Conduction Heat Transfer Model Research Articles

Analytical generalized thermal resistance model for conductive heat transfer in pebble beds based on heat flux weighted temperature difference

A novel model for inter-particle contact thermal resistance based on analytical solutions is proposed. By applying the concept of heat flux weighted temperature difference in thermal resistance modeling for the first time, this model offers greater physical significance than traditional thermal resistance models. It effectively describes the dissipation in the heat transfer process and the influence of particle radius on thermal resistance, making it a generalized thermal resistance model suitable for multi-dimensional systems. The impact of applying different levels of uniform heat flux boundary conditions on thermal resistance is analyzed from the perspective of energy dissipation, revealing that a more uniform heat flux input results in lower thermal resistance. The effects of contact radius and particle size on the dimensionless generalized thermal resistance of inter-particle contact were studied, showing that the dimensionless resistance increases with larger particle contact radius and smaller particle size. Using the thermal discrete element method, the thermal resistance model with uniform heat flux density boundary conditions was applied to calculate the effective thermal conductivity of the pebble bed. Considering the distribution of contact radius, differences in effective thermal conductivity at various heights of the pebble bed due to different contact radii were examined and compared with the traditional fixed-coefficient contact resistance model. It was found that the difference between the two models decreases as the contact radius decreases. Finally, multiple sets of fixed contact radii were established under three different particle sizes, revealing that as the contact radius increases, the deviation between the new generalized resistance model and the traditional fixed-coefficient model rises from 8.18 % to 14.64 % for different particle radii.

Equivalent Thermal Conductivity of Topology-Optimized Composite Structure for Three Typical Conductive Heat Transfer Models

Composite materials and structural optimization are important research topics in heat transfer enhancement. The current evaluation parameter for the conductive heat transfer capability of composites is effective thermal conductivity (ETC); however, this parameter has not been studied or analyzed for its applicability to different heat transfer models and composite structures. In addition, the optimized composite structures of a specific object will vary when different optimization methods and criteria are employed. Therefore, it is necessary to investigate a suitable method and parameter for evaluating the heat transfer capability of optimized composites under different heat transfer models. Therefore, this study analyzes and summarizes three typical conductive heat transfer models: surface-to-surface (S-to-S), volume-to-surface (V-to-S), and volume-to-volume (V-to-V) models. The equivalent thermal conductivity (keq) is proposed to evaluate the conductive heat transfer capability of topology-optimized composite structures under the three models. A validated simulation method is used to obtain the key parameters for calculating keq. The influences of the interfacial thermal resistance and size effect on keq are considered. The results show that the composite structure optimized for the V-to-S and V-to-V models has a keq value of only 79.4 W m−1 K−1 under the S-to-S model. However, the keq values are 233.4 W m−1 K−1 and 240.3 W m−1 K−1 under the V-to-S and V-to-V models, respectively, which are approximately 41% greater than those of the in-parallel structure. It can be demonstrated that keq is more suitable than the ETC for evaluating the V-to-S and V-to-V heat transfer capabilities of composite structures. The proposed keq can serve as a characteristic parameter that is beneficial for heat transfer analysis and composite structural optimization.

Development and validation of the lead-bismuth cooled reactor system code based on a fully implicit homogeneous flow model

The liquid lead-bismuth cooled fast reactor has been in a single-phase, low-pressure, and high-temperature state for a long time during operation. Considering the requirement of calculation efficiency for long-term transient accident calculation, based on a homogeneous hydrodynamic model, one-dimensional heat conduction model, coolant flow and heat transfer model, neutron kinetics model, coolant and material properties model, this study used the fully implicit difference scheme algorithm of the convection-diffusion term to solve the basic conservation equation, to develop the transient analysis program NUSOL-LMR 2.0 for the lead-bismuth fast reactor system. The steady-state and typical design basis accidents (including reactivity introduction, loss of flow caused by main pump idling, excessive cooling, and plant power outage accidents) for the ABR have been analyzed. The results are compared with the international system analysis software ATHENA. The results indicate that the developed program can stably, accurately, and efficiently predict the transient accident response and safety characteristics of the lead-bismuth fast reactor system.

