scholarly journals  A Simplified Model of Low Reynolds Number, immiscible, Gas-Liquid Flow and Heat Transfer in Porous Media (Numerical Solution with Experimental Validation)

2021 ◽  
Author(s):  
Gamal B. Abdelaziz ◽  
M. Abdelgaleel ◽  
Z.M. Omara ◽  
A. S. Abdullah ◽  
Emad M.S. El-Said ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Porous Media ◽  
Numerical Solution ◽  
Single Phase ◽  
Energy Equation ◽  
Numerical Results ◽  
Phase Flow ◽  
Single Phase Flow ◽  
Two Phase

Abstract This study investigates the thermal-hydraulic characteristics of immiscible two-phase flow (gas/liquid) and heat transfer through porous media. This research topic is interested among others in trickle bed reactors, the reservoirs production of oil, and the science of the earth. Characteristics of two-phase concurrent flow with heat transfer through a vertical, cylindrical, and homogeneous porous medium were investigated both numerically and experimentally. A generalized Darcy model for each phase is applied to derive the momentum equations of a two-phase mixture by appending some constitutive relations. Gravity force is considered through investigation. To promote the system energy equation, the energy equation of solid matrix for each phase are deemed. The test section is exposed to a constant wall temperature after filled with spherical beads. Numerical solution of the model is achieved by the finite volume method. The numerical procedure is generalized such that it can be reduced and applied to single phase flow model. The numerical results are acquired according to, air/water downward flow, spherical beads, ratio of particle diameter to pipe radius D=0.412, porosity φ=0.396, 0.01≤Re≤500, water to air volume ratio 0≤W/A≤∞, and saturation ratio 0≤S1≤1. To validate this model an experimental test rig is designed and constructed, and the corresponding numerical results are compared with its results. Also, the numerical results were compared with other available numerical results. The comparisons show good agreement and validate the numerical model. One of the important results reveals that the heat transfer is influenced by two main parameters; saturation ratios of the two fluids; S1 and S2, and the mixture Reynolds number Re. The thermal entry length is directly dependent on Re, S1, and the thermofluid properties of the fluids. A modified empirical correlation for the entrance length; Xe =0.1 Re.Pr.Rm is predicted, where Rm =Rm(S1, S2, ρ1, ρ2, c1, c2). The predicted correlation is verified by comparing with the supposed correlation of Poulikakos and Ranken (1987) and El-Kady (1997) for a single-phase flow; Xe/Pr=0.1 Re.

Hydrodynamic and Thermal Characteristics of Single-Phase and Two-Phase Micro-Pin-Fin Heat Sinks

2007 ◽  
Author(s):  
Abel M. Siu-Ho ◽  
Weilin Qu ◽  
Frank Pfefferkorn
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Nusselt Number ◽  
Single Phase ◽  
Thermal Characteristics ◽  
Heat Sinks ◽  
Phase Flow ◽  
Single Phase Flow ◽  
Two Phase ◽  
Pin Fin

The pressure drop and heat transfer characteristics of single-phase and two-phase micro-pin-fin heat sinks were investigated experimentally. Fabricated from 110 copper, the heat sink contained an array of 1950 staggered square micro-pin-fins with 200×200 μm2 cross-section by 670 μm height. The ratios of longitudinal pitch and transverse pitch to pin-fin hydraulic diameter are equal to 2. Deionized water was employed as the cooling liquid. A coolant inlet temperature of 30 °C, and six maximum mass velocities, ranging from 183 to 420 kg/m2s, were tested. The corresponding inlet Reynolds number ranged from 45.9 to 105.9. General hydrodynamic and thermal characteristics of the two flow regimes of single-phase flow and flow boiling were described. The measured temperature distribution was used to evaluate single-phase heat transfer coefficient and Nusselt number. Predictions of the previous friction factor and heat transfer correlations that were developed for low Reynolds number (Re<1000) single-phase flow in short pin-fin arrays were compared to the present micro-pin-fin single-phase pressure drop and Nusselt number data, respectively. The Short et al friction factor correlation and the Kos¸ar et al. heat transfer correlation provided acceptable predictions.

Experimental Study on Heat Transfer of Single-Phase Flow and Boiling Two-Phase Flow in Vertical Narrow Annuli

2002 ◽  
Author(s):  
Suizheng Qiu ◽  
Minoru Takahashi ◽  
Guanghui Su ◽  
Dounan Jia
Keyword(s):  
Heat Transfer ◽  
Single Phase ◽  
Two Phase Flow ◽  
Annular Channel ◽  
Phase Flow ◽  
Single Phase Flow ◽  
Transfer Coefficients ◽  
Two Phase ◽  
Narrow Annuli ◽  
Narrow Gaps

Water single-phase and nucleate boiling heat transfer were experimentally investigated in vertical annuli with narrow gaps. The experimental data about water single-phase flow and boiling two-phase flow heat transfer in narrow annular channel were accumulated by two test sections with the narrow gaps of 1.0mm and 1.5mm. Empirical correlations to predict the heat transfer of the single-phase flow and boiling two-phase flow in the narrow annular channel were obtained, which were arranged in the forms of the Dittus-Boelter for heat transfer coefficients in a single-phase flow and the Jens-Lottes formula for a boiling two-phase flow in normal tubes, respectively. The mechanism of the difference between the normal channel and narrow annular channel were also explored. From experimental results, it was found that the turbulent heat transfer coefficients in narrow gaps are nearly the same to the normal channel in the experimental range, and the transition Reynolds number from a laminar flow to a turbulent flow in narrow annuli was much lower than that in normal channel, whereas the boiling heat transfer in narrow annular gap was greatly enhanced compared with the normal channel.

