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Common bulkhead (CBH) propellant tanks have the advantage that its structural and space efficiency are high. The tank is a form in which an oxidizer tank and a fuel tank are integrally combined, and the oxidizer and fuel are separated by the CBH. The CBH propellant tank in which two tanks are integrated can reduce unnecessary space between the two tanks. However, there are other difficult problems regarding effectively designing the CBH propellant tanks even though there are structural and space benefit. This paper is a study on the thermal-structural characteristics of CBH tanks containing LOX/LH2 propellant. In order to conduct the thermal-structural analysis, the thermal analysis model was constructed using 2-dimensional axisymmetric elements to reflect the shape features of the tank, and the structural analysis model was built using 3-dimensional elements. The thermal-structural analysis was performed on the length of the bottom tank and the foam core thickness of the CBH. In the structural analysis of the tank, when the thermal load was ignored and only the pressure load was applied, there was a difference in the buckling load factor depending on the thickness of the CBH foam core, but as the thermal load was taken into consideration, there was also a difference in the bottom tank length. The analysis results show that the thermal-structural characteristics of the CBH propellant tank were influenced by the length of the bottom tank as well as the thickness of the foam core. • Influence of the CBH thickness and bottom tank length on the thermal-structural characteristics of the CBH propellant tank. • Increasing CBH thickness and bottom tank length decrease the amount of heat transfer through the CBH. • There is a CBH thickness where the buckling load factor is maximum. • The bottom tank length that is too long can drastically reduce the buckling load factor. [ABSTRACT FROM AUTHOR]

• Heat transfer coefficient of highly subcooled water during flow boiling. • Challenges in minichannels during subcooled flow boiling. • Wall temperature distribution of mini and conventional channels during flow boiling. • Temporal temperature variations in minichannel at near to zero vapor quality. • Wall temperature fluctuations in minichannel for bo > 1.76 × 10−4. Channels of different sizes are employed in diverse engineering applications to enhance the efficiency of heat transfer system. Minichannels are preferred for their compactness, enhanced heat transfer, larger surface area to volume ratio, and high heat transfer coefficient values. There is a dearth of literature addressing flow boiling in minichannels with highly subcooled water at atmospheric system pressure. This research paper analyses the flow boiling phenomenon in a 2 mm diameter minichannel, comparing it with conventional 4 mm and 11.7 mm diameter tubes while maintaining a constant length to diameter ratio of 150. The analysis investigates the wall temperature distribution, local heat transfer coefficient, and temporal heat transfer fluctuations at a mass flux of 150 – 2400 kg/m2s and 109 – 1080 kW/m2 heat flux. The study explores the impact of boiling number on wall temperature fluctuations. Results reveal that mass flux doesn't impact heat transfer in subcooled flow boiling but does in saturated flow boiling in conventional channel. There are no significant temporal fluctuations of wall temperature in a 4 mm tube. However, vapor bubble size affects the circumferential area of minichannels, leading to abrupt flow disturbance. Wall temperature fluctuations occur in the minichannel for the boiling number exceeding 1.76 × 10−4. Temperature fluctuations in minichannel increase with boiling number, but decrease as mass flux is increased. Delving into the depths of minichannel heat transfer, this intriguing study unveils the pivotal role of the boiling number in ensuring process stability. [ABSTRACT FROM AUTHOR]

Highlights • Turbulent convection heat transfer over several artificial and realistic rough surfaces is investigated by means of full-geometry-resolving DNS. • The effects of morphological properties (e.g. density and slope) of the roughness as well as its height (in both inner and outer scales) on Reynolds analogy factor are studied independently and systematically. • A correlation for Reynolds analogy factor is extracted using the present DNS results and the data already published in the literature. Abstract Direct Numerical Simulations are used to solve turbulent flow and heat transfer over a variety of rough walls in a channel. The wall geometries are exactly resolved in the simulations. The aim is to understand the effect of roughness morphology and its scaling on the augmentation of heat transfer relative to that of skin friction. A number of realistic rough surface maps obtained from the scanning of gas turbine blades and internal combustion engines as well as several artificially generated rough surfaces are examined. In the first part of the paper, effects of statistical surface properties, namely surface slope and roughness density, at constant roughness height are systematically investigated, and it is shown that Reynolds analogy factor (two times Stanton number divided by skin friction coefficient) varies meaningfully but moderately with the surface parameters except for the case with extremely low slope or density where the Reynolds analogy factor grows significantly and tends to that of a smooth wall. In the second part of the paper, the roughness height is varied (independently in both inner and outer units) while the geometrical similarity is maintained. Considering all the simulated cases, it is concluded that Reynolds analogy factor correlates fairly well with the equivalent sand roughness scaled in inner units and asymptotically tends to a plateau. [ABSTRACT FROM AUTHOR]

In the paper, the problem of biological tissue freezing is discussed. In contrast to the previously presented models based on the Pennes equation, the thermal interactions between the cryoprobe tip and soft tissue are described using the dual-phase lag model (DPLM). This model contains two delay times (the relaxation and thermalization times) and in this way, the finite velocity of the thermal wave is considered. The model of the freezing process is based on the introduction of a parameter called ‘substitute thermal capacity’ to the dual-phase lag equation. At the stage of numerical computations, the explicit scheme of the finite difference method is used. In the final part of the paper the examples of the computation are shown. A comparison with the solution resulting from the adoption of the Pennes equation and also the model verification with the experimental data are presented in the final part of the paper. [ABSTRACT FROM AUTHOR]

In this paper, enhancement for convection heat transfer of turbulent flow in a solar central receiver tube with porous medium and non-uniform circumferential heat flux was numerically investigated. A new method was introduced to build different porous medium configurations in a unified grid system. Four kinds of enhanced receiver tubes (ERTs) with different porous insert configurations were modeled to optimize the performance of ERT. Furthermore, parameters including filling ratio of porous medium, thermal conductivity ratio (thermal conductivity of porous medium versus that of working fluid), porosity and Reynolds number were analyzed. The results showed that ERT partially filled with porous medium has better heat transfer performance than that fully filled with porous medium. The configuration of porous insert for optimal thermal or thermo-hydraulic performance is interactively affected by all the parameters discussed in this paper. The thermal conductivity ratio is the most crucial parameter to the thermal or thermo-hydraulic performance of ERT. The value of thermal conductivity ratio should be greater than 100 to obtain a good thermo-hydraulic performance. The ERTs with horizontal cylindrical segment shaped porous inserts and hollow cylinder shaped porous inserts are proposed because they can obtain optimal thermal or thermo-hydraulic performance. [ABSTRACT FROM AUTHOR]

