Search

Solar refrigerator machines based on solid adsorption present a highly interesting solution to the Industry of Cooling Production. In one hand, they are significantly attractive economy ways because of the abundance of the solar energy resources. In the other hand, they are environment friendly. As a result, these machines could present one of the most competitive solutions to the improvement of this very industry. The aim of this paperwork is to provide an accurate study on how to design, seize and build a prototype of an adsorption solar refrigerator using activated-carbon/ammonia pair: Firstly, we used a static model, which is based on the use of state equations (vapor/liquid) at thermodynamic equilibrium. This model computes the cycled mass and the cycle coefficient of performance (COPc) for each four characteristic temperatures of the cycle. Secondly, we develop a dynamic simulation program based on conservation equations of energy and mass in the reactor, this program allow the calculation of the temperature, the pressure inside the reactor, the adsorbed mass and the solar coefficient of performance (COPs). Finally, in the light of our results, we design this prototype, it would consist of the reactor: a solar panel, size 1 m2contain tubes with a diameter of 10cm, an air condenser, and a cold chamber containing an air evaporator.

The aim of this paperwork is to provide a performance comparative study of an adsorption refrigeration system powered by solar heat storage based on Moroccan irradiation. The system operates with ammonia as refrigerant and activated carbon as adsorbent. A parabolic through collector is used to collect the solar energy and store it in a heat storage tank. A dynamic simulation program interpreting the real behavior of the system has been developed. The pressure, temperature and adsorbed mass profiles in the Adsorber have been revealed. The system performance is estimated in terms of the specific cooling power (SCP) and the solar coefficient of performance (SCOP). The solar irradiation and the real ambient temperature variations corresponding to the six climatic zones in Morocco are considered. The effect of those conditions on the performance of the system has been investigated. The results show the capability of our system to realize more than one cycle and produce cold during the day. For an optimal configuration of the system and operating conditions of evaporation temperature, Tev=0 °C, condensation temperature, Tcon=30 °C and generation temperature, T3=100 °C, the process could achieve a SCP of 151 W.kg-1and its solar COP could attain 0.148. The system performances improve especially in sunny area.

Thermal energy storage (TES) component improves the revenue of a concentrating solar power (CSP) plant by allowing more heat to be stored and making the electric energy available during the absence of sunlight. The heat can be stored in three ways (sensible, latent, or thermochemical). The present work aims to identify and select cost-effective sensible TES systems suitable for the medium temperature range (100-300 °C) applications (e.g. Fresnel CSP plants, industrial waste heat recovery, etc.). Based on a literature review, a selection methodology is developed to select potential candidate solid TES media (e.g. natural rock, concrete, sand, etc. ) as filler material in direct or indirect contact with thermal oil, which is used generally as heat transfer fluid (HTF) for this temperature range. The main criteria and steps of this selection methodology are identified and they take into account the different decisive storage properties as thermo-physical and mechanical properties of the solid media. Finally, the potential candidate TES materials are identified for the targeted application and further indoor experimental investigations are briefly presented.

Abstract Current approaches to project spatial biodiversity responses to climate change mainly focus on the direct effects of climate on species while regarding land use and land cover as constant or prescribed by global land‐use scenarios. However, local land‐use decisions are often affected by climate change and biodiversity on top of socioeconomic and policy drivers. To realistically understand and predict climate impacts on biodiversity, it is, therefore, necessary to integrate both direct and indirect effects (via climate‐driven land‐use change) of climate change on biodiversity. In this perspective paper, we outline how biodiversity models could be better integrated with regional, climate‐driven land‐use models. We initially provide a short, non‐exhaustive review of empirical and modelling approaches to land‐use and land‐cover change (LU) and biodiversity (BD) change at regional scales, which forms the base for our perspective about improved integration of LU and BD models. We consider a diversity of approaches, with a special emphasis on mechanistic models. We also look at current levels of integration and at model properties, such as scales, inputs and outputs, to further identify integration challenges and opportunities. We find that LU integration in BD models is more frequent than the other way around and has been achieved at different levels: from overlapping predictions to simultaneously coupled simulations (i.e. bidirectional effects). Of the integrated LU‐BD socio‐ecological models, some studies included climate change effects on LU, but the relative contribution of direct vs. indirect effects of climate change on BD remains a key research challenge. Important research avenues include concerted efforts in harmonizing spatial and temporal resolution, disentangling direct and indirect effects of climate change on biodiversity, explicitly accounting for bidirectional feedbacks, and ultimately feeding socio‐ecological systems back into climate predictions. These avenues can be navigated by matching models, plugins for format and resolution conversion, and increasing the land‐use forecast horizon with adequate uncertainty. Recent developments of coupled models show that such integration is achievable and can lead to novel insights into climate–land use–biodiversity relations. Read the free Plain Language Summary for this article on the Journal blog.