Topology optimization of a rectangular phase change material module

Latent heat storages have numerous times been demonstrated to benefit from including highly conductive fin structures for elevated charging and discharging properties. However, to this point it is still unclear how fins should be designed for optimal charging performance while meeting constraints on minimum storage density and manufacturability. Therefore, in the present work, we use topology optimization to obtain optimal designs for rectangular Phase Change Material (PCM) modules charged by a water flow, based on a conductive heat transfer model for the PCM. The optimal topologies are designed for maximum mean charging power of the PCM over a desired charge time. The optimal designs feature tree-like metal structures with an increased amount of branching for higher power requirements. Moreover, the optimal topologies are compared with straight fins with an equal minimal length scale. This comparison reveals the sub-optimality of the obtained tree-like designs for conduction driven phase-change problems.

Reduced order 1 + 3D numerical model for evaluating the performance of solar borehole thermal energy storage systems

This study presents a computationally efficient numerical model for solving the fluid flow and heat transfer phenomena in co-axial boreholes heat exchangers arranged on a rectangular grid (N × N) drill hole pattern. Such systems of boreholes are an integral component of a Solar-Borehole Thermal Energy Storage System for seasonal thermal storage application. The numerical model couples a one-dimensional fluid flow and convective heat transfer model in the heat exchanger with a three-dimensional model of conductive heat transfer in the strata. In addition to solving mass and heat transfer in borehole systems, it integrates a solar thermal collector system and building dynamic thermal load to design a Solar- Borehole Thermal Energy Storage system for a 182-unit residential apartment building. Simulation also considers and evaluates the conductive, convective, and radiative thermal losses of the system. The model is validated using experimental data from a coaxial borehole heat exchanger and compared to the results of a commercial finite volume solver for multiple co-axial boreholes. The computational cost of developed numerical model is reduced by a factor of 194 compared to a commercial finite volume solver. Solar- Borehole Thermal Energy Storage system simulation is performed for a period of five years considering hourly fluctuations in solar irradiance and building dynamic thermal energy demand. Parametric study is performed on depth and spacing of boreholes, and mass flowrate in the solar thermal collectors. It is found that a system of 100 boreholes, each 100 m deep, linked to 674 solar thermal collectors can provide the heating for the building with a total thermal demand of 5600 GJ per year.

Multi-scale modeling and simulation of additive manufacturing based on fused deposition technique

The issue of multi-scale modeling of the filament-based material extrusion has received considerable critical attention for three-dimensional (3D) printing, which involves complex physicochemical phase transitions and thermodynamic behavior. The lack of a multi-scale theoretical model poses significant challenges for prediction in 3D printing processes driven by the rapidly evolving temperature field, including the nonuniformity of tracks, the spheroidization effect of materials, and inter-track voids. Few studies have systematically investigated the mapping relationship and established the numerical modeling between the physical environment and the virtual environment. In this paper, we develop a multi-scale system to describe the fused deposition process in the 3D printing process, which is coupled with the conductive heat transfer model and the dendritic solidification model. The simulation requires a computational framework with high performance because of the cumulative effect of heat transfer between different filament layers. The proposed system is capable of simulating the material state with the proper parameter at the macro- and micro-scale and is directly used to capture multiple physical phenomena. The main contribution of this paper is that we have established a totally integrated simulation system by considering multi-scale and multi-physical properties. We carry out several numerical tests to verify the robustness and efficiency of the proposed model.

Effects of ontogeny and oiling on the thermal function of southern sea otter (Enhydra lutris nereis) fur.

During the evolution of most marine mammals, fur as an insulator has been replaced with more buoyant, energy storing and streamlining blubber. By contrast, the sea otter (Enhydra lutris) relies on insulation from its dense, air-trapping pelage, which differs morphologically between natal and adult stages. In this study, we investigated the ontogenetic changes in thermal function of southern sea otter (Enhydra lutris nereis) pelts in air, in water, and when saturated with crude oil. Pelt thermal conductivity, thickness, and thermal resistance were measured for six age classes: neonate (<1month), small pup (1-2months), large pup (3-5months), juvenile (6months-1year), subadult (1-3years), and adult (4-9years). Thermal conductivity was significantly higher for pelts in air than in water, with oiled pelts exhibiting the highest values (P < 0.001). Oiled pelts had the lowest thermal resistance, which suggests that regardless of age, all sea otters are vulnerable to the effects of oiling (P < 0.001). To scale up our laboratory findings, we used a volume-specific geometric model of conductive heat transfer for a simplified sea otter body, representing all tested age classes and treatments. Neonates, small pups, and large pups are more vulnerable to the effects of oiling compared with older age classes (P < 0.0001) due to a higher surface area-to-volume ratio. These results are consistent with the known thermal conductance values for adult sea otter pelts, yet this is the first time such thermal differences have been demonstrated in young otters. Overall, body size and age play a more important role in the thermal abilities of sea otters than previously thought.

