scholarly journals The Effect of Air leakage through the Air Cavities of Building Walls on Mold Growth Risks

Energies ◽  
2020 ◽  
Vol 13 (5) ◽  
pp. 1177 ◽  
Author(s):  
Yonghui Li ◽  
Xinyuan Dang ◽  
Changchang Xia ◽  
Yan Ma ◽  
Daisuke Ogura ◽  
...  
Keyword(s):  
Masonry Building ◽  
Mold Growth ◽  
Air Conditioner ◽  
Air Leakage ◽  
Existing Buildings ◽  
Air Cavity ◽  
Hygrothermal Simulation ◽  
Historical Masonry ◽  
Building Walls ◽  
Air Cavities

Mold growth poses a high risk to a large number of existing buildings and their users. Air leakage through the air cavities of the building walls, herein gaps between walls and air conditioner pipes penetrating the walls, may increase the risks of interstitial condensation, mold growth and other moisture-related problems. In order to quantify the mold growth risks due to air leakage through air cavity, an office room in a historical masonry building in Nanjing, China, was selected, and its indoor environment has been studied. Fungi colonization can be seen on the surface of air conditioner pipes in the interior side near air cavity of the wall. Hygrothermometers and thermocouples logged interior and exterior temperature and relative humidity from June 2018 to January 2020. The measured data show that in summer the outdoor humidity remained much higher than that of the room, while the temperature near the air cavity stays lower than those of the other parts in the room. Hot and humid outdoor air may condense on the cold wall surface near an air cavity. A two-dimensional hygrothermal simulation was made. Air leakage through the air cavities of walls proved to be a crucial factor for mold growth.

scholarly journals Evaluation of mould growth risks due to air leakage through air cavity of the building walls

2019 ◽  
Vol 282 ◽  
pp. 02060 ◽  
Author(s):  
Xinyuan Dang ◽  
Shuichi Hokoi ◽  
Yonghui Li ◽  
Changchang Xia ◽  
Ma Yan
Keyword(s):  
Measured Data ◽  
Two Dimensional ◽  
Air Leakage ◽  
Mould Growth ◽  
Existing Buildings ◽  
Air Cavity ◽  
Existing Building ◽  
Hygrothermal Simulation ◽  
Building Walls ◽  
Indoor And Outdoor

Mould growth causes damage and poses high risk to a large number of existing buildings and their users. Air leakage through air cavity of the building walls, such as gaps between walls and some pipes penetrating the walls, produces obvious hygrothermal exchange, altering the temperature and humidity distribution of the walls. It would promote condensation and mould growth. Air cavity are common on the walls of existing buildings. In order to make a quantitative analysis on the mould growth risks due to air leakage through air cavity, an office room in an existing building in Nanjing, China was selected and hygrothermometers were arranged indoor and outdoor for monitoring. The measured results showed the room was in high temperature and relative humidity from June to early September. Two-dimensional hygrothermal simulation was made to investigate the hygrothermal conditions of the walls with air cavity, using the measured data as boundary conditions and validation for the numerical simulation. Mould growth risks under these situations were estimated.

Preservation of Historical Masonry Building by House Moving

2017 ◽  
Vol 55 (8) ◽  
pp. 668-673
Author(s):  
T. Kitamura ◽  
K. Tohkai ◽  
F. Kawagishi ◽  
M. Onishi
Keyword(s):  
Masonry Building ◽  
Historical Masonry

Apparent and True Charges in the Partial Discharge Model at Different Defective Domain Sizes

2021 ◽  
Vol 64 (6) ◽  
pp. 94-100
Author(s):  
Nikolay Ignatev ◽  
◽  
Sergey Tetiora ◽  
Dmitry Turkin ◽  
◽  
...  
Keyword(s):  
Equivalent Circuit ◽  
Partial Discharge ◽  
Diagnostic Value ◽  
Partial Discharges ◽  
Active Resistance ◽  
Air Cavity ◽  
Discharge Ignition ◽  
Discharge Model ◽  
Air Cavities ◽  
Solid Insulation

