A comparison of temperature distribution in PEMFC with single-phase water cooling and two-phase HFE-7100 cooling methods by numerical study

Choi, Eun Jung,Park, Jin Young,Kim, Min Soo Elsevier 2018 International journal of hydrogen energy Vol.43 No.29

<P><B>Abstract</B></P> <P>Thermal management has been considered as one of the critical issues in proton exchange membrane fuel cell (PEMFC). Key roles of thermal management system are maintaining optimal operating temperature of PEMFC and diminishing temperature difference over a single fuel cell and stack. Severe temperature difference causes degradation of performance and deterioration of durability, so understanding temperature distribution inside a single fuel cell and stack is crucial. In this paper, two-phase HFE-7100 cooling method is suggested for PEMFC thermal management and investigated regarding temperature change inside a fuel cell. Also, the results are compared to single-phase water cooling method. Numerical study of temperature distribution inside a single PEMFC is conducted under various conditions for the two different cooling methods. Fuel cell model considering mass transfer, electrochemical reaction and heat transfer is developed.</P> <P>The result indicates that two-phase HFE-7100 cooling method has an advantage in temperature maintenance and temperature uniformity than single-phase water cooling method, especially in high current density region. It is also revealed that the cell temperature is less dependent on system load change with two-phase cooling method. It indicates that the fuel cell system with two-phase cooling method has high thermal stability. In addition, the effect of coolant flow rate and coolant inlet pressure in two-phase HFE-7100 cooling method are discussed. As a result, two-phase cooling method showed reliable cooling performance even with low coolant flow rate and the system temperature increased as coolant pressure rose.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Two-phase HFE-7100 cooling method is suggested for PEMFC thermal management. </LI> <LI> Numerical study investigating temperature distribution inside PEMFC is conducted. </LI> <LI> Single-phase water cooling and two-phase HFE-7100 cooling methods are compared. </LI> <LI> Two-phase cooling shows better thermal performance than single-phase cooling. </LI> </UL> </P>

Comparisons of prediction methods for peak cladding temperature and effective thermal conductivity in spent fuel assemblies of transportation/storage casks

Kim, H.,Kwon, O.J.,Kang, G.U.,Lee, D.G. Pergamon Press ; Elsevier Science Ltd 2014 Annals of nuclear energy Vol.71 No.-

When spent fuel assemblies from the reactor of nuclear power plants (NPPs) are transported or stored, the assemblies are exposed to a variety of environments that can affect the peak cladding temperature. There are three models to calculate the peak cladding temperature of spent fuel assemblies in a cask: Manteufel and Todreas's two-region model, Bahney Lotz's effective thermal conductivity model, and Wooton-Epstein correlation. The peak cladding temperatures of Babcock & Wilcox (B&W) 15x15 PWR spent fuel assembly under helium backfill gas were evaluated by using two-dimensional CFD simulation and compared with two models (Wooton-Epstein correlation, two-region model). The peak cladding temperature difference between the two-region model and CFD simulation ranges from -0.2K to 9K. Two-region model over-predicts the measured peak cladding temperature that performs in a spent fuel dry storage cask. Therefore the simulation could be used to calculate peak cladding temperature of spent fuel assemblies. Application using CFD simulation was conducted to investigate the peak cladding temperature and effective thermal conductivity of spent fuel assembly used in Korea NPPs: 16x16 (CE type) and 17x17 (WH type) PWR spent fuel assembly. CFD simulation results are similar to each other, and the difference of temperature drop between the three arrays occurs slightly in all basket wall temperatures. The effective thermal conductivity calculated from the 16x16 PWR spent fuel assembly results was more conservative than those for the 17x17 array.

Development of an Infrared Two-color Probe for Particle Cloud Temperature Measurement

( Mohammed Ali Alshaikh Mohammed ),( Ki Seong Kim ) 한국액체미립화학회 2015 한국액체미립화학회지 Vol.20 No.4

The demands for reliable particle cloud temperature measurement exist in many process industries and scientific researches. Particle cloud temperature measurements depend on radiation thermometry at two or more color bands. In this study, we developed a sensitive, fast response and compact online infrared two-color probe to measure the temperature of a particle cloud in a phase of two field flow (solid-gas). The probe employs a detector contained two InGaAs photodiodes with different spectral responses in the same optical path, which allowed a compact probe design. The probe was designed to suit temperature measurements in harsh environments with the advantage of durability. The developed two-color probe is capable of detecting particle cloud temperature as low as 300°C, under dynamic conditions.

