Experimental Temperature Profiles Research Articles

Thermodynamic and economic comparisons of supercritical water oxidation and gasification of oily sludge under hydrothermal flames

Dual-shell reactors using hydrothermal flames as internal heat source were proposed for supercritical water gasification (SCWG) and oxidation (SCWO) of oily sludge to achieve fast preheating and avoid corrosion, salt plugging, and overheating. The SCWG and SCWO systems with hydrogen-rich syngas and electricity outputs, respectively, were established and simulated using Aspen Plus 11. Simulation models were validated by comparing with experimental products and temperature profiles. The maximum exergy destruction coefficients of 28.01% and 24.31% appear in the combustion reactor for both the SCWG and SCWO systems, respectively, indicating the indirect preheating method with hydrothermal flame is critical to the energy efficiency. The increase of reaction temperature promotes hydrogen but inhibits methane formation in the SCWG, and more steam but less syngas is output at higher reaction temperatures. Although more steam and electricity outputs are present at higher reaction temperatures for the SCWO, more fuel input is required. Lower exergy efficiencies are obtained at higher reaction temperatures in both the SCWG and SCWO systems for more energy is output as low grade steam. Less fuel input is required for both the SCWG and SCWO systems at higher feed concentrations, and higher exergy efficiencies can be obtained. The net treatment cost for the SCWG and SCWO systems are 119.19 and 215.47 USD/t, respectively, indicating the SCWG is more economically competitive compared with the SCWO.

Computational fluid dynamics model-based design of continuous forced convection freezing processes for human induced pluripotent stem cells considering supercooling of extracellular solutions

This work presents a computational fluid dynamics (CFD) model-based process design of forced convection continuous freezing for human induced pluripotent stem (hiPS) cells considering supercooling of extracellular solutions. The overall model consists of a CFD model for velocity field and heat transfer calculations including the effect of the supercooling, and a cell layer model for cell survival rate calculations. Experimental temperature profiles were obtained using a forced convection-based batch freezer, and the validation of the heat transfer and solidification models was performed. The experiments were carried out by applying a 1.0 K min–1 cooling rate with an inlet velocity of 2.0 m s–1. The model was applied to three different freezer sizes with shelves containing 10, 20 and 30 rows. The applied coolant inlet velocities ranged from 0.50 m s–1 to 4.0 m s–1. It was found that the application of an inlet velocity of 3.0 m s−1 yielded an average cell survival rate of 0.934 with low survival rate heterogeneity in the freezers. This way, the freezing process for hiPS cells could be scaled to up to 170-fold compared to currently used equipment for hiPS cell freezing.

Density pedestal prediction model for tokamak plasmas

A model for the pedestal density prediction based on neutral penetration combined with pedestal transport is presented. The model is tested against a pedestal database of JET-ILW Type I ELMy H-modes showing good agreement over a wide range of parameters both in standalone modelling (using the experimental temperature profile) and in full Europed modelling that predicts both density and temperature pedestals simultaneously. The model is further tested for ASDEX Upgrade and MAST-U Type I ELMy H-modes and both are found to agree with the same model parameters as for JET-ILW. The JET-ILW experiment where the isotope of the main ion is varied in a D/T scan at constant gas rate and constant βN is successfully modelled as long as the separatrix density ( ne,sep) and pedestal transport coefficient ratio ( D/χ) are varied in accordance with the experimentally observed variation of ne,sep and the isotope dependence of D/χ found in gyrokinetic simulations. The predictions are found to be sensitive to ne,sep which is why the model is combined with an ne,sep model to predict the pedestal for the STEP fusion reactor.

The temperature profile within Er3+: Yb3+: LuAl3(BO3)4 crystal: Insights uncovered by a combined theoretical and experimental study

This work reports a measured temperature profile along the pump light beam inside the Er3+:Yb3+: LuAl3(BO3)4 crystal and the simulated ones. The temperature profile featured by a high and asymmetrical peak structure shows rather localized nature with respect to its transversal distribution. By scrutinous examination of the discrepancies between the experimental and simulated ones, a) a heat deposition mechanism elucidating the steady state of local heat generations and various heat transfers was suggested; b) a three-beam of lights model together with a formula for analyzing the fractional thermal load was developed, which leads to a good agreement between the simulated and experimental temperature profiles. The new formula provides a more transparent tool in physics to evaluate the various energy losses; The model can easily be adapted to solve the thermal problem in a laser medium, in particular when a medium show unignorable absorption effect for the laser signal.

