Peer-reviewd Publications

Molecular dynamics study on compact heat storage materials

(Master Thesis, WET, No. 2012.04). Eindhoven: Technische Universiteit Eindhoven

Authors
Zhang, H. & Rindt, C.C.M.

Abstract
Storing heat in salt hydrates by the reversible sorption process of water vapor is one of the most promising forms of compact heat storage. The large storage capacity, low loss and low cost make it especially suitable for seasonal heat storage systems. However, the hydration and dehydration mechanisms of salt hydrates are not fully clear. In this study, a molecular dynamics approach towards deep understanding of hydration and dehydration is proposed. The studied material is MgSO4. In the molecular dynamics simulations, pieces of nanometer thick crystals are modeled from perfect crystalline structures and interact with water vapor. The dehydration simulation is performed at 450K, and a constant vapor pressure 20 mbar. The hydration simulation is performed at 300K. The properties including equilibrium pressure, dehydration rate, density, diffusion coefficient and radial distribution functions are studied. In this study, it is discovered that the slowdown in dehydration rate is caused by surface anhydrous MgSO4 aggregates and surface adsorption of water molecules.

Molecular dynamics study on thermal dehydration process of epsomite (MgSO4.7H2O)

(2013) Molecular Simulation, accepted or in press.

Authors
Zhang, H., Iype, E., Nedea, S. V. and Rindt, C. C. M.

Abstract
Water vapor sorption in salt hydrates is one of the most promising means for compact, low loss, and long-term storage of solar heat in the built environment. One of the most interesting salt hydrates for compact seasonal heat storage is magnesium sulfate heptahydrate MgSO47H2O, which can absorb 2.8GJ/m3 when fully dehydrated. In this paper, the thermal dehydration process of the heptahydrate is studied with molecular dynamics (MD) method. The simulation is performed mainly at 450K and a vapor pressure of 20mbar, which is a typical dehydration condition utilizing hot air from the outlet of a solar collector heater. Properties including energy, partial densities, radial distribution functions and diffusion coefficients are analyzed quantitatively. It is discovered that the slowdown in dehydration rate is caused by surface adsorption of water molecules.

Designing and modeling of seasonal thermal energy storage using sugar alcohols as PMC

WET2012.09, Internal Report

Authors
S.R.A.Zaidi

Abstract
The built environment is the largest consumer of energy but its demand has seasonal variation, and a big part of the energy supplied to the buildings comes from environmentally hazardous sources. To reduce the dependence on the polluting sources of energy supply and to decrease the mismatch between energy supply and demand, seasonal storage of solar energy is very important. Solar energy storage using phase change materials is a promising way of compact energy storage for seasonal applications. With this purpose a background study is carried out to determine a phase change material suitable for seasonal energy storage and Erythritol, a sugar alcohol, is selected because of its high phase change temperature and large supercooling. Secondly, a reactor model is developed for detailed analysis of PCM material and the stored energy. This reactor model is used to optimize the size of the reactor. Afterwards, models of an evacuated tube solar collector and a water storage tank are developed and integrated with reactor model for system level analysis. To analyze this system the annual energy demand of a Dutch house is also determined. This system model is examined to determine important parameters and conditions associated to seasonal storage like solar collector area, energy capacity of system and size of water storage tank. Subsequently, this system model is used to assess the annual performance of phase change energy storage by calculating the energy flows in the system and the solar fraction. After the technical feasibility of the seasonal energy storage system a business plan is developed to determine commercial and economic feasibility of this system. The business plan includes customer insights &value proposition, marketing strategy and financial strategy.

