External Heat Source Research Articles

Band-division utilization of core-shell photocatalyst under condenser solar-light and enhancement of synergistic catalytic CO2 reduction

The synergistic effect of intrinsic photoelectrons and thermal effects, provided by intermediate- and long-wave solar energy, is considered as the linchpin in enhancing photo-thermal catalytic CO2 reduction performance. Recently, photocatalysts possessing photothermal conversion capabilities and photocatalytic systems with adjustable incident light energy flow density have garnered significant attention. The strong condensing property of the Fresnel lens was adopted in increasing the density of incident photoelectrons simultaneously, and raising the surface temperature of the photocatalyst significantly without an external heat source. A novel core–shell photocatalyst with the photothermal conversion effect was fabricated, consisting of amorphous TiO2 and CuxO active species on Fe3O4@SiO2 core. Under optimal incident energy flux density of 3200 mW cm−2, the photocatalyst was able to reduce CO2 to CO and CH4 with the production rate of 361.39 and 70.84 μmol g−1h−1, and the solar conversion efficiency reached 1.43 %. Furthermore, a simple reaction kinetic optimization based on Langmuir-Hinshelwood model well simulated the photothermal coupling effect under different incident energy flux densities. This work demonstrates an innovative technology for the full-spectrum utilization of photocatalysts and synergistic photothermal coupling catalysis. It proposes a future development scenario for the new field of efficient solar catalytic conversion to produce solar fuels.

Bonding with brazing alloys as high-temperature interconnection filler through self-propagating exothermic reaction

There has been growing interest in wide bandgap (WBG) semiconductors including SiC and GaN due to the increasing demands for electronic devices serving at high temperatures. However, to maximise the potential capacity of WBG devices, new high-temperature interconnection materials and processes are indispensable as the current existing Sn-based solder alloys and bonding processes developed for Si devices are unable to meet the reliability requirements. In the present work, reactive brazing alloys including Cu-15Ag-5P and Incusil (Ag-27.25Cu-12.5In-1.25Ti) with melting points above 600°C have been utilized as the interconnection materials which offer excellent properties under high operation temperature. The self-propagating exothermic reaction (SPER) was applied for the bonding process via an intense rapid local heating and cooling at a millisecond scale. The strong Cu/Cu-15Ag-5P/Cu and Cu/Incusil/Cu sandwich bonded structures have been created with the assistance of SPER, where the nanofoil was applied from the outside of stacked structures as an external heat source and the bonding process was conducted in the ambient atmosphere without using flux. It has been found that the P element in Cu-15Ag-P alloy has the self-flux effect, which is beneficial for the ultra-fast interfacial reaction process. The experiments where the nanofoil was placed inside of stacked structures between two sheets of brazing alloys have also been conducted, which exhibited the well-bonded interface microstructures between nanofoil and brazing alloys. The outlook on the design for practicality and industrial uses for SPER-assisted bonding with brazing alloys has also been discussed, as a potential viable assembly route for the high-temperature and high-power electronics packaging.

Numerical study for a newtonian nanofluid over a vertical cylindrical vessel surrounded by a hot tissue

This manuscript introduces a theoretical model to study the problem of heat and mass transfer in biological tissues in a magnetic field, which simulates cancer treatment using thermal therapy. In particular, this model incorporates the influence of the Brownian motion and thermal thermophoresis of nanoparticles. Firstly, the non-linear governing equations of motion are transformed into ordinary differential equations using similarity transformations, then solved numerically according to appropriate boundary conditions using MATLAB built-in solver- bvp4c. All parameters and their impacts on the flow have been investigated and studied. The model predictions showed that increasing the heat absorption by nanoparticles in the tissue increases the tumour temperature, which helps to improve the therapeutic efficiency and reduce the concentration of nanoparticles. Hence, the results of this study could enhance the effectiveness of thermal therapy for malignancies.Article HighlightsThe transport of nanoparticles (NPs) to the deep tissue is improved when the heat transfer coefficient is raised.The temperature of interstitial fluid significantly reduces the velocity of the interstitial fluid.Exposing tumours to an external heat source enhances the NP delivery to the tumour.