An effective way to reduce complexity in ecological modelling is by grouping species that share similar characteristics into functional groups or types. Often, the creation of plant functional groups (PFGs) is carried out for each case study in an ad-hoc way using a small set of traits. This limits the transferability of these PFGs to other geographical areas or study systems. We propose a novel generic framework to generate PFGs that considers the most important ecological dimensions, is applicable to case studies globally, and that emerges from patterns of functional redundancy across species. Based on most relevant and measured plant characteristics, we designed a multi-step process that includes: i) data harmonisation and missing values imputation; ii) species clustering based on multiple characteristics encompassing the main ecological dimensions featured in plant community ecological models (i.e., dispersal, competition, and demography) and iii) the combination of ecological dimension-specific groups into comprehensive PFGs. We demonstrate this framework by applying it to a global dataset of plant characteristics including a functional traits dataset and a plant-soil co-occurrence dataset for 19,102 species. Lastly, to test the ability of generated PFGs to summarise species’ functional variation within plant communities, we correlate taxonomical and functional diversity indices calculated at the species and at the PFGs level across a global dataset of plant communities (sPlotOpen). Our framework generated 465 global, robust data-driven PFGs with non-overlapping combinations of traits for each ecological dimension divided by growth form. The validation returned positive correlation values between PFGs and species-level diversity metrics, supporting the ability of the obtained PFGs to capture functional and taxonomic diversity patterns across a variety of plant communities worldwide. The framework allows for the easy integration of newly available species characteristics data. The obtained global PFGs, covering all main known ecological processes and environmental conditions at small resolution, can increase the predictive power and accuracy of process-based models and help furthering varying-scale ecological studies.

Abstract Research is revealing an increasing number of positive effects of nature for humans. At the same time, biodiversity in cities, where most humans live, is often low or in decline. Tangible solutions are needed to increase urban biodiversity. Architecture is a key discipline that has considerable influence on the built‐up area of cities, thereby influencing urban biodiversity. In general, architects do not design for biodiversity. Conversely, urban conservation planning generally focuses on the limited space free of buildings and does not embrace architecture as an important discipline for the creation of urban green infrastructure. In this paper, we argue that the promotion of biodiversity needs to become a key driving force of architectural design. This requires a new multi‐species design paradigm that considers both human and non‐human needs. Such a design approach needs to maintain the standards of the architectural profession, including the aim to increase the well‐being of humans in buildings. Yet, it also needs to add other stakeholders, organisms such as animals, plants and even microbiota. New buildings designed for humans and other inhabitants can then increase biodiversity in cities and also increase the benefits that humans can derive from close proximity to nature. We review the challenges that this new design approach poses for both architecture and ecology and show that multi‐species‐design goes beyond existing approaches in architecture and ecology. The new design approach needs to make ecological knowledge available to the architectural design process, enabling practitioners to find architectural solutions that can facilitate synergies from a multi‐species perspective. We propose that a first step in creating such a multi‐species habitat is the design of buildings with an ecolope, a multi criteria‐designed building envelope that takes into account the needs of diverse organisms. Because there is no framework to design such an ecolope, we illustrate how multi‐species design needs to draw on knowledge from ecology, as well as architecture, and design computation. We discuss how architectures designed via a multi‐species approach can be an important step in establishing beneficial human–nature relationships in cities, and contribute to human well‐being and biodiversity conservation. Read the free Plain Language Summary for this article on the Journal blog.

In this study, we address the optimization of the direct power control of a doubly fed induction generator within a wind conversion system under actual wind conditions. The primary objective is to enhance the dynamic response of the wind energy conversion system (WECS) while minimizing the impact of wind fluctuations on power generation. To achieve this goal, we introduce a novel control methodology based on the super-twisting algorithm (STA). This approach allows for effective regulation of both reactive and active power output in the WECS. We employ comprehensive simulations using a detailed model of the WECS and real wind profiles to evaluate the efficacy of the STA-based control strategy. Our simulations demonstrate that the adopted STA-based control strategy successfully tracks the desired power set-point and effectively mitigates the adverse effects of wind power fluctuations and uncertainties on the WECS power output. Specifically, it exhibits superior performance in managing transients and rejecting disturbances compared to a conventional approach employing a switching table and hysteresis controller. These results suggest the practical viability and potential applications of the STA-based control strategy in real-world wind energy systems.