In order to study the thermal safety of cylindrical battery deeply, based on the theory of heat transfer, thermal explosion and nonlinear modeling, a three-dimensional non-steady state thermal explosion mathematical model of cylindrical fireworks with non-uniform heat dissipation of the lateral surface was established for the first time (three-dimensional partial differential equation group). Combining seven point difference method and Newton-homotopy algorithm, the numerical calculation method of the three-dimensional non-steady state thermal explosion partial differential equation was established and the numerical calculation program was written base on Matlab. The validity of calculation program has been demonstrated by comparison of numerical solutions and classical solutions. The accuracy of model has been validated by example computation and analysis. The critical parameters describing non-steady state model of cylindrical fireworks when stored individually and stored in combination form were calculated in this paper, including temperature distribution, temperature–time history, thermal explosion time to ignition, etc. The results show that when the ambient temperature is 450 K, the fireworks stored individually do not have thermal explosion, but the fireworks stored in combination form will explode finally and the thermal explosion time to ignition is 19013.53 s. When the ambient temperature is 460 K, thermal explosion will occur in both the fireworks stored individually and stored in combination form, and the thermal explosion time to ignition are 3187.07 s and 3066.60 s respectively. It shows a more exact analytical methods and solutions of thermal safety evaluation of fireworks was established in this paper. Thus, it is need to strengthen the safety monitoring and management of cylindrical battery (combined fireworks) because of the higher thermal hazard. [ABSTRACT FROM AUTHOR]

• Thermal performance of novel polymer nanocomposite coatings towards anti-fouling and anti-wetting behaviour on steel substrates is analysed. • The incorporation of reduced graphene oxide lead to a significant reduction in the wettability and surface roughness of coatings. • It is found that even small thickness of bio-foulant layer can significantly impede the heat transfer across the substrate. • In case of the epoxy-based nanocomposite coatings an ∼18° increase in contact angle was observed with the addition of rGO. This paper presents an experimental study on the thermal performance of novel polymer nanocomposite coatings under the fouling environments with particular emphasis on their ability to exhibit anti-fouling and anti-wetting behaviour. Two different weight fractions at 0.3%, and 0.5% of the reduced graphene oxide/Epoxy (rGO-ER7004) and reduced graphene oxide/polyurethane (rGO-UR9002) coatings were applied to stainless steel substrates by a facile spray coating technique. To evaluate the anti-fouling performance of the coatings, the specimens were immersed in the Modified Baar's Medium for 672 h. The antifouling performance was evaluated by comparing the overall heat transfer effectiveness of the nano coated and bare specimens at different immersion intervals. Three different flow rates, viz. 4 lpm, 6 lpm and 8 lpm were used to compare the heat transfer effectiveness. The incorporation of rGO lead to a significant reduction in the wettability and surface roughness of coatings. amongst all the investigated coatings, the heat exchange with rGO/UR9002 0.5 wt.% coatings showed the highest heat transfer effectiveness. A small reduction (∼10%) in the heat transfer effectiveness after an immersion in the fouling media for 672 h was noticed. This can be attributed to the accumulation of salt particles on the coatings, observed visually. Finally, the 1-D heat transfer analysis is performed using finite element method based approach to evaluate the effect of the nano coatings and foulants on the temperature drop. It is deduced that a small foulant layer can significantly impede the heat transfer across the substrate. A strong correlation (∼0.99) between the heat transfer effectiveness and temperature drop is observed. [ABSTRACT FROM AUTHOR]

• Developed methodology for reducing scale of thermo-structural test on wood. • Fire exposure tests of lumber at three scales: full-scale, ½-scale, and ¼-scale. • Thermo-structural three-point bending tests at two scales: ½-scale and ¼-scale. • Maintaining equivalent char depths is vital to scaling thermo-structural behavior. • Created char timescale correction factors to ensure an equivalent charring rate. Standard fire resistance testing is essential to qualifying wood-based materials to be approved for use in building assemblies. In a previous study, we developed a theoretically based, experimentally validated scaling methodology for reducing the size of the test article while maintaining the same thermal and structural response exhibited in the large-scale test. This paper is focused on demonstrating these scaling laws for wood with combined thermo-structural loading. Due to load capacity limits, dimensional lumber boards at ½-scale and ¼-scale were subjected to combined bending and thermal loading. Samples were placed in static three-point bending with the loading scaled to have structural similitude, while simultaneously, the bottom surface was exposed to a scaled fire exposure. Analytical modeling of wood pyrolysis demonstrated that, due to char kinetics as the heating rate is increased in the tests, equivalently less char is formed in the reduced-scale tests. Therefore, we developed a char timescale correction factor, calculated from both model predictions and measured charring rates, which modified the previous Fourier number time scaling laws. Scaling exposure time by our updated thermo-structural test scaling laws, the smaller ¼-scale test deflection results predict the behavior of the equivalent larger ½-scale tests by between 11.0% to 16.1%. [ABSTRACT FROM AUTHOR]

In the paper a numerical analysis of thermal processes proceeding in a soft tissue subjected to a laser irradiation is presented. The transient bioheat transfer in the 3D domain considered is described by the generalized dual-phase lag equation. The internal heat source resulting from the laser irradiation based on the solution of the diffusion equation is taken into account. The process of the thermal destruction of the tissue is also analyzed. At the stage of numerical realization the explicit scheme of finite difference method is used. In the final part of the paper the results of computations for different variants of tissue porosity are shown. [ABSTRACT FROM AUTHOR]

Artificial neural networks (ANN) have been widely used for thermal analysis of heat exchangers during the last two decades. In this paper, the applications of ANN for thermal analysis of heat exchangers are reviewed. The reported investigations on thermal analysis of heat exchangers are categorized into four major groups, namely (i) modeling of heat exchangers, (ii) estimation of heat exchanger parameters, (iii) estimation of phase change characteristics in heat exchangers and (iv) control of heat exchangers. Most of the papers related to the applications of ANN for thermal analysis of heat exchangers are discussed. The limitations of ANN for thermal analysis of heat exchangers and its further research needs in this field are highlighted. ANN is gaining popularity as a tool, which can be successfully used for the thermal analysis of heat exchangers with acceptable accuracy. [ABSTRACT FROM AUTHOR]