Analytical assessment of heat transfer due to Williamson hybrid nanofluid (MoS2 + ZnO) with engine oil base material due to stretched sheet

The efficiency of fuel consumptions and improved performances is real challenge in the vehicle engines. Recent advances in thermal engineering suggested various tools to improve the capacitance of engine oil for which the interaction of nanoparticles is more dynamical. The aim of current research is to enhance the thermal aspects of engine oil with suspension of Williamson hybrid nanofluid. The hybrid nanofluid is the suspension of molybdenum disulfide MoS2 and zinc oxide ZnO. In order to increase the heating capability of system, external heat source and viscous dissipation features are contributed. The flow analysis is based on moving surface contains porous medium. After modelling the problem, the analytical outcomes of attributed with variational iteration method (VIM). The computational simulations are performed with help of Lagrange Multiplier technique. The impact of numerous physical parameters on skin fraction, Nusselt numbers, temperature distribution and velocity profile is exhibited.

New energy effect in non-cylindrical domains with a thermally insulated moving boundary

Objectives. To develop mathematical model representations of the energy effect in non-cylindrical domains having a thermally insulated moving boundary; to introduce a new boundary condition for thermal insulation of a moving boundary both for locally equilibrium heat transfer processes in the framework of classical Fourier phenomenology, as well as for more complex locally non-equilibrium processes in the framework of Maxwell–Cattaneo–Lykov–Vernott phenomenology, taking into account the finite rate of heat propagation into analytical thermophysics and applied thermomechanics; to consider an applied problem of analytical thermophysics according to the theory of thermal shock for a domain with a moving thermally insulated boundary free from external and internal influences; to obtain an exact analytical solution of the formulated mathematical models for hyperbolic type equations; to investigate the solutions obtained using a computational experiment at various values of the parameters included in it; to describe the wave nature of the kinetics of the processes under consideration.Methods. Methods and theorems of operational calculus, Riemann–Mellin contour integrals are used in calculating the originals of complex images with two branch points. A new mathematical apparatus for the equivalence of functional constructions for the originals of the obtained operational solutions, which considers the computational difficulties in finding analytical solutions to boundary value problems for equations of hyperbolic type in the domain with a moving boundary, is developed.Results. Developed mathematical models of locally nonequilibrium heat transfer and the theory of thermal shock for equations of hyperbolic type in a domain with a moving thermally insulated boundary are presented. It is shown that, despite the absence of external and internal sources of heat, the presence of a thermally insulated moving boundary leads to the appearance of a temperature gradient in the domain and, consequently, to the appearance of a temperature field and corresponding thermoelastic stresses in the domain, which have a wave character. A stochastic analysis of this energy effect forms the basis for a proposed transition of the kinetic energy of a moving thermally insulated boundary into the thermal energy of the domain. The presented model representations of the indicated effect confirmed the stated assumption.Conclusions. Mathematical models for locally nonequilibrium heat transfer processes and the theory of thermal stresses are developed and investigated on the basis of constitutive relations of the theory of thermal shock for equations of hyperbolic type in a domain with a thermally isolated moving boundary. A numerical experiment is presented to demonstrate the possibility of transiting from one form of analytical solution of a thermophysical problem to another equivalent form of a new type. The described energy effect manifests itself both for parabolic type equations based on the classical Fourier phenomenology, as well as for hyperbolic type equations based on the generalized Maxwell–Cattaneo–Lykov–Vernott phenomenology.

A Novel Approach of Heat Assisted Parallel Turning Process

Hard materials are widely used in industry due to qualities such as strong fatigue strength and the ability to maintain strength at a high temperature. Still forming certain raw materials into the appropriate shapes is the challenge in subtractive manufacturing industries and these materials are categorized as hard to machine material. To solve this problem Heat Assisted Machining (HAM) is an emerging and most dominating method, which requires an external heat source subjected to the workpiece either before or during the machining to increase the ductility. As a result, the workpiece yield and shear strength are reduced. This is an advanced technique to enhance the tool’s life, and productivity. The present paper provides in-depth knowledge of thermal assisted machining process where various heat sources are used like laser, plasma, LPG, Induction heating and etc. The comparison analysis between various heat sources is made and their impact on various parameters like tool wear, material removal rate, surface roughness, stability and etc. were illustrated and provide the novel approach for selecting the correct heat-assisted technique which is used for turning process in order to increase the machining process.

