Prospects for the Improvement of Energy Performance in Agroindustry Using Phase Change Materials

This work was partially supported by the Fundação para a Ciência e Tecnologia, UIDB/00066/2020 (CTS – Center of Technology and Systems).The use of Phase Change Materials (PCMs), able to store latent heat, represents an opportunity to improve energy efficiency in the agroindustry by means of thermal energy storage. PCMs provide higher energy density then sensible heat storage mediums, thus paving the way to multiple applications, like supporting the integration of renewables or allowing for new storage architectures, decentralized and directly installed in the chain production equipment, creating e.g. the opportunity to recover and value low-grade operational heat sub-products. Such new and decentralized architecture, not currently applied in agroindustry, is proposed in this work. A chocolate tempering machine using an organic PCM is conceived and analyzed using ANSYS Fluent software for computational fluid dynamics simulations, comparing the main aspects in the storage capacity and discharging process with a conventional sensitive heat storage solution that uses water. PCMs allows improving the stored energy, keeping the chocolate in the working temperature after being tempered for more than four times longer than using only hot water. If the PCMs are charged by renewables, the self-consumption ratio can be improved while providing energy flexibility to the user.authorsversionpublishe

Aquaponics in the Built Environment

Aquaponics’ potential to transform urban food production has been documented in a rapid increase of academic research and public interest in the field. To translate this publicity into real-world impact, the creation of commercial farms and their relationship to the urban environment have to be further examined. This research has to bridge the gap between existing literature on growing system performance and urban metabolic flows by considering the built form of aquaponic farms. To assess the potential for urban integration of aquaponics, existing case studies are classified by the typology of their building enclosure, with the two main categories being greenhouses and indoor environments. This classification allows for some assumptions about the farms’ performance in their context, but a more in-depth life cycle assessment (LCA) is necessary to evaluate different configurations. The LCA approach is presented as a way to inventory design criteria and respective strategies which can influence the environmental impact of aquaponic systems in the context of urban built environments

Plant cognition : ability to perceive ‘touch’ and ‘sound’

Plants’ sessile life-style has enabled them to develop enormous sensitivity towards their dynamic, tactile and clamorous surroundings. Consequently, besides a range of different stimuli, plants can even perceive subtle stimuli, like ‘touch’ and unanticipatedly ‘sound’. Importantly, touch sensitivity in plants is not just limited to sensitive plant and carnivorous species, which respond through eye-catchy movements; instead every plant and living plant cell senses and responds to mechanostimulation, whether intrinsic or extrinsic in nature. For instance, plant roots are extremely touch-sensitive, and upon encountering a barrier in soil, they are able to effectively redirect their growth to transcend it. Similarly, tendrils in climbing plants exhibit extreme sensitivity towards touch, which enable them to sense and grab a support in close vicinity. Unlike touch sensitivity, which was recognized long ago by Robert Hooke and Darwin, plants’ sensitivity towards sound has started gaining attention only recently. The past decade has seen major advances in this area of plant biology; many breakthrough discoveries were made that revealed the, otherwise debatable, ecological significance of sound perception in plants’ life. It has come to light that plants not just sense but also distinguish relevant sound among a mixture of irrelevant sound frequencies; plants distinguish buzz produced by a true pollinator among pollen thieves in the sophisticated process of buzz pollination. Similarly, plants distinguish sound typical of a herbivore for elicitation of defence response. Interestingly, plant roots can sense sound of flowing water in order to direct their growth towards the water source. Given the similarity in the physical properties of touch and sound stimuli, many recently discovered signaling events and molecular players in touch and sound perception are noted to be common. However, in view of the contrasting responses tailored according to the stimuli, plants appear to distinguish well among the two in an ecologically meaningful manner