Effect of heat and moisture transport and storage properties of building stones on the hygrothermal performance of historical building envelopes

2016 ◽  
Author(s):  
Dana Koňáková ◽  
Václav Kočí ◽  
Jaromír Žumár ◽  
Martin Keppert ◽  
Ondřej Holčapek ◽  
...  
Keyword(s):  
Moisture Transport ◽  
Building Stones ◽  
Historical Building ◽  
Building Envelopes ◽  
Hygrothermal Performance ◽  
Heat And Moisture Transport ◽  
Heat And Moisture ◽  
And Storage ◽  
Storage Properties

Heat and Moisture Transport and Storage Parameters of Bricks Affected by the Environment

2018 ◽  
Vol 39 (5) ◽  
Author(s):  
Václav Kočí ◽  
Monika Čáchová ◽  
Dana Koňáková ◽  
Eva Vejmelková ◽  
Miloš Jerman ◽  
...  
Keyword(s):  
Moisture Transport ◽  
Heat And Moisture Transport ◽  
Heat And Moisture ◽  
And Storage

scholarly journals Utilization of Crushed Pavement Blocks in Concrete: Assessment of Functional Properties and Environmental Impacts

Materials ◽  
2021 ◽  
Vol 14 (23) ◽  
pp. 7361
Author(s):  
Václav Kočí ◽  
Jan Kočí ◽  
Jan Fořt ◽  
Lukáš Fiala ◽  
Jiří Šál ◽  
...  
Keyword(s):  
Environmental Impacts ◽  
Moisture Transport ◽  
Computational Prediction ◽  
Concrete Pavements ◽  
Coarse Aggregates ◽  
Energy Demands ◽  
Hygrothermal Performance ◽  
Heat And Moisture Transport ◽  
Coupled Heat And Moisture ◽  
Heat And Moisture

Production of concrete is connected to extensive energy demands, greenhouse gases production or primary sources depletion. Reflecting current economical, social, or environmental trends, there is strong pressure on mitigation these requirements and impacts. The exploitation of secondary- or waste materials in production processes has therefore a great potential which is not related solely to binders but also to fillers. In this light, this paper aims at thorough investigations of concrete mixtures with crushed concrete pavements as partial or full replacement of natural coarse aggregates. The research combines experimental techniques to quantify the influence of the substitution on basic physical, mechanical, and heat/moisture transport/storage parameters. The experimental data obtained are further exploited as input data for computational prediction of coupled heat and moisture transport to assess the influence of the aggregates substitution on hygrothermal performance of the built-in concretes. In the last step, the environmental impacts are assessed. Since the changes in the hygrothermal performance were found to be insignificant (i), the compressive strength were improved by up to 25% (ii) and most of the environmental impact indicators were decreased (iii) at the same time, the findings of the research presented predeterminate such a reuse strategy to wider application and use.

scholarly journals Heat and Moisture Transport in Multi-Layer Walls: Interaction and Heat Loss at Varying Outdoor Temperatures / Siltuma Un Mitruma Pārnese Caur Daudzslāņainām Būvkonstrukcijām: Āra Temperatūras Izmaiņu Ietekme Uz Siltuma Zudumiem Iekštelpā

2012 ◽  
Vol 49 (6-I) ◽  
pp. 32-43 ◽  
Author(s):  
A. Ozolinsh ◽  
A. Jakovich
Keyword(s):  
Mathematical Model ◽  
Energy Efficiency ◽  
Moisture Transport ◽  
Heat Losses ◽  
Condensate Formation ◽  
Heat And Moisture Transport ◽  
U Value ◽  
Technical Solutions ◽  
Heat And Moisture ◽  
Humidity Profiles

Abstract The heat and moisture transport in multi-layer walls is analysed for five building units. Using the developed program, a typical of Latvian conditions temperature and relative humidity profiles in multi-layered constructions has been obtained and the indoor heat losses estimated. Consideration is also given to the risk of condensate formation and to the influence of moisture on the U-value. The created mathematical model allows forecasting the energy efficiency and sustainability of different technical solutions as refer to the heat and moisture transport in buildings.

Heat and Moisture Transport Through the Micro-Climate Air Annulus of the Clothing-Skin System Under Periodic Motion

2005 ◽  
Author(s):  
N. Ghaddar ◽  
K. Ghali ◽  
E. Jaroudi
Keyword(s):  
Heat Loss ◽  
Latent Heat ◽  
Moisture Transport ◽  
Contact Region ◽  
Heat Losses ◽  
Sensible Heat ◽  
Skin Contact ◽  
Cylinder Model ◽  
Heat And Moisture Transport ◽  
Heat And Moisture

A dynamic thermal model is developed using the 2D cylinder model of Ghaddar et al [1] of ventilated fabric-skin system where a microclimate air annulus separates an outer cylindrical fabric boundary and an inner human body solid boundary for closed and open apertures. The cylinder model solves for the radial, and angular flow rates in the microclimate air annulus domain where the inner cylinder is oscillating within an outer fixed cylinder of porous fabric boundary. The 2-D cylinder model is further developed in the radial and angular directions to incorporate the heat and moisture transport from the inner cylinder when the fabric touches the skin boundary at repetitive finite intervals during the motion cycle. The touch model is based on a lumped fabric transient approach based on the fabric dry and evaporative resistances at the localized touch regions at the top and bottom of points of the cylinder. The film coefficients at the inner cylinder are needed for the model simulation. Experiments are conducted in an environmental chamber under controlled conditions to measure the mass transfer coefficient at the skin to the air annulus separating the wet skin and the fabric in the cylindrical geometry. In addition, experiments have also been conducted at ventilation frequencies of 30, 40, and 60 rpm to measure the sensible heat loss from the inner cylinder to validate the predictions of sensible and latent heat losses of the 2-D ventilation model for the two cases when fabric is in contact with the skin surface and when no contact is present for close aperture. The model prediction of time-averaged steady-periodic sensible heat loss agreed well with the experimentally measured values. A parametric study is performed to predict sensible and latent heat losses from the system by ventilation at different frequencies, fabric skin contact times during the motion cycle measured by a dimensionless amplitude parameter (ζ = amplitude/mean annular spacing). The rate of heat loss increases with increased ventilation frequency at fixed ζ. The latent heat loss in the contact region increases by almost 40% due to increase in fabric temperature during contact. The sensible heat loss decreases between 3% at f = 60 rpm, and 5% at f = 25 rpm in the contact region due to higher air temperature and lack of heat loss by radiation during the contact between fabric and skin.

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