MHD hybrid nanofluid flow over a stretched surface with convective boundary conditions: Applications of heat transfer

The main objective of this research is to analytically study an innovative, viscous, time-independent, and incompressible (HFN) hybrid nanofluid flow on a slanderous stretched surface. This study examines thermal conductivity, heat absorption/omission, thermal radiation, and the magnetic effect of in the existence of HFN. Incorporating an external heat source into the heat transfer process increases the effect of the dissipative heat and thermal radiation. The flow characteristics are governed by the mathematical form which is further transferred to ordinary differential equations (ODEs) via appropriate assumptions regarding similarity variables and stream functions. The strong nonlinearity was successfully solved using the analytical technique homotopy analysis method (HAM) for these nonlinear equations. The results and discussion section provides a thorough explanation of the main outcomes of the study. This research focuses on the enhancement of heat transfer and the effects.

Ammonia autothermal reformer with air side-stream distribution for hydrogen production

Recently, there has been growing interest in utilizing ammonia through its decomposition process for on-site hydrogen production, primarily due to technical problems in hydrogen generation and storage. As ammonia decomposition is an endothermic reaction, an external heat source is required to facilitate the reaction. To address this, an ammonia autothermal reforming process that directly integrates ammonia decomposition and oxidation using air as the source of oxygen within a single reactor vessel was proposed. This process eliminates the need for additional external heat sources and simplifies the process. The design of the reactor incorporates an air distribution structure that allows for achieving a specified temperature range for the desired reaction. Thermodynamic analysis of the autothermal system revealed that high feed temperature, high reaction temperature, and low pressure are the most beneficial conditions for generating a high yield of hydrogen. The proposed process was simulated to assess its feasibility using kinetic parameters obtained from experimental data in the literature [27]. An optimization problem to minimize the reactor length in designing the proposed reactor was developed. The reactor design produces a high yield of hydrogen while maintaining the reaction temperature within the desired range. Adjusting the air flow rate at distribution points along the reactor to maintain peak temperatures at predetermined levels was shown to provide good load flexibility for variations in ammonia flow rate.

Effect of Arrhenius activation energy on two-phase nanofluid flow and heat transport inside a circular segment with convective boundary conditions: Optimization and sensitivity analysis

This paper analyzes the heat transport phenomena of two-phase nanofluid within a permeable circular segment with an interaction of Arrhenius activation energy and, examines the interaction of convective boundary conditions affecting the flow characteristics. The pre-exponential factor of the Arrhenius equation deals with the collision between molecules, and it has significant applications for getting the rate of a chemical reaction and is used to estimate material properties with changes in temperature and energy. To a greater extent, the external uniform heat source encourages thermal properties on account of the behavior of Brownian and thermophoresis parameters. The transformation of the standard nondimensional form of the governing equations is obtained for the assumption of appropriate similarity variables and stream function. The set of these transformed equations is tackled numerically with the shooting technique. The characteristics of physical parameters on the flow phenomena are presented graphically and the validation with earlier research displays a strong correlation for the specific case. The special attraction of the present investigation is the regression analysis for the simulated results of heat and solutal transfer rates using Response Surface Methodology considering various characterizing parameters like heat source, thermal radiation, curvature, activation energy, thermal and solutal Biot numbers within certain range.

Combine influence of charged particles and dust particles in tri-cross hybrid nanomaterials on 3D surface via GFET

Nanoparticles are used in many industrial processes due to their wider applications. The current inspection deals the utilization of nanoparticles to boost thermal efficiency. This research reports the inclusion of nanoparticles and dust particles for the flow of tri-hybridized nanofluid with thermal transport in a stretchable porous sheet with Hall and Ion slip contribution. The mechanism of thermal transport is carried out by engaging the radiation and Joule heating effects and the flow-presenting equations are derived from the principle of boundary layer theory in Cartesian coordinates. The principle of boundary layer theory was engaged to derive momentum transport for tri-hybridized nanoparticles, dust particles and thermal transport in the presence of Joule heating and external heat sources. The derived equations are in the form of coupled PDEs (partial differential equations) for three-dimensional model which are converted into coupled ODEs (ordinary differential equations) and the simplified expressions are handled numerically via finite element procedure. The results are prepared for the solution in the form of tables and graphs against different involved parameters. The results reveal that thermal enhancement and motion of the particles for the case of the fluid phase are higher than the thermal enhancement and motion for the case of the dusty phase and additionally, thermal performance for the case of tri-hybrid nano-structures (SiO2-TiO2-Al2O3/engine oil) is higher than thermal performance for the cases of hybrid nano-fluid.

Small Island Effects on the Thermal Biology of the Endemic Mediterranean Lizard Podarcis gaigeae.

