Grid-scale pumped hydro energy storage for the low countries

Penetration of intermittent renewable energy sources into the power grid requires large-scale energy storage to ensure grid stability. Pumped Hydro Energy Storage (PHES) is among the most mature, environmentally friendly, and economical energy storage technologies, but has traditionally only been feasible at sites with large natural topographic gradients. ALPHEUS addresses this by developing reversible pump-turbines efficient at low heads, that operate between an enclosed inner basin (that functions as the upper or lower reservoir) and a shallow sea or lake

Algorithmic generation of vascular network models for additive manufacturing

Fabrication of functional vascularised three-dimensional tissue constructs has been a long-standing objective in the field of tissue engineering. Currently, the main limitation in this field is the inability to produce fully vascularised tissue with an internal mass transport system (vascular network) that can provide cells with nutrients and oxygen while removing waste, to imitate the functions of human living tissue. Achieving such a system would allow the development of large-scale tissue constructs and increase the potential for in vivo integration. There are different approaches to attempt vascularisation, which use a diversity of techniques. Among these, one of the most promising is additive manufacturing due to its versatility, reproducibility, and compatibility with suitable materials. With the aim of contributing towards the efforts in this field, the present work presents a method for the automatic generation of physiologically-based vascular network structures as solid 3D models suitable for additive manufacturing technologies. Considering the natural hierarchical branching vasculature as an ideal solution, an algorithm was developed to generate branching tree structures connected at the ends to form vascular networks. The implementation is based on previous work in the field of computational bio-simulation of arterial tree growth. It consists of a space-filling algorithm that connects all given points to a growing tree within a defined three-dimensional volume, while fulfilling constraints associated with the physiological laws of circulation. The networks are generated using a CAD environment and thus can be used in additive manufacturing processes. An investigation was carried out on the effect of three input parameters (namely volumetric flow rate, pressure difference across the tree, and number of terminal points) in order to find a suitable combination of parameters that would produce networks with diameters above the fabrication threshold. In order to demonstrate feasibility and functionality of the networks fabricated using this proposed method, two network models were produced by 3D printing and subsequently used as a sacrificial structure to produce PDMS blocks with the hollow vascular networks embedded in it. Particle tracking was used to measure the flow velocity in the channels at two different inlet flow rates. Comparisons were made with theoretical values obtained from computational fluid dynamics simulations and show a good agreement between experiment and theory. From the measurements of maximum velocity, it was observed that at a lower flow rate, the experimental values were closer to the theoretical values than at a higher flow rate. This might be due to the challenges that higher flow rates represent, such as less accurate particle tracking. Given the overall agreement, it is concluded that computational fluid dynamics simulations are a fast and effective way to analyse flow in vascular network models produced by the method here proposed.The Cambridge Trust, CONACyT (Consejo Nacional de Ciencia y Tecnologia), EPSRC Cambridge & Cranfield Doctoral Training Centre in Ultra Precisio

Creep behaviour of densified wood

Due to the reproducibility, good workability, suitable mechanical properties, and attractive aesthetic appearance, timber is widely used in the building industry. Among those properties, mechanical properties are important for the useability of timber in construction applications. It is well known that there is a positive relationship between wood density and its mechanical properties. That means the thermo-hydro-mechanical (THM) densification, i.e. transverse compression of the wood cells only by using additional temperature, moisture and mechanical action to increase its density without structural fracturing is a practicable method to increase the performance of low-density species and thereby improve its mechanical properties. The previous studies on wood densification mainly focused on the influence of process parameters on wood physical and mechanical properties and how to use post-treatment to reduce the set recovery. This study is in the field of increasing the use of densified timber in construction applications and thereby strengthen the competitiveness of wood as a construction material. In construction, however, densified timber normally needs to be exposed to long-term loading which may lead to creep deformation and reduction of load-bearing capacity. There is an obvious risk of reduced serviceability and safety of constructions containing densified wood. Studies of creep characteristics of densified wood are rare, and therefore the purpose of this study was to fill the gap in knowledge if the field of densified under bending load. Scots pine specimens subjected to THM densification, THM densification with a post-heat treatment, and THM densification combined with phenol resin impregnation were loaded under 3-point bending under the 35% of maximum stress level at 20℃ and 65% RH. Results from these tests will be presented.Finansiär: Republic of Slovenia</p