Thermal radiation is a significant mode of energy transmission besides conduction and convection in most combustion systems. Accurate treatment of thermal radiation is a crucial element for predicting the flame structure and pollutant formation. However, thermal radiation to fuel droplet evaporation is often neglected in the numerical simulations of two-phase spray combustion systems. In this paper, computational analysis on the thermal radiation to evaporation and combustion of fuel droplets in two-phase spray combustion is conducted. The influence of flame radiation on droplet evaporation and combustion is studied by adding radiation source term to the energy equation describing droplet evaporation process. Radiation transfer equation is solved, in which the radiation of CO 2 , H 2 O and soot is imposed to consider radiation effect of the flame. The partially premixed combustion model is employed, in which radiation heat transfer between droplet and ambient gases is taken into account. A reduced chemical reaction mechanism for n-heptane consisting of 76 species and 349 reactions is used. Four different numerical setups have been used and compared, and the simulation results coincide with the experiment data in terms of spray statistics and flame shapes. The peak flame temperature increases by 28 K when the radiative heat source term in the evaporation process is considered. The droplet evaporation is significantly enhanced by thermal radiation, leading to a promotion of 34.8% in C 7 H 16 concentration in the center region of combustor. The concentration of combustion products, such as H 2 O and CO 2 , increases by 13.2% in the reaction region. [ABSTRACT FROM AUTHOR]

Highlights • Stability of quasi-equilibrium states of Williamson fluid subjected to vibrations is studied. • Enhancement of viscoplastic properties of fluid exerts destabilizing effect. • In viscoplastic limit the instability threshold does not depend on rheological parameters. • The supercritical regimes are excited through supercritical bifurcation. Abstract In this paper we investigate a linear stability of quasi-equilibrium states and supercritical regimes of thermal vibrational convection of a Williamson fluid between two rigid parallel plates, maintained at constant different temperatures in zero gravity conditions. Calculations are made for different angles of inclination of the vibration axis relative to the layer. It has been found that, as in the case of a Newtonian fluid, most dangerous are the hydrodynamic monotonic perturbations. Enhancement of viscoplastic properties of a fluid has a destabilizing effect at all angles of inclination of the vibration axis. An increase in the Prandtl number stabilizes the quasi-equilibrium states of the pseudoplastic fluids. In the viscoplastic limit, the critical value of the modified Rayleigh number, which determines the quasi-equilibrium stability threshold, does not depend on the Prandtl number and rheological parameters. The critical value of the perturbation wave number for pseudo- and viscoplastic fluids depends only on the angle of inclination of the vibration axis. The type of the convection excitation and the structure of the supercritical convective flows under longitudinal vibrations have been studied on the basis of full nonlinear equations of thermal vibrational convection. It has been found that the supercritical bifurcation takes place. [ABSTRACT FROM AUTHOR]

Highlights • The general interfacial thermal characteristics of a coated tool tip-sheet system has been studied. • The tool-tip velocity is considered by means of the Galilean transform. • The conjugate gradient method (CGM) is applied for calculating the heat partition. • A sensitivity analysis evaluates the influence of material properties and their coupling on the peak temperature. Abstract This paper reports a semi-analytical model for studying general and critical heat-transfer characteristics at the interface between a coated sheet and a moving coated tool tip in incremental forming considering heat partition. Both of the tool tip and the sheet can be treated as a coating-substrate material system. The frequency response functions (FRFs) for temperature rise in each material system are analytically derived, in which the tool-tip velocity is incorporated by means of the Galilean transform. The FRFs are then converted into influence coefficients (ICs) in the frequency domain for solution efficiency and convenience. Fast numerical techniques are applied, such as the conjugate gradient method (CGM) for searching the distributed tool-tip/sheet heat partition and the fast Fourier transform (FFT) for obtaining temperature solutions. The proposed model is implemented to analyze the combined influences of Péclet number, coating thicknesses of the tool tip and the sheet, sheet thickness, and heat conductivity of each material on the temperature rise and the heat partition at the interface, and the sensitivity of the dependence of the peak temperature on these system parameters. [ABSTRACT FROM AUTHOR]

Highlights • PCM/3D-OHP and PCM/OHPs systems were designed, tested and compared. • Melting time and thermal balance temperature of two systems were studied. • Solidification characteristics of two systems and pure PCM were compared. • Thermal performance enhancement mechanism of 3D-OHP was approached. Abstract Phase change material (PCM) has been widely used in thermal management for its high latent heat and low price. However, further development of its application is limited by the low thermal conductivity. Oscillating heat pipe (OHP), an effective thermal transfer device, can be used to enhance the heat transfer of PCM and then improve the thermal performance. In this paper, both novel 3D-OHPs and regular OHPs were hired for PCM thermal performance enhancement. PCM coupled with two kinds of novel 3D-OHPs (4 layers 3D-OHP and 3 layers 3D-OHP) system and PCM coupled with multiple 2D-OHPs system were experimentally investigated. Results showed that the paraffin wax/3D-OHP system needed more time for completely melting of paraffin wax than paraffin wax/OHPs system. The temperature of wall and paraffin wax in the former system was lower during melting process. In the solidification process, both two systems performed better than paraffin wax only. The solidification time of the paraffin wax/4 OHPs system was about 0.48 times than that of pure paraffin wax and the paraffin wax/4-layers 3D-OHP only 0.29 times, which meant that paraffin wax/3D-OHP system had better performance. [ABSTRACT FROM AUTHOR]

Highlights • We made simultaneous observations of the dynamics and thermal behavior of dry patches. • The critical heat flux phenomenon occurred during the rewetting of a large dry patch. • The bubbles nucleating at the advancing liquid front played a key role in the failure of the rewetting. • We determined an empirical value for the critical line density of the bubbles at the triple contact line. Abstract We observed the dynamics of dry patches underneath massive bubbles during the pool boiling of saturated water under atmospheric pressure, and measured the associated temperature distribution. We synchronized the observations both spatially and temporally using high-speed total reflection and infrared thermometry techniques. The observations presented in this paper provide evidence that the critical heat flux phenomenon is triggered during the rewetting of large dry patches with periphery temperatures that are much lower than minimum film boiling temperature, so-called Leidenfrost point. As the liquid meniscus advanced toward the dry patch, numerous secondary bubbles nucleated and impeded the flow of liquid toward the dry patch. This prevented the liquid from rewetting the dry patch. The key physical mechanism for triggering CHF is initiated when the line density of the secondary bubbles nucleating at the periphery of a shrinking dry patch underneath a departing mushroom bubble exceeds a critical value. These bubbles completely block the liquid inflow into the dry patch and prevent rewetting, eventually causing the dry patch to expand irreversibly. We used our experimental data to determine an empirical value of the critical line nucleation site density. [ABSTRACT FROM AUTHOR]