Assessment of permafrost disturbances caused by two parallel buried warm-oil pipelines: A case study at a high-latitude wetland site in Northeast China

Multiple studies demonstrate that narrow-linear strong disturbances triggered by pipeline engineering activities have resulted in rapid permafrost degradation. However, the extent, duration, and severity of permafrost disturbances induced by two parallel buried warm-oil pipelines remain unclear. Here, we examine the thermal disturbances of the China-Russia crude oil pipelines (CRCOPs I and II) on the surrounding permafrost. Ground temperature measurements on and off the right-of-way of the CRCOPs and an electrical resistivity tomography survey were conducted at a selected high-latitude wetland site in northeastern China. The observations showed that warm oil flow in pipelines dissipated heat to the surrounding soil, resulting in the thawing of underlying permafrost accompanied by the formation and development of thaw bulbs around the pipes. Currently, the thaw bulb of CRCOP-I was about four times as large as that of CRCOP-II, mainly due to the longer 7-year working duration of CRCOP-I. To quantify the permafrost disturbances around the pipeline, a conductive heat transfer model was established. A numerical simulation of the soil thermal regime around the pipeline suggested the initial growth of the thaw bulb was quite fast but gradually slowed with time, of which the shape was modified to ellipse from a semicircle. The existence of CRCOP-II would accelerate the warming of permafrost on the CRCOP-I right-of-way due to the small separation distance between them. We expect that the thaw bulbs of the two pipelines will expand larger than previously estimated due to the adverse effects of pipeline settlement and surface water flow, sparking a wider permafrost disturbance.

Numerical analysis of the thermal energy storage in cellular structures filled with phase-change material

This paper reports the results of a numerical study on the thermal performance of metal cellular structures that can be obtained by additive manufacturing (selective laser melting) when they are impregnated with phase change material (PCM) for possible applications in electronic cooling. Two body-centered cubic (BCC) periodic structures with cell sizes of 5 mm and 10 mm and a porosity of 87%, made of two solid materials (aluminum alloy and copper), and two paraffins with characteristic melting temperatures of 55 and 64 °C were considered. The numerical simulations are carried out using the commercial code ANSYS Fluent and are based on a previously validated purely conductive heat transfer model. The computational domains include just small repetitive portions of the considered composite structures, thus allowing substantial savings of computational time. Computed results show that, with both paraffins, the copper made finer BCC structure (5 mm) yields the best thermal performances, i.e, the shortest PCM melting time and the highest rate of thermal energy storage during transients.

Numerical investigation of the temperature field and frost damages of a frost-penetration tunnel considering turbulent convection heat transfer

Accurate evaluation of tunnel temperature field plays an essential role in anti-freezing measures of cold-region tunnels. The aim of this study is to establish turbulence-based theoretical models for the temperature field of cold-region tunnels and to investigate the temperature field and frost damages of an actual cold-region tunnel with negative mean annual air temperature. A transient convection–conduction heat transfer model with turbulent flow and phase change was established. The proposed theoretical model was validated using model test results. The temperature field and frost damages of the Daban Mountain tunnel were investigated. The influence of global warming on the temperature field was also deeply discussed. The results indicate that for the Daban Mountain tunnel, the freezing circle develops to the radial surrounding rock and simultaneously develops along the longitudinal direction of the tunnel. Permafrost occurs at the tunnel entrance in the 7th year and along the whole tunnel in the 16th year. The formation rate and maximum freezing depth of permafrost is significantly influenced by the mean annual air temperature. The annual air temperature amplitude has significant effect on the formation rate of permafrost but little effect on the maximum freezing depth. Under global warming, the mean annual temperature of the surrounding rock decreases first and then increases. In the early years, the unfrozen surrounding rock freezes yearly and develops into permafrost. However, as the mean annual air temperature rises, the permafrost gradually degenerates into seasonally frozen rock and the maximum freezing depth decreases yearly.