Rapid millisecond heating via ferromagnetic resonance in MnFe2O4 nanoparticles

This study undertakes an exhaustive analysis of rapid heat generation in MnFe2O4 nanoparticles through ferromagnetic resonance within an ultra-fast timeframe of 1 ms. Real-time monitoring of temperature during single-field-pulse excitations provided detailed insights into the temperature rise profiles. By integrating micromagnetic simulations with analytical modeling—taking into account both convective and radiative losses—we have deepened our understanding of the heat transfer dynamics at play. Adjusting the analytical model to align with experimental temperature profiles enabled us to determine the efficiency of converting spin dissipation energy into heat, which stands at 17%. This figure reflects not only the surface area of the nanoparticles but also includes considerations for radiative and convective losses. Notably, employing a low AC-field strength of 17.6 Oe facilitated a rapid temperature increase of up to 90 K in just 0.5 s, showcasing a peak initial temperature rise rate of approximately 680 K/s. This research advances the frontiers of high-power heat generation driven by spin dynamics and provides a comprehensive exploration of heat transfer mechanisms over exceptionally short pulse durations. These findings could revolutionize precise and rapid temperature management at the nanoscale, unlocking prospects in bio applications, accelerated material processing, and inducing color and phase shifts in polymer matrices.

Large Eddy Simulation of Hydrogen/Air MILD combustion in a cyclonic burner

In this work Large Eddy Simulation (LES) of a Hydrogen/Air cyclonic burner operating in the MILD combustion regime at 1 atm is performed. The cyclonic flow configuration may represent a proper way to enhance the mixing process in a very short time while allowing for residence times long enough to achieve complete oxidation of diluted and preheated mixtures. Accurate molecular transport properties and a reduced chemical mechanism for hydrogen-air combustion, consisting of 18 transported species and 244 elementary reactions are considered. Results show that at the center of the combustor, where MILD combustion occurs, temperature exhibits a statistically steady trend (a mean of 1450 K) with peak values lower than 1700 K. This implies that the Zeldovich mechanism for thermal NO formation is negligible, so NO levels are low and statistically steady with a maximum peak of 20 ppm. These values are lower than those observed in standard combustion, confirming the ability of MILD to reduce NOx pollutants also with hydrogen as fuel. Finally, the simulations outcomes are in very good agreement with the experimental results, in particular radiative heat transfer must be taken into account to better capture the preheating of the reactants and consequently fit the experimental temperature profiles in the combustion chamber.

Evaluation of acoustic-thermal simulations of invivo magnetic resonance guided focused ultrasound ablative therapy.

To evaluate numerical simulations of focused ultrasound (FUS) with a rabbit model, comparing simulated heating characteristics with magnetic resonance temperature imaging (MRTI) data collected during invivo treatment. A rabbit model was treated with FUS sonications in the biceps femoris with 3D MRTI collected. Acoustic and thermal properties of the rabbit muscle were determined experimentally. Numerical models of the rabbits were created, and tissue-type-specific properties were assigned. FUS simulations were performed using both the hybrid angular spectrum (HAS) method and k-Wave. Simulated power deposition patterns were converted to temperature maps using a Pennes' bioheat equation-based thermal solver. Agreement of pressure between the simulation techniques and temperature between the simulation and experimental heating was evaluated. Contributions of scattering and absorption attenuation were considered. Simulated peak pressures derived using the HAS method exceeded the simulated peak pressures from k-Wave by 1.6 ± 2.7%. The location and FWHM of the peak pressure calculated from HAS and k-Wave showed good agreement. When muscle acoustic absorption value in the simulations was adjusted to approximately 54% of the measured attenuation, the average root-mean-squared error between simulated and experimental spatial-average temperature profiles was 0.046 ± 0.019 °C/W. Mean distance between simulated and experimental COTMs was 3.25 ± 1.37 mm. Transverse FWHMs of simulated sonications were smaller than in invivo sonications. Longitudinal FWHMs were similar. Presented results demonstrate agreement between HAS and k-Wave simulations and that FUS simulations can accurately predict focal position and heating for invivo applications in soft tissue.

