AN EXPERIMENTAL STUDY ON TWO-PHASE PRESSURE DROP IN SMALL DIAMETER HORIZONTAL, DOWNWARD INCLINED, AND VERTICAL TUBES by (original) (raw)
Related papers
Thermal Science, 2013
An experimental study of two-phase pressure drop in small diameter tubes orientated horizontally, vertically and at two other downward inclinations of ?= 300 and ? = 600 is described in this paper. Acrylic transparent tubes of internal diameters 4.0, 6.0, and 8.0 mm with lengths of 400 mm were used as the test section. Air-water mixture was used as the working fluid. Two-phase pressure drop was measured and compared with the existing correlations. These correlations are commonly used for calculation of pressure drop in macro and mini-microchannels. It is observed that the existing correlations are inadequate in predicting the two-phase pressure drop in small diameter tubes. Based on the experimental data, a new correlation has been proposed for predicting the two-phase pressure drop. This correlation is developed by modification of Chisholm parameter C by incorporating different parameters. It was found that the proposed correlation predicted two-phase pressure drop at satisfactory ...
Experimental Investigation of Two-Phase Pressure Drop in a Microchannel
Heat Transfer Engineering, 2011
Following the general tendency of miniaturization of devices in many branches of industry, smaller and smaller components are used. Mini channels are used to construct mini heat exchangers and mini reactors. Because of this fact, predicting two-phase pressure drops along the mini tube plays an important role already at the design stage. It defines the proper and safe operating conditions of such devices. It was decided to research this phenomena in five single mini channels and undertake a comparison of various correlations models reported in literature and check how the process of changing critical Reynolds value affects the conformity of the experimental data and results reported in literature. It was found that the Mishima-Hibiki model derived from literature offers the possibility of most accurate mathematical modelling. It was also found that changing critical Reynolds value because of mini channel roughness can significantly improve the accuracy of the existing correlations models e.g. for Lee-Lee model the improvement is equal to almost 9%.
Thermal Science, 2014
Experimental results of adiabatic two-phase pressure drop in small diameter tubes are presented in this work. Air-water mixture is used as the working substance. Four test sections made of transparent acrylic tubes of different internal diameters ranging from 3.0 mm to 8.0 mm are used with different test section lengths from 150 mm to 400 mm. The investigation is carried out within the range of mass flux of water 16.58 -3050 kg/m2s, mass flux of air 8.25-204.10 kg/m2s and total mass flux 99.93-3184.69 kg/m2s. Some of the existing correlations for macro and mini-channels are compared with the experimental data. Based on the experimental data; a new correlation has been developed to predict two-phase pressure drop in horizontal channels.
Experimental Study on Two-Phase Pressure Drop of Air-Water in Horizontal Mini Channel
ASME 2014 12th International Conference on Nanochannels, Microchannels and Minichannels, 2014
The new correlation for two-phase pressure drop for mini channel is developed by performing experiment on adiabatic two-phase pressure drop in mini channel with 3.1 mm diameter. Air-water mixture is used as the working substance. 180°-90°-90° (straight flow) test sections made of transparent glass tubes of 3.1 mm diameter with lengths of 900 mm. The superficial velocity varies from 0.2238 m/s to 1.1876 m/s for liquid (UL) and air (UG). Two phase flow pressure drop experiment is divided into two parts. First single phase pressure drop for air and water is experimented. The diameter is verified by measuring pressure drop of the air. Single phase pressure drop for air and water is experimented first which is followed by two phase pressure drop in the same mini channel. The existing correlations for macro and mini-channels are compared with the experimental data. Using Matlab & Minitab; a new correlation has been developed to predict two-phase pressure drop in horizontal mini channels.
Two-Phase Pressure Drop Calculations in Small Diameter Inclined Tubes
International Journal of Engineering & Technology, 2012
Effect of inclination on two-phase frictional pressure drop was investigated in small diameter circular tubes with inner diameters of 4.0, 6.0, 8.0 and 10.0 mm using air and water. Pressure drop was measured and compared with various existing models commonly used for macro and micro channels such as homogeneous, Lockhart-Martinelli, Chisholm, Friedel, Mishma Hibiki, and Zang Mishma. It was found that existing correlations are inadequate in predicting pressure drop for small diameter inclined tubes. The void fraction is calculated using a general void fraction correlation in two-phase flow for various pipe orientations. Based on analysis of present experimental frictional pressure drop data, a correlation is proposed for predicting Chisholm parameter C in small diameter inclined tubes. There was a significant ordering of pressure drop data with respect to Reynolds number, Webber number and Bond number for each diameter.
