Conjugate Heat Transfer Approach Research Articles

Thermohydrodynamic analysis of magnetorheological conical bearings with conjugated heat transfer

This study presents a comprehensive investigation into a 3D simulation of magnetorheological (MR) conical bearings, focusing on considering viscous dissipation using the conjugated heat transfer approach. The behavior of MR fluids is expressed through the utilization of the Bingham-Papanastasiou constitutive equation. Notably, this study considers variations in viscosity and yield stress as functions of both magnetic field intensity and temperature. The study utilizes a multidisciplinary approach, encompassing fluid dynamics, magnetism, and heat transfer, to model and analyze the behavior of MR fluids within conical bearing geometries. The governing equations containing Cauchy momentum, energy, and Maxwell equations are solved using the finite element method. This research delves into the impacts of viscous dissipation on the functional and characteristic attributes of conical bearings. The energy equations in solid and fluid domains and extended considerations to the plug region within viscous dissipation are specifically addressed. Extensive validation is performed through a comparative analysis involving experimental, numerical, and analytical studies to ensure the validity of results. The results reveal the substantial impact of temperature on both the characteristics and functionality of magnetorheological conical bearings.

Numerical investigation on the performance of combinational spike and transpiration cooling concept for nose cone under hypersonic conditions

Abstract Aiming at solving the thermal protection problems of the nose cone for hypersonic vehicles, a novel combinational spike and transpiration cooling concept is proposed in this paper. Although the temperature of the nose cone structure can be effectively reduced by traditional transpiration cooling, the cooling effect is not ideal due to the extremely high heat flux and pressure near the stagnation point. In the combinational configuration, the bow shock wave at the leading edge of the nose cone is pushed away by the spike, so that the pressure and heat flux along the nose cone surface are reduced obviously, and the cooling effect is also improved significantly. The flow field generated by this innovative concept has been thoroughly examined through numerical simulations employing the compressible Reynolds-Averaged Navier-Stokes (RANS) equations in conjunction with the shear stress transport (SST) k-ω turbulence model. The fluid-thermal interaction is considered by using the conjugate heat transfer approach. The performance of three configurations based on the nose cone are numerically investigated, including transpiration cooling, spike, combinational spike and transpiration cooling. The numerical results show that, compared with the traditional transpiration cooling, the temperature at the stagnation point of the nose cone for the combinational configuration is reduced by about 64%, which proves the feasibility and high efficiency of the novel combinational concept. With the increase of coolant mass flow, the temperature along the nose cone surface for combinational configuration decreases, while the magnitude of the temperature reduction decreases. Therefore, under certain incoming flow conditions, the appropriate coolant mass flow should be considered to achieve better thermal protection effect.

Analysis of cooling effects and measurement errors in water-cooled thermocouples for total temperature measurement in aviation engine combustion chambers

Accurate measurement of the total temperature in the main combustion chamber of an aviation engine is crucial for assessing engine performance. However, a significant challenge exists in balancing the heat transfer errors caused by the necessary cooling of the measuring device with measurement precision. The research employs a combination of numerical simulations and experimental methods to investigate this issue. The numerical simulations utilized the Reynolds-averaged Navier Stokes (RANS) coupled with a conjugate heat transfer approach to study the primary flow characteristics and heat transfer properties within the combustion chamber and the probe body. The experiments were conducted in a heat-calibration wind tunnel, validating the results of the numerical simulations. The results show that by implementing water cooling, the probe's body temperature can be reduced from 1200 °C in high-temperature conditions to 400 °C, with localized temperature imbalances still present in the edge areas of the probe. Tracing the cooling water path reveals that the vertical bends in the internal channels lead to an increase in localized pressure loss of the cooling water. The study quantitatively analyzes measurement errors caused by three heat transfer modes: radiation, convection, and conduction. In low-load conditions of the combustion chamber, heat conduction plays a dominant role, with measurement errors due to conduction reaching up to 70 % of the total measurement error. Radiation further increases the temperature measurement errors of the thermocouple's junctions near the chamber wall. As the combustion chamber temperature increases, entering high-load conditions, the cooling effect of water becomes limited, reducing conduction errors and increasing radiation errors. In these conditions, radiation errors constitute 60–70 % of the total measurement error. It suggests the importance of considering temperature corrections when using water-cooled temperature measurement devices. The research reveals several crucial insights regarding the performance and limitations of water-cooled thermocouples.