High Pressure Solutions-Turning the energy levels of inorganic-organic interfaces may open new applications in life sciences and energy storage

Science &Technology, vol. 7, June 2013, pp. 108

Authors
R.R. Piticescu

Abstract
Advanced materials are one of the key enabling technologies enabling design and fabrication of a large number of systems and components. Many of them require a perfect control over the interfaces and involve activities from modeling to process development and components integration. Nano-enabled surfaces are therefore one of the most interesting value chain for multi-sectorial applications. It is important to note that high pressure chemistry solution ensure the kinetic control toward different morphologies such as nano-rods, nano-whiskers, flower-like structures, etc. An example is the control of graphite-zinc oxide adhesion energy leading to interfaces with design hydrophobicity and thermal properties for energy storage systems. Furthermore other applications may be developed using the new research infrastructure developed by the institute with help from the Structural Funds Project High PTMET.

Ultralow cost reticulated carbon foams from household cleaning pad wastes

CARBON, Vol. 62; Year 2013, Elsevier, p. 517-520

Authors
P. Jana, V. Fierro, A. Celzard

Abstract
A very simple method is described for preparing ultra lightweight and ultralow cost carbon foams (density 0.04–0.075 g cm⁻³ and porosity 98–96%) by impregnation with sucrose of household cleaning pad wastes used as sacrificial templates, followed by pyrolysis in inert atmosphere. Scanning electron microscopy showed that the resultant reticulated vitreous carbon (RVC) foams had a fully open and interconnected porous structure. These materials are more thermally insulating (thermal conductivity 0.042–0.065Wm⁻¹ K⁻¹) than commercial RVC foams having similar compressive strengths (0.11–0.23 MPa) and similar densities.

Simple and versatile one-step synthesis of highly interconnected graphitized macroporous carbon foam

Conference Paper; Annual International World Conference on Carbon (Carbon 2013), Rio de Janeiro, Brazil, 14-19 July 2013,

Authors
Mani Karthik, Vladimir Roddatis and Stefania Doppiu, CIC Energigune, Spain

Abstract
The highly interconnected graphitized macroporous carbon foams were successfully synthesised by one-step low temperature process using resorcinol and formaldehyde as carbon precursors and metal nitrate as a graphitization catalyst. The commercially available polyurethane foam was used as a sacrificial polymer template. The obtained three-dimensional (3D) highly interconnected graphitized carbon foams were extensively characterized by using powder X-ray diffraction (XRD), nitrogen adsorption-desorption measurement, transmission electron microscopy (TEM), scanning electron microscopy (SEM), raman spectroscopy and thermogravimetric analysis (TGA). XRD and TEM results clearly demonstrated the presence of a well-defined graphitic framework. The surface morphology of the macroporous carbon foam was studied by using SEM and the results clearly showed the presence of a highly interconnected porous network throughout the structure. The thermal stability of the carbon foam was also examined by TGA. The effects of various parameters such as precursor ratio, curing time & temperature, concentration of the metal nitrate and graphitization temperature were investigated. The physical properties of the carbon foam as such density, pore size and total porosity were also studied and the salient results are discussed.

EU gives boost to compact thermal energy R&D

Newsletter of the International Energy Agency Solar Heating and Cooling Programme - SolarUpdate, vol. 56, June 2012

Co-author
E. Palomo (U. of Bordeaux, CNRS, France), coordinator of SAM.SSA

BIOFOAMS 2013 conference – SAM.SSA contribution

RECENT ADVANCES FOR PRODUCING HIGHLY POROUS, BIOSOURCED, MONOLITHS

Authors
Alain Celzard, Andrzej Szczurek, Prasanta Jana, Vanessa Fierro, and Antonio Pizzi

Abstract
Tannins are non toxic, cheap and abundant polyphenolic oligomers extracted from tree barks, which can be easily used for preparing thermoset resins that are natural at the 90% level. From these resins, highly porous monoliths can be obtained by different techniques such as physical and mixed physical/chemical foaming, of by less conventional methods such as emulsion-templating, and stabilisation and hardening of liquid foams or foamy emulsions. The resultant materials are not only interesting per se, but are also key precursors of novel cellular carbons having a broad range of applications.