Highlights • New data for evaporation of R32 in specially designed single pass parallel flow tube. • Heat transfer coefficient, adiabatic pressure drop, diabatic pressure drop are measured and reported. • Experimental results are compared to predictive correlations. Abstract This paper presents heat transfer coefficient and pressure drop of R32 measured in the same facility as introduced in Li and Hrnjak (2017). Experiments are conducted on a 24-port microchannel tube with a hydraulic diameter of 0.643 mm. The pressure drop of R32 is lower than R134a, and the heat transfer coefficient is higher at the same condition. The pressure drop increases with quality and mass flux but decreases with reduction of saturation pressure. R32 heat transfer coefficient increases when heat or mass flux rises. Heat transfer coefficient of R32 first increases when quality increases due to convective effects and then drops at moderate quality due to the absence of nucleate boiling and dry-out. A comparison of adiabatic pressure drop and heat transfer coefficient to correlations has been made. Based on the Blasius equation and homogeneous density, the viscosity model from Cicchitti et al. (1960) has the best fit to predict two-phase pressure drop. Kim and Mudawar (2012) has the smallest MAE to predict pressure drop. For heat transfer coefficient, Sun and Mishima (2009) is the best fit. Further research will be on expanding the database and understanding hydraulic and boiling behavior. [ABSTRACT FROM AUTHOR]

Highlights • Machining performances using ethylene glycol/nanocellulose based nanofluid. • 0.5 vol% EG/nanocellulose based MWF generates 1130 J of heat transfer at 30 °C. • Maximum temperature at chip formed by using nanofluid is 154 °C. Abstract In this paper, cellulose nanocrystal (CNC) – ethylene glycol (EG) + Water (W) based nanofluid was developed and assessed for their thermophysical properties and the usefulness towards machining performances. The nanofluid was prepared by adopting two-step preparation method and at volume concentration of 0.1%, 0.3%, 0.5%, 0.7%, 0.9%, 1.1%, 1.3% and 1.5%. The nanofluid with 1.3% and 1.5% concentration showed to have superior the conductivity properties, around 0.559 W/m·K at 70 °C. However, the 0.5% concentration has the highest stability with 0.52 W/m·K at 70 °C. The 0.5% nanofluid concentration was then selected for the machining performance evaluation. The machining performance was evaluated by using a lathe machining operation to determine the heat transfer and tool life properties. The cutting variables such as cutting speed, depth of cut and feed rate are varied to understand the effect of developed nanofluid on the machining bahaviour. Findings revealed that the tool failure on machining using MWF is flank wear, chipping and abrasion and fractured at the maximum cutting distance of 500 mm. However, machining using CNC-EG+W nanofluid revealed the tool failure to be flank wear, adhesion and build- up-edge (BUE) and fractured at the maximum cutting distance of 772 mm. [ABSTRACT FROM AUTHOR]

Highlights • Constructal design of the first to fifth order line-to-line vascular channels. • Application of entropy generation minimization principle. • Angles of line-to-line vascular channels are optimization variables. • Fixed vascular channel areas and total volumes constraints. • Optimal constructs and influences of the mass flow rate are obtained. Abstract Constructal optimizations of the first to fifth order line-to-line vascular channels (LVCs) with convective heat transfer are carried out in this paper by taking minimum entropy generation rate (EGR) and minimum entropy generation number (EGN) as the optimization objectives, respectively. The angles of the LVCs are taken as the optimization variables, and the fixed vascular channel areas and total volumes of LVCs are taken as the constraints. The optimal constructs corresponding to minimum EGR and minimum EGN are obtained, respectively. The influences of the mass flow rate (MFR) on the optimal results are analyzed. The results show that the EGR of the LVCs decreases when the angle freedom increases with the constant dimensionless MFR, which is more obvious when the order increases. When the order increases, the EGR increases but the EGN decreases. Both the EGR and the EGN increase with the increase of the dimensionless MFR. The results obtained herein can provide some thermal design and management guidelines for the applications of LVCs. [ABSTRACT FROM AUTHOR]

Highlights • A novel graded-grooves wick design was put forward for flat heat pipe. • An accurate mathematical model is established for mini-grooves flat heat pipe. • Effective thermal conductivity of proposed heat pipe is increased by 12.4%. • Local wick size & vapor chamber volume have great effects on thermal performance. • Grooves wick in slope type is suggested for practical application. Abstract Thermal management of micro electronic devices is one of the major issues for electronics application. Mini-grooves flat heat pipe is suitable to be used for small space electronics rapid cooling due to its high thermal conductivity, simple structure and good temperature uniformity. In this paper, an axial fluid flow and heat transfer mathematical model of mini-grooves flat heat pipe in steady state is built to study the axial distributions of key parameters such as pressure, velocity and wall temperature. As the wick structure plays an important role in the mini-grooves flat heat pipe heat transfer enhancement, the influence of mini-grooves size and wall with grooves along the axial direction on the heat transfer coefficient of mini-grooves flat heat pipe is studied. It is found that aiming at designing the optimum mini-grooves flat heat pipe, the local wick needs to be close to in saturated state, and the vapor chamber needs to be large. In this way, a novel graded-grooves wick design is put forward for flat heat pipe, which can increase the effective thermal conductivity coefficient by 12.4% with heat transfer rate 5.0 W. And the grooves wick in slope type with simple fabrication accords with practical application. [ABSTRACT FROM AUTHOR]

Highlights • Presented methodology for optimization of component reliability of heat supply system. • Presented mathematical models for determine optimal reliability parameters. • Considered case study illustrating applying of models and methods. Abstract The paper suggests a methodology to determine optimal reliability parameters (failure and restoration rates) of heat supply system components, which provide the required level of heat supply reliability. The methodological approach consists in the economically rational distribution of the total effect of reliability improvement among the system components, which is calculated using the average reliability parameters of the components. This task, along with the task to ensure structural reliability, is one of the key reliability tasks within a more general problem of optimal synthesis of heat supply systems and is urgent for both the systems under design and the existing insufficiently reliable systems. The methodology of solving the stated problem is based on the methods of the theory of hydraulic circuits, nodal reliability indices of heat supply, models of Markov random process and general regularities of cogeneration and heat transfer processes. The methodology also takes into account changes in thermal loads during the heating period and time redundancy of consumers related to heat storage. The results of the practical research based on the calculation experiment that confirms the viability of the presented methodology for the schemes of real heat supply systems are presented. The advantages of the proposed methodology compared to the existing approaches to solving this problem consist in joint optimization of the component reliability of heat source and heat network schemes, integration of procedures for the reduction in failure rates and the improvement in restoration rates of the components in one calculation pattern of search for the optimal system reliability, the absence of the need to conduct iterative calculations when using the average reliability parameters of components, considering the required levels of reliability indices. [ABSTRACT FROM AUTHOR]