Ectotherms are vastly affected by climatic conditions as they rely on external sources of heat to regulate their body temperature, and changes in their habitat thermal quality could seriously affect their overall biology. To overcome the problems of a thermally unfavorable habitat, lizards need to either adjust their thermoregulatory behavior or respond to directional selection and shift their preferred body temperatures. To assess the impact of habitat thermal quality on the thermoregulatory profile, we studied multiple islet and 'mainland' populations of the Skyros wall lizard Podarcis gaigeae, an endemic lacertid to Skyros Archipelago, Greece. We evaluated the effectiveness of thermoregulation (E) using the three main thermal parameters: body (Tb), operative (Te), and preferred (Tpref) temperatures. We first hypothesized that the spatial homogeneity, the scarcity of thermal shelters, and the exposure to higher winds on islets would result in more demanding climate conditions. Second, we anticipated that islet lizards would achieve higher E in response to the lower thermal quality therein. As hypothesized, thermal parameters differed between populations but not in the expected manner. Skyros 'mainland' habitats reached higher temperatures, had more intense fluctuations, and were of lower thermal quality. As a result, lizards showed higher accuracy, precision, and effectiveness of thermoregulation. Noteworthy, we found that lizards from different populations have shifted their thermal profile and preferred body temperatures to cope with the particular conditions prevailing in their habitats. The latter supports the labile view on the evolution of thermoregulation.

Influence of Chemical reaction and heat generation/absorption on Unsteady magneto Casson Nanofluid flow past a non-linear stretching Riga plate with radiation

The use of Casson fluid is of considerable importance in the manufacturing of pharmaceutical products, including the incorporation of china clay and biological fluids such as synovial liquids. Therefore, the primary objective of this work is to examine the characteristics of the Casson fluid flow. The Casson fluid is a non-Newtonian model often used to analyze the unsteady magnetohydrodynamic (MHD) heat and mass transfer in nanofluid flow scenarios across a non-linearly stretched Riga plate. The heat and mass transfer equations include the analysis of radiation and chemical reactions, respectively. Furthermore, the process of heat transmission is intensified by the existence of an external heat source or heat sink. By applying appropriate similarity transformations, the partial differential equations (PDEs) are converted into a set of nonlinear ordinary differential equations (ODEs). These ODEs are then solved numerically by utilizing the Runge-Kutta-Fehlberg-45 method, with the help of a shooting strategy. The validity of the study is determined by a comparative analysis of the present results in relation to prior research. The main objective of this research is to assess the influence of relevant flow parameters on the fluid flow, temperature, and concentration gradients, which will be visually represented and reported in tabular form. The augmentation of the Casson fluid coefficient (β) hinders the advancement of both velocity and temperature. The augmentation of the thermophoresis parameter (Nt) and magnetic factor (M) results in an elevation of θ(η) and a reduction in the curves depicting the volume fraction of nanoparticles. This study establishes a significant connection between many biological and engineering applications, particularly in the analysis of blood samples and the administration of drugs via blood circulation.

Thermal damage analysis in tissue caused by electromagnetic radiation using space–time collocation method

Over the past half-century, the usage of external heat sources in medical applications has increased substantially. Controlling heat damage is essential for ensuring the efficacy of the treatment. Living tissues are highly non-homogeneous; hence, it is important to take into account the effects of local non-equilibrium on their thermal behavior. In the present study, two- and three- space dimensional time-space fractional single-phase-lag (SPL) and dual-phase-lag (DPL) models for bio-heat transfer in tissue are considered to study the thermal damage and temperature in tissue caused by electromagnetic radiation as an external heat source. The considered mathematical models are more general and consider non-Fourier as well as non-local effects. We obtain the numerical solution for the models by combining Gaussian RBFs and shifted Chebyshev polynomials in the space and time directions, respectively. The RBFs depend on Euclidean distance, so they can easily be used in multidimensional space domain, and the use of Chebyshev polynomials gives spectral accuracy in time direction. It is also explored how different parameters, such as blood perfusion rate Wb, phase lags τq, τt, and fractional derivatives α, β, affect the temperature distribution and thermal damage in the tissue.

