Parallel Steel Research Articles

Technical Problems Connected with the Adaptation into a Loft of a Post-industrial Building. Case Study

Adaptation of post-industrial facilities for modern residential buildings improves the results and aesthetics of urban spaces with a full respect for the protection of cultural heritage. Adaptation of post-industrial of the historic building requires a series of the preliminary research facility. The article presents the results of the diagnosis of the technical condition preceding the adaptation of the former factory to lofts in Zielona Góra. The building at Fabryczna 14 in Zielona Góra was built in 1913 and for over 60 years, it was a weaving mill in a textile factory complex. In the 70s of the 20th century, the building was adapted to the office of the “POLON” Nuclear Apparatus, in the first years of the twenty-first century, the building served as a commercial facility and storage. The building is 4-storey, made of solid brick, covered with a desktop roof, with a 5-storey corner tower from the south. The building’s facades are made of non-plastered bricks, have numerous profiling - pilaster strips, cornices, bands, panels. From the north, in the 70s of the 20th century, a part containing the reinforced concrete staircase was added. The interior of the building is three-tract, the supporting structure is made of longitudinal brick external walls and parallel steel beams based on cast iron pillars. The main assumptions of the adaptation to lofts primarily assumed changes in the interior of the building. Flats with an area of 60 to 150 square meters were designed, for this purpose, additional transverse walls were made. The brick façade remained, the attachment for the staircase and elevator was changed. At this point, the architect used modern trends related to modern technologies and finishing materials. The projection housing the new elevator and staircase was made of a steel structure with a reflex glass cladding. Modern solutions have been integrated into the brick architecture of the historic building. The political and social changes of the 1990s meant that many industrial facilities, often with a rich history, were out of use. A prolonged break in the use of buildings often causes irreversible degradation of their construction. This is mainly due to the neglect of basic maintenance principles.

Combined electrocoagulation and electrochemical treatment on BDD electrodes for simultaneous removal of nitrates and phosphates

The present study investigates the combination of electrocoagulation (EC) and electrochemical treatment (ET) for a simultaneous removal of nitrates and phosphates from synthetic wastewater. In the EC process, four parallel mild steel electrodes in a batch reactor were used. The increase of the current density from 1 to 40 mA cm−2 led to a total removal rates of both nitrates and phosphates at natural pHs (6 and 7). However, at high current density a rise of the electric energy consumption from 0.32 kW h m-3 for 1 mA cm−2 to 105.78 kW h m−3 for 40 mA cm−2 was recorded. Whereas the EC process is an inefficient method that generated ammonia as by-product, which needs additional treatment. ET process using boron doped diamond (BDD), which was evaluated as one of the most promising methods for the removal of nitrogenous compounds. Combining the two processes offers a practical hybrid treatment. Such combination resulted in the oxidation of the elector-generated ammonia and therefore enhanced the final quality of the treated wastewater. Additionally, the combined EC-ET method offer a low energy consumption per unit of removed pollutant (about 0.99 kW h (kg-N)−1). The kinetic modeling showed that phosphates adsorption fit the pseudo-second order, while nitrates fit the pseudo-first order. However, the nitrogenous products oxidation/reduction fit the pseudo-first order on mild steel as well on BDD electrodes.

Influence of cell size effect on the vertical cutting of hexagonal thin-walled honeycombs by parallel blades

This study investigates the cutting response of AL3003H18 hexagonal honeycombs loaded with vertical array blades. Quasi-static cutting tests were performed on aluminum honeycombs of various cell sizes and the same single-walled thickness (0.04 mm) using five groups of parallel steel blades of thickness 0.24 mm. The deformation mechanism was numerically simulated in the explicit solver LS-DYNA. In addition, the cutting process was described using a theoretical model based on dimensional analysis. The cutting response of honeycombs could be divided into three stages: elastic, transitional, and stable cutting. The cutting stress was found to decrease with increasing single-walled edge (SE) length. In an empirical analysis, the cutting force equation was derived as F=1.3CNcσyt1.92d0.30l−0.22, where C is a constant, Nc is the total number of cutting points, σy is the yield strength of the matrix material, d is the cutting depth, and t and l are the thickness and length of an SE, respectively. In particular, the cutting force is proportional to the 0.30th power of the cutting depth and inversely proportional to the 0.22th power of the SE length.