Experimental and Computational Evidence of Damped Axial Conduction with Reciprocating Flow

Abstract Axial conduction is a crucial performance deteriorating factor in miniaturized heat transfer devices, primarily due to the low fluid flow rates, high solid cross-sectional to free-flow area ratio, and use of high thermal conductivity materials. These causative factors, inherent to micro-scale systems, should be such that the axial conduction is minimum. The reciprocating flow of the convective fluid (instead of steady unidirectional flow) is proposed per se as an alternative, which directly alters the solid temperature profile, the root cause of axial conduction. An experimental setup is built as a proof of the concept. In the test rig, a double-acting reciprocating pump generates a fully reversing periodic flow of air through a flow channel carved into a steel block embedded with a heater. The experimental temperature profile in the solid at the cyclic steady state is bell-shaped, indicating a virtual adiabatic plane capable of restricting axial heat transfer. The experimental results are verified taking the help of an independent finite-element-based numerical analysis. Similarly, the non-dimensional interfacial flux ratio (?_0 ), integrally related to axial conduction, for unidirectional and reciprocating flow is significantly different. This ratio in the vicinity of the inlet is ~53% less with the reciprocating compared to the equivalent unidirectional flow. The optimal thermal performance with the reciprocating flow is correlated through a critical Strouhal number expression, Sr ≤ (pDh)/L. In thermal management applications employing reciprocating flow, the limiting relation can be used to determine flow parameters and optimum geometry design.

Agitation of liquid eggs during ohmic heating pasteurization—Experimental and computer simulation study

AbstractTraditional pasteurization process of liquid eggs deals with food safety regulations; however, detriment of functional quality properties is also promoted. In this study, an agitated ohmic heating system at 20 kHz was evaluated experimentally and using a 3D computer simulation model, developed using COMSOL Multiphysics. The accuracy of the model was successfully validated by experimental temperature profiles results, showing low errors (RMSRE < 10%), at two different locations. The temperature distribution and flow behavior of liquid eggs during processing were analyzed using the 3D model. Safety and quality retention assessments of processed liquid eggs were performed by calculating the thermal pasteurization value (P‐value) and thermal protein non‐denaturation ratio (X), respectively. A better temperature uniformity was found under 20 rpm than at 10 rpm of rotational speed (temperature difference was reduced from 1.8 to 1.4°C and 5.1 to 4.3°C for egg white and yolk, respectively). Moreover, the degree of protein denaturation (at the point where the P‐value was accomplished) at 20 and 10 rpm were 0.92 and 0.89, and 0.99 and 0.98 for egg white and yolk, respectively. These results are of potential value for the design of ohmic pasteurization systems for fluid foods.Practical applicationsThe applications of the findings of this study include but are not limited to: (a) utilize the measured electrical conductivity values at 20 kHz of egg whites and yolks for further studies; (b) predict the temperature and velocity profiles and distributions of liquid eggs during agitated ohmic pasteurization processes using the developed 3D computer simulation model; (c) evaluate improvements in temperature uniformity, pasteurization efficiency, and quality retention by fine‐tuning processing parameters as evaluated in this study; and (d) use the design and the conducted analysis of agitated ohmic heating system of liquid eggs for developing novel pasteurization applications of fluid foods.

Numerical study of the flow and heat transfer characteristics in a scale model of the vessel cooling system for the HTTR

The reactor cavity cooling system (RCCS) is a passive reactor safety system commonly present in the designs of High-Temperature Gas-cooled Reactors (HTGR) that removes heat from the reactor pressure vessel by means of natural convection and radiation. It is one of the factors responsible for ensuring that the reactor does not melt down under any plausible accident scenario. For the simulation of accident scenarios, which are transient phenomena unfolding over a span of up to several days, intermediate fidelity methods and system codes must be employed to limit the models’ execution time. These models can quantify radiation heat transfer well, but heat transfer caused by natural convection must be quantified with the use of correlations for the heat transfer coefficient. It is difficult to obtain reliable correlations for HTGR RCCS heat transfer coefficients experimentally due to such a system’s size. They could, however, be obtained from high-fidelity steady-state simulations of RCCSs. The Rayleigh number in RCCSs is too high for using a Direct Numerical Simulation (DNS) technique; thus, a Reynolds-Averaged Navier–Stokes (RANS) approach must be employed. There are many RANS models, each performing best under different geometry and fluid flow conditions. To find the most suitable one for simulating an RCCS, the RANS models need to be validated. This work benchmarks various RANS models against three experiments performed on the HTTR RCCS Mockup by the Japanese Atomic Energy Agency (JAEA) in 1993. This facility is a 1/6 scale model of a vessel cooling system (VCS) for the High Temperature Engineering Test Reactor (HTTR), which is operated by JAEA. Multiple RANS models were evaluated on a simplified 2d-axisymmetric geometry. They were found to reproduce the experimental temperature profiles with errors of up to 22% for the lowest temperature benchmark and 15% for the higher temperature benchmarks. The results highlight that the pragmatic turbulence models need to be validated for high Rayleigh natural convection-driven flows and improved accordingly, more publicly available experimental data of RCCS resembling experiments is needed and indicate that a 2d-axisymmetric geometry approximation is likely insufficient to capture all the relevant phenomena in RCCS simulations.