Copyright of People & Nature is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The ideal free distribution theory predicts that mobile species distribute themselves among habitat patches so as to optimize their fitness. Changes in land use alter the quality of habitat patches and thereby affect the distribution of species. Following the loss of native habitat, habitat specialists are expected to move to patches where native habitat still remains in order to survive. Competition for resources in habitat remnants should consequently increase. As generalists are able to use other habitats, generalists are expected to gradually disappear in remnants in order to avoid increasing competition with specialists. Here, we test these predictions by studying the response of habitat specialist and generalist birds to land-use change in Brazil's southern grasslands. Using a space-for-time substitution approach, we surveyed bird communities in native grassland sites (~4 ha) in 31 regions (10 × 10 km) with differing levels of conversion to agriculture (1–94%). We found a higher abundance of specialists in native grassland patches with increasing agricultural cover in the region, while the total number of individuals in remnants remained constant. At the same time, the share of generalists in total abundance and total species richness decreased. To gain insights into whether these patterns could be driven by shifts in competition, we tested whether generalists that continued to co-occur with specialists in remnants, had less dietary overlap with specialists. As a consequence of community composition in remnants, a higher proportion of generalists were omnivorous and the average generalist species fed less on seeds, whereas the average specialist species fed more on seeds when agricultural cover was high in the region. Our results, therefore, support predictions of the ideal free distribution theory. Specialists that are assumed to have a low survivorship outside of their specialized habitat, distribute to remnants of this habitat when it is converted elsewhere, while generalists, being able to survive in other habitats, disappear gradually in remnants. Such a process could partly explain the segregation of habitat specialist and generalist birds observed in many agricultural landscapes. Finally, our results suggest that native habitat remnants can be important temporary refugia for specialists.

This study investigates the thermal energy potentials and economic feasibility of an air-conditioned family household-integrated phase change material (PCM) considering different climate zones in Morocco. A simulation-based optimisation was carried out in order to define the optimal design of a PCM-enhanced household envelope for thermal energy effectiveness and cost-effectiveness of predefined candidate solutions. The optimisation methodology is based on coupling Energyplus® as a dynamic simulation tool and GenOpt® as an optimisation tool. Considering the obtained optimum design strategies, a thermal energy and economic analysis are carried out to investigate PCMs’ integration feasibility in the Moroccan constructions. The results show that the PCM-integrated household envelope allows minimising the cooling/heating thermal energy demand vs. a reference household without PCM. While for the cost-effectiveness optimisation, it has been deduced that the economic feasibility is stilling insufficient under the actual PCM market conditions. The optimal design parameters results are also analysed.

A modelling approach based on the Substitutive Coefficients Network (SCN) is developed to predict the thermal behavior of a system in the dynamic state-space, without requiring knowledge of the thermal mass. The method can apply either to large- (building, combined solar systems, geothermal energy, and thermodynamic installations) or to small-scale systems (heat exchangers, electronic devices cooling systems, and Li-ion batteries). This current method is based on a dimensionless formulation of the simplified dynamic thermal balance model, using relaxation time as a key parameter to establish the model. The introduction of relaxation time reduces the parameters set as guidance coefficients. The parameters are finally expressed by a combination of global heat transfer coefficients related to each layer and/or sub-layer of the system. Advantages of the method are reliability, “non-destructibility”, i.e., it allows a reliable prediction of the thermal behavior which experimentally is inaccessible, and reducibility of the parameters size estimate. Additionally, the method is inexpensive in terms of computation memory. It is also easy to implement in practical numerical schemes. In this paper, the method leads to a simplified mathematical model that predicts the thermal behavior of a mono-zone eco-cottage building installed at Lorraine University (in Longwy, France) as a case study. Thermal performance of the building is estimated under the hourly weather conditions onsite, as obtained from the Meteonorm software. The thermal dynamics within hourly Typical Meteorological Year 2 (TMY2) Meteonorm data disturbances and the internal heating input state in the winter period were simulated with a simplified numerical discretization method. Results provide a general dynamic state of the different sub-components of the system, with limited design of the model parameters.