The bonding mechanism between straw and concrete was analyzed through testing the compressive strength and flexural strength of hollow block, with different straw amount and different dosage and types of admixtures. T...The bonding mechanism between straw and concrete was analyzed through testing the compressive strength and flexural strength of hollow block, with different straw amount and different dosage and types of admixtures. The test results show that the mechanical properties of hollow blocks reduced after adding straws, and the more straws was added, the more hollow block density decreased. But adding A12（SO4）3 and CaC12 could improve the dense degree between rice straw and concrete. And when the proportion of straw mixing amount was 10%, the flexural strength of the early strength agent （2% A12（SO4）3, CaC12） added hollow block reached as maximal as 3.1 MPa, while the compressive strength was 9.1 MPa, consisting with the strength grade of common concrete hollow block MU7.5.展开更多
In this paper,some effort is provided to optimize the geometry of a concrete hollow brick(used in the construction of building roofs)in order to increase the related thermal resistance,thereby reducing energy consumpt...In this paper,some effort is provided to optimize the geometry of a concrete hollow brick(used in the construction of building roofs)in order to increase the related thermal resistance,thereby reducing energy consumption.The analysis is conducted for three different configurations of the hollow concrete bricks.Coupling of conduction,natural convection and thermal radiation phenomena is considered.Moreover,the flows are assumed to be laminar and two-dimensional for the whole range of parameters examined.The conservation equations are solved by a finite difference method based on the control volumes approach and the SIMPLE algorithm for velocity-pressure coupling.The results show that the aspect ratio affects neither the nature of the fluid flow nor the number of convective cells.However,the extension of the circulation cells increases with this parameter.Moreover,the cavities with a large aspect ratio lead to significant reductions in the heat transfer through the hollow block,these reductions reaching approximately 14%.展开更多
During both hot and cold seasons,masonry walls play an important role in the thermal performance between the interior and the exterior of occupied spaces.It is thus essential to analyze the thermal behavior at the hol...During both hot and cold seasons,masonry walls play an important role in the thermal performance between the interior and the exterior of occupied spaces.It is thus essential to analyze the thermal behavior at the hollow block’s level in order to better understand the temperature and heat flux distribution in its structure and potentially limit as much as possible the heat transfer through the block.In this scope,this paper offers an experimental and numerical in-depth analysis of heat transfer phenomena inside a hollow block using a dedicated experimental setup including a well-insulated reference box and several thermocouples and fluxmeters distributed at the boundaries and inside the hollow block.The block was then numerically 3D modelled and simulated using COMSOL Multiphysics under the same conditions,properties,and dimensions as the experimentally tested block.The comparison between the numerical and experimental results provides very satisfactory results with relative difference of less than 4%for the computed thermal resistance.展开更多
This work presents the results of a set of steady-state numerical simulations about heat transfer in hollow blocks in the presence of coupled natural convection,conduction and radiation.Blocks with two air cells deep ...This work presents the results of a set of steady-state numerical simulations about heat transfer in hollow blocks in the presence of coupled natural convection,conduction and radiation.Blocks with two air cells deep in the vertical direction and three identical cavities in the horizontal direction are considered(typically used for building ceilings).Moreover,their outside horizontal surface is subjected to an incident solar flux and outdoor environment temperature while the inside surface is exposed to typical indoor environment conditions.The flows are considered laminar and two-dimensional over the whole range of parameters examined.The conservation equations are solved by means of a finite difference method based on the control volumes approach,relying on the SIMPLE algorithm for what concerns the coupling of pressure and velocity.The effects of the number of cells in the horizontal direction and the thermal conductivity on the heat transfer through the alveolar structure have been investigated.The results show that the number of holes has a significant impact on the value of the overall heat flux through the considered structure.展开更多
Agricultural wastes and sawdust combined with cement matrix in the manufacture of building elements has been practiced with success in developed countries. In this study, sawdust from wood species (Pinus caribaea and ...Agricultural wastes and sawdust combined with cement matrix in the manufacture of building elements has been practiced with success in developed countries. In this study, sawdust from wood species (Pinus caribaea and Eucalyptus grandis) and an agricultural waste—rice husk (Oriza sativa) were combined with Portland cement type V (high initial strength), modified by polymer styrene-butadiene (SBR) addition. Hollow blocks produced with Eucalyptus grandis and rice husk residues showed better compressive strength;however, those produced with residues derived from Pinus caribaea presented non-satisfactory results, due to the particle size that was used.展开更多
Hollow blocks are used widely in buildings for their lightweight construction and high thermal resistance charac-teristics.When used with a phase change material(PCM),these blocks can reduce the heating and cooling lo...Hollow blocks are used widely in buildings for their lightweight construction and high thermal resistance charac-teristics.When used with a phase change material(PCM),these blocks can reduce the heating and cooling loads of buildings compared to conventional hollow blocks.However,it is essential that the block inner forms and PCMs should be selected based on climate conditions.In this study,hollow blocks containing PCM in different climate types are thermally analysed.In the first step,ten different formed blocks are thermally analysed.In these blocks,the effects of hollow ratio(HR),inner form,and the number of cavities on heat flux and temperature distribution are investigated.The inner form of the hollow block with the least heat flux is determined in this step.The second step consists of optimization for the PCM melting temperature and layer thickness for the different provinces.The optimization results are evaluated on a building in terms of primary energy consumption and global costs.The best performing locations of the PCMs within the block are defined for all provinces in the last step.The results of the study are discussed in terms of the block surface temperatures and liquid fraction.The best PCM locations are found close to the block’s centerline in hot and warm climates and close to the indoor side in cold climates.展开更多
基金Funded by The National Key Technology R&D Program of China for the 12th Five-Year Plan(No.2012BAJ20B03)
文摘The bonding mechanism between straw and concrete was analyzed through testing the compressive strength and flexural strength of hollow block, with different straw amount and different dosage and types of admixtures. The test results show that the mechanical properties of hollow blocks reduced after adding straws, and the more straws was added, the more hollow block density decreased. But adding A12（SO4）3 and CaC12 could improve the dense degree between rice straw and concrete. And when the proportion of straw mixing amount was 10%, the flexural strength of the early strength agent （2% A12（SO4）3, CaC12） added hollow block reached as maximal as 3.1 MPa, while the compressive strength was 9.1 MPa, consisting with the strength grade of common concrete hollow block MU7.5.