Fully penetrated keyhole welding process can be achieved by employing the free burning arc in Tungsten Inert Gas (TIG). The interaction between the heat source and weld pool determines the dynamic behaviour of the keyhole and the resultant weld quality. To determine the energy transfer behaviour, in this paper, the dynamic keyhole behaviour was imaged with the vision system when the heat source was changed by adjusting the welding current or welding speed in real time. It was found that (1) keyhole exit positional and dimensional parameters were all changed as a response to the welding speed changing; (2) keyhole exit size parameters changed much faster than the positional parameters did when the welding current was suddenly decreased or increased; (3) a sharp pulse emerged in the position curve of the keyhole exit center point after the welding current was suddenly changed. The behaviour mechanism was analyzed in view of dynamic changing of the force field and heat field in the arc-keyhole-weld pool system. [ABSTRACT FROM AUTHOR]

In this paper, a numerical model describing the heat transfer and air flow inside and outside the casing of the permanent magnet brushless direct current (PM BLDC) motor is presented. In the model, a conjugate heat transfer including the heat conduction with heat sources in windings, magnets, bearings, natural and forced convection and radiation phenomena within internal and external air domain were analysed. The complex geometrical model included windings, a magnet circuit, a rotor with neodymium magnets, a PCB electronic plate, plastic covers, internal air between solid parts as well as a portion of the external air. The validation process of the developed model was realised on the basis of the velocity and temperature fields. The experimental data were recorded by 7 constant temperature anemometers at 4 levels above the motor housing, Laser Doppler Anemometry sensors in two axes inside the rear portion of the motor and 25 thermocouples fixed inside and outside the motor. The experimental and numerical tests were performed for 4 motor loadings and 3 rotational speeds. The average temperature error for the internal point was of 9 K, while that of the external points was of 2 K. The velocity field was very well predicted close to the housing wall in terms of horizontal and vertical components. A slightly worse agreement was found for the vertical component, especially in the vicinity of the shaft. The results were consistent for all the considered motor loadings and rotational speeds. [ABSTRACT FROM AUTHOR]

The research presented in this article is a contribution to the characterization of thermal dual analysis. The aim of a dual analysis based on two complementary numerical methods is to calculate the stationary temperature field. The two methods are respectively the classical Kinetically Admissible (KA) finite element or temperature method, and the Statically Admissible (SA) flow method. The originality of this work is twofold. First, it uses a flow approach (SA) in 2D and 3D that naturally respects flow conservation (in contrast to the KA method). Second, calculating the dissipation energy allows the exact solution of a problem to be enclosed, with the lower and upper bounds being calculated respectively by the KA and SA methods. Thermal bridges are areas of risk in the building walls, because they can give rise to uncontrolled increments in heat transfer. A number of studies have looked at thermal bridges, but much of the numerical code for building energy simulations uses heat transfer models based on one-dimensional heat flow analysis. Fabrizio Ascione (2014) showed that this can lead to unreliable results. The originality of this paper is to consider 2D and 3D thermal bridges using dual analysis with mesh sizes smaller than those used in conventional finite element approaches. [ABSTRACT FROM AUTHOR]

This paper investigates the thermal performance of a translucent solar wall providing, concurrently, storage and restitution of heat, super thermal-acoustic insulation and daylighting to the interior environment. The wall is composed of glazing, silica aerogel used as a transparent insulation material (TIM) and glass bricks filled with fatty acid, an eutectic phase change material (PCM). To assess the TIM–PCM wall thermal behavior, experimentations were conducted in-situ in a full-sized test cell located in Sophia Antipolis, southern France. Experimental data shows that the tested wall is more effective in winter and might cause overheating during the summer mainly due to solar gains and un-cycling behavior of PCM which remains in liquid state. To enhance the energy performance of the wall in summertime, a numerical model describing the heat transfer mechanisms occurring in the PCM layer in combination with the other transparent wall layers is developed. Then, the model of the wall is linked to TRNSYS software to assess the thermal performance of the whole building. The numerical model is validated experimentally and a good agreement is shown comparing the simulated values with the measured data for seven consecutive days in summer and winter. The importance of considering the natural convection effect in the liquid PCM is also demonstrated. Moreover, it was shown that shading devices can effectively reduce overheating while natural night ventilation decreases the indoor temperature without affecting the PCM performance since the outdoor temperature is always higher than the phase change temperature. The use of a glass with selective solar reflection properties depending on the season instead of the ordinary glazing is shown also to be very effective way to overcome the overheating problem. Finally, the TIM-PCM wall is tested under different climate conditions and passive solutions are given to ensure thermal comfort in summer season. [ABSTRACT FROM AUTHOR]

This paper presents experimental results obtained during tests on the evaporation heat transfer inside tube of a coaxial heat exchanger for residential and industrial geothermal heat pumps. The experimental device and instrumentation of the test section using evaporation inside a water heated double tube, have been described. The results obtained for evaporation local heat transfer of refrigerants R134a and R407C have been compared to the existing correlations. The aim of this comparison is to evaluate the validation of the well-known correlations to predict evaporation heat transfer in the geothermal operating conditions. A complete experimental analysis of the local evaporation of the R134a and R407C is carried out as a function of vapor quality inside a smooth horizontal tube. Various refrigerant mass fluxes are tested. Moreover, new correlations for local heat transfer and pressure drop predictions have been developed and validated basing on the measurements. [ABSTRACT FROM AUTHOR]

This paper proposes a cascaded packed bed cool thermal energy storage (CTES) unit using multiple phase change materials (PCM). In terms of the solidification processes, the basic heat transfer characteristics were analyzed based on an experimentally validated simulation model. Thermal performances, including cold charging rate, the quantity of cold and exergy charged, as well as the exergy efficiency of the cascaded CTES unit were compared with those of a single-stage CTES unit. In order to further achieve better thermal performance, the materials, stages and thickness of each stage were optimized. According to the results, the 24-stage CTES unit with a phase change temperature difference between the highest and lowest stage (denoted as T d ) of 6 °C has the best thermal performance, because it shows a 15.1% reduction in charging time compared with a single-stage unit, while its quality and quantity of cold charged remains almost equivalent to the single-stage unit. Moreover, 3–5 stages are recommended for an evenly distributed cascaded CTES as their thermal performances are quite close to the optimal 24-stage unit. [ABSTRACT FROM AUTHOR]

