Porous Block Research Articles

The relative-velocity version of the Morison equation for obstacle arrays in combined steady, low and high frequency motion

This paper revisits the problem of forces on obstacle arrays in combined waves, an in-line steady current and structural dynamic motions. The intended application is the design and re-assessment of dynamically responding offshore platforms. Planar grids of perforated plates are moved in forced motion on three scales through otherwise stationary water. A new analytical wave–current–structure blockage model is developed by building on the existing wave–current blockage model presented by Santo et al. (J. Fluid Mech., vol. 739, 2014b, pp. 143–178) using a similar set of experiments but with forced motion on two scales. The new model, which is an improved Morison relative-velocity formulation, is tested against the experimental data for a range of structural to wave oscillation frequency ratios, $f_{s}/f_{w}=2$, 2.5 and 3. For relatively small current speed ($u_{c}$) and oscillatory structural velocity ($u_{s}$) compared with the oscillatory wave velocity ($u_{w}$), the drag force time history on grids is well approximated by a summation of the wave drag and the current drag components independently, without a $u_{w}\times u_{c}$ cross-term, consistent with the previous model. The wave drag component contains an additional $u_{s}$ contribution, while the current drag component may or may not contain an additional $u_{s}$ contribution depending on $f_{s}/f_{w}$. The measured drag force is observed to be asymmetric in time due to biasing from the mean flow. This is supported by numerical simulation using a porous block as a numerical model of the grids, although the simulated force asymmetry is weaker. All these effects can be sufficiently accounted for in the analytical model. The new model is shown to fit the variation of the experimental forces and force harmonics in time well for a wide range of cases, requiring only calibration of the Morison type drag and inertia coefficients. In contrast, the industry-standard version of the Morison relative-velocity formulation cannot reproduce the variation of the measured force in time, so present practice should be regarded as inadequate for combined steady, low frequency and high frequency motion acting on obstacle arrays.

Mathematical Modeling of Non-Fickian Diffusional Mass Exchange of Radioactive Contaminants in Geological Disposal Formations

Deep geological repositories for nuclear wastes consist of both engineered and natural geologic barriers to isolate the radioactive material from the human environment. Inappropriate repositories of nuclear waste would cause severe contamination to nearby aquifers. In this complex environment, mass transport of radioactive contaminants displays anomalous behaviors and often produces power-law tails in breakthrough curves due to spatial heterogeneities in fractured rocks, velocity dispersion, adsorption, and decay of contaminants, which requires more sophisticated models beyond the typical advection-dispersion equation. In this paper, accounting for the mass exchange between a fracture and a porous matrix of complex geometry, the universal equation of mass transport within a fracture is derived. This equation represents the generalization of the previously used models and accounts for anomalous mass exchange between a fracture and porous blocks through the introduction of the integral term of convolution type and fractional derivatives. This equation can be applied for the variety of processes taking place in the complex fractured porous medium, including the transport of radioactive elements. The Laplace transform method was used to obtain the solution of the fractional diffusion equation with a time-dependent source of radioactive contaminant.

