Inlet Saturation Research Articles

Experimental and theoretical study of critical heat flux in vertical upflow with inlet vapor void

This study explores the mechanism of flow boiling critical heat flux (CHF) for FC-72 in a 2.5 mm × 5 mm vertical upflow channel that is heated along its 2.5 mm sidewall downstream of an adiabatic development section. Unlike most prior CHF studies, where the working fluid enters the channel in liquid state, the present study concerns saturated inlet conditions with finite vapor void. Temperature measurements and high-speed video imaging techniques are used to investigate the influence of the inlet vapor void on interfacial behavior at heat fluxes up to CHF as well during the CHF transient. The flow entering the heated portion of the channel consists of a thin liquid layer covering the entire perimeter surrounding a large central vapor core. Just prior to CHF, a fairly continuous wavy vapor layer begins to develop between the liquid layer covering the heated wall and the heated wall itself, resulting in a complex four-layer flow consisting of the liquid layer covering the insulated walls, the central vapor core, the now separated liquid layer adjacent to the heated wall, and the newly formed wavy vapor layer along the heated wall. This behavior in captured in a new separated control-volume-based model that facilities the determination of axial variations of thicknesses and mean velocities of the four layers. Incorporating the results of this model in a modified form of the Interfacial Lift-off CHF Model is shown to provide fairly good predictions of CHF data for mass velocities between 185 and 1600 kg/m 2 s, evidenced by a mean absolute error of 24.52%.

Partial condensation of R407C and R410A refrigerants inside a plate heat exchanger

This work investigates the condensation heat transfer of two refrigerants mixtures, R407C and R410A, in a brazed plate heat exchanger (BPHE) reporting the experimental measurements of the heat transfer coefficient. The prototype consists of six plates with two refrigerant ducts and three water channels. The condensation heat transfer coefficients of R407C and R410A have been measured at constant inlet saturation pressure of 1.6 MPa and 2.2 MPa, respectively. For both refrigerants, the superheating at the inlet of the heat exchanger was around 15 K; the mass flux has been varied from 15 to 40 kg m −2 s −1 whereas the outlet vapour quality has been changed between 0.07 and 0.58 in order to investigate the effect of vapour quality. The experimental measurements have been compared against three models suggested in the open literature; moreover, a new computation procedure for the design of BPHE condensers has been developed and validated against the present experimental database.

Two-phase flow of refrigerants in 85 μm-wide multi-microchannels: Part I – Pressure drop

This article is the first part of a study on flow boiling of R236fa and R245fa. This part presents pressure drop measurements obtained on a silicon multi-microchannel evaporator with 85 μm wide and 560 μm high channels separated by 46 μm wide fins. The 135 microchannels were 12.7 mm long. Dielectric refrigerants R236fa and R245fa were used as the evaporating test fluids. The inlet saturation temperature was maintained at 30.5 °C while the mass fluxes were varied from 499 to 1100 kg/m 2 s and the base heat flux was tested from 130 to 1400 kW/m 2. A new experimental technique was developed to measure the outlet pressure losses, which represented up to 30% of the total pressure drop and thus cannot be neglected. The microchannel pressure drop measurements were very well predicted by the method of Cioncolini et al. (2009).

Numerical Solution of Equation for Dynamic, Spontaneous Imbibition with Variable Inlet Saturation and Interfacial Coupling Effects

In the oil industry, dynamic spontaneous imbibition plays an important role in several flow processes in porous media. A numerical approach is developed to simulate dynamic spontaneous imbibition with variable inlet saturation and interfacial coupling. The inclusion of interfacial coupling effects invalidates the assumption that the interfaces (fluid/fluid and fluid/solid) act in the same way. The one-dimensional numerical simulation model is developed using a Lagrangian formulation discretized in time and saturation. The solution of the partial differential equations utilizes an iteration process that includes two material balance criteria to ensure the validity of the variable inlet saturation. Furthermore, an error analysis, the validation of the model and a sensitivity study on the optimal number of time steps and saturation grid cells are undertaken. The numerical simulation solution represents an accurate approach to investigate the effect of fluid and rock properties on dynamic spontaneous imbibition.