The problem addressed in this paper is the thermal buckling behaviour of thin-walled steel cylindrical fixed-roof tanks under non-uniform loading, induced by an adjacent tank. This specific type of thermal loading can be triggered by a neighboring tank fire where heat is transferred mainly through radiation. Since the calculation of the temperature field of the heated tank lies in other scientific fields (e.g. Computational Fluid Dynamics), a thermal pattern, proposed in literature, is used for the simulation of the fire-induced load and the investigation of the structural response of the tank due to heating. The study is conducted numerically through the Finite Element method, using coupled thermo-mechanical analysis. The general purpose Finite Element code MSC Marc, is used for the simulation. Three-dimensional models are developed using shell elements. Firstly, a detailed study of the failure mechanisms that take place in case of non-uniform loading is carried out. Furthermore, tanks with different geometries are studied. The main objective is the calculation of the critical temperature i.e. the temperature where the failure appears and the determination of the failure modes. Finally, a parametric study is conducted for the evaluation of the effectiveness of stiffening methods that are commonly used at ambient temperature design (stiffeners and stepwise wall thickness), in the case of the non-uniform heating load. In this study, the heated tanks are considered to be empty, which is the most severe scenario, for their structural integrity. [ABSTRACT FROM AUTHOR]

This paper presents the stability, convergence and optimization characteristics of interface treatments for steady conjugate heat transfer problems. The Dirichlet-Robin and Neumann-Robin procedures are presented in detail and compared on the basis of the Godunov-Ryabenkii normal mode analysis theory applied to a canonical aero-thermal coupling prototype. Two fundamental parameters are introduced, a “numerical” Biot number that controls the stability process and an optimal coupling coefficient that ensures unconditional stability. This coefficient is derived from a transition of the amplification factor. A comparative study of these two treatments is made in order to implement numerical schemes based on adaptive and local coupling coefficients, with no arbitrary relaxation parameters, and with no assumptions on the temporal advancement of the fluid domain. The coupled numerical test case illustrates that the optimal Dirichlet-Robin interface conditions provide effective and oscillation-free solutions for low and moderate fluid-structure interactions. Moreover, the computation time is slightly shorter than the time required for a CFD computation only. However, for higher fluid-structure interactions, a Neumann interface condition on the fluid side presents good numerical properties so that no relaxation coefficients are required. [ABSTRACT FROM AUTHOR]

The paper deals with the problem of heat conduction in a nonhomogeneous rigid body which is a homogeneous conductive layer with a periodic composite coating. The coating layer is a composite in which every unit cell in general case is composed of four rigid beams with rectangular cross-sections. The assumed structure permits to analyse some special cases of coatings: laminated composites with layer parallel or perpendicular to the boundary, composites with periodically distributed inclusions with rectangular cross-section and a homogeneous layer. The distributions of temperature and heat flux distributions on the interface between the coating and the homogenous layer are investigated. [ABSTRACT FROM AUTHOR]

In this paper, a new single micro-channel heat sink with 0.55 × 0.55 mm cross-section and 78 mm length based on R134a flow boiling is established to investigate the heat transfer coefficient and heat transfer mechanism with different inlet vapor quality. The experiment is conducted under the condition of heat flux in 0.918–6.993 kW/m 2 , mass velocity in 1821–4115 kg/(m 2  s) and original saturation temperature in 20 °C. In the study, the relationship between various inlet vapor quality and average heat transfer coefficient is discussed, and the heat transfer mechanism is illustrated by the flow patterns captured by the high-speed camera with microscope lenses. Four major flow patterns are found in the experiment: bubbly, slug, churn and annular/wavy-annular flow, they appear in different inlet vapor quality regions. The result shows that the heat transfer coefficient increases with increasing inlet quality in low inlet quality dominated by nucleate boiling, but decreases in high inlet quality dominated by convective boiling. In the middle inlet quality, the heat transfer coefficient starts to decrease. Interestingly the forming process of churn flow is clearly seen in the experiment, it is formed by two steps: the bubble formation is restricted by the liquid film of a long vapor slug; the bubble tears apart the liquid film. It results the heat transfer mechanism of churn flow is a fierce confrontation of nucleate boiling and convective boiling. The effects of heat flux and mass velocity during different inlet quality region are also discussed. [ABSTRACT FROM AUTHOR]

Making clear how thermal loads are equilibrated and transferred through a structure is of importance for identifying optimal heat conduction topologies in problems of cooling scheme design. This paper proposes a new method for computing the orientations and locations of heat transfer paths from a standard finite element analysis. First, a non-dimensional parameter ( C ⁎ ) is introduced, based on the variation in thermal compliance of the structure, to quantify the contribution of an arbitrary point in the structure to heat conduction performance. Then, a plotting algorithm is presented to search for the ridge lines of the calculated C ⁎ curved surface, which provide the steepest ascent in C ⁎ values from the points of heat sink to the points of heat source. Based on this, mathematical conditions (termed uniformity and continuity requirements) are discussed in detail and utilized as new criteria for tailoring the layouts of heat transfer paths in order for conductive cooling to be more effective. Finally, the derived criteria are incorporated into a commonly used topology optimization algorithm (SIMP algorithm), and validated though several benchmark cases. Unlike the conventional methods, the suggested approach optimizes only the orientations and locations of heat transfer paths and does not intentionally concern the overall temperature distribution, the application of which can potentially lead to worthwhile improvements at the conceptual stage of cooling design processes. [ABSTRACT FROM AUTHOR]

In this paper, dispersion effects on forced convection heat transfer in a gaseous slip flow through a microtube filled with anisotropic porous medium are investigated semi-numerically. Microtube is subjected to constant heat flux and a local thermal non-equilibrium condition is assumed. Rarefaction effects are taken into account by applying first-order velocity slip and temperature jump boundary conditions. Dispersion is proven to have a significant impact on heat transfer in rarefied gases. Temperature distributions for both solid and fluid phases are obtained. Nusselt number variation with respect to porous shape factor and Biot number is illustrated, indicating enhancement up to 10% in predicted heat transfer due to dispersion. The influence of Reynolds number on thermal dispersion is proven to be insignificant. Dispersion plays a significant role as gas becomes more rarefied. It is seen that an increase in shape factor of a porous media can improve Nu for a non-rarefied gas, but as rarefaction effects grow, this can affect heat transfer negatively. Also, effects of dispersion on heat transfer diminishes for higher values of Biot Number due to the overcoming of interstitial heat transfer to thermal dispersion effect. [ABSTRACT FROM AUTHOR]