A model of the partial discharges in a sample of solid insulation with air cavity is presented. The material of the insulation is cross-linked polyethylene. The model is based on an active-capacitive equivalent circuit, in which the resistance of the air cavity at the instant of a partial discharge ignition is shunted by the active resistance of the spark. The model takes into consideration the delay of the discharge development. The evaluation of the diagnostic value of the apparent and true charges is carried out. The results of the apparent and true charges relationship with the dimensions and proportions of the air cavity are presented. It is shown that the same magnitude of both true and apparent charges can correspond to the different volumes and shapes of the air cavities in the insulation.

scholarly journals Thermal bridge effect of vertical diagonal tie connectors in precast concrete sandwich panels: an experimental and computational study

2020 ◽  
Vol 172 ◽  
pp. 08001
Author(s):  
Paul Klõšeiko ◽  
Reimo Piir ◽  
Marti Jeltsov ◽  
Targo Kalamees
Keyword(s):  
Computational Study ◽  
Precast Concrete ◽  
Sandwich Panels ◽  
Building Envelope ◽  
Heat Fluxes ◽  
Air Cavity ◽  
Thermal Transmittance ◽  
Thermal Bridge ◽  
Thermal Bridging ◽  
Air Cavities

The purpose of this work was to quantify the thermal bridge effect of vertical diagonal tie connectors in precast concrete sandwich panels (PCSPs). Special interest was in cases where the use of rigid insulation (e.g. PIR) would leave air gaps between insulation boards and diagonal ties, thus intensifying the thermal bridge. A climate chamber experiment using 5 different joint types was performed to gather reference data for CFD model validation. In the experiment, natural convection was observed in joints where no additional insulation was used, i.e. in air cavities. Significantly larger heat fluxes were measured in these cavities compared to insulated joints. The thermal bridging effect was evaluated for a typical PCSP (thermal transmittance without thermal bridges U = 0.11 W/(m²·K)) using CFD software taking into account 3D heat conduction and convection. Simulation results indicate that diagonal ties without adjacent air cavities increased the average thermal transmittance (U-value) of the envelope by 8%, diagonal ties with a 6 mm air cavity – 19...33% and diagonal ties with a 10 mm air cavity – 45...56%. In conclusion, it was found that the joints in insulation caused by diagonal ties affect the overall thermal performance of the building envelope significantly when efforts are not made to fill the air cavities around the connectors.

scholarly journals Analysis of Equivalent Diaphragm Vault Structures in Masonry Construction under Horizontal Forces

Heritage ◽  
2020 ◽  
Vol 3 (3) ◽  
pp. 989-1017
Author(s):  
Pier Silvio Marseglia ◽  
Francesco Micelli ◽  
Maria Antonietta Aiello
Keyword(s):  
Seismic Design ◽  
Complex Geometry ◽  
Geometrical Parameters ◽  
Masonry Building ◽  
Masonry Construction ◽  
Horizontal Connections ◽  
Historical Masonry ◽  
Side Walls ◽  
Definition Of ◽  
The Ideal

In seismic areas, masonry construction is prone to brittle failures due to the mechanical behavior of the constituent materials and to the low capacity of force redistributions. The redistribution capacity is mainly due to the presence of horizontal connections upon the walls and to the stiffness of the roof, which is typically a vaulted structure. The modeling of the global behavior of a masonry building, taking into account the accurate stiffness of the vaults, is a major issue in seismic design and assessment. The complex geometry of the vaults can be considered as an equivalent plate, able to replicate the stiffness behavior and the force redistribution capacity of the real vault. In this study, the efforts of the authors are addressed to the definition of a plate, able to replace the vaulted surfaces in a global numerical model. The ideal diaphragm is considered as a generally orthotropic plate with the same footprint and the same thickness of the original vault. An extended parametric study was conducted in which the mechanical and geometrical parameters were varied, such as the vault thickness, its dimensions, the constraint conditions, and the possible presence of side walls. The results are presented and discussed herein, with the aim of providing useful information to the researchers and practitioners involved in seismic analyses of historical masonry construction.