Evaluating the impact of water supply strategies on p-xylene biodegradation performance in an organic media-based biofilter

The influence of water irrigation on both the long-term and short-term performance of p-xylene biodegradation under several organic loading scenarios was investigated using an organic packing material composed of pelletised sawdust and pig manure. Process operation in a modular biofilter, using no external water supply other than the moisture from the saturated inlet air stream, showed poor p-xylene abatement efficiencies (≈33 ± 7%), while sustained irrigation every 25 days rendered a high removal efficiency (RE) for a critical loading rate of 120 g m −3 h −1. Periodic profiles of removal efficiency, temperature and moisture content were recorded throughout the biofilter column subsequent to each biofilter irrigation. Hence, higher p-xylene biodegradation rates were always initially recorded in the upper module, which resulted in a subsequent increase in temperature and a decrease in moisture content. This decrease in the moisture content in the upper module resulted in a higher removal rate in the middle module, while the moisture level in the lower module steadily increased as a result of water condensation. Based on these results, mass balance calculations performed using measured bed temperatures and relatively humidity values were successfully used to account for water balances in the biofilter over time. Finally, the absence of bed compaction after 550 days of continuous operation confirmed the suitability of this organic material for biofiltration processes.

Theoretical Development of a Novel Equation for Dynamic Spontaneous Imbibition with Variable Inlet Saturation and Interfacial Coupling Effects

In oil recovery from fractured reservoirs, dynamic spontaneous imbibition (DSI) plays an important role. Conventional equations used for characterizing dynamic spontaneous imbibition neglect the effects of the driving forces acting across the wetting and non-wetting phases which are flowing in opposite directions. Such effects, defined as interfacial coupling effects (ICE), are known to cause a decrease in the calculated flow rate in drainage processes. Moreover, none of the numerical models have considered a variable inlet saturation (S*) for DSI. A new theoretical model has been developed using generalized transport equations to describe dynamic spontaneous imbibition for immiscible two-phase flow processes. The inclusion of interfacial coupling effects provides a more accurate way to describe dynamic spontaneous imbibition. Furthermore, the addition of variable inlet saturation allows one to establish whether the inlet-face saturation (S*) increases from the initial saturation to 1−Sro, or whether it can remain constant and equal to one minus the residual saturation to the non-wetting phase (1−Sro).

Experimental study on evaporation heat transfer of CO 2/DME mixture refrigerant in a horizontal smooth tube

In-tube evaporation heat transfer coefficient of pure dimethyl ether (DME) and CO 2/DME mixtures have been measured with water heated double tube heat exchanger under the conditions of mass flux of 100, 200, 300 kg m −2 s −1 and inlet saturation temperature of 10 °C. Test section was horizontally installed smooth tube with inner diameter of 4.2 mm. The heat transfer coefficient of mixture decreases with mixing CO 2 into DME in which the degradation was about 20% for 10%CO 2 and 48% for 25%CO 2. Existent correlations predict the heat transfer coefficients of pure DME within ±30% error. On the other hand, heat transfer coefficient of the mixture with higher concentration 25%CO 2 could not be predicted well by existent correlations, though those of 10%CO 2 could be correlated fairly well.

Flow boiling performance in horizontal microfinned copper tubes with the same geometric characteristics

This article reports an experimental investigation on flow boiling heat transfer and pressure drop of refrigerant R-134a in a smooth horizontal and two microfinned tubes from different manufacturers with the same geometric characteristics. Experiments have been carried out in an experimental facility developed for change of phase studies with a test section made with 9.52 mm external diameter, 1.5 m long copper tubes, electrically heated by tape resistors wrapped on the external surface. Tests have been performed under the following conditions: inlet saturation temperature of 5 °C, vapor qualities from 5% to 90%, mass velocity from 100 to 500 kg/s m 2, and a heat flux of 5 kW/m 2. Experimental results indicated that the heat transfer performance was basically the same for both microfin tubes. The pressure drop is higher in the microfinned tubes in comparison to the smooth tube over the whole range of mass velocities and vapor qualities. The enhancement factor, used to evaluate the combination of heat transfer and pressure drop, is higher than one for both tubes for mass velocities lower than 300 kg/s m 2. Values lower than one have been obtained for both tubes in the mass velocity upper range as a result of a significant pressure drop increment not followed by a correspondent increment in the heat transfer coefficient. Some images, illustrating the flow patterns, were obtained from the visualization section, located in the exit of the test section with the same internal diameter of the tested tube.