Steady- and transient-state analyses of fully ceramic microencapsulated fuel loaded reactor core via two-temperature homogenized thermal-conductivity model

Lee, Yoonhee,Cho, Nam Zin Elsevier 2015 Annals of nuclear energy Vol.76 No.-

<P><B>Abstract</B></P> <P>Fully ceramic microencapsulated (FCM) fuel, a type of accident-tolerant fuel (ATF), consists of TRISO particles randomly dispersed in a SiC matrix. In this study, for a thermal analysis of the FCM fuel with such a high heterogeneity, a two-temperature homogenized thermal-conductivity model was applied by the authors. This model provides separate temperatures for the fuel-kernels and the SiC matrix. It also provides more realistic temperature profiles than those of harmonic- and volumetric-average thermal conductivity models, which are used for thermal analysis of a fuel element in VHTRs having a composition similar to the FCM fuel, because such models are unable to provide the fuel-kernel and graphite matrix temperatures separately.</P> <P>In this study, coupled with a neutron diffusion model, a FCM fuel-loaded reactor core is analyzed via a two-temperature homogenized thermal-conductivity model at steady- and transient-states. The results are compared to those from harmonic- and volumetric-average thermal conductivity models, i.e., we compare <I>k<SUB>eff</SUB> </I> eigenvalues, power distributions, and temperature profiles in the hottest single-channel at steady-state. At transient-state, we compare total powers, reactivity, and maximum temperatures in the hottest single-channel obtained by the different thermal analysis models. The different thermal analysis models and the availability of fuel-kernel temperatures in the two-temperature homogenized thermal-conductivity model for Doppler temperature feedback cause significant differences as revealed by comparisons.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Fully ceramic microencapsulated fuel-loaded core is analyzed via a two-temperature homogenized thermal-conductivity model. </LI> <LI> The model is compared to harmonic- and volumetric-average thermal conductivity models. </LI> <LI> The three thermal analysis models show ∼100pcm differences in the <I>k<SUB>eff</SUB> </I> eigenvalue. </LI> <LI> The three thermal analysis models show more than 70K differences in the maximum temperature. </LI> <LI> There occur more than 3 times differences in the maximum power for a control rod ejection accident. </LI> </UL> </P>

Two-temperature thermoelastic surface waves in micropolar thermoelastic media via dual-phase-lag model

Abouelregal, A.E.,Zenkour, A.M. Techno-Press 2017 Advances in aircraft and spacecraft science Vol.4 No.6

This article is concerned with a two-dimensional problem of micropolar generalized thermoelasticity for a half-space whose surface is traction-free and the conductive temperature at the surface of the half-space is known. Theory of two-temperature generalized thermoelasticity with phase lags using the normal mode analysis is used to solve the present problem. The formulas of conductive and mechanical temperatures, displacement, micro-rotation, stresses and couple stresses are obtained. The considered quantities are illustrated graphically and their behaviors are discussed with suitable comparisons. The present results are compared with those obtained according to one temperature theory. It is concluded that both conductive heat wave and thermodynamical heat wave should be separated. The two-temperature theory describes the behavior of particles of elastic body more real than one-temperature theory.

Temperature field and demagnetization analysis of in‑wheel motors based on magneto‑thermal two‑way coupling

Xiuping Wang,Jiawei Zhang,Chunyu Qu,Chuqiao Zhou 전력전자학회 2024 JOURNAL OF POWER ELECTRONICS Vol.24 No.2

Due to the narrow working space of an in-wheel motor, the heat generated by the motor loss is difficult to dissipate. This makes it easier for the in-wheel motor to demagnetize the permanent magnet due to the mega-temperature, which affects the output efficiency. To solve this problem, an external rotor hub motor is studied. First, in accordance with the theory of magnetic field modulation, the in-wheel motor to be studied is designed. By analyzing the electromagnetic characteristics of the motor, the correctness of the motor design is verified, and the losses of the motor under different working conditions are calculated. To acquire a more rigorous temperature increase record, the magnetic-thermal bidirectional coupling method is utilized to analyze the temperature field under different load conditions. The mechanism of the demagnetization of permanent magnets is analyzed, and demagnetization at different temperatures is obtained by magneto-thermal two-way coupling. Research shows that when the motor is overloaded for a long time, the temperature can reach a maximum of 220 °C. At this temperature, the permanent magnet undergoes irreversible demagnetization, which results in a 93.44% decrease in torque. Finally, temperature increase tests of a permanent magnet motor are carried out to verify the validity of the magneto-thermal two-way coupling analysis.