An Experimental Investigation of Gas-Liquid Heat Transfer in Rectangular Micro-Channels

2013 ◽  
Author(s):  
Sira Saisorn ◽  
Somchai Wongwises ◽  
Piyawat Kuaseng ◽  
Chompunut Nuibutr ◽  
Wattana Chanphan
Keyword(s):  
Heat Transfer ◽  
Single Phase ◽  
Flow Direction ◽  
Flow Characteristics ◽  
Phase Flow ◽  
Single Phase Flow ◽  
Two Phase ◽  
Camera System ◽  
Micro Channels ◽  
Flow Mechanisms

The investigations of heat transfer and fluid flow characteristics of non-boiling air-water flow in micro-channels are experimentally studied. The gas-liquid mixture from y-shape mixer is forced to flow in the 21 parallel rectangular microchannels with 40 mm long in the flow direction. Each channel has a width and a depth of 0.45 and 0.41 mm, respectively. Flow visualization is feasible by incorporating the stereozoom microscope into the camera system and different flow patterns are recorded. The experiments are performed under low superficial velocities. Two-phase heat transfer gives better results when compared with the single-phase flow. It is found from the experiment that heat transfer enhancement up to 53% is obtained over the single-phase flow. Also, the change in the configuration of the inlet plenum can result in the different two-phase flow mechanisms.

scholarly journals Iterative Numerical Scheme for Non-Isothermal Two-Phase Flow in Heterogeneous Porous Media

Algorithms ◽  
2019 ◽  
Vol 12 (6) ◽  
pp. 117
Author(s):  
Mohamed F. El-Amin
Keyword(s):  
Heat Transfer ◽  
Porous Media ◽  
Energy Equation ◽  
Body Force ◽  
Two Phase Flow ◽  
Boussinesq Approximation ◽  
Heterogeneous Porous Media ◽  
Phase Flow ◽  
Two Phase ◽  
Coupled Equations

In the current paper, an iterative algorithm is developed to simulate the problem of two-phase flow with heat transfer in porous media. The convective body force caused by heat transfer is described by Boussinesq approximation throughout with the governing equations, namely, pressure, saturation, and energy. The two coupled equations of pressure and saturation are solved using the implicit pressure-explicit saturation (IMPES) scheme, while the energy equation is treated implicitly, and the scheme is called iterative implicit pressure, explicit saturation, implicit temperature (I-IMPES-IMT). In order to calculate the pressure implicitly, the equations of pressure and saturation are coupled by linearizing the capillary pressure which is a function of saturation. After that, the equation of saturation is solved explicitly. Then, the velocity is computed which is used in the energy equation to calculate the temperature implicitly. The cell-centered finite difference (CCFD) method is utilized for spatial discretization. Furthermore, a relaxation factor along is used with the Courant–Friedrichs–Lewy (CFL) condition. Finally, in order to illustrate the efficiency of the developed algorithm, error estimates for saturation and temperature for different values of time steps and number of iterations are presented. Moreover, numerical examples of different physical scenarios of heterogamous media are presented.

Thermofluid Characteristics of Two-Phase Microgap Coolers

2007 ◽  
Author(s):  
Dae W. Kim ◽  
Emil Rahim ◽  
Avram Bar-Cohen ◽  
Bongtae Han
Keyword(s):  
Heat Transfer ◽  
Numerical Model ◽  
Pressure Drop ◽  
Single Phase ◽  
Flow Boiling ◽  
Phase Flow ◽  
Dissolved Gas ◽  
Single Phase Flow ◽  
Two Phase ◽  
Phase Water

The thermofluid characteristics of a chip-scale microgap cooler, including single-phase flow of water and FC-72 and flow boiling of FC-72, are explored. Heat transfer and pressure drop results for single phase water are used to validate a detailed numerical model and, together with the convective FC-72 data, establish a baseline for microgap cooler performance. Experimental results for single phase water and FC-72 flowing in 120 μm, 260 μm and 600 μm microgap coolers, 31mm wide by 34mm long, at velocities of 0.1 – 2 m/s are reported. “Pseudo-boiling” driven by dissolved gas and flow boiling of FC-72 are found to provide significant enhancement in heat transfer relative to theoretical single phase values.