Cooling enhancement for engine parts using jet impingement

A computational study has been performed to evaluate the use of jet impingement for cooling applications in the automotive industry. The current study uses an entire internal combustion engine cylinder with its components as a computational domain. An unsteady numerical solution for the Navier-Stokes equations was carried out using Improved Delayed Detached Eddy Simulation (IDDES). The volume of fluid approach is proposed to track and locate the liquid jet surface that is in contact with the air. The conjugate heat transfer approach is used to link the heat transfer solution between the fluid and the solid. The boundary conditions that are employed in the study are provided from lab experiments and one-dimensional simulations. The cooling jet in this study targets the hottest region in the piston, i.e., the region underneath the exhaust valve. Three nozzle sizes with flows at different Reynolds numbers are chosen to examine the thermal characteristics of the cooling jet. The computational study reveals that for a specific Reynolds number, the smaller diameter nozzle provides the highest heat transfer coefficient around the impingement point. The maximum relative velocity location at the impingement point slightly leads the location of the maximum Nusselt number. The maximum temperature in the piston decreases by 7% to 11% as the nozzle diameter changes from 1.0 to 3.0 mm for a jet Reynolds number of 4,500. If a correct selection is made for the nozzle size, the cooling jet can be efficiently used to reduce the temperature and alleviate the thermal stresses in the piston in the region underneath the exhaust valve where the maximum temperature occurs.

Film Boiling around a Finite Size Cylindrical Specimen—A Transient Conjugate Heat Transfer Approach

The DNS of film boiling requires strong computational resources that are difficult to obtain for daily CFD use by expert practitioners of industrial R&D. On the other hand, film boiling experiments are associated with the usage of expensive and highly sophisticated apparatus, and research to this end is relatively difficult due to high heat flow rates that are present in the process itself. When combined with transient heat conduction in a solid, the problem becomes significantly difficult. Therefore, a novel method in computation of conjugate heat transfer during film boiling in a quiescent liquid is proposed in this paper. The method relies on the solution of mass, momentum and energy conservation equations in a two-fluid framework, supplemented with the appropriate closures. Furthermore, turbulent flow was determined as an important parameter in obtaining an accurate solution to temperature field evolution in a solid specimen, via the proper modeling of the turbulent kinetic energy (TKE) value, that was imposed as a constant value, i.e., the frozen turbulence approach. It was found, in addition, that the appropriate TKE value can be obtained by use of Kelvin–Helmholtz instability theory in conjunction with boundary layer theory. The obtained results show excellent agreement with the experimental data within the first 15 s of the experiment, i.e., the first ca. 10% of the total duration of the film boiling mode of heat transfer. Furthermore, the heat transfer coefficient matched the error bands prescribed by the authors of this paper, which presented the correlations, whilst the averaged values are far beyond this band, i.e., are slightly more than 30% higher. Further inspection revealed a measure of similarity between the computational result of the volume fraction field distribution and the experiment, thus confirming the capability of the method to obtain realistic interface evolution in time. The method shows full capability for further pursuing industrial-scale film boiling problems that involve turbulent flow and the conjugate heat transfer approach.

Flow–heat topology optimization of internally cooled high temperature applications using a voxelization approach for domain initialization

ABSTRACT A method is presented for obtaining topology optimized designs for internally cooled high temperature applications, using a flexible geometry description, by means of a voxelization methodology and a novel boundary detection algorithm. A conjugate heat transfer approach is taken; the physics is described by a Stokes–Brinkman model for the flow, weakly coupled with a convection–diffusion model for the heat transfer. A practically relevant optimization formulation, consisting of a maximum temperature objective with a mass flow constraint, is used, and applied to an industrial-relevant non-trivial geometry resembling a guide vane in a gas turbine. Temperatures and velocities from the optimized design are compared with the response from a Stokes flow model with body-fitted mesh and a high-fidelity Reynolds-averaged Navier–Stokes model. A comparison of the performance from a mixed and a penalty approach for solving the flow problem is included. The voxelization approach shows good promise for handling complex design domains.