Design of a rail–road asymmetrical low-pylon cable-stayed bridge with a main span of 588 m

The Shangqiu–Hangzhou high-speed railway is 794.55 km long with a design speed of 350 km/h. The third Wuhu Yangtze River Bridge stands out as the key project of the whole railway. Restricted by the site conditions, the bridge is an asymmetrical low-pylon cable-stayed bridge with a main span of 588 m. To overcome the technical challenges of low stiffness and unfavourable axial force induced by the low pylons, a box-truss type composite section with a strong box at the lower deck and a weak truss above was creatively used in the design of the main girder. In addition, parallel steel wire cables coated with a zinc–aluminium alloy and with a tensile strength of over 2000 MPa were developed to withstand the tremendous axial force in the inclined cables. These two innovative solutions were successfully implemented in the construction of the bridge. This paper describes problem solving through creativity by addressing a few key issues faced by the designers.

Parametric study and experimental investigation of hydroxy (HHO) production using dry cell

The aim of the paper is to redesign and fabricate of hydroxy (HHO) dry cell to produce the maximum gas flow rate and enhance the electrolyser efficiency. HHO was produced by water electrolysis in parallel stainless steel 316 L plates (130 × 105 mm2), gasket of 3 mm thickness using different concentrations of NaOH and KOH. Effects of flow current, voltage, electrolyte concentration, temperature, operating time and electrolyte types on HHO flow rate were studied. The voltage increase from 2 to 4 VDC led to the electrolyser efficiency increase to 51.12% but after that it was decreased. The applied voltage increase from 2 to 11 VDC increased the HHO flow rate from 110 to 450 ml/min. The current increase from 6 to 14 A, produced the electrolyser efficiency of 72.9% and decreased after that. The current increase from 6 to 42 A, led the actual flow rate increase from 137 to 654 ml/min. After operating time of 30 min., the HHO flow rate reached the highest stable values of 866, 985, 1040 and 1090 ml/min at 5, 10, 15 and 20 g NaOH concentrations, respectively. The temperatures were increased to 32, 38, 44 and 52 °C at 10, 15 and 20 g NaOH concentrations, respectively, and remained constant. The electrolyte concentration of 5 g NaOH in cell configuration [4C3A19N] and supplied current of 14 A led to the highest HHO productivity of 866 ml/min and electrolyser efficiency of 72.1%. HHO dry cell is economical and efficient to be applied to the engine.

Evaluating ultra low cycle fatigue based on ductile fracture model in double core BRBs

While lots of efforts have been made to develop accurate numerical models for prediction of ultra-low cycle fatigue (ULCF), it still needs more studies. As it is crucial to exactly define the mechanical behavior of steel for entire range up to failure, this study first examines the required theories and presents a simple single-parameter model to predict the crack initiation. After selecting appropriate behavior models, to ensure the proper performance in numerical solution of the problem, the cyclic performance of steel coupons and two types of buckling restrained braces (BRBs) are validated comparing their local and global behaviors to experimental ones. The double core BRB consisting of two parallel steel cores is then introduced and its cyclic behavior is evaluated. Its advantages include easy connection to gusset plates, increased brace moment of inertia around the weak axis, high stability of connections under local buckling, and low impact of unpredictable defects. Finally, hysteresis curves, energy absorption rate, crack initiation and evolution, and cumulative ductility are discussed in this research.

Xiakou Xiangxi River Bridge structure design

Xiakou Xiangxi River Bridge is located in the upstream of the Three Gorges reservoir area. It is a (90+238) m single tower, Leaning Tower central cable surface mixed beam cable-stayed bridge. Its main span adopts a cross the river to meet navigation and flood control needs. The main concrete beam and the steel box girder of the main span are of large-angle inclined web box section with cantilever flange. The steel and mixed surface is at 11.05m across the bridge tower. The full width of the bridge deck is 25.5m. This bridge adopts the oblique “pipa” shaped main tower, the height of the main tower is 126m, composed of the upper tower column, the lower tower column, diaphragm and so on. The tower body deviates from the vertical surface of the bridge by 10° and leans towards the bank side. The foundation of the main tower is an integral pile foundation of the pile bearing platform. 2×17×2 high-strength parallel steel wire stay cables are used to arrange the fan-shaped space cable surface.