Critical heat flux in multi-microchannel copper elements with low pressure refrigerants

New saturated critical heat flux (CHF) data have been obtained experimentally in two different multi-microchannel heat sinks made in copper with three low pressure refrigerants (R134a, R236fa, R245fa). One of the test sections has 20 parallel rectangular channels, 467 μ m wide and 4052 μ m deep while the second has 29 channels, 199 μ m wide and 756 μ m deep. The microchannels are 30 mm long in the flow direction where a 20 mm length in the middle is heated with an electrical resistance deposited on a silicon plate. Base CHF values were measured from 37 to 342 W / cm 2 for mass velocities from 100 to 4000 kg / m 2 s . When increasing the mass velocity, CHF was observed to increase while the rate of increase was slower at high velocities. While CHF increased moderately with large inlet subcooling (e.g. 20 K) in the H = 4052 μ m channels, inlet subcooling seemed to play less a role as the channel size decreased. CHF showed reversed tendency with increasing inlet saturation temperature ( 10 ⩽ T sat ⩽ 50 ° C ) depending on the flow condition and the channel size. The experimental data were compared with existing prediction methods. The data demonstrated good agreement with several predictive methods using the heated equivalent diameter D he and the actual mass velocity G eq to implement the circular tube correlations.

Analysis of gas turbine operating parameters with inlet fogging and wet compression processes

Abstract Inlet fogging has been widely noticed in recent years as a method of gas turbine air inlet cooling for increasing the power output in gas turbines and combined cycle power plants. The effects of evaporative cooling on gas turbine performance were studied in this paper. Evaporative cooling process occurs in both compressor inlet duct (inlet fogging) and inside the compressor (wet compression). By predicting the reduction in compressor discharge air temperature, the modeling results were compared with the corresponding results reported in literature and an acceptable difference percent point was found in this comparison. Then, the effects of both evaporative cooling in inlet duct, and wet compression in compressor, on the power output, turbine exhaust temperature, and cycle efficiency of 16 models of gas turbines categorized in four A–D classes of power output, were investigated. The results of this analysis for saturated inlet fogging as well as 1% and 2% overspray are reported and the prediction equations for the amount of actual increased net power output of various gas turbine nominal power output are proposed. Furthermore the change in values of physical parameters and moving the compressor operating point towards the surge line in compressor map was investigated in inlet fogging and wet compression processes.

Capillary Pressure Measurement on Cores by MRI

This article, written by Technology Editor Dennis Denney, contains highlights of paper OTC 19234, "Capillary Pressure Measurement in Petroleum-Reservoir Cores With MRI," by Prisciliano F. de J. Cano Barrita, Bruce J. Balcom, and Michael J. McAloon, University of New Brunswick, and Derrick P. Green, SPE, and Josh Dick, Green Imaging Technologies, prepared for the 2008 Offshore Technology Conference, Houston, 5-8 May. The paper has not been peer reviewed. The quantitative nature of the double half-K-space single-point ramped imaging with longitudinal-relaxation-time (T1) enhancement (2HK-SPRITE) magnetic-resonance-imaging (MRI) method enables measurement of fluid distribution in core plugs, reducing the number of speeds necessary to obtain a full capillary pressure curve compared with the standard centrifuge method. This centrifuge/MRI method requires the use of only a moderate-rotational-speed centrifuge and a low-field permanent magnet. Capillary pressure curves were obtained for primary drainage, imbibitions, and secondary drainage in water/oil systems. Introduction The SPRITE-MRI method has proved suitable to establish the capillary pressure curve of core plugs. To determine the capillary pressure with this technique, the distribution of the fluids along the length of the core is obtained without assumptions required in traditional centrifuge testing. This technique is directly quantitative compared to traditional, less-quantitative, spin-echo-based MRI. The procedure to establish capillary pressure curves for core plugs by use of double half-K-space MRI, combined with a moderate-speed centrifuge, is presented. Capillary Pressure Two immiscible fluids in contact with each other in the pore network of a porous medium produce a discontinuity in pressure across the interface. The pressure difference across the interface is called the capillary pressure. Capillary pressure is a result of the curvature of the fluid interfaces and of the interfacial tension. Traditional Centrifuge Methods Capillary pressure curves for rocks are used to predict potential hydrocarbon recovery from a reservoir. Traditional methods to establish these curves include mercury intrusion, porous plate, and centrifuge. Mercury intrusion is considered a rapid method, but it has limitations in providing information on reservoir wettability. Porous plate is a direct and accurate technique, but it is time-consuming because the equilibration time can be weeks or months for each pressure point. The centrifuge uses centrifugal force by rotating a core plug at different speeds and allowing time for saturation equilibrium in the core at each speed. The amount of fluid expelled from the core at each speed is measured, and an average saturation in the core is determined. An approximate solution is used to obtain the inlet saturation corresponding to the inlet capillary pressure. This solution makes the assumptions that the outlet face of the core remains 100% saturated with the wetting phase at all centrifuge speeds, and that the core length is negligible with respect to the radius of rotation.