THE ROLE OF FRACTURE CAPILLARY PRESSURE ON THE BLOCK-TO-BLOCK INTERACTION PROCESS

Characterization of fractures and the study of multiphase fluid movement through fractures in fractured porous media present difficult challenges to reservoir engineering. Interaction between porous matrix blocks and fractures plays a significant role in oil recovery from double-porosity reservoirs. The block-to-block interaction (or capillary continuity) between porous matrix blocks is a key contributor to the gas-oil gravity drainage mechanism in the gas-invaded zone of naturally fractured reservoirs, which increases the oil recovery. In a continuum scale, fracture is a part of the stack of blocks where there is a pressure difference between the gas and oil phases inside the fracture (called fracture capillary pressure). However, the physics of this capillary pressure and how it affects the gravity drainage mechanism in a stack of porous matrix blocks through the block-to-block interaction process need to be addressed theoretically. In this work a direct fine-grid numerical simulation along with various fracture capillary pressure models, including zero, constant, and saturation-dependent Brooks and Corey (1964), van Genuchten (1980), and Dindoruk and Firoozabadi (1995) functions, are applied to study their influence on oil recovery and therefore the block-to-block interaction process in fractured porous media. Numerical simulation predictions show the positive effect of fracture capillary pressure on oil recovery of a stack porous matrix blocks. The results reveal that the zero fracture capillary pressure model results in a lower ultimate oil recovery factor (23.8%) as compared to the constant (25.8%) and saturation-dependent Brooks and Corey (1964) (28.1%), van Genuchten (1980) (27.5%), and Dindoruk and Firoozabadi (1995) (24.6%) models. These observations are in good agreement with the results in literature. The findings can improve our understanding of the role of fracture capillary pressure on the block-to-block interaction process, which is important in oil recovery from naturally fractured reservoirs using the gravity drainage mechanism.

О гидрировании α-пинена при гидродесульфации скипидара на блочном высокопористом ячеистом катализаторе

Гидродесульфация скипидара на блочном катализаторе с нанесенным на него Ni и Pd позволяет снизить содержание общей серы в скипидаре до значений ниже 50 ppm. Хорошо известно, что двойные связи, в том числе и кратная связь α-пинена, также могут подвергаться гидрированию, хотя в меньшей степени, чем связь С–S. С целью контроля содержания α-пинена в процессе гидродесульфации скипидара параллельно с контролем содержания серы в сульфатном скипидаре осуществляли анализ концентрации α-пинена до и после процесса на катализаторе. После гидродесульфации скипадара Братского ЦБК на катализаторе 0,4 % Pd/6,0 % γ-Al 2 O 3 при 75 °С, 1,5 МПа потеря α-пинена, вероятнее всего, за счет гидрирования, составляет 5 %. Кроме того, при изменении содержания Pd на катализаторе от 0,2 до 1 % очевидна тенденция уменьшения концентрации α-пинена, что вполне закономерно: увеличение концентрации металла способствует увеличению скорости реакции, в том числе и реакции гидрирования α-пинена. Показано, что при гидродесульфации скипидара Усть-Илимского ЛПК при 1,5 МПа и 120 °С в течение 12 ч в присутствии 10 % Ni на ВПЯК и 7 % ZnO и последующем проведении процесса при 25 °С в течение 5 ч в присутствии 0,4 % Pd и оксида цинка гидрирования α-пинена практически не происходит. Это важно, так как α-пинен является исходным соединением в составе скипидара для получения путём кислотно-каталитической гидратации высококачественных коммерчески востребованных продуктов – соснового масла марок МС-85, МС-95 и парфюмерного терпинеола. Небольшие потери его имеют место при уменьшении концентрации Pd до 0,2 % и увеличении температуры процесса, однако в этом случае содержание серы в конечном продукте значительно. Хороший результат по содержанию серы получен при увеличении содержания Pd до 1 %, при этом не требуется предварительное обессеривание на никелевом катализаторе. Однако в этом случае имеют место заметные потери (более 30 %) основного компонента скипидара – α-пинена. Результаты, представленные в работе, являются подтверждением селективности реакции каталитического гидрирования в мягких условиях по отношению к связи C–S в сравнении с кратной связью С=С: несмотря на то, что скипидар состоит преимущественно из α-пинена, а содержание серосодержащих соединений в пересчете на общую серу исчисляется в ppm, гидрируется преимущественно связь C–S. Хотя в более жестких условиях удалось получить продукт количественного гидрирования предварительно очищенного от серы скипидара α-пинена – цис -пинана.