Thermal modelling of cutting tool under different cutting environment in turning

In most of the manufacturing industry, turning is one of the essential machining operation, due to which the study of the turning tool becomes a necessary part for most of the manufacturing researchers. During dry turning of workpiece excessive amount of heat is generated which results in a localized distribution of heat at the tool tip, thus increasing the cutting temperature, which further decreases the tool life by making the tool blunt and also decreases the surface finish of the workpiece while machining. Excessive heat generation can be controlled by the use of different cutting fluids as per convenience and availability as they carry away most of the heat away from the workpiece and thus decreasing the temperature at the tool tip. This present study deals with the thermal modelling of carbide tool that is the distribution of temperature over its rake surface due to localised heat source at its tool tip. Conjugate heat transfer approach have been established for the distribution of temperature over the rake surface using ANSYS. The present study focusses of the temperature distribution by using air and water as the cutting fluids.

Numerical simulations of high Prandtl number liquid jets impinging on a flat plate

In this work, 3D simulations of oil jets impinging on a flat, heated wall are presented. The numerical setup uses the Volume of Fluid (VoF) method to model the two-phase flow. A careful grid definition across the liquid film, along with the use of the Conjugate Heat Transfer (CHT) approach allowed local heat transfer to be solved with fine resolution at the wall. Variations of liquid flow rate, liquid temperature and surface temperature allow to cover a wide range of local Reynolds and Prandtl numbers (226<Re<2850, 77<Pr<161). Resulting surface-averaged heat transfer compares very well with experimental measurements conducted in a previous study. In-depth analysis of the flow has identified expected features from the literature. In particular, the impact of jet axial velocity profiles on the heat transfer distribution in the stagnation zone was clearly stated. The increase in heat transfer when warming the liquid film was also reproduced and explained by a decrease in oil viscosity and an increase in film velocity. All those effects were taken into account in correlations for stagnation and local values of Nusselt number. A grid sensitivity study was also conducted, showing that if the grid solving the thermal boundary layer in the stagnation zone can be coarsened without impacting local and surface-averaged predictions of heat transfer, a minimum resolution (2 to 3 cells) within the thermal boundary layer is however required for an accurate prediction of heat transfer.

CFD investigation of the radiative heat transfer effects on the adoption of an electrical heated catalyst to increase the abatement efficiency

The thermal transient of the after-treatment system (ATS) during the cold start and the typical urban drive low load engine operations is a crucial point for the conversion efficiency. In this context, the adoption of electrical heating is regarded as an effective solution to promote the catalytic activity and the pollutants abatement. This paper focuses on the evaluation of the radiative heat transfer affecting the operation of an electrical heated catalyst employed to increase the abatement efficiency of a standard catalyst. The modeling methodology relies on a CFD framework based on a Conjugate Heat Transfer (CHT) approach in OpenFOAM, so that a detailed characterization of the thermal transient of the different components of the exhaust line can be achieved. The electrical heating device under investigation is based on a metallic support and it is heated by the Joule effect. The distribution of the heat and its subsequent interaction with the gas flow significantly influence the catalyst operations. In this context, the CFD modeling framework has been further developed so that it is possible to accurately evaluate the radiative heat transfer in correspondence of the porous regions. The description of such features is mandatory for an accurate prediction of the maximum electrical heating device temperatures, resulting in a reliable estimation of the gas flow temperature and its subsequent interaction with the catalyst. The simulation methodology has been applied at first excluding the radiative heat transfer. Then, the developed radiation modeling is applied, so that its influence on the ATS performance can be fully evaluated.

A novel conjugate heat transfer approach to determine the temperature distribution in single-point cutting tool under different conditions

Measurement of accurate temperature of the tooltip, rake face, and flank face during the machining operation has always been difficult and a topic of interest among researchers. Thermal modeling for determining the temperature distribution across the tool surface is one of the approaches to determining the other physical properties associated with temperature in machining. Various attempts have been made to predict the temperature during machining operations. The exact determination of temperature can predict the tool wear and minimize the tooling cost and ideal time in the metal cutting industries. The present work describes the development of an alternative approach for the online tool temperature measurement. The four conditions namely dry cutting with different boundary conditions, flooded water cooling, and the mist flow environment have been considered in the turning operation. Computational fluid dynamics has been used to determine the temperature distribution on tool inserts under different machining environments. The prediction model is developed to compute the temperature across the profile through different numerical equations. Furthermore, the simulated data has also been validated through experimentation with turning operation using a carbide tool and AISI 304 stainless steel as work material. The experimental results are in close agreement with simulated results and have a variation of 25% to 35% in all the machining environments. Among all the cases, the lowest temperature has been recorded in flood water cooling followed by the machining under a mist environment as compared to dry conditions.