High heat flux flow boiling in silicon multi-microchannels – Part III: Saturated critical heat flux of R236fa and two-phase pressure drops

New experimental critical heat flux results for saturated boiling conditions have been obtained for R236fa flowing in a silicon multi-microchannel heat sink composed of 67 parallel channels, 223 μm wide, 680 μm high and with 80 μm thick fins separating the channels. The microchannel length was 20 mm. The footprint critical heat fluxes measured varied from 112 to 250 W/cm 2 and the wall critical heat fluxes from 21.9 to 52.2 W/cm 2 for mass velocities from 276 to 992 kg/m 2s. When increasing the mass velocity, the wall critical heat flux was observed to increase. The inlet saturation temperatures (20.31 ⩽ T sat,in ⩽ 34.27 °C) and the inlet subcoolings (0.4 ⩽ Δ T sub ⩽ 15.3 K) were found to have a negligible influence on the saturated CHF. The best methods for predicting the data were those of Wojtan et al. [L. Wojtan, R. Revellin, J. R. Thome, Investigation of critical heat flux in single, uniformly heated microchannels, Exp. Therm. Fluid Sci. 30 (2006) 765–774] and Revellin and Thome [R. Revellin, J. R. Thome, A theoretical model for the prediction of the critical heat flux in heated microchannels, Int. J. Heat Mass Transfer 50 (in press)]. They both predict the experimental CHF results with a mean absolute error of around 9%. Using the critical vapour quality, an annular-to-dryout transition is also proposed as a limit in a diabatic microscale flow pattern map. Pressure drop measurements were measured and analysed, showing that the homogeneous model could correctly predict the observed trends.

Two-phase pressure drop during CO 2 vaporization in horizontal smooth minichannels

Pressure drop experiments for a natural refrigerant vaporization of CO 2 were performed in horizontal minichannels. The test section was made of stainless steel tubes with inner diameters of 1.5 mm and 3.0 mm and with lengths of 2000 and 3000 mm. This test section was uniformly heated by applying electric current directly to the tubes. Experiments were performed at inlet saturation temperatures of −10, −5 and 10 °C, mass flux ranges from 200 to 600 kg m −2 s −1 and heat flux ranges from 10 to 30 kW m −2. The current study showed the significant effect of mass flux, tube diameter, and saturation temperature on the pressure drop. The experimental results were compared against 13 existing two-phase pressure drop prediction methods. A new pressure drop prediction method based on the Lockhart–Martinelli method was developed with 9.41% mean deviation.

Two-phase pressure drop of R-410A in horizontal smooth minichannels

Convective boiling pressure drop experiments were performed in horizontal minichannels with a binary mixture refrigerant, R-410A. The test section was made of stainless steel tubes with inner diameters of 1.5 mm and 3.0 mm and with lengths of 1500 mm and 3000 mm, respectively. This test section was uniformly heated by applying electric current directly to the tubes. Experiments were performed at inlet saturation temperature of 10 °C, mass flux ranges from 300 to 600 kg m −2 s −1 and heat flux ranges from 10 to 40 kW m −2. The current study showed the significant effect of mass flux and tube diameter on pressure drop. The experimental results were compared against 15 two-phase pressure drop prediction methods. The homogeneous model predicted well the experimental pressure drop, generally. A new pressure drop prediction method based on the Lockhart–Martinelli method was developed with 4.02% mean deviation.

Convective boiling performance of refrigerant R-134a in herringbone and microfin copper tubes

This paper reports an experimental investigation of convective boiling heat transfer and pressure drop of refrigerant R-134a in smooth, standard microfin and herringbone copper tubes of 9.52 mm external diameter. Tests have been conducted under the following conditions: inlet saturation temperature of 5 °C, qualities from 5 to 90%, mass velocity from 100 to 500 kg s −1 m −2, and a heat flux of 5 kW m −2. Experimental results indicate that the herringbone tube has a distinct heat transfer performance over the mass velocity range considered in the present study. Thermal performance of the herringbone tube has been found better than that of the standard microfin in the high range of mass velocities, and worst for the smallest mass velocity ( G=100 kg s −1 m −2) at qualities higher than 50%. The herringbone tube pressure drop is higher than that of the standard microfin tube over the whole range of mass velocities and qualities. The enhancement parameter is higher than one for both tubes for mass velocities lower than 200 kg s −1 m −2. Values lower than one have been obtained for both tubes in the mass velocity upper range as a result of a significant pressure drop increment not followed by a correspondent increment in the heat transfer coefficient.