Influence of internal heat transfer on reactive force applied to powder particles in laser cladding

Formation of two-phase powder-gas flows is the key factor determining the quality of materials synthesized by laser cladding and similar laser processes. Currently, the influence of the processing laser beam on such flows is insufficiently studied. Recent experiments on high-speed imaging show that the laser beam can considerably accelerate and deviate the exposed powder particles. This phenomenon is commonly explained by the reactive force arising at laser evaporation of particles. It seems that the existing theoretical approaches considerably overestimate the reactive force because they ignore internal heat transfer in the particle. The aim of the present work is to analyze theoretically the combined conductive-convective heat transfer in the particle exposed to laser radiation and the related evaporation and formation of the resultant reactive force. Computational Fluid Dynamic (CFD) simulation has shown that the internal heat transfer can reduce the temperature gradient in the particle, thus considerably reducing the resultant reactive force in the typical conditions of laser cladding. The CFD indicates that in such conditions, the influence of convection on the reactive force is low. An analytic model of conductive heat transfer and evaporation of a spherical particle is developed. The CFD validates this model and indicates that the confidence interval of the estimated resultant reactive force is within 1%. This model can be useful for analyzing experimental data and simulation of gas-powder flows exposed to laser radiation.

Proposed specific heat capacity model for a concrete wall containing phase change material (PCM) under field experiment conditions

This study compares (1) the specific heat capacity (CP) model obtained from the differential scanning calorimetry (DSC) measurement, (2) the conventional CP model using the step function and normal distribution function, and (3) the newly proposed CP model using the non-central F-distribution function. The CP models were implemented into the numerical conductive heat transfer model for the PCM-containing Portland cement (PC) concrete wall. Except for the heat capacity of PCM, other experimental data such as density, thermal conductivity, heat flux, or inner temperature profiles were obtained from the previous studies to build the numerical model. Through the validation process, the CP model using the non-central F-distribution function was selected as the best model, including the thermal properties of PCM. The proposed model was applied to the parametric study to investigate the best thermal efficiency, such as thermal comfort and diurnal temperature difference when applying PCM to PC concrete walls.

Techno-economic analysis of decarbonizing building heating in Upstate New York using seasonal borehole thermal energy storage

On average, fossil fuel space heating constitutes 56% of a building’s total energy usage in Upstate New York due to the cold winter climate. Similar levels of fossil fuel heating pertain in at least 15 states in the U.S. northern tier. To meet aggressive carbon reduction goals in this tier, decarbonizing the heat supply in the residential and commercial sector must be pursued. Using Borehole Thermal Energy Storage (BTES) to seasonally store excess thermal energy in the subsurface for later heating use is an innovative way to increase heating efficiency and lower carbon emissions. This paper investigates the technical and economic feasibility of heating Snee Hall on Cornell campus with unused summer steam from Cornell’s Combined Heat and Power Plant stored in an optimized BTES array. Snee Hall is a 6855 m2 building with an annual total heating load of 3040 GJ. A standard 2-D transient subsurface conductive heat transfer model is coupled to a high temperature heat pump (delivering > 60 °C) that can supply Snee Hall’s existing radiators with 70 °C water. For local geological parameters, 94% of Snee Hall’s winter space heating demand can be supplied by a 37-borehole array (90 m depth, 3 m spacing) and a 250-kW high temperature heat pump capacity with average coefficient of performance of 3.85. The calculated storage efficiency is 68.7% and the system has a 30-year net present value of about $526,400, an internal rate of return of 13%, and a payback period of 10 to 11 years. The system offsets about 6900 MMBTU (7280 GJ) of natural gas combustion and saves 250 MT CO2 emissions annually. The results of the single building analysis can be applied to other buildings on campus or in similar geologic settings in the U.S northern tier.

Characteristics of heat fluxes of an oil pipeline armed with thermosyphons in permafrost regions

Abstract Permafrost degradation negatively affects the thermal stability of northern infrastructure. The quantification of heat loss through a buried oil pipeline is imperative to determine the thermal interaction between the pipe and underlying permafrost. However, the magnitudes and patterns of heat flux have not been studied methodically. This study quantifies how lateral and vertical heat fluxes from a buried warm oil pipeline increase the permafrost thawing rate and promote talik (i.e., bodies or layers of unfrozen ground in permafrost areas) development in subarctic regions by employing a three-dimensional conductive heat transfer model. In addition, the sensitivities of daily and annual heat fluxes to insulation thickness and its thermal conductivity were determined. Simulated results indicate that the heated oil pipeline acts as a heat source with the maximum daily heat flux of 6.7 W/m2 and maximum annual heat flux of 4.3 W/m2. The mean annual heat flux exponentially decreases with increasing insulation thickness, while has a logarithmical increase with the increase of the thermal conductivity of insulation material. For an insulated (0.04-m thickness) oil pipeline, a fast-growing talik initiates and enlarges laterally and vertically over time. By contrast, two-phase closed thermosyphons can be used as a remedying measure to mitigate the accelerated permafrost thaw around a buried oil pipeline. Thermosyphons increase the lateral daily heat flux by an average of 0.5 W/m2 and lower mean annual soil temperature at depth by an average of 2 °C. Within the context of climate warming, we expect that talik beneath the oil pipeline will enlarge faster than previously estimated in the coming decades due to the adverse effects of the subsurface water flow. The net founding of our results is applicable to improve the engineered design and assess the vulnerability of the oil pipeline in cold regions.