Effects of the Conjugate Heat Transfer and Heat Flux Strength on the Thermal Characteristics of Impinging Jets

A numerical study using the conjugate heat transfer approach has been performed to investigate the effects of boundary heat flux, conduction effect, and working fluid on the thermal characteristics due to the jet impingement process. Air and water are used in this study as working fluids. For the water jet, the volume of fluid method is used to capture and track the interface in the multiphase flow. It is found that the wall conduction may change the fluid-solid interfacial thermal characteristics compared with no conduction or pure convection process. The amount of influence depends on the working fluid, nozzle size, metal thermal conductivity, metal thickness, and boundary heat flux. The conduction inside the solid wall tends to reorganize the uniform heat flux distribution at the boundary to a non-uniform heat flux distribution at the fluid-solid interface. This is mainly attributed to the conjugate effect of the solid. For a given jet Reynolds number and boundary heat flux, the conjugate heat transfer results divulge that the convective heat flux removed from the stagnation point is higher for the air jet than for the water jet. Contrary to the air jet, the effect of thermal boundary on the stagnation Nusselt number profile is negligible for the water jet. The disc material and thickness have no obvious effect on the stagnation Nusselt number profile for both air and water fluids.

Conjugate Heat Transfer Analysis of the Aero-Thermal Impact of Different Feeding Geometries for Internal Cooling in Lifetime Extension Processes for Heavy-Duty Gas Turbines

Regulations from the European Union move towards a constant reduction of pollutant emissions to match the single-digit goal by 2050. Original equipment manufacturers propose newly designed components for the lifetime extension ofgGas turbines that both reduce emissions and allow for increasing thermodynamic performance by redesigning turbine cooling geometries and optimizing secondary air systems. The optimal design of internal cooling geometries allows for reducing both blade metal temperature and coolant mass-flow rates. In the present study, four different geometries of the region upstream from the blade’s internal cooling channels are investigated by using computational fluid dynamics with a conjugate heat transfer approach. The baseline configuration is compared to solutions that include turbulators, vanes, and a diffuser-like shapes. The impact of each solution on the blade metal temperature is thoroughly analysed. The diffuser-like solution allows for a more uniform distribution of the coolant and may reduce the metal temperature by 30% in the central part of the blade. There are also regions where the metal temperature increases up to 15%, thus requiring a specific thermal fatigue analysis. Eventually, the non-negligible impact of the coolant flow purged in the tip clearance region on the generation of the tip leakage vortex is described.

Conjugate heat transfer investigation of impingement cooling for ribbed internal passage of a turbine vane

In this study, the effect of internal cooling configuration on overall cooling effectiveness of gas turbine vane is investigated using conjugate heat transfer approach. The C3X turbine vane with internal cooling and a turbine vane leading edge model with combined impingement and film cooling scheme are used as primary cases. An impingement cooling configuration is designed in order to enhance cooling effectiveness on the leading edge of the internally cooled C3X vane. In an attempt to further improvement, two rows of ribs are added on regions where impingement jets do not cover. In the leading edge model, the effect of modification for internal cooling channel and within film cooling holes are investigated by adding different rib configurations in those regions. The SST model is adopted for turbulence modeling in fluid zones. In the C3X vane, overall cooling effectiveness is generally enhanced using impingement cooling configuration. Furthermore, span wise distribution of overall cooling effectiveness becomes uniform in the leading edge of the vane. In the leading edge model, it is found that overall cooling effectiveness is varied due to the change in distribution of coolant flow in internal cooling channel and on external surface of the vane by adding ribs in internal cooling channel. The case with ribs perpendicular to the internal channel cross flow provides higher overall effectiveness. The results also indicate that cooling performance of the film cooled vane is sensitive to the location of ribs installed within film holes. The interaction between coolant flow and hot gas flow and its contribution in cooling performance of the vane are elaborately discussed for the leading edge model.