Operation of Nafion®-based PEM fuel cells with no external humidification: influence of operating conditions and gas diffusion layers

Abstract Polarization tests were conducted on proton exchange membrane fuel cells (PEMFCs) at cell temperatures between 60 and 80 °C with various reactant humidification levels; varied from no external humidification to fully saturated on both the anode and the cathode. Elimination of cathode external humidification, while maintaining a fully humidified anode inlet, resulted in cell performance loss of only 5% or 33 mV (from 0.674 to 0.641 V) at 400 mA/cm 2 at an anode stoichiometry of 3 and a cathode stoichiometry of 4. When both the anode and the cathode humidification were removed (“dry operation”), cell performance strongly depended on the cell operating temperature and the inlet gas stoichiometric flow rates. High performance of non-humidified PEMFCs was demonstrated by optimizing the operating cell temperature and the inlet gas stoichiometric flow rates, to find a balance between cell “flooding”, oxygen mole fraction, and proton conductivity. Performance of a cell with an in-house cathode gas diffusion layer (GDL) showed a loss of only 4% or 29 mV (from 0.674 to 0.645 V) compared to the near-saturated condition, at 400 mA/cm 2 and optimum stoichiometry. Using a commercial E-TEK_V.2.11 carbon cloth cathode GDL showed significantly greater loss when operated with no external humidification at the same optimized condition. An overall system analysis suggested that at optimum stoichiometric flow rates and cell temperatures, with the in-house GDL, while the net power output might be reduced by at most 17% under dry operation the total required non-stack energy duty would be cut by over 46% when compared to operation with saturated inlet gases.

Thermal and hydrodynamic analysis of the condensation and evaporation processes in horizontal tube desalination plant

This paper considers the hydrodynamic and thermal analysis for the case where steam is condensing inside a horizontal tube while simultaneously a thin water film is evaporating on the outside of the tube. An analysis of the collective three-dimensional effects influencing the condensing and evaporating sides are presented at different operating conditions. The operating conditions include the effects of the brine mass feed rate, saturation temperatures of the condensing steam and the falling brine, and vapour flow rates. The analysis is extended to account for further effects produced by the vapour pressure and shear stresses, and also by the temperature differences between both sides of the tube. The model presented in this work consists of three regions on the condensation side and two regions on the evaporation side. The condensation side is categorized by a thin laminar condensing layer (at the top of the tube) , a stratified laminary layer (at the bottom of the tube) , and a laminar or turbulent vapour zone. The evaporation side has a thermally developing laminar liquid film and a thermally fully developed zone. The results of the condensation/evaporation analysis show that the dominant effects are due mainly to the brine mass feed rates, secondly to the saturation temperature differences, and least to the incoming condensing steam rates. Calculations are carried out for vapour flow of Reynolds number between 20 000 and 30 000, inlet saturation temperature of incoming steam between 60 and 70°C, and brine mass feed rate between 0.01 and 0.15 kg m −1 m s −1.

Impact of Model Error on the Measurement of Flow Properties Needed to Describe Flow Through Porous Media

Indirect methods are commonly employed to determine the fundamental flow properties needed to describe flow through porous media. Consequently, if one or more of the postulates underlying the mathematical description of such indirect methods is invalid, significant model error can be introduced into the measured value of the flow property. In particular, this study shows that effective mobility curves that include the effect of viscous coupling between fluid phases differ significantly from those that exclude such coupling. Moreover, it is shown that the conventional effective mobilities that pertain to steady-state, cocurrent flow, steady-state, countercurrent flow and pure countercurrent imbibition differ significantly. Thus, it appears that traditional effective mobilities are not true parameters; rather, they are infinitely nonunique. In addition, it is shown that, while neglect of hydrodynamic forces introduces a small amount of model error into the pressure difference curve for cocurrent flow in unconsolidated porous media, such neglect introduces a large amount of model error into the pressure difference curve for countercurrent flow in such porous media. Moreover, such neglect makes it difficult to explain why the pressure gradients that pertain to steady-state, countercurrent flow are opposite in sign. It is shown also that improper handling of the inlet boundary condition can introduce significant model error into the analysis. This is because, if a short core is used with one of the unsteady-state methods for determining effective mobility, it may take many pore volumes of injection before the inlet saturation rises to its maximal value, which is in contradiction with the usual assumption that the inlet saturation rises immediately to its maximal value. Finally, it is pointed out that, because of differences in flow regime and scale, the effective mobilities measured in the laboratory may not be appropriate for inclusion in the data base for a reservoir-scale simulation.

