Modelling moisture ingress and impact on PV module degradation: Development of a FEM model to predict the moisture ingress and module degradation under different conditions

A moisture ingress model is developed using the FEM software COMSOL. The model uses Fick’s second law of diffusion to model the diffusion of moisture in the module. The model also reflects the temperature dependent nature of parameters affecting moisture ingress by using an Arrhenius equation. The model is validated with experimental and...

The distribution and transport of water in oil paintings: A numerical moisture diffusion model

Oil paintings are complex, multi-layered systems that are prone to chemical degradation. While it is increasingly recognised that water plays an important role in these degradation reactions, little is known about moisture concentrations in oil paint systems and their temporal variation in response to fluctuating ambient air humidity. This...

A Numerical Study of Moisture and Ionic Transport in Unsaturated Concrete by Considering Multi-ions Coupling Effect

Understanding the transport mechanisms within unsaturated porous media is essential to the durability problems associated with cement-based materials. However, the involvement of multi-ions electrochemical coupling effect, especially under unsaturated condition makes the transport mechanisms even more complex. In this study, the moisture and...

Modelling of capillary water absorption in sound and cracked concrete using a dual-lattice approach: Computational aspects

Lattice models have been used to simulate mass transport to predict durability of cementitious materials. In particular, the use of dual lattice meshes allows for the coupling of fracture and transport processes, which commonly occur at the same time in these materials. Literature has shown good agreement between simulations and experimental...

Moisture transportation for extreme precipitation: On how dynamics enhances precipitation intensification in a warmer climate in the Netherlands

It is well understood that precipitation extremes will increase in a warming climate. On (sub-)hourly timescales, the apparent scaling of precipitation extremes is stronger than expected from the Clausius-Clapeyron relation. Here, we focus on a common hypothesis which states that feedbacks from the local dynamics of clouds are responsible.<br/>...

The influence of phosphor particles on the water transport in optical silicones for LEDs

The reliability of LEDs decreases in moist environments. One potential gateway of moisture ingress, reducing the product lifetime is the lens. In white LEDs, phosphor particles are embedded into the optical silicone of the lens to convert the blue light emitted by the diode down in frequency and achieve a light output that appears white. In this...

Simulation of moisture transport in hydrating cement-based overlay systems

Drying of cement-based overlay systems is a critical issue, because it causes differential shrinkage between the overlay material and the concrete substrate and may induce cracking or debonding of the overlay material. In this paper the mechanisms of moisture transport in hydrating cement-based overlay systems are studied. A model is proposed...

The impact of non-isothermal soil moisture transport on evaporation fluxes in a maize cropland

The process of evaporation interacts with the soil, which has various comprehensive mechanisms. Multiphase flow models solve air, vapour, water, and heat transport equations to simulate non-isothermal soil moisture transport of both liquid water and vapor flow, but are only applied in non-vegetated soils. For (sparsely) vegetated soils often...

Microstructure and transport phenomena in visco-elastic modelling of hardening cementitious materials

Since the durability depends, among other things, on the quality of the concrete and presence of cracks, it is necessary to calculate the probability of cracking in hardening concrete as reliable as possible in case of durability predictions. In this thesis, it is investigated how the accuracy of stress prediction in hardening concrete can be...

Moisture transport in coated plaster

In the framework of the research project: 'Water balance of water-borne paint systems on plaster substrates in relation to fungal growth', a study is carried out to moisture transport mechanisms in coated gypsum plaster. In this contribution, the set-up of the study is described. Besides a description of the experiments to investigate the...

The influence of water flow (reversal) on bond strength development in young masonry

Water loss from the fresh mortar is believed to be related to mortar-brick bond strength development in masonry. Recent research on mortar-brick bond has shown that, particularly, effects of water flow on the composition and the hydration conditions of the mortar-brick interface have to be taken into account to explain bond strength development....

Composition of mortar as a function of distance to the brick-mortar interface: A study on the formation of cured mortar structure in masonry using NMR, PFM and XRD

The formation of cured mortar structure in masonry was studied using multiple experimental techniques. Starting with fresh mortar, nuclear magnetic resonance (NMR) was used to measure the water extraction during brick laying. After curing, the composition of cured mortar was investigated with polarizing and fluorescent microscopy (PFM) and X-Ray...

Field evidences and theoretical analysis of the gravity-driven wetting front instability of water runoffs on concrete structures

A series of field observations of the evolution of water runoffs over several vertical concrete walls directly exposed to rain falls is reported in this note. In all the cases, the main water flow originated from the top horizontal surface of the walls. The observations show that the gravity-driven wetting front may propagate in a very unstable...