Experimental and Numerical Analysis of an Innovative Mixer Geometry for Urea Injection in SCR Applications

Selective catalytic reduction (SCR), based on the injection of urea-water-solution (UWS), is one of the prevailing and more effective approaches to reduce NOx emissions in diesel engines. To improve the performance and durability of the system, it is crucial to develop reliable simulation tools able to correctly describe not only the urea conversion into ammonia and the mixing with exhaust gases but also the possible formation of solid deposits along with the engine’s exhaust line.In the present paper, two different exhaust systems for off-road applications are analyzed, both of them consisting of a diesel oxidation catalyst (DOC) followed by a diesel particulate filter (DPF), a UWS injection and a mixing device, and an SCR catalyst. Two alternative UWS mixing subsystems are evaluated, including a newly developed design. A 3D-CFD numerical analysis is carried out to assess the performance of both systems in terms of pressure drop, UWS spray, and liquid film development, in addition to flow velocities and species concentration uniformities at SCR catalyst inlet. A detailed analysis of droplet impingement on walls and liquid film development is enabled, thanks to a conjugate heat transfer (CHT) approach. Moreover, a deposit risk index is used to identify the areas of the systems where urea deposit formation is expected.Eventually, numerical results are compared with experiments on one operating condition chosen as the most challenging in terms of exhaust temperature and flow rate, both in terms of systems NOx conversion efficiency and deposit formation, showing a satisfactory agreement, thus paving the way to use the proposed synergetic numerical and experimental approach to further optimize the design and the system’s performance.

A comparison study on thermal performance enhancement of corrugated oil cooler with internal turbulators – Numerical and experimental approach

Oil coolers play an important role in dissipating excess heat from engine oil to surroundings. In this work, performance study of an oil cooler with internal turbulators of dimple and offset type is performed using numerical approach and compared with experimental results for validation. In numerical approach, oil cooler with turbulators are numerically modeled using Conjugate Heat Transfer (CHT) approach to solve for heat transfer characteristics. Turbulence physics modeling is done using Reynolds Averaged Navier Stokes equations (RANS) through realizable k-epsilon model with standard wall function. The air side Heat Transfer Coefficient (HTC) estimation is done with CHT model using one corrugation, as the air flow in fins is periodic. In experimental study, Required Inlet Temperature Difference (ITD), Oil Flow Rate, Air Flow Rate is maintained, measurements are recorded to create performance data matrix with combinations of various operating data points for air and oil sides respectively. Numerical results are compared with experimental results obtained; Deviation for heat rejection of oil-cooler with dimple turbulator fall in range of ±7%, offset turbulator fall in the range of −2.0 to 9.4%. Numerical data shows that the thermal performance of offset type is better than dimple type by 10–13.5%, while the test data depicts that performance of oil-cooler with offset turbulator is high by 12–19% than dimple type and thereby proving its performance superiority. In offset turbulator additional turbulent scales of the offset length scale range are generated, these additional scales are evident by increasing the Turbulent Kinetic Energy (TKE) of 46–51% than dimple turbulator from numerical study. Thus, for same plate and fin, oil-cooler with offset turbulator has better thermal performance than oil cooler with dimple turbulator.

Design improvement of thermal management for Li-ion battery energy storage systems

Thermal management of lithium-ion battery cells provides several advantages to reach high performance electric-vehicles and hybrid-electric-gadgets. Geometrical features and patterns of internal channels of liquid cooling plate (LCP) are key factors for the battery cell cooling efficiency. This paper concerns a new design of battery thermal management and the effect of ribbed channels with double inlets and outlets on the reduction of mass flowrate in the coolant channels of LCP, the hydrothermal performance factor of the battery, the friction coefficient, and the reduction of pumping power by utilizing comprehensive 3D simulations. The Conjugate Heat Transfer approach is employed for the fluid flow and the heat transfer calculations. To enhance the heat transfer surface and cooling efficiency, longitudinal ribs are considered in four different configurations inside the cooling channels. Furthermore, the effects of ribs on the aforementioned parameters in comparison with the non-rib channels are investigated. The results demonstrated that the optimized ribbed configuration increases the total amount of heat transfer by up to 68%, reduces the mass flowrate to 16%, and lowers the pumping power by 20% in comparison with rib-less channels. Meanwhile, the hydrothermal cooling performance factor of enhanced up to 58% and the maximum temperature approximately remains constant.