In hot strip rolling, the work roll shifting method has been widely used to disperse thermal crown and wear of the work rolls in the axial direction. This paper provides a strategic control method for the work roll profile which surpasses the conventional work roll shifting method. A numerical simulation model which enables prediction of thermal crown and wear of work rolls with high accuracy has been developed, and a new shifting method has been proposed, focusing on the problems of the conventional shifting method. In the conventional shifting method, the work roll shift position follows the prearranged pattern, and the work roll profile is not controlled intentionally. On the other hand, in a new work roll shifting method, the work roll profile of all coils in the rolling campaign are predicted by the numerical calculation, and controlled so as to be equal to the target profile by considering the work roll shift position. An evaluation function consisting of the error between predicted work roll profile and the target profile of all coils in the rolling campaign has been used, and the work roll shift position has been decided by the optimum calculation with minimizing the evaluation function. [ABSTRACT FROM AUTHOR]

The fracture with the formation of crack patterns instead of a single main crack may occur in the structures for several reasons. The main factor is always the presence of high gradients through the depth of a structure at almost constant stresses near the surface. In this case a growing crack can get into the zone of low stresses and stop, and the fracture will continue by formation of new cracks. Such fracture type is typical for heat-stressed structures, but can also occur under mechanical loading. This paper discusses the possible mechanisms of the crack pattern formation. It is shown that in addition to the form of stress field, the fracture type depends on material properties - in particular, its creep. The considered fracture by crack pattern formation could be characteristic of not only the metallic structural elements, but also for the natural formations, for instance rock or ice massives. [ABSTRACT FROM AUTHOR]

Recently researchers have proposed innovative solutions aiming to improve the energy performance of building envelope components such as Trombe walls, ventilated storage walls. The principle of all the innovative systems can be simplified as heat/cold sources in walls. However, the thermal performance and energy savings potential of the innovative heating walls comparing to the traditional heating pattern with heat sources in room air are still lack of clarification. In this paper, the thermal response of an ideal building model under two ideal heating patterns, are analyzed by using a simple thermal and airflow macroscopic model. The analytical formulas for indoor air temperature and thermal mass temperature are also derived to identify the critical parameters that affect the levels and fluctuations of them. By numerical calculation, it can be observed that the indoor air temperature under HP1 quickly falls down as the heat source removed and has big variation, while the results of HP2 look favourable with less variation, and the mean air temperature during the non-heating period is higher than that of HP1. This implies that the heating pattern HP2 has the potentials to create a stable indoor thermal environment. [ABSTRACT FROM AUTHOR]

When designing ground source heat pump systems in northern regions, we usually face the problem of soil freezing/melting around ground heat exchanger. The impact of freezing on heat transfer should be evaluated. An improved thermal resistance and capacity model based on the effective heat capacity method is developed in the paper to evaluate the effect. Further comparisons have been carried out against measured data from an experimental set-up, and agreement of the results validates the proposed model when the parameters of the model are set properly. The heat transfer capacity could rise by 30% because of phase change. The quantity of heat transfer could stay at 75 W/m to 80 W/m during three-month operation, which is feasible for a GSHP system to operate normally in such extreme condition. [ABSTRACT FROM AUTHOR]

Steam air heater is one of the most effective ways to avoid the corrosion and ash deposition of air preheater, but it increases the temperature of exhaust gas from the boiler and as a result, reduces cycle efficiency of the power plants. The current paper investigates the economic performance of a pre-fixed type of extend air preheater(EAPH). Based on the quantitative analysis of energy conservation and equivalent enthalpy method, the results indicate that the economic performance of the new preheater is not good when no air is required to be heated. In such case, an optimized system is proposed and the economic performance of the system is analyzed when applied in a 320 MW unit. The results show that the incremental ratio of the plant efficiency employing the optimized system increases from 0.11% (for EAPH) to 0.51% when no air is required to be heated. The saved value of annual-average standard coal consumption rate is 1.50 g/(kW•h) compared to EAPH of 0.54 g/ (kW•h). [ABSTRACT FROM AUTHOR]

Characteristics and problem of building automation system (BAS) existed in the practical engineering application are analyzed, and then the development of BAS is discussed from the perspective of network structure and supplied function service. Aiming at the space distribution feature, this paper presents the network architecture of Ubi-bus fieldbus, and then essential feature, operation mechanism and standardized information model are introduced respectively. Software and hardware are designed and developed in the control platform of variable air volume (VAV) air conditioning system. Based on the network architecture of Ubi-bus, it is potential for the solution of BAS integration in the practice application. [ABSTRACT FROM AUTHOR]

In this paper, two sets of design schemes of air source heat pump heating and gas boiler heating are given, and the economical performance of the two heating modes is compared. Through the simulation and calculation of the two kinds of heating system economy, it can be concluded that the operating cost of the gas-fired boiler is about 21.39 RMB•m -2 in the normal operation of the whole year. The operating cost of the air-source heat pump system in the regular operation is about 17.81 RMB•m -2 , and it is about 10.82 RMB•m -2 in the valley operation. [ABSTRACT FROM AUTHOR]

In this paper, The utility model relates to a heating system which is composed of a traditional solar air collector, a floor air supply and a phase change heat storage air duct, which is used for heating the room in winter. Using Fluent software to simulate the whole system in winter. The results show that this system conforms to the standard of winter heating. The system needs to add an electric heating auxiliary heat source, which is used to heat the room in the night or rainy day. [ABSTRACT FROM AUTHOR]

During the past decades, physiological responses of the human body in extremely hot environments have been studied. Most research has focused on the human heat tolerance, and assessment of the heat stress. In this context, parameters of environments and physiological parameters were introduced, and important heat stress indexes were explained. This article aims to summarize the progress in the literature concerning heat stress indexes and heat acclimatization. The research priorities should shift to the relationship between human heat acclimatization and the indoor thermal environments. This paper will hopefully aid the understanding of human heat acclimatization in extremely hot environments and guide the future research. [ABSTRACT FROM AUTHOR]

The scale of urban construction has increased gradually, a large amount of energy consumption and human activities have affected the outdoor thermal environment and the quality of the urban air. Based on this situation, this paper uses PHOENICS to simulate and evaluate outdoor thermal environment, taking a university campus in Jinan as an example. Google Sketchup and AutoCAD software are used to build a three-dimensional model with 30m elevation difference. It is found that among the main outdoor area of the university campus, the thermal environment meets the requirements of the Green Campus Evaluation Criteria basically. Because of the variation of the terrain height, the distribution of average wind speed and temperature mostly exist the lamination at the pedestrian level. The simulation results provide the reference for the optimization of thermal environment. [ABSTRACT FROM AUTHOR]