Critical flow in convergent-divergent nozzles with cavity nucleation model

A transient critical flow experiment with convergent-divergent nozzle as the break geometry was conducted in the high-pressure steam-water test loop of Man Jiaotong University. The test parameters were pressure 3.0–16.0 MPa, inlet liquid stagnation subcooling 0–60°C, and corresponding critical mass flow rate (40−120) × 103 kg/(m 2 s). The concept of the incipient flashing, with the choking plane occurring at the throat location, was applied in a wall surface cavity nucleation model. The total pressure difference between the inlet pressure P 0 and the pressure at the throat location P t was divided into two parts, one determined by the inlet fluid properties and the other being the pressure undershoot. Our experimental results show that the pressure undershoot and the liquid superheat at the incipient flashing location reach their maximum values with saturated inlet conditions; with increased inlet subcooling, thermal nonequilibrium decreased. A cavity nucleation model was developed for prediction of the pressure undershoot. The model includes a discharge coefficient, and it has been verified experimentally that this coefficient is a function of only the inlet liquid subcooling. Based on the present theory, the predicted critical mass flow rates are compared with not only our own experimental data but also other experimental data, and good agreement is achieved.

Impact Of Inlet Boundary Conditions On The Numerical Simulation Of One Dimensional Coreflooding

Abstract Numerical simulators developed to match coreflooding performance provide a powerful means for the determination of relative permeabilities of a core sample. However, the application of proper capillary boundary conditions at the ends of a sample is not straightforward. In this paper, the impact of inlet boundary conditions on the numerical simulation of one-dimensional coreflooding is studied. It is found that (i) the widely used inlet saturation boundary condition - the inlet saturation rises instantly to its maximum value - is not correct, and instead the inlet saturation increases gradually depending on the capillary number; (ii) if the maximum inlet saturation condition is applied, numerical solutions would not satisfy both the frontal advance equation and the fractional flow equation; and (iii) the pressure drop history is directly related to the inlet saturation. Hence, a variable inlet saturation boundary condition must be used in the simulation to account for inlet capillary end effects. Thereafter, the pressure drop history (including initial responses) can be used to make performance matches. Introduction Numerical simulations of immiscible corefloods have been widely used to study two-phase flows in a core sample including capillary and gravity force effects(1,2,3,4.5.6.7), and to interpret the results of unsteady state coreflooding experiments-history matching to determine relative permeabilities and capillary pressure(8,9,10). In coreflooding experiments, capillary end effects always exist and can greatly affect displacement performance(11,12,13,14,15.16,17). Although some experimental techniques have been developed to eliminate these effects(18,19), they may still exist and affect displacement performance, especially when reservoir fluids and flow parameters are utilized. To account for the capillary end effects, proper boundary or initial conditions must be applied at the core ends in numerical simulations. The outlet end capillary effect has been incorporated into the simulations performed by Fassihi(10). Recently, Shen and Ruth(7) derived a set of initial and boundary conditions which can properly describe the capillary effect on the variation of the inlet saturation and applied them in their simulations. The application of proper capillary boundary conditions at the ends of a sample in simulations is not straight forward. In spite of long awareness of the inlet end effect on coreflooding flow (11,12,13,15,17), previous numerical simulations(1,2.3,4,5,6) usually could not account for it, with the result of errors in the solutions. It can be anticipated that the solution with proper initial and boundary conditions will be self-consistent and the solution with improper ones will not be. Therefore, the theme of the present study is to investigate the impact of the inlet end capillary effect on the results of numerical simulations. In the subsequent part of the paper, the notion of an inlet end effect indicates the inlet end capillary effect on the variation of the inlet saturation. The numerical simulation technique employed in this study is the same one as used in the previous study(7). The finite element method was employed to obtain dynamic solutions of a Lagrangian equation derived by Bentsen(6) (Bentsen's equation). This paper consists of the following parts: Firstly, a brief summary of the derivation of Bentsen's equation is presented.