Development of a correlation for pressure drop of two-phase flow inside horizontal small diameter smooth and microfin tubes

2020 ◽  
Vol 119 ◽  
pp. 80-91
Author(s):  
M. Khairul Bashar ◽  
Keisuke Nakamura ◽  
Keishi Kariya ◽  
Akio Miyara
Keyword(s):  
Pressure Drop ◽  
Two Phase Flow ◽  
Small Diameter ◽  
Phase Flow ◽  
Two Phase ◽  
Microfin Tubes

Experimental Study of Heat Transfer, Pressure Drop, and Dryout for Flow Boiling of Water in an Oil Heated Minichannel

2004 ◽  
Author(s):  
Levi A. Campbell ◽  
Satish Kandlikar
Keyword(s):  
Heat Transfer ◽  
Pressure Drop ◽  
Test Section ◽  
Two Phase Flow ◽  
Flow Boiling ◽  
Small Diameter ◽  
Constant Heat Flux ◽  
Phase Flow ◽  
Two Phase ◽  
Mass Fluxes

Heat transfer and pressure drop, are experimentally recorded for flow boiling water in a single 706 μm circular copper channel 158.75 mm long. Heat is supplied by heat transfer oil at specified temperatures to a helical channel in the test section. In contrast to other current experimental techniques for flow boiling in small diameter tubes, a uniform temperature boundary condition is employed rather than a constant heat flux condition. The principal results of these experiments are two-phase flow boiling heat transfer rates and an analysis of the time-dependent pressure drop signature during two-phase flow in a minichannel. The range of experiments includes mass fluxes of 43.8–3070 kg/m2s and wall temperatures of 100°C–171.2°C. In all cases the test section water inlet is subcooled to between 72.9°C and 99.6°C. The inlet pressures used are 1.1–230.5 kPa (gage).

Adiabatic Horizontal and Vertical Pressure Drop of Carbon Dioxide Inside Smooth and Microfin Tubes at Low Temperatures

2008 ◽  
Vol 130 (11) ◽  
Author(s):  
Yoon Jo Kim ◽  
Jeremy Jang ◽  
Predrag S. Hrnjak ◽  
Min Soo Kim
Keyword(s):  
Pressure Drop ◽  
Mass Flux ◽  
Two Phase Flow ◽  
Interfacial Shear Stress ◽  
Smooth Tube ◽  
Phase Flow ◽  
Two Phase ◽  
Vertical Pressure ◽  
Frictional Pressure Drop ◽  
Microfin Tubes

This paper presents the pressure drop data and the analysis of adiabatic CO2 flow in horizontal and vertical smooth and microfin tubes at saturation temperatures around −20°C. The test tubes had 3.48mm inner diameter smooth tube and a 3.51mm melt-down diameter microfin tube. The test was performed over a mass flux range of 200–800kg∕m2s and at saturation temperatures of −25°C and −15°C. The effects of various parameters—mass flux, saturated temperature, and tube diameter—on pressure drop were qualitatively analyzed. The analyses showed that the frictional pressure drop characteristics of vertical two-phase flow were much different from that of the horizontal two-phase flow. The microfin tube can be considered as “very rough tube” having the roughness of “fin height.” The data were compared with several correlations. The existing frictional pressure drop correlation is sufficient to predict the horizontal pressure drop in smooth tube. For the vertical pressure drop, the simple combination of the frictional pressure drop and void fraction model was in comparatively good agreement. However, the qualitative results showed that there were some limits to cover the different mechanisms related to the interfacial shear stress. The average enhancement factors and penalty factors evidenced that it was not always true that the internally finned geometry guaranteed the superior in-tube condensation performance of microfin tube in refrigeration system and air-conditioning systems.

scholarly journals Flow boiling instabilities of nitrogen in horizontal small diameter tube

2018 ◽  
Vol 189 ◽  
pp. 06010
Author(s):  
Qiaoyu Zhang ◽  
Jianjun Liu
Keyword(s):  
Pressure Drop ◽  
Two Phase Flow ◽  
Flow Boiling ◽  
Characteristic Curve ◽  
Small Diameter ◽  
Dynamical Response ◽  
Total System ◽  
Phase Flow ◽  
Two Phase ◽  
System Pressure

The flow boiling instability characteristics of nitrogen flow boiling in a horizontal small diameter tube were numerically studied, and a numerical model coupled with two phase flow boiling and system flow supplying was developed. With the steady state solution of the model, the flow boiling characteristic curve and flow supplying curve were obtained. The flow boiling characteristic curve was affected by the heat flux and inlet subcooling, meanwhile the flow supplying curve was affected by the total system pressure drop and friction feature of the flow supplying section. With the transient solution of the model, The dynamical response of pressure drop oscillations type (PDOs) instability of two phase flow were investigated, occurring region and trigging conditions were also obtained.

Frictional Pressure Drop during Two-Phase Flow of Pure Fluids and Mixtures in Small Diameter Channels

2015 ◽  
Vol 13 (4) ◽  
pp. 493-502 ◽  
Author(s):  
Davide Del Col ◽  
Marco Azzolin ◽  
Alberto Bisetto ◽  
Stefano Bortolin
Keyword(s):  
Heat Transfer ◽  
Pressure Drop ◽  
Two Phase Flow ◽  
Small Diameter ◽  
Mass Composition ◽  
Vapor Flow ◽  
Phase Flow ◽  
Two Phase ◽  
Frictional Pressure Drop ◽  
Two Phase Heat Transfer

Abstract Two-phase flow is widely encountered in minichannels heat exchangers such as air-cooled condensers and evaporators for automotive, compact devices for electronic cooling and aluminum condenser for air-conditioning applications. In the present work, frictional pressure drop during adiabatic liquid-vapor flow is experimentally investigated inside a single 0.96 mm diameter minichannel. Tests have been run with three mixtures of R32/R1234ze(E) (23/77%, 50/50% and 75/25% by mass composition) at mass flux ranging between 200 and 600 kg m−2 s−1. Since pressure drop has a strong influence on the two-phase heat transfer, it is crucial to have reliable pressure drop prediction methods for two-phase heat transfer modeling and optimization. Therefore, with the aim of extending its validity range, a model to calculate the frictional pressure gradient during two-phase flow in small diameter channels is tested against the present two-phase pressure drop database. An assessment is also done with two low-GWP refrigerants: the halogenated olefin R1234ze(E) and the hydrocarbon R290. The present model accounts for the effect of internal surface roughness as a function of the liquid-only Reynolds number.

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