Design, Manufacturing and Testing of Biaxial Mechanical Travelling Pluviator

This paper includes design, manufacturing, operation and testing of a special device for preparation of granular or sandy soil (cohesionless soil) models that widely used as a part of the physical modelling in geotechnical engineering which is a main part of the civil engineering. To achieve a desired and uniform relative density of sandy soil models during preparation, air pluviation technique using pluviator is more suitable as the sand particles can be dandified through falling of sand grains from different heights and may even reaches to very dense state. Steel materials from local markets are used in the design of mechanical pluviator manufacturing. The mechanical pluviator consist of main steel frame, movable bench that can be moved up and down mechanically, crane lever to control on the pluviator container, pulleys and wheels. CPT tests are conducted at different prepared sandy models to investigate the skin resistance at different densities and the results shows great agreement. Different steel sections materials with different light steel plates which reduce the device weight available in the local markets were used in the manufacturing of the pluviator machine. The machine was provided by crane lever and gear box that can be controlled mechanically to achieve the desired height for the falling sand grains. The maximum height that can be attained is 120 cm and 40 cm is the minimum value. The machine contained also a v-shape container provided with 4 reels or pulleys that can be moved back and forth along two parallel steel tubes girders which the filled sandy model is located below it. The v shape container has two plate sides; the first one is fixed while the other is movable to achieve the desired opening depth or slot width and can be changed easily. The container with its carried frame can be controlled via mechanical rode that can be move up and down using multi-coil wire. The machine is verified using cone penetration test at results at different soil relative densities.

DEVELOPMENT AND EXPERIMENTAL INVESTIGATION OF SELF-CENTERING DAMPERS WITH PARALLEL HIGH STRENGTH STEEL RING SPRING GROUPS

Based on the self-centering damper with high-strength steel ring spring, a self-centering damper with parallel high-strength steel ring spring is proposed. The seismic performance of the parallel ring spring self-centering damper under multiple seismic conditions was verified by a hysteretic test. The test results show that the parallel high-strength steel ring spring self-centering damper has good self-centering ability, and will not experience performance degradation after multi-time earthquakes. It does not need to be replaced after the earthquake. Compared with the self-centering damper with a single group of ring springs, the damper bearing capacity can be effectively improved under the same size, and the damper internal space can be fully utilized. The different frictional conditions of the annular spring contact surface have a certain influence on the performance of the self-centering damper. The theoretical prediction model proposed is in a good agreement with the experimental results.

Numerical and Experimental Study on the Steel Strands under the Coupling Effect of a Salt Spray Environment and Cyclic Loads.

Composed of multi-strand parallel high-strength wires or steel strands, the stayed cables have been widely used recently in stayed bridges or suspension bridges owing to their light weight and high bearing capacity, especially the steel strands. Meanwhile, chloride-induced corrosion of steel strands is one of the most considerable factors for the durability of the stayed cable exposed to marine environments. The fatigue caused by both cyclic loading and corrosion can affect the life of the steel strands. Besides, the current studies related to the effects of the aforementioned two impact factors on the life of the steel strands either considered the fatigue only, or took the two impact factors into account separately. The coupling effects of fatigue and corrosion on the life of the steel strands are required to be further explored and discussed. Consequently, it is essential to create a model to predict the life of the steel strands with the coupling effects taken into consideration. In this paper, an indoor physical experiment of the steel strand specimens exposed to marine tidal environment was carried out. To avoid accidental errors, the whole specimens were divided into 20 groups, with each group having two steel wires with a 5 days, 10 days, and 15 days cycle for the test. The corrosion of steel strands was observed at various exposure times and it was found that the pits were formed on the surface with the chloride ion erosion to the steel strands. Deeper and sharper pits result in greater pitting-local stress and a shorter fatigue life, which is also the main reason for reducing the carrying capacity of the steel strands. However, a detailed description for this problem is lacking in current domestic and foreign literature, because the pit is hard to predict owing to its complex nature. In order to simulate the evolution of the pits, the stochastic pitting-corrosion model was set up by the neural network method to evaluate the pit evolutions over time. In addition, an empirical formula consisting of length–width ratios, length–depth ratios, and depth-to-width ratios of the pits was obtained to determine the stress concentration factor based on the multi-dimensional linear regression method. The fatigue notch factor of components can be deduced by the stress concentration factor, and the life of the steel strands can be deduced by both of them. The findings are expected to be useful in realistically predicting the durability of wire structures.