文摘In this paper,some effort is provided to optimize the geometry of a concrete hollow brick(used in the construction of building roofs)in order to increase the related thermal resistance,thereby reducing energy consumption.The analysis is conducted for three different configurations of the hollow concrete bricks.Coupling of conduction,natural convection and thermal radiation phenomena is considered.Moreover,the flows are assumed to be laminar and two-dimensional for the whole range of parameters examined.The conservation equations are solved by a finite difference method based on the control volumes approach and the SIMPLE algorithm for velocity-pressure coupling.The results show that the aspect ratio affects neither the nature of the fluid flow nor the number of convective cells.However,the extension of the circulation cells increases with this parameter.Moreover,the cavities with a large aspect ratio lead to significant reductions in the heat transfer through the hollow block,these reductions reaching approximately 14%.
文摘During both hot and cold seasons,masonry walls play an important role in the thermal performance between the interior and the exterior of occupied spaces.It is thus essential to analyze the thermal behavior at the hollow block’s level in order to better understand the temperature and heat flux distribution in its structure and potentially limit as much as possible the heat transfer through the block.In this scope,this paper offers an experimental and numerical in-depth analysis of heat transfer phenomena inside a hollow block using a dedicated experimental setup including a well-insulated reference box and several thermocouples and fluxmeters distributed at the boundaries and inside the hollow block.The block was then numerically 3D modelled and simulated using COMSOL Multiphysics under the same conditions,properties,and dimensions as the experimentally tested block.The comparison between the numerical and experimental results provides very satisfactory results with relative difference of less than 4%for the computed thermal resistance.
文摘This work presents the results of a set of steady-state numerical simulations about heat transfer in hollow blocks in the presence of coupled natural convection,conduction and radiation.Blocks with two air cells deep in the vertical direction and three identical cavities in the horizontal direction are considered(typically used for building ceilings).Moreover,their outside horizontal surface is subjected to an incident solar flux and outdoor environment temperature while the inside surface is exposed to typical indoor environment conditions.The flows are considered laminar and two-dimensional over the whole range of parameters examined.The conservation equations are solved by means of a finite difference method based on the control volumes approach,relying on the SIMPLE algorithm for what concerns the coupling of pressure and velocity.The effects of the number of cells in the horizontal direction and the thermal conductivity on the heat transfer through the alveolar structure have been investigated.The results show that the number of holes has a significant impact on the value of the overall heat flux through the considered structure.
文摘Agricultural wastes and sawdust combined with cement matrix in the manufacture of building elements has been practiced with success in developed countries. In this study, sawdust from wood species (Pinus caribaea and Eucalyptus grandis) and an agricultural waste—rice husk (Oriza sativa) were combined with Portland cement type V (high initial strength), modified by polymer styrene-butadiene (SBR) addition. Hollow blocks produced with Eucalyptus grandis and rice husk residues showed better compressive strength;however, those produced with residues derived from Pinus caribaea presented non-satisfactory results, due to the particle size that was used.
基金This research was funded by Karadeniz Technical University through Scientific Research Projects Coordination Unit,under the project code FDK-2021-9298.
文摘Hollow blocks are used widely in buildings for their lightweight construction and high thermal resistance charac-teristics.When used with a phase change material(PCM),these blocks can reduce the heating and cooling loads of buildings compared to conventional hollow blocks.However,it is essential that the block inner forms and PCMs should be selected based on climate conditions.In this study,hollow blocks containing PCM in different climate types are thermally analysed.In the first step,ten different formed blocks are thermally analysed.In these blocks,the effects of hollow ratio(HR),inner form,and the number of cavities on heat flux and temperature distribution are investigated.The inner form of the hollow block with the least heat flux is determined in this step.The second step consists of optimization for the PCM melting temperature and layer thickness for the different provinces.The optimization results are evaluated on a building in terms of primary energy consumption and global costs.The best performing locations of the PCMs within the block are defined for all provinces in the last step.The results of the study are discussed in terms of the block surface temperatures and liquid fraction.The best PCM locations are found close to the block’s centerline in hot and warm climates and close to the indoor side in cold climates.