Manninen’s mixture model for conjugate conduction and mixed convection heat transfer of a nanofluid in a rotational/stationary circular enclosure

PurposeThis study aims to investigate numerically the problem of conjugate conduction and mixed convection heat transfer of a nanofluid in a rotational/stationary circular enclosure using a two-phase mixture model.Design/methodology/approachHot and cold surfaces on the wall or inside the enclosure (heater and cooler) are maintained at constant temperature of Th and Tc, respectively, whereas other parts are thermally insulated. To examine the effects of various parameters such as Richardson number (0.01 = Ri =100), thermal conductivity ratio of solid to base fluid (1 = Kr = 100), volume fraction of nanoparticle (0 = φ = 0.05), insertion of conductive covers (C.Cs) around the heater in a different shape (triangular, circular or square), segmentation and arrangement of the conductive blocks (C.Bs) and rotation direction of the enclosure on the flow structure and heat transfer rate, two-dimensional equations of mass, momentum and energy conservation, as well as volume fraction, are solved using finite volume method and Semi-Implicit Method for Pressure Linked Equations (SIMPLE) algorithm.FindingsThe results show that inserting C.C around heater can increase or decrease heat transfer rate, and it depends on thermal conductivity ratio of solid to pure fluid. Also, it is found that by the division of C.B and location of its portions in a horizontal configuration, heat transfer rate reduces. Moreover, it is observed that external heating and cooling of the enclosure causes enhancement of heat transfer relative to that of internal heating and cooling. Finally, results illustrate that under the condition that cylinders rotate in the same direction, the heat transfer rate increases as compared to those that rotate in the opposite direction. Hence rotation direction of cylinders can be used as a desired parameter for controlling heat transfer rate.Originality/valueA comprehensive report of results for the problem of conjugate conduction and mixed convection heat transfer in a circular cylinder containing different shapes of C.C, conducting obstacle and heater and cooler has been presented. An efficient numerical technique has been developed to solve this problem. The achievements of this paper are purely original, and the numerical results were never published by any researcher.

MAGCPD: a MATLAB-based GUI to calculate the Curie point-depth involving the spectral analysis of aeromagnetic data

The Curie point-depth, frequently related to the depth to the bottom of the magnetic source, is widely employed as an estimator of temperature at depth when borehole temperature data are not available. The Curie point-depth is calculated using the spectral analysis of the magnetic data derived from aeromagnetic or satellite surveys. In this paper, MATLAB user-friendly GUI are constructed to calculate the Curie Point Depth using the inversion of aeromagnetic data assuming 2D fractal magnetization and modeling the temperature at depth assuming a 1D steady-state conductive heat transfer model. The program, tested in synthetic and aeromagnetic data, is running under MATLAB 2020a or standalone application with these input parameters: Aeromagnetic data, fractal parameter, Curie temperature, surface temperature, thermal conductivity, surface radiogenic heat production and scaling length of surface radiogenic heat production. The radially averaged amplitude spectrum, scaled spectrum, modeled spectrum, Curie point-depth, and temperature profile at depth are the output parameters of the program. Finally, the program is tested with Texas aeromagnetic data, and the results of the Curie point-depth were compared with borehole data.

A pore-scale thermo–hydro-mechanical model for particulate systems

A pore scale numerical method dedicated to the simulation of heat transfer and associated thermo–hydro-mechanical couplings in granular media is described. The proposed thermo–hydro-mechanical approach builds on an existing hydro-mechanical model that employs the discrete element method for simulating the mechanical behavior of dense sphere packings and combines it with the finite volume method for simulating pore space fluid flow and the resulting hydro-mechanical coupling. Within the hydro-mechanical framework, the pore space is discretized as a tetrahedral network whose geometry is defined by the triangulation of discrete element method (DEM) particle centers. It is this discretization of DEM particle contacts and tetrahedral pore spaces that enables the efficient conductive and advective heat transfer models proposed herein. In particular, conductive heat transfer is modeled explicitly between and within solid and fluid phases: across DEM particle contacts, between adjacent tetrahedral pores, and between pores and incident particles. Meanwhile, advective heat transfer is added to the existing implicit fluid flow scheme by estimating mass–energy–flux from pressure induced fluid fluxes. In addition to the heat transfer model, a thermo-mechanical coupling is implemented by considering volume changes based on the thermal expansion of particles and fluid. The conduction and advection models are verified by presenting comparisons to an analytical solution for conduction and a fully resolved numerical solution for conduction and advection. Finally, the relevance of the fully coupled thermo–hydro-mechanical model is illustrated by simulating an experiment where a saturated porous rock sample is subjected to a cyclic temperature loading.