MHD natural convection and entropy generation in an open cavity having different horizontal porous blocks saturated with a ferrofluid

In this study, natural convection combined with entropy generation of Fe3O4–water nanofluid within a square open cavity filled with two different porous blocks under the influence of uniform horizontal magnetic field is numerically studied. Porous blocks of different thermal properties, permeability and porosity are located on the bottom wall. The bottom wall of the cavity is kept at hot temperature Th, while upper open boundary is at constant cold temperature Tc and other walls of the cavity are supposed to be adiabatic. Governing equations with corresponding boundary conditions formulated in dimensionless stream function and vorticity using Brinkman-extended Darcy model for porous blocks have been solved numerically using finite difference method. Numerical analysis has been carried out for wide ranges of Hartmann number, nanoparticles volume fraction and length of the porous blocks. It has been found that an addition of spherical ferric oxide nanoparticles can order the flow structures inside the cavity.

COMPUTATIONAL ANALYSIS OF INSERTED POROUS BLOCKS INTO HORIZONTAL CONCENTRIC ANNULI IN MIXED CONVECTION MODE

This study numerically investigates the effect of porous blocks thickness on laminar mixed convection in a horizontal annulus. With attached four porous blocks on the inner cylinder, steady 3D laminar mixed convection is presented for the fully developed region of horizontal concentric annuli. Results are presented for two values of porous blocks thickness and a range of the values of the Grashoff number, Darcy number and the conductivity ratio between the porous medium and the fluid. Results are presented in the form of contours plots of the streamlines and for the temperature isotherms, and in terms of the overall heat transfer coefficients and friction factor. The average Nusselt number increases significantly with an increase of the thickness of porous blocks. With the use of the four porous blocks, the friction factor is consequently increased compared with the situation without porous blocks. The decrease of the Darcy number leads to an increase of the friction factor. If the fully fluid case is taken as a reference, the use of porous blocks is justified only when the ratio of the average Nusselt number to the friction factor is enhanced .

Determination of the diffusivity, dispersion, skewness and kurtosis in heterogeneous porous flow. Part I: Analytical solutions with the extended method of moments.

Abstract The extended method of moments (EMM) is elaborated in recursive algorithmic form for the prediction of the effective diffusivity, the Taylor dispersion dyadic and the associated longitudinal high-order coefficients in mean-concentration profiles and residence-time distributions. The method applies in any streamwise-periodic stationary d-dimensional velocity field resolved in the piecewise continuous heterogeneous porosity field. It is demonstrated that EMM reduces to the method of moments and the volume-averaging formulation in microscopic velocity field and homogeneous soil, respectively. The EMM simultaneously constructs two systems of moments, the spatial and the temporal, without resorting to solving of the high-order upscaled PDE. At the same time, the EMM is supported with the reconstruction of distribution from its moments, allowing to visualize the deviation from the classical ADE solution. The EMM can be handled by any linear advection-diffusion solver with explicit mass-source and diffusive-flux jump condition on the solid boundary and permeable interface. The prediction of the first four moments is decisive in the optimization of the dispersion, asymmetry, peakedness and heavy-tails of the solute distributions, through an adequate design of the composite materials, wetlands, chemical devices or oil recovery. The symbolic solutions for dispersion, skewness and kurtosis are constructed in basic configurations: diffusion process and Darcy flow through two porous blocks in “series”, straight and radial Poiseuille flow, porous flow governed by the Stokes–Brinkman–Darcy channel equation and a fracture surrounded by penetrable diffusive matrix or embedded in porous flow. We examine the moments dependency upon porosity contrast, aspect ratio, Peclet and Darcy numbers, but also for their response on the effective Brinkman viscosity applied in flow modeling. Two numerical Lattice Boltzmann algorithms, a direct solver of the microscopic ADE in heterogeneous structure and a novel scheme for EMM numerical formulation, are called for validation of the constructed analytical predictions.