Monotonic and Fatigue Performance of Double-skin Push-out and Tensile Segments of Divers Shear Connectors – Review

Double skin composite (DSC) construction or Steel/concrete/steel sandwich construction (SCSS) is an innovative and relatively new form of composite construction that can be used in submerged tube tunnels, bridges deck, nuclear structures, liquid and gas containment structures, offshore and onshore structures, military shelters, and shear walls in buildings. The system consists of a plain concrete core sandwiched between two steel plates interconnected together by various types of mechanical shear connectors. The DSC construction perceives advantages that the external steel plates act as both formwork and primary reinforcement, and also as impermeable, blast and impact resistant membranes. The major duty of the shear connectors is to withstand longitudinal shear force and beam/slab separation, while in the bi-steel type where shear connectors are friction welded at both their two ends to two parallel steel plates, the longitudinal and transverse shear force, as well as plate buckling are resisted. The present paper highlights the previous prime researches concerning the subjects of SCSS composite construction, specifically on the conducted tests (push-out tests, tensile, direct shear tests, and bending tests) in which the components of partial interaction (uplift and slip forces) are resisted by various types of shear connectors.

Research on the Method of Predicting Corrosion width of Cables Based on the Spontaneous Magnetic Flux Leakage.

The detection of cable corrosion is of great significance to the evaluation of cable safety performance. Based on the principle of spontaneous magnetic flux leakage (SMFL), a new method for predicting the corrosion width of cables is proposed. In this paper, in order to quantify the width of corrosion, the parameter about intersecting point distance between curves of magnetic flux component of x direction at different lift off heights (Dx) is proposed by establishing the theoretical model of the magnetic dipole of the rectangular corrosion defect. The MATLAB software was used to analyze the influencing factors of Dx. The results indicate that there exists an obvious linear relationship between the Dx and the y (lift off height), and the Dx–y curves converge to near the true corrosion width when y = 0. The 1/4 and 3/4 quantiles of the Dx–y image were used for linear fitting, which the intercept of the fitting equation was used to represent the predicted corrosion width. After the experimental study on the corrosion width detection for the parallel steel wire and steel strand, it is found that this method can effectively improve the detection accuracy, which plays an important role in cable safety assessment.

Experimental Investigation for Non and Partially Composite Cold-Formed Steel Floor Beams

In this study, six full-scaled models of RC floors supported by cold-form steel sections have been tested. Each model consists of RC 75mm thick slab supported on two parallel cold-formed steel beams with a span of 3m and spacing of 500mm. The slab has an overhang part of 250mm on each side. In the first and fourth models, the slab has been casted directly on the top flanges with no shear connector to simulate the effectiveness of friction in resisting of the lateral-torsional buckling. Shear studs have been drilled in the second and fifth models to ensure the composite action. Finally, the flanges have been embedded for the third and sixth models. A single channel beam is used in the first, second, and third models while a built-up beam is used in the fourth, fifth, and sixth models. Each model has been loaded up to failure under a pure bending with two-line loads located at the third points. Data for loads, deformations, and strains have been gathered. Except the fourth and the sixth models that failed in local buckling modes, all other models failed in global lateral-torsional buckling modes. For the single beam models; the load carrying capacity of the non-composite model is 82.9% less than the capacity of the composite models with shear studs and embedded flange. For the built-up models; the load carrying capacity of the non-composite model is 44.2 % less than the loads of the composite model with shear stud and 48.7% less than the model with the embedded flange.

Non-destructive Method for Evaluating Grouted Ratio of Soil Nail Using Electromagnetic Wave

Although soil nails have been widely used for stabilizing slopes, they are often only partially grouted. Thus, grouted ratio of soil nails should be evaluated to prevent landslides. The purpose of this study was to investigate the suitability of a non-destructive method using electromagnetic waves for evaluating grouted ratio of soil nails. Experimental studies were performed with steel bars, partially grouted steel bars, and fully grouted steel bars in air. Partially and fully grouted steel bars were also installed in soils to simulate soil nails installed on slopes. Electromagnetic waves were generated and received using a time domain reflectometer by configuring a two-conductor transmission line formed by two parallel steel bars or two parallel grouted steel bars. Results of experiments showed that the respective round-trip travel time of electromagnetic waves increased with increasing length of the steel bar, grouted steel bar in air, and grouted steel bar in soils. The velocity of electromagnetic waves was the greatest in steel bars but the lowest in grouted steel bars in soils. In addition, the velocity of the electromagnetic waves decreased with increasing grouted ratio. This study suggests that electromagnetic waves might be useful for evaluating grouted ratios of soil nails to stabilize slopes.