Simulating the Moisture Diffusion and Evaporation of Sawdust during Convective Drying using the Spatial Reaction Engineering Approach

AbstractThe spatial reaction engineering approach (S‐REA) was used to simulate hot air drying of sawdust. The studies extended the previous work reported in literature where the sawdusts were dried using hot air at 70 °C, 80 °C, and 90 °C. The simulated results were found to agree well with the experimental moisture content (R2 > 0.98) and temperature (R2 > 0.82) profiles. In a further analysis using S‐REA, the spatial profiles of moisture content and vapor concentration were generated to understand better the physics behind. Simulation also revealed that the external mass transfer resistance was more dominant as compared to the internal diffusion resistance. The vapor concentrations were observed peaked at time range of about 10 800– 18 000 s and dropped thereafter upon further heating. This observation could be supported by the variation in the vapor effective diffusivities where peak diffusivity values typically occur after most of the moisture evaporates towards the end of drying.

Simulation of temperature profile in fused filament fabrication 3D printing method

PurposeTemperature is a critical factor in the fused filament fabrication (FFF) process, which affects the flow behavior and adhesion of the melted filament and the mechanical properties of the final object. Therefore, modeling and predicting temperature in FFF is crucial for achieving high-quality prints, repeatability, process control and failure prediction. This study aims to investigate the melt deposition and temperature profile in FFF both numerically and experimentally using different Acrylonitrile Butadiene Styrene single-strand specimens. The process parameters, including layer thickness, nozzle temperature and build platform temperature, were varied.Design/methodology/approachCOMSOL Multiphysics software was used to perform numerical simulations of fluid flow and heat transfer for the printed strands. The polymer melt/air interface was tracked using the coupling of continuity equation, equation of motion and the level set equation, and the heat transfer equation was used to simulate the temperature distribution in the deposited strand.FindingsThe numerical results show that increasing the nozzle temperature or layer thickness leads to an increase in temperature at points close to the nozzle, but the bed temperature is the main determinant of the overall layer temperature in low-thickness strands. The experimental temperature profile of the deposited strand was measured using an infrared (IR) thermal imager to validate the numerical results. The comparison between simulation and observed temperature at different points showed that the numerical model accurately predicts heat transfer in the three-dimensional (3D) printing of a single-strand under different conditions. Finally, a parametric analysis was performed to investigate the effect of selected parameters on the thermal history of the printed strand.Originality/valueThe numerical results show that increasing the nozzle temperature or layer thickness leads to an increase in temperature at points close to the nozzle, but the bed temperature is the main determinant of the overall layer temperature in low-thickness strands. The experimental temperature profile of the deposited strand was measured using an IR thermal imager to validate the numerical results. The comparison between simulation and observed temperature at different points showed that the numerical model accurately predicts heat transfer in the 3D printing of a single-strand under different conditions. Finally, a parametric analysis was performed to investigate the effect of selected parameters on the thermal history of the printed strand.

Avoiding false runaway prediction by properly describing axial conductive heat transfer in a low dt/dp industrial-scale packed bed reactor