Natural convection in a differentially heated enclosure having two adherent porous blocks saturated with a nanofluid

Laminar natural convection in a square cavity having two centered adherent porous blocks filled with an alumina/water nanofluid under the effect of horizontal temperature gradient is studied numerically. Each porous block has the unique values of the porosity and permeability. Water-based nanofluids with alumina nanoparticles are chosen for investigation. The control characteristics of this study are the Darcy number of the first porous block ( $10^{-7}\le Da_{1}\le 10^{-3}$ ), the dimensionless porous blocks size ( $0.1\le\delta\le 0.4$ ) and nanoparticles volume fraction ( $0\le\phi\le 0.04$ ). The developed computational code has been validated comprehensively using the grid independency test and experimental data of other authors. The obtained results revealed the heat transfer enhancement at the hot wall with the Darcy number, while a growth of the porous layers size reduces the heat transfer rate at this hot wall. The behavior of the average Nusselt number at the right cold wall is opposite.

Evaluation of ammonia-hydrogen-air combustion in SiC porous medium based burner

Based on its well-known merits ammonia has been gaining special attention as a potential renewable energy carrier which can be replaced in power generation systems. Considering its low flame speed as one of the main challenges of combusting ammonia, flame stability is experimentally investigated. Focus is on premixed ammonia-hydrogen-air flames with high mixture fractions of ammonia (60-90% by volume) under standard temperature and pressure conditions. Silicon-carbide (SiC) porous blocks are used for stabilizing flame in a wide range of conditions. Upper and lower stability criteria are established for various mixture compositions. Also, combustion completeness is evaluated by analyzing measured and predicted temperature. The remarkable capability of the porous medium burners to efficiently operate at very high fractions of ammonia in a wide range of equivalence ratios provides a new achievability in more efficient combustion in power generation applications.

Some remarks on the homogenization of immiscible incompressible two-phase flow in double porosity media

This paper presents a study of immiscible incompressible two-phase flow through fractured porous media. The results obtained earlier in the pioneer work by A. Bourgeat, S. Luckhaus, A. Mikelic (1996) and L. M. Yeh (2006) are revisited. The main goal is to incorporate some of the most recent improvements in the convergence of the solutions in the homogenization of such models. The microscopic model consists of the usual equations derived from the mass conservation of both fluids along with the Darcy-Muskat law. The problem is written in terms of the phase formulation, i.e. the saturation of one phase and the pressure of the second phase are primary unknowns. We will consider a domain made up of several zones with different characteristics: porosity, absolute permeability, relative permeabilities and capillary pressure curves. The fractured medium consists of periodically repeating homogeneous blocks and fractures, the permeability being highly discontinuous. Over the matrix domain, the permeability is scaled by \begin{document}${\varepsilon }^θ$\end{document} , where \begin{document}$\varepsilon$ \end{document} is the size of a typical porous block and \begin{document}$θ>0$\end{document} is a parameter. The model involves highly oscillatory characteristics and internal nonlinear interface conditions. Under some realistic assumptions on the data, the convergence of the solutions, and the macroscopic models corresponding to various range of contrast are constructed using the two-scale convergence method combined with the dilation technique. The results improve upon previously derived effective models to highly heterogeneous porous media with discontinuous capillary pressures.

Fabrication of interconnected porous β-tricalcium phosphate (β-TCP) based on a setting reaction of β-TCP granules with HNO3 followed by heat treatment.

β-Tricalcium phosphate [β-TCP] is the typical bone substitute due to its excellent osteoconductivity and bioresorbability. One of the keys to improve its potential as bone substitute is to introduce porous structure and its regulation. In this study, interconnected porous β-TCP blocks were fabricated through a setting reaction of β-TCP granules and subsequent heat treatment. First, β-TCP granules were mixed with HNO3 . Upon mixing, β-TCP granules were bridged with dicalcium phosphate dihydrate [DCPD: CaHPO4 ·2H2 O] containing Ca(NO3 )2 . Then, the DCPD-bridged β-TCP was heated at 1100°C. During the heating process, DCPD containing Ca(NO3 )2 transformed into β-TCP and bonded with β-TCP granules. As a result, an interconnected porous β-TCP block formed. The diametral tensile strength and porosity of the interconnected porous β-TCP block fabricated from 200-300-μm β-TCP granules and 5 N HNO3 and then heated at 1,100°C were 1.4 ± 0.2 MPa and 57% ± 2%, respectively. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 106A: 797-804, 2018.