Architectural Design for Re-functioning Historic Ottoman Warehouses: Case Study in Istanbul

Restoration of historical buildings is important because they maintain cultural and historical continuity and transmit the cultural and social values from our precedents to the future generations. Historical buildings need to adapt themselves to a changing cultural, social, economic and political context. In this paper re-functioning project of a historic Ottoman warehouse is presented. The aim of the project is to re-gain this historical structure for public use by re-newing it to the modern comfort level and making the required functional changes. The main structural system of the warehouse consists of thick masonry stone walls. The idea in the proposed restoration project is to build a two story steel structure inside the available volume of the warehouse. The columns of the new steel construction run parallel to the existing structural system of the historic building and are fixed at their base to the existing building foundation. So there is no connection between the proposed steel structure walls and the existing masonry walls, and this will save the historic fabric of the warehouse. The project proposal shows the details of planned restoration stages, the process of programming the new interior space, construction materials, and lighting and ventilation solutions. Furthermore in this project two and three dimensional computer drawings were used. Finally the proposed parallel steel structure is able to re-gain the warehouse and re-new it to be used as a modern housing and workshop.

Experimental identification of the fluid-elastic coupling forces on a flexible tube within a rigid square bundle subjected to single-phase cross-flow

The importance of fluid-elastic coupling forces in tube bundle vibrations is well documented and can hardly be over-emphasized, in view of their damaging potential. Even when adequate tube supports are provided to suppress fluid-elastic instabilities, the flow-coupling forces still affect the dynamical tube responses and remain a significant issue, in particular concerning the vibro-impact motions of tubes assembled using clearance supports. Therefore, the need remains for more advanced models of fluid-elastic coupling, as well as for experimental flow-coupling coefficients to feed and validate such models. In this work, we report an extensive series of experiments performed at CEA-Saclay leading to the identification of stiffness and damping fluid-elastic coefficients, for a 3×5 square tube bundle (D = 30 mm, P/D = 1.5) subjected to single-phase transverse flow, in a water test-loop. The bundle is rigid, except for the central tube which is mounted on a flexible suspension (two parallel steel blades) allowing for translation motions of the tube in the lift direction. The system is thus single-degree of freedom, allowing fluid-elastic instability to arise through a negative damping mechanism. The flow-coupling stiffness and damping coefficients, Kf(Vr) and Cf(Vr), are experimentally identified as functions of the reduced velocity Vr. The maximum value of the Reynolds number ranged from 105 to 2.16 105 (based on the maximum pitch velocity), according to the tested configuration. Identification is achieved on the basis of changes in tube vibration frequency and reduced damping as a function of flow velocity, assuming a constant fluid added mass. In the present experiments, coefficient identification is performed well beyond the instability boundary, by using active control, thereafter allowing exploration of a significant range of flow velocity. The modal frequency and the modal mass of the system are respectively modified by changing the tube suspension stiffness, and/or by adding a mass to the system. We can thus assert how the fluid-elastic coefficients change, for this configuration, with these two system parameters, all other parameters being kept constant. The results obtained from the configurations tested suggest that formulations for coefficient reduction may be improved, in order to better collapse the identified data.

Experimental Study and Numerical Simulation on Hybrid Coupled Shear Wall with Replaceable Coupling Beams

The coupled shear wall with replaceable coupling beams is a current research hotspot, while still lacking comprehensive studies that combine both experimental and numerical approaches to describe the global performance of the structural system. In this paper, hybrid coupled shear walls (HSWs) with replaceable coupling beams (RCBs) are studied. The middle part of the coupling beam is replaced with a replaceable “fuse”. Four ½-scale coupled shear wall specimens including a conventional reinforced concrete shear wall (CSW) and three HSWs (F1SW/F2SW/F3SW) with different kinds of replaceable “fuses” (Fuse 1/Fuse 2/Fuse 3) are tested through cyclic loading. Fuse 1 is an I-shape steel with a rhombic opening at the web; Fuse 2 is a double-web I-shape steel with lead filled in the gap between the two webs; Fuse 3 consists of two parallel steel tubes filled by lead. The comparison of seismic properties of the four shear walls in terms of failure mechanism, hysteretic response, strength degradation, stiffness degradation, energy consumption, and strain response is presented. The nonlinear finite element analysis of four shear walls is conducted by ABAQUS software. The deformation process, yielding sequence of components, skeleton curves, and damage distribution of the walls are simulated and agree well with the experimental results. The primary benefit of HSWs is that the damage of the coupling beam is concentrated at the replaceable “fuse”, while other parts remain intact. Besides, because the “fuse” can dissipate much energy, the damage of the wall-piers is also alleviated. In addition, among the three HSWs, F1SW possesses the best ductility and load retention capacity while F2SW possesses the best energy dissipation capacity. Based on this comprehensive study, some suggestions for the conceptual design of HSWs are further proposed.