The effect of two temperatures on a FG nanobeam induced by a sinusoidal pulse heating

Zenkour, Ashraf M.,Abouelregal, Ahmed E. Techno-Press 2014 Structural Engineering and Mechanics, An Int'l Jou Vol.51 No.2

The present investigation is concerned with the effect of two temperatures on functionally graded (FG) nanobeams subjected to sinusoidal pulse heating sources. Material properties of the nanobeam are assumed to be graded in the thickness direction according to a novel exponential distribution law in terms of the volume fractions of the metal and ceramic constituents. The upper surface of the FG nanobeam is fully ceramic whereas the lower surface is fully metal. The generalized two-temperature nonlocal theory of thermoelasticity in the context of Lord and Shulman's (LS) model is used to solve this problem. The governing equations are solved in the Laplace transformation domain. The inversion of the Laplace transformation is computed numerically using a method based on Fourier series expansion technique. Some comparisons have been shown to estimate the effects of the nonlocal parameter, the temperature discrepancy and the pulse width of the sinusoidal pulse. Additional results across the thickness of the nanobeam are presented graphically.

The effect of two temperatures on a FG nanobeam induced by a sinusoidal pulse heating

Ashraf M. Zenkour,Ahmed E. Abouelregal 국제구조공학회 2014 Structural Engineering and Mechanics, An Int'l Jou Vol.51 No.2

The present investigation is concerned with the effect of two temperatures on functionally graded (FG) nanobeams subjected to sinusoidal pulse heating sources. Material properties of the nanobeam are assumed to be graded in the thickness direction according to a novel exponential distribution law in terms of the volume fractions of the metal and ceramic constituents. The upper surface of the FG nanobeam is fully ceramic whereas the lower surface is fully metal. The generalized two-temperature nonlocal theoryof thermoelasticity in the context of Lord and Shulman's (LS) model is used to solve this problem. The governing equations are solved in the Laplace transformation domain. The inversion of the Laplace transformation is computed numerically using a method based on Fourier series expansion technique. Somecomparisons have been shown to estimate the effects of the nonlocal parameter, the temperature discrepancy and the pulse width of the sinusoidal pulse. Additional results across the thickness of the nanobeam are presented graphically.

Steady- and Transient-State Analyses of Fully Ceramic Microencapsulated Fuel with Randomly Dispersed Tristructural Isotropic Particles via Two-Temperature Homogenized Model-I: Theory and Method

이윤희,BUM HEE CHO,조남진 한국원자력학회 2016 Nuclear Engineering and Technology Vol.48 No.3

As a type of accident-tolerant fuel, fully ceramic microencapsulated (FCM) fuel was proposedafter the Fukushima accident in Japan. The FCM fuel consists of tristructural isotropic particlesrandomly dispersed in a silicon carbide (SiC) matrix. For a fuel element with such highheterogeneity, we have proposed a two-temperature homogenized model using the particletransport Monte Carlo method for the heat conduction problem. This model distinguishesbetween fuel-kernel and SiC matrix temperatures. Moreover, the obtained temperatureprofiles are more realistic than those of other models. In Part I of the paper, homogenizedparameters for theFCM fuel in which tristructural isotropic particles are randomly dispersedin the fine lattice stochastic structure are obtained by (1) matching steady-state analyticsolutions of the model with the results of particle transport Monte Carlo method for heatconduction problems, and (2) preserving total enthalpies in fuel kernels and SiC matrix. Thehomogenized parameters have two desirable properties: (1) they are insensitive to boundaryconditions such as coolant bulk temperatures and thickness of cladding, and (2) they areindependent of operating power density. By performing the Monte Carlo calculations withthe temperature-dependent thermal properties of the constituent materials of the FCM fuel,temperature-dependent homogenized parameters are obtained.

Steady- and Transient-State Analyses of Fully Ceramic Microencapsulated Fuel with Randomly Dispersed Tristructural Isotropic Particles via Two-Temperature Homogenized Model-II: Applications by Coupling with COREDAX

이윤희,BUM HEE CHO,조남진 한국원자력학회 2016 Nuclear Engineering and Technology Vol.48 No.3

In Part I of this paper, the two-temperature homogenized model for the fully ceramicmicroencapsulated fuel, in which tristructural isotropic particles are randomly dispersed in afine lattice stochastic structure, was discussed. In this model, the fuel-kernel and siliconcarbide matrix temperatures are distinguished. Moreover, the obtained temperature profilesare more realistic than those obtained using other models. Using the temperature-dependentthermal conductivities of uranium nitride and the silicon carbide matrix, temperaturedependenthomogenized parameters were obtained. In Part II of the paper, coupled withthe COREDAX code, a reactor core loaded by fully ceramic microencapsulated fuel in whichtristructural isotropic particles are randomly dispersed in the fine lattice stochastic structureis analyzed via a two-temperature homogenized model at steady and transient states. Theresults are compared with those from harmonic- and volumetric-average thermalconductivity models; i.e., we compare keff eigenvalues, power distributions, and temperatureprofiles in the hottest single channel at a steady state. At transient states, we compare totalpower, average energy deposition, and maximumtemperatures in the hottest single channelobtained by the differentthermal analysismodels. The different thermal analysis models andthe availability of fuel-kernel temperatures in the two-temperature homogenized model forDoppler temperature feedback lead to significant differences