A Mechanistic Model of Two-Phase Pressure Drop in Microchannels
Volume 6: Fluids and Thermal Systems; Advances for Process Industries, Parts A and B, 2011
A mechanistic model of two-phase pressure drop has been developed for microchannel flow. The primary flow regimes observed in microchannel two-phase flow regime maps were the inertial dominated regime (annular flow) and the surface tension dominated regime (slug or bubbly flow). Mechanistic models of pressure drop for each of these regimes are developed and compared to pressure drop in microchannel flows of four different refrigerants with widely varying fluid properties: R134, R410A, R290 (propane) and R717 (ammonia) of varying hydraulic diameters between 70 microns to 305 microns. The mechanistic model compares favourably to the experimental pressure drop data from microchannel flow measurements with an overall mean deviation of 18.1%. The model is also compared with refrigerant-oil flow of R134a and two different weights of POE oil, using fluid property correlations developed for those mixtures, with a mean deviation of 18.9%. While this accuracy is not stellar, the significance ...
Single phase pressure drop in microchannels
International Journal of Heat and Fluid Flow, 2007
This article focuses on investigating fully developed liquid and vapor flow through rectangular microchannels with hydraulic diameters varying from 69.5 to 304.7 lm and with aspect ratios changing from 0.09 to 0.24. R134a liquid and vapor were used as the testing fluids. During the experiments, the Reynolds numbers were varied between 112 and 9180. Pressure drop data are used to characterize the friction factor in the laminar region, the transition region and the turbulent region. When the channel surface roughness was low, both the laminar friction factor and the critical Reynolds number approached the conventional values, even for the smallest channel tested. Hence, there was no indication of deviation from the Navier-Stokes flow theory for rectangular microchannels. The friction factor data in the turbulent region were larger than the predictions from the [Churchill, S.W., 1977, Friction factor equations spans all fluid-flow regimes, Chemical Engineering 45, 91-92] equation for smooth tubes, even for the smoothest channel tested (R a /D h = 0.14%). In addition, it was likely that surface roughness was responsible for higher laminar flow friction and earlier transition to turbulent flow in one of the channels tested.
A review of single-phase pressure drop characteristics microchannels with bends
Journal of Mechatronics, Electrical Power, and Vehicular Technology, 2021
Microfluidic use in various innovative research, many fields aimed at developing an application device related to handling fluid flows in miniature scale systems. On the other hand, on the use of micro-devices for fluid flow the existence of bends cannot be avoided. This research aims to make a comprehensive study of fluid flow characteristics through a microchannel with several possible bends. This study was conducted by comparing Reynolds number versus pressure drop in a serpentine microchannel to gain bends loss coefficient. The result showed that the fluid flow with Re 100 did not affect the pressure drop, but on the Reynolds number above that, the pressure drop was increased along with the appears of vortices in the outer and inner walls around the channel bends which causes an increase in an additional pressure drop. The other finding shows that the reduction in diameter bend tube can increase the pressure drop.
Experimental Analysis of Pressure Drop in Single and Two Phase in Mini Channels
Revista de Engenharia Térmica, 2018
Evaporators with mini and micro channels are one of the main focuses in the design and development of equipment applied to compact refrigeration systems. The objective of this work is to investigate pressure drop of natural refrigerant, isobutane (R-600a), in the single-phase flow through two small tubes, with 1.0 mm and 2.6 mm of internal diameter. Also, the pressure drop was analyzed in the boiling flow in a 2.6 mm internal diameter tube. The experimental tests included mass velocities of 188, 240, 280 and 370 kg/(m²s), heat fluxes in the range from 0 to 134 kW/m² and boiling flow the saturation temperature of 22 ºC and vapor quality up to 0.8. It was possible to observe the significant influence of the diameter and mass velocity on the total pressure drop and the frictional pressure drop, respectively. The experimental frictional pressure drop in flow boiling in 2.6 mm of internal diameter was compared with four different correlations in literature.
Flow-Regime-Based Model for Pressure Drop Predictions in Microchannels
HVAC&R Research, 2006
A flow-regime based pressure drop model is developed to correlate experimental data in the intermittent and annular flow regime. For the intermittent region, an alternative method for microchannel pressure drop predictions based on the average kinetic energy of the mixture is developed. A parameter based in the Weber number, the Lockhart-Martinelli parameter, and the liquid to vapor density ratio is proposed for pressure drop predictions in the annular flow region.