Numerical simulations of porous medium with different permeabilities and positions in a laterally-heated cylindrical enclosure for crystal growth

This paper presents an investigation of flow and heat transfer in a large diameter (6.25 in) cylindrical enclosure heated laterally and containing a porous block that simulates the basket of nutrients used in a crystal growth reactor. The numerical model entails the use of a commercially available computational engine provided by ANSYS FLUENT, and based on a two-dimensional (2D) axisymmetric Reynolds-averaged Navier Stokes (RANS) equations. The porous medium is simulated using the Brinkman-extended model accounting for the Darcy and Forchheimer induced pressure drops. The porous ‘plug’ effects are analyzed as both its permeability/inertial resistance and locations in the reactor are changed on a parametric basis, while the Rayleigh number (Ra=gβΔTL3να) is kept constant at 1.98 × 109. Additionally, the effect of different ratios of the hot to the cold zone lengths are investigated as a part of the current effort. For all cases, the velocity and temperature distributions in the reactor are analyzed together with the flow patterns in, and around the porous block. A comprehensive discussion is provided with regard to the effects of the position of the porous block and its permeability on both the immediately adjacent, and far flows. The consequences on the temperature distribution in the enclosure, when the ratio of the length of the hot-to-cold zones is changed, are also analyzed.

Sound absorption and morphology characteristic of porous concrete paving blocks

In this study, sound absorption and morphology characteristic of Porous Concrete Paving Blocks (PCPB) at different sizes of coarse aggregate were presented. Three different sizes of coarse aggregate were used; passing 10 mm retained 5 mm (as Control), passing 8 mm retained 5 mm (8 – 5) and passing 10 mm retained 8 mm (10 – 8). The sound absorption test was conducted through the impedance tube at different frequency. It was found that the size of coarse aggregate affects the level of absorption of the specimens. It also shows that PCPB 10 – 8 resulted in high sound absorption compared to the other blocks. On the other hand, microstructure morphology of PCPB shows a clearer version of existing micro-cracks and voids inside the specimens which affecting the results of sound absorption.

GFRP 보강 다공성 콘크리트 블록의 내력 및 인성 평가

본 연구에서는 다공성 블록의 내구성 향상을 위해 압축강도 3MPa 및 공극률 30%를 만족하는 배합설계를 확인하였으며, 선정된 배합에서 GFRP 보강 방법에 따른 보의 내력 및 인성 증가를 평가하였다. 다공성 콘크리트의 목표성능 만족을 위해서는 골재입도 15~20mm에서 물-시멘트 비 및 시멘트-골재 비가 각각 25% 및 15%로 추천될 수 있었다. GFRP로 보강된 다공성 콘크리트 보의 거동은 전단파괴에 의해 지배되었다. 이에 따라 GFRP의 휨 저항 발휘는 매우 적었으며, GFRP 보강근의 장부작용에 의한 전단내력상승은 결과적으로 다공성 콘크리트 보의 하중 저항성과 인성을 향상시켰다. GFRP 보강근을 압축과 인장측에 각각 1본(D9)씩 배근한 경우 내력은 무보강 보에 비해 약 2.1배 증가하였으며, 인성지수 <TEX>$I_{30}$</TEX>값은 43.4를 보임으로서 인성지수 값을 측정할 수 없었던 무보강 보에 비해 상당히 향상되었다. In this study, mix proportioning of porous concrete with compressive strength and porosity exceeding 3MPa and 30%, respectively, was examined and then load capacity and flexural toughness of the porous concrete block were evaluated according to the different arrangements of the GFRP bars. To achieve the designed requirements of porous concrete, it can be recommended that water-to-cement ratio and cement-to-coarse aggregate ratio are 25% and 20%, respectively, under the aggregate particle distribution of 15~20mm. The failure mode of porous concrete blocks reinforced with GFRP bars was governed by shear cracks. As a result, very few flexural resistance of the GFRP was expected. However, the enhanced shear strength of porous concrete due to the dowel action of the GFRP bars increased the load capacity and toughness of the blocks. The porous concrete blocks reinforced with one GFRP bar at each compressive and tensile regions had 2.1 times higher load capacity than the companion non-reinforced block and exhibited a high ductile behavior with the ultimate toughness index (<TEX>$I_{30}$</TEX>) of 43.4.

