals Experimental Investigation of the Vertical Upward Single- and Two-Phase Flow Pressure Drops Through Gate and Ball Valves

2019 ◽  
Vol 142 (2) ◽  
Author(s):  
Ammar Zeghloul ◽  
Hiba Bouyahiaoui ◽  
Abdelwahid Azzi ◽  
Abbas H. Hasan ◽  
Abdelsalam Al-sarkhi
Keyword(s):  
Experimental Investigation ◽  
Pressure Drop ◽  
Single Phase ◽  
Gate Valve ◽  
Two Phase Flow ◽  
Phase Flow ◽  
Flow Conditions ◽  
Two Phase ◽  
Pressure Drops ◽  
Flow Pressure

Abstract This paper presents an experimental investigation of the pressure drop (DP) through valves in vertical upward flows. Experiments were carried out using a 1¼″ (DN 32) ball and gate valve. Five opening areas have been investigated from fully open to the nearly fully closed valve, using air with a superficial velocity of 0–3.5 m/s and water 0.05–0.91 m/s. These ranges cover single-phase and the bubbly, slug and churn two-phase flow regimes. It was found that for the single-phase flow experiments, the valve coefficient increases with the valve opening and is the same, in both valves, for the openings smaller than 40%. The single-phase pressure drop increases with the liquid flowrate and decreases with the opening area. The two-phase flow pressure drop was found considerably increased by reducing the opening area for both valves. It reaches its maximum values at 20% opening for the ball valve and 19% opening for the gate valve. It was also inferred that at fully opening condition, the two-phase flow multiplier, for both valves, has been found close to unity for most of the tested flow conditions. For 40 and 20% valve openings the two-phase multiplier decreases in the power-law with liquid holdup for the studied flow conditions. Models proposed originally for evaluating the pressure drop through an orifice in single-phase and two-phase flows were also applied and assessed in the present experimental data.

MODELING OF THE MINIMIZED TWO-PHASE FLOW FRICTIONAL PRESSURE DROP IN A SMALL TUBE WITH DIFFERENT CORRELATIONS

2016 ◽  
Vol 78 (6-11) ◽  
Author(s):  
Qais Abid Yousif ◽  
Normah Mohd-Ghazali ◽  
Nor Atiqah Zolpakar ◽  
Sentot Novianto ◽  
Agus Sujiantro Pamitran ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Surface Roughness ◽  
Pressure Drop ◽  
Laminar Flow ◽  
Friction Factor ◽  
Two Phase Flow ◽  
Phase Flow ◽  
Flow Conditions ◽  
Two Phase ◽  
Frictional Pressure Drop

The major parameters of interest in heat transfer research are the refrigerant charge, pressure drop, and heat transfer capacity. Smaller channels reduce the refrigerant charge with higher heat transfer capability due to the increased in surface area to volume ratio but at the expense of a higher pressure drop. Differences between the predicted and experimental frictional pressure drop of two-phase flow in small tubes have frequently been discussed. Factors that could have contributed to that effect have been attributed to the correlations used to model the flow, some being modified from the originals developed for a macro system. Experimental test-rigs have varied in channel geometry, refrigerant type, and flow conditions. Thousands of data have been collected to find a common point among the differences. This paper reports an investigation of four different two-phase friction factor correlations used in the modeling of the frictional two-phase flow pressure drop of refrigerant R-22. One had been specifically developed for laminar flow in a smooth channel, another was modified from a laminar flow in a smooth pipe to be used for a rough channel, and two correlations are specific for turbulent flow that consider internal pipe surface roughness. Genetic algorithm, an optimization scheme, is used to search for the minimum friction factor and minimum frictional pressure drop under optimized conditions of the mass flux and vapor quality. The results show that a larger pressure drop does come with a smaller channel. A large discrepancy exists between the correlations investigated; between the ones that does not consider surface roughness and that which does, as well as between flow under laminar and turbulent flow conditions.

Developing Lengths in Horizontal Two-Phase Bubbly Flow

1995 ◽  
Vol 117 (3) ◽  
pp. 512-518 ◽  
Author(s):  
B. A. Warren ◽  
J. F. Klausner
Keyword(s):  
Pressure Drop ◽  
Two Phase Flow ◽  
Volume Fraction ◽  
Bubbly Flow ◽  
Phase Flow ◽  
Flow Conditions ◽  
Relative Deviation ◽  
Two Phase ◽  
Fully Developed Flow ◽  
Local Measurements

An air-water two-phase flow facility with a 19.1 mm i.d. test section has been fabricated. Local measurements of pressure drop for two-phase horizontal bubbly flow and single-phase flow downstream of various orifices have been obtained over a range of flow conditions. The wall shear stress developing length is obtained from the pressure drop profile. A developing length correlation is presented in which the relative deviation is 6 percent. The fully developed vapor volume fraction has also been measured up- and downstream of the orifice. A simple correlation for vapor volume fraction is presented in which the relative deviation is 7 percent. Photographs of the two-phase flow pattern in the developing region reveal that the flow structure is extremely complex and continuously evolves until approximately fully developed flow conditions are achieved.

Pressure Drop for Oil-Gas Two-Phase Flow Through Straight Horizontal Pipe

2007 ◽  
Author(s):  
Wenhong Liu ◽  
Liejin Guo ◽  
Ximin Zhang ◽  
Kai Lin ◽  
Long Yang ◽  
...  
Keyword(s):  
Pressure Drop ◽  
Two Phase Flow ◽  
Phase Flow ◽  
Two Phase ◽  
Horizontal Pipe ◽  
Flow Through ◽  
Oil Gas

scholarly journals Experimental Investigation and Prediction on Pressure Drop during Flow Boiling in Horizontal Microchannels

Micromachines ◽  
2021 ◽  
Vol 12 (5) ◽  
pp. 510
Author(s):  
Yan Huang ◽  
Bifen Shu ◽  
Shengnan Zhou ◽  
Qi Shi
Keyword(s):  
Pressure Drop ◽  
Flow Model ◽  
Two Phase Flow ◽  
Flow Boiling ◽  
Separated Flow ◽  
Heat Fluxes ◽  
Phase Flow ◽  
Vapor Quality ◽  
Two Phase ◽  
Gas Flux

In this paper, two-phase pressure drop data were obtained for boiling in horizontal rectangular microchannels with a hydraulic diameter of 0.55 mm for R-134a over mass velocities from 790 to 1122, heat fluxes from 0 to 31.08 kW/m2 and vapor qualities from 0 to 0.25. The experimental results show that the Chisholm parameter in the separated flow model relies heavily on the vapor quality, especially in the low vapor quality region (from 0 to 0.1), where the two-phase flow pattern is mainly bubbly and slug flow. Then, the measured pressure drop data are compared with those from six separated flow models. Based on the comparison result, the superficial gas flux is introduced in this paper to consider the comprehensive influence of mass velocity and vapor quality on two-phase flow pressure drop, and a new equation for the Chisholm parameter in the separated flow model is proposed as a function of the superficial gas flux . The mean absolute error (MAE ) of the new flow correlation is 16.82%, which is significantly lower than the other correlations. Moreover, the applicability of the new expression has been verified by the experimental data in other literatures.

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