The Pipe-encapsulated PCM (PEPCM) is a new type of thermal storage and insulation structure used in the building envelopes to improve the performance of buildings. CFD models are often used to investigate the thermal characteristics of the PEPCM. However, the CFD model is usually complicated and computationally intensive. In this paper, a fast and reliable quasi-steady-state simplified model of PEPCM is developed to improve the effectiveness while maintaining the accuracy. A numerical model of the PEPCM is built to validate the developed model. Thermal characteristics in the phase transition process obtained from the simplified model and the CFD model are compared. Results show that the mean temperature difference of the working fluid is less than 0.5 °C and the mean difference of the heat fluxes through the PEPCM is less than 10% while the computation time can be significantly reduced. It proves that the quasi-steady-state simplified model is highly efficient and reliable. [ABSTRACT FROM AUTHOR]

In this paper, the dryout occurrence was discussed on the tube bundles in falling film evaporators for refrigeration. A numerical simulation was carried out on the bundles of horizontal tubes based on the distributed parameter method. In the simulation, the liquid flow rate and maldistribution on the tube bundles were analyzed about their influences on the dry patch formation and heat transfer performance of evaporators. These results are helpful to guide the design of falling film evaporators. [ABSTRACT FROM AUTHOR]

Gas-solid flows are commonly found in nature, as well as in industries. In such flows the size of the solid particles generally is not uniform. In addition, usually there is heat transfer between solid particles and gas flows. The hydrodynamics and heat transfer both make the behavior of gas-solid flows extremely complicated. In order to reveal these effects, in this paper three cases: (1) two isothermal, (2) two hot and (3) two cold spherical particles with various size ratios are investigated using lattice Boltzmann method-immersed boundary (LB-IB). It is observed that, for the first time, the tumbling duration of both two hot particles and two cold particles settling in vertical channel, is prolonged with size ratio increasing. The differences of threshold size ratio among the three cases are significant and the threshold size ratio of two hot particles is the largest one. Especially, it is found that heat transfer affects critically the interaction of two hot particles with low size ratios. In addition, against particle size ratio increasing, heat transfer effects on the interaction between two non-identical particles become weak. [ABSTRACT FROM AUTHOR]

The present paper deals with the study of heat transfer and pressure drop behaviors in a small heat exchanger filled with various metallic foam samples, during flow boiling. The tested metallic foam samples are made with copper, NiFeAlCr and Inconel. With 20 PPI (Pore per Inch) and 93% of porosity and the working fluid is the n -pentane. The independent variables are the inlet velocity, which is calculated by dividing the volume flow rate by the cross section. It is varied in the range of 0.02–0.06 m/s and the boiling heat flux density varied between 30 and 70 kW/m 2 . The heat transfer coefficient versus boiling heat flux and vapor quality is presented. The metallic foam made from copper enhanced the heat transfer by a factor varying between 130 and 300%, while its increase the pressure drop with average factor equal to 42%. The two other samples have a negative influence on the heat transfer coefficient and pressure drop compared to the copper one. [ABSTRACT FROM AUTHOR]

Developing countries are grappling with energy and water insecurity, impelling governments to encourage end-users to conserve and efficiently consume these vital resources. With water heating being among the largest energy users in residential buildings, it is imperative that the efficiency and conservation of both energy and water are achieved. Heat pump water heaters (HPWHs) are a superior choice in efficiently providing domestic hot water. However, there are still challenges in their optimal operation and high initial cost in developing nations. Further, since they are normally centrally located in a house, there are water and associated energy losses during hot water conveyance to the end-use, as the cold water has to be poured away. This paper introduces an optimal control strategy of a hybrid HPWH and instantaneous shower powered using integrated renewable energy systems. This strategy has the potential to save 23.4% and 19 l of energy and water in a day respectively, while also promising lower energy and water bills to the end users. Further economic benefit can be achieved through the sale of excess renewable energy back to the grid through an appropriate feed-in tariff. [ABSTRACT FROM AUTHOR]

The double-ellipsoidal heat power density model proposed by Goldak, has been widely used as the basis for modelling heat transfer in arc welding operations for more than thirty years. This approach has proved to be extremely effective for a wide range of arc welding operations. However, the application of a double-ellipsoidal heat power density distribution is less appropriate for keyhole-laser or electron-beam welding operations, or in situations where arc welding takes place within deep narrow grooves. In this paper the double-ellipsoidal distribution is extended to a double-ellipsoidal-conical heat power density model in order to accurately describe transient temperature fields for a wider range of geometries and welding processes. The new extended model was validated through comparing predicted welding thermal cycles with those measured for a single pass electron beam weld, as well as those measured in a multi-pass narrow groove gas-tungsten-arc weld. In both cases, excellent agreement was obtained between predicted and measured thermal transients. [ABSTRACT FROM AUTHOR]

Since timber is a combustible material, its safe use in construction will depend on a proper knowledge and modelling of the physical and chemical reactions involved in the pyrolysis, that affect the temperature growth and thus the performance of timber in fire. Based on the comprehensive one-dimensional analytical models of the pyrolysis available in the literature, it is required to implement a predictive FE model via a user-defined subroutine in the dedicated commercial software in order to describe more closely the real physical phenomena that undergo timber exposed to fire. This paper presents the implementation of the UMATHT subroutine in the Abaqus software. The obtained results showed a fairly good agreement with experimental ones from the literature. However, at this stage of the study the pyrolysis is taken into account implicitly in the developed UMATHT through gradually modified thermo-physical properties of the timber, as commonly adopted in the published literature. Work is now in progress to implement explicitly the different reactions of the pyrolysis in the developed UMATHT. [ABSTRACT FROM AUTHOR]

Both measurement and modeling of thermal performance in lithium-ion battery cell are considered crucial as they directly affect the safety. Even though the operation of a lithium-ion battery cell is transient phenomena in most cases, most available thermal models for lithium-ion battery cell predicts only steady-state temperature fields. This paper presents a mathematical model to predict the transient temperature distributions of a large sized 20Ah-LiFePO 4 prismatic battery at different C-rates. In this regard, the lithium-ion battery is placed in a vertical position on a stand inside the lab with an ambient air cooling and the battery is discharged under constant current rate of 1C, 2C, 3C, and 4C in order to provide quantitative data regarding thermal behavior of lithium-ion batteries. Additionally, IR images are taken for the same battery cell during discharging. The present model predictions are in very good agreement with the experimental data and also with an IR imaging for temperature profiles. The present results show that the increased C-rates result in increased temperatures on the principle surface of the battery. [ABSTRACT FROM AUTHOR]