Design and Evaluation of a Moisture/Suction TDR Probe

Abstract Soil moisture content and suction are two key geotechnical properties that are commonly measured by separate moisture and suction sensors, which require double installation efforts and often result in questionable correlation between the measured moisture content and suction. In this study, attempts were made to combine time domain reflectometry (TDR) technique and porous gypsum block functioning as a tensiometer for simultaneous measurements of soil moisture content and suction. A new moisture/suction TDR probe was designed and evaluated in the laboratory. The TDR probe had two parts with one half portion embedded in a gypsum block whose suction is equilibrated with surrounding soils for soil suction measurement. The other half portion of the TDR probe was also inserted into soils to measure moisture content. The probe was calibrated by the pressure plate and filter paper tests to establish a relationship between suction (ψ) and dielectric constant (Ka) of the gypsum block for suction measurement. Three laboratory tests (i.e., staged-drying tests, absorption tests, and desorption tests) were then performed on a silty sand to evaluate the probe performance. It is demonstrated that the probe can measure the soil moisture content and suction satisfactorily in the range 50 kPa &amp;lt; ψ &amp;lt; 10,000 kPa with a response time less than 5 h. Additionally, the probe is fabricated easily and fast, without any additional maintenance, and has a great potential for field measurements of soil moisture content and suction.

Unsaturated hydraulic behaviour of a permeable pavement: Laboratory investigation and numerical analysis by using the HYDRUS-2D model

An adequate hydrological description of water flow in permeable pavement systems relies heavily on the knowledge of the unsaturated hydraulic properties of the construction materials. Although several modeling tools and many laboratory methods already exist in the literature to determine the hydraulic properties of soils, the importance of an accurate materials hydraulic description of the permeable pavement system, is increasingly recognized in the fields of urban hydrology. Thus, the aim of this study is to propose techniques/procedures on how to interpret water flow through the construction system using the HYDRUS model. The overall analysis includes experimental and mathematical procedures for model calibration and validation to assess the suitability of the HYDRUS-2D model to interpret the hydraulic behaviour of a lab-scale permeable pavement system. The system consists of three porous materials: a wear layer of porous concrete blocks, a bedding layers of fine gravel, and a sub-base layer of coarse gravel. The water regime in this system, i.e. outflow at the bottom and water contents in the middle of the bedding layer, was monitored during ten irrigation events of various durations and intensities. The hydraulic properties of porous concrete blocks and fine gravel described by the van Genuchten functions were measured using the clay tank and the multistep outflow experiments, respectively. Coarse gravel properties were set at literature values. In addition, some of the parameters (Ks of the concrete blocks layer, and α, n and Ks of the bedding layer) were optimized with the HYDRUS-2D model from water fluxes and soil water contents measured during irrigation events. The measured and modeled hydrographs were compared using the Nash-Sutcliffe efficiency (NSE) index (varied between 0.95 and 0.99) while the coefficient of determination R2 was used to assess the measured water content versus the modelled water content in the bedding layer (R2=0.81÷0.87). The parameters were validated using the remaining sets of measurements resulting in NSE values greater than 0.90 (0.91÷0.99) and R2 between 0.63 and 0.91. Results have confirmed the applicability of HYDRUS-2D to describe correctly the hydraulic behaviour of the lab-scale system.