The impact of axial conductive heat transfer on the simulation and prediction of hot spots and, more particularly, runaway, within an industrial-scale wall-cooled packed-bed reactor with low tube-to-particle diameter ratio (dt/dp ∼ 3) has been assessed in this work. To this purpose, the effective axial conductivity (keff,z) was first determined from adiabatic experiments in a bench-scale packed bed in the absence of reaction. Next, non-adiabatic and non-isothermal bench-scale and industrial-scale packed bed experimental data were used in the assessment of the impact of axial heat conduction on the prediction of the temperature profile. The so-called Pseudo-local Internal Heat Transfer Approach (PL-IHTA) was used for the adequate description of the radial temperature gradients. Finally, an industrial-scale wall-cooled packed bed reactor for the highly exothermic catalytic oxidative dehydrogenation of ethane was modeled to assess the impact of the axial thermal conductivity on temperature profile simulations. When disregarding axial heat conduction or adopting literature-based values for keff,z, determined from either experiments at low dt/dp ratios (<8) and Rep ≤ 1000 or high dt/dp ratios (>8) and Rep ≤ 700 at a wide panel of operating configurations, runaway is simulated at conditions where it has not been observed experimentally or a negligible hot-spot prediction is obtained. When considering the keff,z determined for the specific reactor configuration in this work, hot spots are predicted at Rep of 700 and 1400, but no runaway. The discrepancies between experimental findings and temperature profiles simulated using literature-based values for keff,z indicate the need for a specific determination of keff,z in packed bed reactors with low dt/dp ratio to more accurately predict hot spots, resulting in more reliable reactor design and operation.

Transient Thermal Analysis of a Double Duct Solar Roof Chimney Coupled With a Scaled Room

Abstract This research presents a detailed transient experimental and computational study of heat transfer and airflow in a scaled room linked with a double-duct vertical roof solar chimney (SC). The analysis was made in the coupled system, varying the heat flux supplied to the roof SC absorber during the day. Experimental temperature profiles were obtained at six different depths and heights, the empirical heat transfer coefficient was computed for the SC absorber, and the variation of air changes per hour was determined. A good agreement between experimental and numerical temperature profiles and average Nusselt number (Nut) is shown in the latter of average difference of 3.41%. The validated computational model was used to analyze the effect of the transient heating of the SC on temperature fields and flow patterns in the thermal system. Almost symmetrical temperature and y-velocity profiles are formed in the ducts at different hours of the day, with thermal boundary layers of about 4 mm. Correlations of the Nusselt number and air changes per hour (ACH) are provided as a function of the modified Rayleigh number.

Dimensionless characterization of the problem of heat transfer in soils with horizontal, underground and permeable thin layer: Direct and inverse problems

From the dimensionless mathematical model of a scenario 2D, in which heat is transferred from a fluid flow within a thin, horizontal underground layer to the surrounding soil, the dimensionless groups that ruled the solutions are derived. The dependencies of the main unknowns of interest on the parameters of the problem are deduced after the introduction of a characteristic length and time, also assumed as unknowns, for which a constant temperature profile is developed. These dependencies are verified and depicted by universal curves and abacus than can be used in an easy way for the solution of the direct problem in any scenario. The number of dimensionless groups that appear in the solutions are reduced and some of them are collected in the characteristic length and time. In addition, two protocols are proposed for the estimations of flow velocity in the permeable layer from the measurements of experimental temperature profiles, one for the steady state and other for the transient profiles. An illustrative standard application shows the efficiency of such protocols.

An Iterative Method for the Simulation of Rice Straw-Based Polyol Hydroxyl Moieties

Bio-derived polyol products have gained global interest as a green and sustainable substitute for fossil-based polyols in a diverse range of polyurethane (PU) applications. According to previous studies, PU properties are highly influenced by the reaction kinetics during their formation. One major factor affecting this is the reactivity of their polyol’s functional hydroxyl moieties that are classified as primary, secondary, and hindered-secondary. However, experimental quantitative characterization of these polyol hydroxyl moieties remains a challenge in the field due to various factors affecting them, including extensive time requirements, the need for substantial and expensive resources, large potential errors, and the generation of wastes, as well as health and safety considerations. In this study, the molar fraction of primary, secondary, and hindered-secondary hydroxyl moieties of a petroleum-based polyol (V490) and a rice straw-based polyol were determined via an iterative computational method. The method employed a MATLAB script that can simultaneously solve multiple differential equations involving PU gelling reaction kinetics and thermodynamics. In this manner, numerical combinations of the fraction of each type of hydroxyl moiety are generated by looping together the respective numerical fractions for each moiety. The best-fit combinations of the fractions of the mixed polyol’s hydroxyl moieties were successfully found via curve fitting of the simulated and experimental gelling temperature profile with an average numerical deviation of less than 1%. Thus, the method presented in this study offers a faster and more reliable characterization of the polymeric reaction kinetics than the experimental and conventional computational methods for product property enhancement and development in the field.

