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Hybrid photovoltaic/thermal (PV/T) systems provide both electrical and thermal energy. The development of seawater-proof PV/T systems can enlarge the, by now, very limited PV/T application fields to a new one: sustainable reverse osmosis (RO) desalination. There, the PV/T systems' disadvantage of heat at low temperature level can redound to its advantage: the RO freshwater output is increased at elevated seawater temperatures while the PV efficiency is improved due to cooling with seawater. In this paper, the development of a novel seawater-proof PV/T system with the aim of low cost and high electrical and thermal performance is presented. Low-cost is achieved by using standard components combining a polypropylene thermal absorber with a commercial PV system. Experimental investigations on a PV/T prototype include thermal and electrical efficiency characterization at different fluid temperature levels, mass flow rates and ambient conditions. The results are compared the state-of-theart PV/T systems.

a b s t r a c tMotivation of this paper is the hypothesis of permeate flux enhancement due to the dynamic operation of Reverse Osmosis (RO) systems powered by fluctuating renewable energies or by active control. Therefore, in this paper the influence of laminar pulsating flows in spacer filled channels with two porous walls is considered and numerically analysed using the opensource Computational Fluid Dynamics (CFD) tool OpenFOAM. Three different 2-D spacer configurations typically found in literature are investigated: Cavity, Submerged and Zig-Zag. The simulations are performed using typical conditions for seawater desalination. A literature review about dynamically operated membrane systems showed that the results achieved in previous studies are contradictory. Most of them were experimentally or numerically performed in open channels at different conditions. A comparison of the results is therefore difficult. As a first approach this study discusses the dynamics of the mass transfer through the membrane using an analysis based on Biot number. For the CFD simulations, boundary conditions based on the Solution-Diffusion model are implemented and validated with literature data. It shows good agreement at steady state conditions for typical seawater and brackish water desalination conditions. A qualitative analysis of the flow patterns shows that the flow is mainly disturbed in the decelerating phase of the pulsation cycle, which increases the mixing inside the channel. Different local concentration profiles at the membrane and Sherwood number profiles showed that especially in the middle part of two cylinders the mass transfer is significantly influenced whereas at the attachment points of cylinder and membrane, the influence is only marginal. At Womersley numbers of Wo = 17.7 the concentration profiles along the membrane are highly disturbed and the patterns change significantly, also qualitatively. The influence of the Amplitude Ratio is lower than that of the influence of the Womersley number.

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Besides a sufficient energy supply, concepts for accommodations require an intelligent water management. Using the example of quarters that do not have water and energy access, a dynamic simulation model is presented in which a rainwater harvesting concept is implemented and simulated over one year using MATLAB-Simulink. The aim is to minimize respectively suspend the use of fossil energy sources and to guarantee the provision of decentralized clean drinking water. Since traditional water bodies, e.g. groundwater, are increasingly polluted and depleted, utilisation of alternative sources is prudent. Especially in rural areas, where access to drinking water is scarce, rainwater is suitable for providing potable water. Besides its beneficial chemical water properties, it is easily accessed in a decentralized manner, which makes it a preferred choice in areas with sufficient precipitation. However, access to rainwater is limited by its occurrence and contamination, calling for proper storage, utilisation, and treatment strategies. For this purpose, a rainwater harvesting system, including different water and energy management systems, was modelled and implemented using the site of the Angkor Centre for Conservation of Biodiversity in Cambodia as an example. For the simulation, a precipitation generator was implemented using real historical rain event data. An appropriate rainwater treatment process was chosen, consisting of a microfiltration and a subsequent ultrafiltration unit removing bacteriological loads entirely. Both were modelled and implemented dynamically. Using the site of the Angkor Centre of Conservation of Biodiversity, a complete rainwater harvesting plant was implemented including harvest, storage, and utilization of rainwater. Further, a renewable energy * Corresponding author Journal of Sustainable Development of Energy, Water and Environment SystemsYear 2017 Volume 5, Issue 4, pp 626-644 627 management strategy is developed, using photovoltaic modules and batteries. It was shown that the cumulative runoff meets the water demand of the Angkor Centre for Conservation of Biodiversity and that the energy demand of the rainwater system as well as the site can be met by the installed photovoltaics on the existing roof area.