Analysis and optimization of the curved trapezoidal winglet geometry in a high-efficiency compact heat exchanger

The present work is undertaken to optimize the geometry of the curved trapezoidal winglet mounted over each cooling tube to enhance the overall performance of the heat exchanger. Before conducting the optimization study, the most critical geometric entities have been identified, and this has helped in significantly reducing the computational overheads. It has been found that the three most critical design parameters are the arc radius (R), the angle subtended (θ) and the winglet's leading-edge height (h1), and the same are chosen for optimization. To plan the experiment, we make use of the Latin hypercube sampling (LHS) scheme. The system responses viz. the Colburn factor (j) and the friction factor (f) ‒ for different combinations of the independent variables ‒ are computed using the numerical simulations together with the conjugate heat transfer approach. To get the best outcome from computations, both fluid and solid domains have been discretized using hexahedra. We make use of the Reynolds-averaged Navier-Stokes (RANS) approach ‒ with SST k–ω (a 2-equation) turbulence model as a closure to RANS ‒ for evaluating the dependent variables. The artificial neural network (ANN) is trained using the data from the DoE table to build the metamodel necessary for conducting the multiobjective optimization. The genetic algorithm (GA) is employed to generate the optimized data sets. The study reveals that the optimized HE variants outperform the baseline model not only at the on-design condition but also at the off-design conditions. The resulting Pareto front points reveal very interesting results, and these data would facilitate the designers to make choices over a wide range of the VG geometry of the heat exchanger.

Experimental and numerical study of the additive layer manufactured inter-layer channel heat exchanger

In this paper the performance of a recently patented additive layer manufactured (ALM) concept inter-layer heat exchanger (HE) is evaluated experimentally and numerically. Two numerical HE models are developed using the conjugate heat transfer (CHT) methodology. The first is an idealised HE core model, consisting of a single period width HE corrugation section (termed superchannel). The second approach uses a fully detailed HE unit model which resolves the flow and heat transfer inside the complete HE unit. A close agreement was found between the HE unit simulations and the experimentally obtained results, such that the fully detailed HE model could be validated. It was also shown that, a full CHT approach is necessary to accurately evaluate complex inter-layer ALM HE core flow and heat transfer behaviour and can serve as an approach for optimising HE designs. The results also reinforce the occurrence of the inter-layer flow mixing inside the HE core of the same flow streams and allows the mass flow to redistribute inside the HE core which is impossible with the current HE generation geometries. The superchannel model results in a slight over-estimation in heat transfer (ΔT≈4 K on average) making the simplified model acceptable as a conservative estimate. Using validated simulations a parametric study was conducted by changing the solid properties of the full CHT HE model to aluminium to investigate the effects of a significantly more conductive material. This resulted in ≈3% higher heat transfer effectiveness (ϵ) of the HE unit. All the simulations were carried out using CFD package OpenFOAM.

Analysis and optimization of the curved trapezoidal winglet geometry in a compact heat exchanger

The present work is aimed at optimizing the geometry of the curved trapezoidal winglets to enhance the overall performance of the heat exchanger. Prior to optimization, the most critical geometric entities are identified to reduce computational overheads. Based on the performance, three design parameters viz. arc radius (R), the angle subtended (θ), and winglet’s larger end height (h2) are chosen for optimization. By making use of the Latin hypercube sampling plan, the design of experiments has been conducted for the above mentioned variables. The required responses for different combinations of the independent variables – that include the Colburn factor (j) and friction factor (f) – are computed by making use of computational fluid dynamics. Both fluid and solid domains are discretized using hexahedral control volumes and the numerical simulations are performed by accounting the conjugate heat transfer approach. The SST k–ω (a 2-equation based) turbulence model is used as a closure model for Reynolds-averaged Navier-Stokes equations to evaluate the values of j and f. The data from DoE are used to train an artificial neural network for multiobjective optimization. Finally, the optimized data sets are generated using genetic algorithms and very encouraging results have been obtained. These Pareto front points range from an energy-efficient to a high-performance heat exchanger design. Therefore, the designers can make the choice(s) of the winglet geometry over a wide range depending on the desired performance of the heat exchanger.

The effect of convective motion within liquid fuel on the mass burning rates of pool fires – A numerical study

To improve numerical simulation of liquid pool fires and remove the need for experimentally measured or empirically calculated mass burning rates as boundary conditions, a fully coupled three-dimensional (3-D) numerical formulation, which directly solves convective motion in the fuel region by incorporating inhomogeneous heat feedback, is formulated. The fire dynamics is modelled using the large eddy simulation (LES) approach. Incompressible laminar flow formation is applied to the liquid fuel region, assuming constant thermo-physical properties except for the density which follows the Boussinesq approximation. The numerical formulation of the two phases is solved using a fully coupled conjugate heat transfer approach at the pool surface. The coupled model is validated against published measurements for a thin-layer heptane pool fire and a deep methanol pool fire. The convective motion within the liquid phase is found to have important effects on the pool fire mass burning rate and its neglection would result in a fast rise and over-prediction of the mass burning rate.