Control of Air-Ventilated Cavity Under Ship Hull in Abnormal Waves

2019 ◽  
Author(s):  
Konstantin I. Matveev
Keyword(s):  
High Amplitude ◽  
Maritime Transportation ◽  
Practical Implementation ◽  
Frictional Drag ◽  
Air Cavity ◽  
Fuel Savings ◽  
Ship Hulls ◽  
Reduction Techniques ◽  
Air Supply ◽  
Air Cavities

Abstract Practical implementation of ship drag reduction techniques can lead to substantial fuel savings and lessening environmental impacts of maritime transportation. One of such technologies is based on injecting air underneath ship hulls, which results in the formation of thin air cavities that decrease the wetted hull surface and hence its frictional drag. In realistic sea wave conditions, however, these cavities become unsteady and may easily disintegrate upon interaction with high-amplitude abnormal waves. In this study, the air-cavity dynamics in such situations is simulated with a potential flow model and empirical correlations. A method for controlling the air cavity by varying the air supply rate is numerically investigated. It is shown that degradation of the air-cavity power savings in the event of a rogue wave passing can be partly mitigated by briefly boosting the air supply right after the abnormal wave occurrence. For one considered example, it is found that 20% of power savings is lost in a condition with abnormal waves and constant air supply. In case of temporary augmentation of air injection, the overall decrease of power savings is reduced to 10%.

scholarly journals SSI on the Dynamic Behaviour of a Historical Masonry Building: Experimental versus Numerical Results

Buildings ◽  
2014 ◽  
Vol 4 (4) ◽  
pp. 978-1000 ◽  
Author(s):  
Francesca Ceroni ◽  
Stefania Sica ◽  
Angelo Garofano ◽  
Marisa Pecce
Keyword(s):  
Dynamic Behaviour ◽  
Numerical Results ◽  
Masonry Building ◽  
Historical Masonry ◽  
Experimental Versus

Use of Structural Steel Frames for Structural Restoration of URM Historical Buildings in Seismic Areas

2017 ◽  
Vol 11 (04) ◽  
pp. 1750012
Author(s):  
Vail Karakale
Keyword(s):  
Structural Steel ◽  
Seismic Performance ◽  
Steel Frames ◽  
Masonry Building ◽  
Lateral Stiffness ◽  
Historic Buildings ◽  
Structural System ◽  
Historical Buildings ◽  
Structural Restoration ◽  
Historical Masonry

Historic buildings and monuments are an important part of our cultural heritage that must be protected and their sustainability ensured, especially when earthquakes occur. In this paper, a technique that uses structural steel frames is proposed as one way of strengthening unreinforced masonry (URM) in historical buildings. The idea underpinning this technique is to reduce the earthquake displacement demand on non-ductile URM walls by attaching steel frames to the building floors from inside. These frames run parallel to the structural system of the building and are fixed at their base to the existing foundation of the building. Furthermore, they are constructed rapidly, do not occupy architectural space, save the building’s historic fabric, and can be easily replaced after an earthquake if some minor damage ensues. The proposed technique was applied to a five-story historical masonry building in Istanbul. The results of seismic performance analysis indicate that even though the building has plan irregularities, the proposed steel frames are able to effectively enhance the building’s seismic performance by reducing inter-story drifts and increasing lateral stiffness and strength.

Study of the Suitability between Artificial Cavity and Traffic Vessel

2013 ◽  
Vol 401-403 ◽  
pp. 282-286
Author(s):  
Ji Sheng Li ◽  
Wen Cai Dong ◽  
Yong Peng Ou
Keyword(s):  
Drag Reduction ◽  
Cavity Flow ◽  
Multiphase Model ◽  
Flat Bottom ◽  
Air Cavity ◽  
Rans Equations ◽  
Ship Hulls ◽  
Artificial Cavity ◽  
Air Cavities

The use of air cavities beneath ship hulls can lead to significant drag reduction. A study of air-ventilated cavities under a traffic vessel with flat bottom has been undertaken based on solving the RANS equations and VOF multiphase model. Macroscopic features in the air-cavity flow are predicted. Why the existing cavity form leads to unsatisfactory results on the traffic vessel is analyzed. The influence of parameters of artificial cavity on air cavity patterns is parametrically studied. Suggestions on improving cavity parameters and a new cavity form that can obtain stable air cavity are given, which may provide reference for the design of air cavity traffic vessels.

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