Pressure Drop During Two-Phase Flow of R134a and R32 in a Single Minichannel

2009 ◽  
Vol 131 (3) ◽  
Author(s):  
Alberto Cavallini ◽  
Davide Del Col ◽  
Marko Matkovic ◽  
Luisa Rossetto
Keyword(s):  
Heat Transfer ◽  
Surface Roughness ◽  
Single Phase ◽  
Two Phase Flow ◽  
Vapor Flow ◽  
Phase Flow ◽  
Single Phase Flow ◽  
Roughness Effects ◽  
Two Phase ◽  
Adiabatic Flow

Condensation in minichannels is widely used in air-cooled condensers for the automotive and air-conditioning industry, heat pipes, and compact heat exchangers. The knowledge of pressure drops in such small channels is important in order to optimize heat transfer surfaces. Most of the available experimental work refers to measurements obtained within multiport smooth extruded tubes and deal with the average values over the number of parallel channels. In this context, the present authors have set up a new test apparatus for heat transfer and fluid flow studies in single minichannels. This paper presents new experimental frictional pressure gradient data, relative to single-phase flow and adiabatic two-phase flow of R134a and R32 inside a single horizontal minitube, with a 0.96 mm inner diameter and with not-negligible surface roughness. The new all-liquid and all-vapor data are successfully compared against predictions of single-phase flow models. Also the two-phase flow data are compared against a model previously developed by the present authors for adiabatic flow or flow during condensation of halogenated refrigerants inside smooth minichannels. Surface roughness effects on the liquid-vapor flow are discussed. In this respect, the friction factor in the proposed model is modified, in order to take into consideration also effects due to wall roughness.

Performance Evaluation of Liquid Flow With PCM Particles in Microchannels

2005 ◽  
Vol 127 (8) ◽  
pp. 931-940 ◽  
Author(s):  
K. Q. Xing ◽  
Y.-X. Tao ◽  
Y. L. Hao
Keyword(s):  
Heat Transfer ◽  
Fluid Flow ◽  
Laminar Flow ◽  
Phase Change ◽  
Performance Index ◽  
Single Phase ◽  
Suspension Flow ◽  
Phase Flow ◽  
Single Phase Flow ◽  
Two Phase

A two-phase, non thermal equilibrium-based model is applied to the numerical simulation of laminar flow and heat transfer characteristics of suspension with microsize phase-change material (PCM) particles in a microchannel. The model solves the conservation of mass, momentum, and thermal energy equations for liquid and particle phases separately. The study focuses on the parametric study of optimal conditions where heat transfer is enhanced with an increase in fluid power necessary for pumping the two-phase flow. The main contribution of PCM particles to the enhancement of heat transfer in a microsize tube is to increase the effective thermal capacity and utilize the latent heat effect under the laminar flow condition. An effectiveness factor εeff is defined to evaluate the heat transfer enhancement compared to the single-phase flow heat transfer and is calculated under different wall heat fluxes and different Reynolds numbers. The comparison is also made to evaluate the performance index, i.e., the ratio of total heat transfer rate to fluid flow power (pressure drop multiplied by volume flow rate) between PCM suspension flow and pure water single-phase flow. The results show that for a given Reynolds number, there exists an optimal heat flux under which the εeff value is the greatest. In general, the PCM suspension flow with phase change has a significantly higher performance index than the pure-fluid flow. The comparison of the model simulation with the limited experimental results for a MCPCM suspension flow in a 3mmdia tube reveals the sensitivity of wall temperature distribution to the PCM supply temperature and the importance of characterizing the phase change region for a given tube length.

Heat Transfer Augmentation in 3D Inner Finned Helical Tube

Volume 3 ◽  
2004 ◽  
Author(s):  
Longjian Li ◽  
Wenzhi Cui ◽  
Quan Liao ◽  
Mingdao Xin ◽  
Tien-Chien Jen ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Boiling Heat Transfer ◽  
Flow Resistance ◽  
Single Phase ◽  
Flow Boiling ◽  
Phase Flow ◽  
Single Phase Flow ◽  
Helical Tube ◽  
Helical Tubes

Experiments were performed to investigate the performance enhancement of single-phase flow and boiling heat transfer in the 3D inner finned helical tubes. The tests for single-phase flow and heat transfer were carried out in the helical tubes with a curvature of 0.0663 and a length of 1.15m, the range of the Reynolds number examined varies from 1000 to 8500. In comparison to the smooth helical tube, the experimental results of two finned helical tubes with different inner fin geometry showed that the heat transfer and flow resistance in the 3D inner finned helical tube gains greater augmentation. Within the measured range of Reynolds number, the average augmentation ratio of heat transfer of the two finned tubes are 71% and 103%, compared with the smooth helical tube, and 90% and 140% for flow resistance, respectively. The tests for flow boiling heat transfer was carried out in the 3D inner finned helical tube with a curvature of 0.0605 and a length of 0.668m. Compared with that in the smooth helical tube, the boiling heat transfer coefficient in the 3D inner finned helical tube is increased by 40%∼120% under varied mass flow rate and wall heat flux conditions, meanwhile, the flow resistance coefficient increased by 18%∼119%.

Sign in / Sign up

Export Citation Format

Share Document