Multi-source directional heat conduction method based on coordinate transformation

Based on the optical transformation theory, the formal invariance of the heat conduction equation was used to realize the transformation of constitutive parameters of heat conducting materials through coordinate transformation, so as to control the distribution of heat flow in physical space. In addition, based on the research on the control method of heat flow propagation path, a multi-heat source directional heat conduction method with complex boundary was studied for the case where the object is affected by a variety of internal and external heat sources, and the temperature field is uneven, resulting in irregular deformation. Based on translation transformation and compression transformations, the thermal conductivity distribution of the material was derived for the directional heat conduction structure. And the controllable propagation of heat flow from high temperature region to low temperature region was realized. By analyzing three distributions of multiple heat sources, applicable directional heat conduction structures with multiple sources and complex boundaries were designed to realize passive control of temperature field. The performance of directional heat conduction structures in transient state was analyzed by Comsol software simulation, where the direction of the heat flow is observed through the temperature cloud. Then, from the comparison graph of the average temperature of different sides of the heat conduction structure after 60 min, it can be concluded that the difference between the average temperature of different areas decreases, and the temperature field of the structure becomes more uniform.

Exergetic and energetic evaluation of a modified tc-CO2 refrigeration system assisted with an absorption chiller using natural refrigerants

Transcritical CO2 (tc-CO2) refrigeration system is a pertinent option for refrigeration at low temperature, but it has high energy consumption with low coefficient of performance (COP) and exergetic efficiency. Thermodynamic properties of CO2 are favorable to be used as refrigerant with zero ozone depletion potential (ODP) and very low global warming potential (GWP). The tc-CO2 system rejects a huge amount of energy at higher temperature in the gas cooler which can be utilized to run the absorption chiller and produce desired cooling effect, in various combinations. The current research focuses on the energy and exergy analysis of a tc-CO2 refrigeration system that aspires to accomplish low-temperature refrigeration. A single-effect absorption chiller is used to give subcooling to the tc-CO2 refrigeration system, which is powered by the heat available at high temperatures and pressures at the exit of the compression process of the former system, rather than any other external heat source. A work recovery turbine is also used as the expansion device to reduce throttling losses and electricity consumption to power the integrated system. The parametric study reveals that there is a significant improvement in the refrigerating capacity, COP and exergetic efficiency of the system.

Numerical simulation of non–linear skin model with energy dissipation during hyperthermia and its validation with experimental data

This work deals with a non–linear skin model with energy dissipation exposed to hyperthermia therapy based on a Gaussian–type external heat source and also consider that the blood perfusion rate relies linearly on temperature. Since skin tissue is very sensitive to temperature, it is crucial to predict the temperature response with energy dissipation to ensure hyperthermia efficacy and minimize adverse effects. The present model, which is supported by experimental data, indicates that the temperature profile of skin tissue increases less in comparison to the non–linear Pennes model due to energy dissipation. A hybrid strategy is utilized to get computed outcomes for the present problem and obtained outcome is compared to the analytical outcome in a specific situation and is confirmed with high precision through table and graph. To damage a significant number of cancerous cells width, we have to manage or reduce enough value of the antenna constant accordingly, and the length of the probe region may be changed according to the position of the tumor or cancer cells in skin tissue. The temperature profile at the targeted area reduces when the values of rate of thermal conductivity, rate of blood perfusion per unit volume and blood perfusion constant increase.

Holistic and dynamic mathematical model for the assessment of offshore green hydrogen generation and electrolyser design optimisation

The decarbonisation of the energy system will imply the use of unexplored locations and technologies. In this sense, generation of green H2 in far-offshore farms may be an alternative. However, the offshore green H2 generation potential is commonly assessed by using constant conversion rates. This paper presents a holistic and dynamic mathematical model coupling the aero-hydrodynamic model with the polymer electrolyte membrane (PEM) electrolyser model. The model enables a more accurate and comprehensive analysis of the realistic H2 generation capacity considering the power-to-gas system efficiency. First, the model of the PEM electrolyser is validated and a wide sensitivity analysis is computed in order to report the impact of the operational conditions. Then, H2 production is assessed focused on (i) the stack performance and (ii) the system performance. The system performance results in a efficiency reduction of up to 10% in the case of FOWTs and up to 70% in WECs due to the fluctuations of the power signal. Hence, results highlight the need for a holistic system assessment instead of focusing on the stack. Finally, transient effects are considered, concluding that in highly fluctuating applications, such as renewables, external heat sources may improve the performance of the system.