Towards a better understanding of heat transfer and flow mechanisms in a cavity channel with numerical simulations

In this work, both numerical simulations performed with ANSYS Fluent using the kT-kL-ω turbulence model and experimental data are employed to investigate heat transfer in water flow in a uniformly heated (9500–19,350 W/m2) asymmetric channel for transitional Reynolds numbers ranging from about 3640 to 4970. The model predicts the experimental data mostly within about 15% and 16% respectively for the Nusselt number and pressure drops, with larger deviations for the Nusselt number occurring at the highest Reynolds numbers investigated. Simulations reveal the occurrence of a recirculation in the upper part of the channel. A new dimensionless parameter is introduced to characterize the strength of the recirculation with respect to the inertia flow which showed a distribution similar to the Nusselt number, thus suggesting an important role of the recirculation in enhancing the heat transfer. The thickness of both the thermal boundary layer and the conductive sublayer is determined both experimentally and numerically. While the former increases along the channel, the latter undergoes mostly a thinning, which can be attributed to the recirculation region. Peaks of negative turbulent heat flux are attributed to the flow recirculation and explain the minimum observed in the experimental temperature profiles. Among the RANS models, the kT-kL-ω model resulted to be the best in predicting the experimental local Nusselt numbers. This work may aid in achieving a more efficient design of passive configurations for thermal management applications.

Thermal-Coupled Single Particle Modeling and Multi-Objective Stepwise Parameter Identification of Lithium-Ion Batteries Over Different Temperatures

The establishment of electrochemical-thermal coupling model for a lithium-ion battery (LIB) is an important issue in developing an appropriate thermal management system of LIB packs. In this paper, a novel thermal-coupled single particle model with few parameters is first developed to promote battery parameter identification at various temperatures. Then, after collecting the experimental profiles of battery voltage, current, and temperature, a multi-objective stepwise identification scheme based on genetic algorithm is proposed to identify the classified parameters of LIB at different temperatures. Finally, the proposed battery model and the stepwise parameter identification are validated in terms of the simulations and experiments. The results demonstrate that this proposed battery model and parameter identification method can not only describe inherent electrochemical and thermal characteristics of the battery, but also identify the battery electrochemical states with high precision, which provides a strong foundation for the development and implementation of battery thermal management system.

Protein Stability─Analysis of Heat and Cold Denaturation without and with Unfolding Models.

Protein stability is important in many areas of life sciences. Thermal protein unfolding is investigated extensively with various spectroscopic techniques. The extraction of thermodynamic properties from these measurements requires the application of models. Differential scanning calorimetry (DSC) is less common, but is unique as it measures directly a thermodynamic property, that is, the heat capacity Cp(T). The analysis of Cp(T) is usually performed with the chemical equilibrium two-state model. This is not necessary and leads to incorrect thermodynamic consequences. Here we demonstrate a straightforward model-independent evaluation of heat capacity experiments in terms of protein unfolding enthalpy ΔH(T), entropy ΔS(T), and free energy ΔG(T)). This now allows the comparison of the experimental thermodynamic data with the predictions of different models. We critically examined the standard chemical equilibrium two-state model, which predicts a positive free energy for the native protein, and diverges distinctly from the experimental temperature profiles. We propose two new models which are equally applicable to spectroscopy and calorimetry. The ΘU(T)-weighted chemical equilibrium model and the statistical-mechanical two-state model provide excellent fits of the experimental data. They predict sigmoidal temperature profiles for enthalpy and entropy, and a trapezoidal temperature profile for the free energy. This is illustrated with experimental examples for heat and cold denaturation of lysozyme and β-lactoglobulin. We then show that the free energy is not a good criterion to judge protein stability. More useful parameters are discussed, including protein cooperativity. The new parameters are embedded in a well-defined thermodynamic context and are amenable to molecular dynamics calculations.

Testing a prediction model for the H-mode density pedestal against JET-ILW pedestals

The neutral ionisation model proposed by Groebner et al (2002 Phys. Plasmas 9 2134) to determine the plasma density profile in the H-mode pedestal, is extended to include charge exchange processes in the pedestal stimulated by the ideas of Mahdavi et al (2003 Phys. Plasmas 10 3984). The model is then tested against JET H-mode pedestal data, both in a ‘standalone’ version using experimental temperature profiles and also by incorporating it in the Europed version of EPED. The model is able to predict the density pedestal over a wide range of conditions with good accuracy. It is also able to predict the experimentally observed isotope effect on the density pedestal that eludes simpler neutral ionization models.