Application of interconnected porous hydroxyapatite ceramic block for onlay block bone grafting in implant treatment: A case report.

Autogenous block bone grafting as treatment for alveolar ridge atrophy has various disadvantages, including a limited availability of sufficiently sized and shaped grafts, donor site morbidity and resorption of the grafted bone. As a result, interconnected porous hydroxyapatite ceramic (IP-CHA) materials with high porosity have been developed and used successfully in orthopedic cases. To the best of the author's knowledge, this is the first report of clinical application of an IP-CHA block for onlay grafting for implant treatment in a patient with horizontal alveolar atrophy. The present study performed onlay block grafting using an IP-CHA block to restore bone volume for implant placement in the alveolar ridge area without collecting autogenous bone. Dental X-ray findings revealed that the border of the IP-CHA block became increasingly vague over the 3-year period, whereas CT scanning revealed that the gap between the block and bone had a smooth transition, indicating that IP-CHA improved the process of integration with host bone. In follow-up examinations over a period of 5 years, the implants and superstructures had no problems. An IP-CHA block may be useful as a substitute for onlay block bone grafting in implant treatment.

Cyclodextrin-functionalized ordered porous block copolymer films: Preparation and property

Ordered porous block copolymer films (PBCFs) have attracted much attention because of their potential applications in several fields. In this paper, we first reported a non-destructive, controllable, and efficient approach for preparation of β-cyclodextrin (β-CD)-functionalized PBCFs (β-CD-PBCFs). The key point of the approach is to incorporate β-CD units into the hydrophilic segment of amphiphilic block copolymers before the preparation of films. β-CD-PBCFs with structural integrity and controllable pore parameters were fabricated through combining of self-assembly and breath figure methods. And then, the effective adsorption capacity of β-CD-PBCFs toward Congo red was confirmed through UV-Vis spectroscopy and was found to be affected by β-CD content and solution pH values. Adsorption kinetic results showed that the adsorption behavior of β-CD-PBCFs was consistent with the pseudo-second-order kinetic model and the chemisorption mechanism.

Experimental investigation of heat transport through single synthetic fractures

A laboratory physical model has been set up to analyze heat transport dynamics through single synthetic fractures. The Synfrac program together with a 3d printer have been used to build several fracture planes having different geometrical characteristics that have been moulded to generate concrete porous fractured blocks. The tests regard the observation of the thermal breakthrough curves obtained through a continuous flow injection in correspondence of eight thermocouples located uniformly on one of the fractured blocks.The physical model developed permits to reproduce and understand adequately some features of heat transport dynamics in fractured media

Thermal performance of building wall materials in villages and towns in hot summer and cold winter zone in China

Based on the current state of building wall materials of rural buildings in China consume large amounts of energy and have poor thermal performances, theoretical calculation and test detection of thermal performances were carried out for concrete block, cavity wall made of sintered Dalun brick, non-clay sintered porous brick wall, rectangular porous block construction, composite ceramic concrete block construction, steam-pressed sand concrete block masonry with gas, and concrete porous brick wall. And the experimental results of heat transfer coefficients were generallyconsistentwith the theoretical calculations. Both test results and theoretical calculation results of the wall heat transfer coefficients are processed using the weighted average method. Among the above-mentioned walls, we found that the heat transfer coefficients for the rectangular porous block construction, composite ceramic concrete block construction and steam-pressed sand concrete block masonry with gas were 1.22W/m2·K, 0.99W/m2·K, and 0.97W/m2·K. All of these materials met the standards such as Design Standard for Energy Efficiency of Rural Residential Buildings. These materials which met the standard were suitable for exterior walls of buildings and could meet the standard requirement of 50% energy saving. Gray theory analysis showed that the influencing factors such as coefficient of thermal conductivity of wall materials, wall thickness and mortar thickness had successively decreasing gray correlation degrees with the wall heat transfer coefficient.