Nanofluid bioconvective transport for non-Newtonian material in bidirectional oscillating regime with nonlinear radiation and external heat source: Applications to storage and renewable energy

The enhanced thermal performances of nanofluids reports different applications in solar systems energy storage and renewable energy. The renewable enhancement in thermal management systems is predicted in recent years. Following such motivations of nanomaterials in the renewable systems, the objective of current wok is to present nanofluid flow with suspension of non-Newtonian material with additional impact of external heating source. The Williamson nanofluid is signifies to suggests the rheological impact of nonlinear material. The stability of nanofluid is reported with bioconvection assessment due to microorganisms. The thermal model is further modified in view of nonlinear radiative electromagnetic source and activation energy. Time dependent flow is induced due to bidirectional accelerating surface with uniform magnitude. The formulation of problem is based in partial differential systems. The solution procedure is based on analytical homotopy analysis technique. The thermal outcomes in variation of parameters are observed. It is claimed that external heat presentation can boosted the thermal profile more exclusively. With increasing the Williamson fluid parameter, the heat and mass transfer phenomenon can be improved.

Modeling of Non-Isothermal Viscoelastic-Viscoplastic Deformation of Bending Reinforced Plates

A model of non-isothermal viscoelastic-viscoplastic deformation of multidirectionally reinforced flexible plates has been developed. The viscoplastic deformation of isotropic materials of the composition is described by the relations of the flow theory with isotropic hardening, which take into account the dependences of the loading functions on temperature and strain rate intensity. The viscoelastic behavior of the composition components is described by the equations of the Maxwell–Boltzmann model. The weakened resistance of reinforced plates to transverse shifts is modeled by the Ambartsumian bending theory relations, and the geometric nonlinearity is modeled in the Karman approximation. The connection between the thermophysical and mechanical components of the problem of inelastic dynamic deformation of reinforced plates is taken into account. The temperature over the thickness of structures is approximated by a 7th order polynomial. The numerical solution of the formulated nonlinear two-dimensional problem is constructed using an explicit scheme of time steps. The viscoelastic-viscoplastic dynamic behavior of a relatively thin glass-plastic plate is studied with and without allowance for the thermal response in it. The structure is loaded transversely with an air blast wave. It is shown that the failure to take into account the thermal response in a fiberglass plate can significantly distort the calculated fields of residual deformations of the components of its composition, despite the fact that the maximum heating of such a structure does not exceed 10°C. Viscoelastic-plastic calculations, when the sensitivity of the composite materials to the rate of their deformation can be neglected, can reasonably be carried out without taking into account the thermal response of the composite plate, if there are no external heat sources of non-mechanical origin.

Thermal Integration of Solid Oxide Electrolysis Cell Systems with External Heat Sources to Maximize Heat Recuperation and Exergetic Efficiency

Green hydrogen is expected to play a significant role as an energy carrier in the future energy system. As the issue of climate change due to greenhouse gas emissions has recently emerged, efforts are being made to change from a carbon-based energy society to a hydrogen-based energy society worldwide. Among several hydrogen production technologies, green hydrogen refers to hydrogen that does not generate carbon dioxide at all in production processes such as water electrolysis by using renewable energy. The hydrogen production through water electrolysis is more mature than other green hydrogen production technologies and is the most popular green hydrogen production method because it is easy to mass-produce with a modular structure. In particular, a solid oxide electrolysis cell (SOEC) system, which has the highest efficiency among electrolysis systems, is drawing significant attention.The high efficiency of SOEC systems originates from heat utilization for water electrolysis, which makes it critical to have optimal thermal integration. The SOEC systems operating at the high temperature above 700°C need a significant amount of thermal energy for steam generation and inlet gas heating. To deal with these thermal energy requirements, the internal heat recuperation and the external heat source integration with system components must be implemented in an effective manner. The thermal integration is the most important part of the SOEC system design. However, the majority of previous studies have concentrated on the performance of unit-cells and stacks, ignoring thermal energy consumption of the systems and heat integration.The purpose of this study is to explain the basis of thermal integration and to investigate the effects of internal and external thermal integration on the whole system performance. The basic concept of the thermal integration of SOEC system is presented while considering internal heat recuperation and coupling with external heat sources. By using temperature-heat transfer analysis, the procedure to design the optimal thermal integration of the SOEC system is described. Based on the proposed system, a parametric study with respect to stack operating conditions (i.e., stack inlet temperature, air utilization, steam conversion, hydrogen fractions) is conducted in order to elucidate their effect on the system level performance. Then, the effects of external heat sources such as steam injection, indirect heat transfer with hot fluids and heat supply by an electrical heater are examined, with pinch analysis and exergetic performance evaluation. The results show that high temperature external heat is not always a prerequisite for the SOEC system. The systematic comparison with several heat integration methods provides a clear guideline to maximize the exergetic efficiency when designing and operating SOEC systems. Through the analysis, this study provides understanding the internal and external characteristics of the thermal integration.