Transverse Strength Evaluation of Light Cured Resin Impregnated Fiber Glass Reinforced Complete Denture

Background: The transverse strength of heat-polymerized denture base resins considerably enhanced by including either metal wires or glass fibers. Moreover, the transverse strength of specimens reinforced with continuous unidirectional glass fibers was significantly higher than that of metal wire or woven fiber reinforcements. Materials and Methods: Acrylic resin specimens had divided into two groups according to the type of material tested (group I: conventional heat cured acrylic resin, group II: resin impregnated fiberglass reinforced complete denture base). Static load on the prepared specimen using universal testing machine. Three points bending apparatus used to position the specimens with 7.5 KN load on each specimen. The three-point bending apparatus consisted of two parallel stainless steel rods away from each other by 50 mm. While the 7.5 KN load was applied centrally by a 10 mm diameter cylindrical stainless steel rod with 5 mm/min speed. Results: The transverse strength values of resin impregnated fiberglass reinforced acrylic resin showed statistically significant higher values (as P < 0.05) than conventional heat cured acrylic resin. Conclusion: that Fibers critical length was a measure of minimum fiber length required for maximum stress transfer within polymer matrix. Working with bisGMA resin, the critical fiber length established for acrylics with increased values.

A low-cost towed video camera system for underwater surveys: comparative performance with standard methodology.

Technological advances in the field of underwater video have led to an exponential increase in the use of drifting cameras (DC) and remotely operated vehicles (ROVs) to monitor the diversity, abundance, and size structure of marine life. Main advantages of DCs relative to ROVs are their lower costs and the much simpler logistics required to operate them. This study compares the performance of a new low-cost DC system equipped with a novel measuring device with that of a standard DC bearing an array of laser pointers. The new DC, which can be operated from a small boat, carries a pair of parallel steel "whiskers" that are dragged on the seabed within the field of view of the camera, providing a scale for measuring and estimating the density of benthic biota. An experiment conducted using an array of objects of known sizes laid on the bottom showed that its performance in terms of both size and density estimation was similar to that of the standard technique based on laser pointers. Measurement errors had a negligible negative bias (- 2.3%) and a standard deviation that ranged between 13 and 8% for objects from 25 to 110mm in size. The whiskers offered a simplified method for density estimation that avoids the need to calculate the width of the field of view, thus reducing the video processing time by around 60% with respect to the standard method. Briefly, the new system offers an efficient low-cost alternative for benthic ecology studies conducted on soft or non-irregular bottoms.

A novel experimental-numerical method for studying the thermal behaviors of phase change material in a porous cavity

Experiment and numerical simulation were carried out in this work to investigate the thermal transport behaviors of Newtonian fluids, phase change material (PCM), and composite PCM in a cavity, filled with porous media for thermal energy storage (TES) applications. Herein a novel experimental system was developed by using numerous long and parallel steel wires embedded in the cavity to construct a two-dimensional (2-D) porous structure, which provided an accessible way for numerical simulation by directly meshing the porous structure. As Rayleigh number (Ra) over than 1.0E8, the flow was simulated by standard k-ε turbulent model. The effects of heat conduction through metal structure, natural convection of liquid PCM, and geometric configuration of porous medium and porosity on improving the thermal transport efficiency were discussed. For Newtonian fluid flow and heat transfer, higher Rayleigh number led to stronger natural convection, and the deviation between experimental and numerical is less than 10% that confirmed the reliability of numerical method for further application in phase change process; for phase change behavior of PCM in the cavity with wires, natural convection was apparently weakened as porosity (ε) decreased to 80% and heat conduction started to dominate the heat transfer. The full charging time (tfull, wire) of PCM mixed with wires was then compared to that (tfull, EG) of PCM mixed with expanded graphite (EG) under the same porosity. The results showed that EG significantly improved the heat transfer efficiency that tfull,EG for four cases (ε = 95%, 90%, 85%, 80%) is only 24.4%, 9.5%, 5.7% and 4.0% of tfull,wire, respectively. This result indicates that when mixing PCM with material of high thermal conductivity to improve the thermal conductivity of composite PCM, the porosity and geometric configuration of the material are essentially needed to be considered. Furthermore, the cross-linked structure of material plays a more important role than porosity in enhancing thermal transport efficiency through heat conduction. This work brings deep insights into sensibly improving the thermal conductivity of PCM by adding materials with high thermal conductivity.