Optically-switchable thermally-insulating VO2-aerogel hybrid film for window retrofits

Developing easy-to-install energy-efficient window retrofitting materials is important for reducing the heating and cooling loads of buildings. However, it is very challenging to achieve window retrofits that are simultaneously thermally insulating, visible-light transparent, and dynamically switchable in solar transmission. Here, a visibly transparent and thermally insulating film was proposed to reduce the energy loss through windows. By embedding insulator–metal phase transition vanadium dioxide (VO2) nanoparticles inside an ultralow thermal conductivity aerogel film, the thermal insulation performance is greatly improved in such thermochromic film while the solar transmission can be dynamically switched in response to ambient conditions. A coupled heat conduction and solar radiation heat transfer model was developed to evaluate the effect of geometric features such as film thickness, nanoparticle size, and concentration on the thermal and optical performance of the proposed films. It was shown that a 3.0 mm thick film could achieve a low U-value of ~ 3.0 W/(m2K), and a high luminous transmittance of > 60% and a solar modulation ability of ~ 20%. This film improves the performance of single-pane windows by reducing the energy loss, improving thermal comfort, and avoiding moisture condensation in cold climates and overheating in hot climates.

Reduction of Heat Losses Using Quadruple Heating Pre-Insulated Networks: A Case Study

The paper presents an analysis of heat loss and reductions of annual emissions of air pollutants of a quadruple pre-insulated heating network by comparing this solution with the existing pre-insulated network consisting of four pre-insulated single pipes and the variant consisting of two twin pipe pre-insulated. For calculations, an existing heating network located in central Poland was adopted, where heat is transported for heating purposes of buildings and domestic hot water with circulation of domestic hot water through four separate pre-insulated underground pipes. The idea of the construction of four pre-insulated pipes presented in the paper consists in the location of four steel pipes in a common round thermal insulation, which perform the role of heat transport for heating purposes in multi-family buildings (supply and return) and two pipes transporting hot water (a pipe with domestic hot water with circulation). In Poland, heating pipes used in multi-family housing have a larger diameter compared to domestic hot water pipes, which is why standard twin pipe heating pipes have been used in the construction of four pre-insulated networks, in which the domestic hot water pipe has been added to the thermal insulation and circulation of domestic hot water. In order to determine heat losses, a simplified two-dimensional model of conductive heat transfer was developed using Fortran to create a computer program. The results of numerical simulations show that the use of twin pipes for the construction of pre-insulated quadruple networks has contributed to a significant reduction in heat loss in relation to the existing single pre-insulated network (up to 57.1%), while reducing the thermal insulation field of the cross-section of the pre-insulated pipe by 21.4%.

Thermal analysis of methane hydrate formation in a high-pressure reactor packed with porous SiC foam ceramics

The porous SiC foam ceramic (SFC) packings were recently demonstrated capable of enhancing methane hydrate formation in the hydrate-based separation technologies, while the heat transfer analysis is one of the key requirements for effective implementation of this technology. In this study, the evolution of thermal resistance during hydrate formation was obtained based on hydration heat and gas consumption in experiments, while the effects of the packings’ properties (e.g. quantity, porosity, materials, stacking patterns) on the overall and local thermal resistances were predicted by the conductive heat transfer models. The overall tendency predicted by the model agreed with the experimental data. Results clearly indicated that the SFC packings could maintain the reaction system at a low thermal resistance for a longer time under relative low driving force. It also highlighted the role of the stacking patterns of SFC packings on heat transfer. The overall thermal resistance was reduced by about 39% after rotation of the SFC packings. When the SFC packings were stacked parallel to the reactor bottom, the composites formed by packings and hydrates was the main resistance for heat transfer which accounted for 30–50% of the overall thermal resistance. However, the contribution of this portion was only 13–25% if the SFC packings were stacked perpendicular to the reactor bottom. Overall results from this study were beneficial for better understanding where the main heat transfer resistance was from and how it varied against the packings’ properties when employing the foam packings for enhancing gas hydrate formation.