Search

• Ejector cycles achieved higher performance than booster cycle within the gas cooler outlet temperature range of 31 and 50°C. • Multi-ejectors can be applied to ejector cycles with different configurations. • Up to 17% annual energy consumption reduction was found using ejector cycles. • Unit product exergy costs of ejector cycles are up to 28% lower than booster cycle. Restrictions on high-GWP refrigerants have made the use of transcritical CO 2 refrigeration systems widespread. Using transcritical booster refrigeration cycle in warm climates is unsatisfactory due to its high energy consumption. This paper presents theoretical analysis and performance comparison of three different transcritical CO 2 supermarket refrigeration cycle configurations with ejector expansion in Türkiye, which has different climatic regions. Bin-hour data were derived using hourly dry-bulb temperature values for provinces from 7 different regions in Türkiye. The applicability of multi-ejectors to each modeled cycle was also investigated. Annual energy consumption and environmental impact reductions of up to 17% were obtained using ejector expansion cycle compared to booster cycle. Ejector expansion cycles achieved higher performance than booster cycle up to 46% in terms of exergy efficiency at investigated ambient temperatures. Unit product exergy costs of the ejector cycles were found up to 28% lower than booster cycle. [Display omitted] [ABSTRACT FROM AUTHOR]

As digitalization increases globally and ecological awareness grows, this article attempts to question the narrative of a natural alliance between the digital transition and the necessary ecological transition. To this end, this article proposes to focus on the main steps that led to the structuration of a research field on the environmental impact of digital technologies, as well as the various relations between Information and Communication Technologies (ICTs) and the environment. [ABSTRACT FROM AUTHOR]

In this study, a method to evaluate the environmental effects of household refrigerators is newly developed in terms of life cycle climate performance (LCCP). The energy consumption model of the refrigerator is developed with three types of typical single evaporator refrigerators. The operation ratio of the evaporators, which is critical for calculating the energy consumption of dual evaporator refrigerators, is determined using experimental results of serial, bypass, and parallel-circuit cycle refrigerators. The LCCP results show that the system performance and equipment manufacturing emissions are dominant factors in lifetime CO 2 emissions. Therefore, energy- and material-related factors, such as refrigerator cycle options, refrigerator material, insulation, and power sources, are primarily investigated. For cycle options, CO 2 emissions can be reduced by 14.7% using a two-stage cycle. For condenser materials, CO 2 emissions can be reduced by 2% to 2.5% using aluminum instead of steel. For insulation, the total emissions can be reduced by up to 7.7% by applying vacuum insulation panels on each side of the refrigerator. When 20% renewable energy is supplied, the total emissions are expected to be reduced by 13% in the baseline, 19.9% in the parallel-circuit cycle, and 26% in the two-stage cycle. [ABSTRACT FROM AUTHOR]

The Port of Santos has been undergoing continuous expansion of its activities. The article aims to analyse globally the contexts related to the policy and actions of maritime and coastal protection against oil spills, as a contribution to the proposal of an integrated risk management tool for oil spills in the coastal zone related to port activities. The methodology includes a bibliographic review and synthesis of the current state of knowledge, inventory of port activities, quantitative and qualitative methods of risk assessment, identification of factors that determine it, evaluation of its paradigms (Danger-Exposure- Vulnerability) and risk quantification. The study permitted the characterization of the temporal evolution and the spatial distribution of accidents involving oil spills, to identify critical success factors on a risk management tool for oil spills and to evaluate the risk of these kinds of spillage in the coastal zone of Port of Santos/SP. [ABSTRACT FROM AUTHOR]

For competitive purposes, manufacturers of household appliances need to produce appliances that use less electricity. One way of doing this for a dishwasher is to add a heat pump system. Previous studies using R134a as refrigerant have shown that the addition of a heat pump can reduce total electricity consumption by about 24%. This paper reports on the use of a capillary tube in a heat pump dishwasher during the transient heating period. Working with an available compressor, the mass of R600a and the length of a 0.9 mm capillary tube were varied in order to find the configuration with the lowest electricity consumption. Three methods of calculating the length of the capillary tube were used to determine five lengths for evaluation. The results show that using a single capillary tube throughout the transient heating period yields similar electricity consumption to a variable expansion device which occurred by switching the capillary tube between two or three different lengths during the heating period. [ABSTRACT FROM AUTHOR]

This paper presents life cycle assessment approach to study the impact of structure and envelope types on the energy consumption and environmental impact of an office building in New York City, USA. In addition, the future costs of environmental impact for various structure and envelope options are assessed according to the current practice and market price of CO2. Eight structure and envelope types for the low-rise office building are investigated, which include concrete and steel structures with various combinations of envelopes. The parameters such as life cycle energy use, global warming potential, and water, air and land emissions are analyzed. The energy simulation is performed by using eQUEST software while the environmental impact is assessed by using ATHENA® impact estimator. The building with concrete frame is proved to have lower environmental impact compared to that with steel frame. The precast concrete building is found to be the most economical alternative due to the minimal environmental impact cost. This study is expected to enable the decision makers and building owners to select the best alternative with respect to energy use, and environmental and economic constraints. [ABSTRACT FROM AUTHOR]

Supermarket refrigeration systems have high environmental impact due to their large refrigerant charge and high leak rates. Consequently, the interest in using low GWP refrigerants such as carbon dioxide (CO 2 ) and new refrigerant blends is increasing. In this paper, an open-source Life Cycle Climate Performance (LCCP) framework is presented and used to compare the environmental impact of four supermarket refrigeration systems: a transcritical CO 2 booster system, a cascade CO 2 /N-40 system, a combined secondary circuit with central DX N-40/L-40 system, and a baseline multiplex direct expansion system utilizing R-404A and N-40. The study is performed for different climates within the USA using EnergyPlus to simulate the systems' hourly performance. Further analyses are presented such as parametric, sensitivity, and uncertainty analyses to study the impact of different system parameters on the LCCP. [ABSTRACT FROM AUTHOR]

Cet article s'intéresse à la concurrence que se livrent une multitude d'entités pour le contrôle du marché des appareils électriques et électroniques d'occasion en Chine. Il analyse les stratégies qu'elles déploient afin d'obtenir ou de conserver un avantage concurrentiel. Des agences du gouvernement central, des instituts de recherche scientifique et de grands groupes spécialisés dans le recyclage, en particulier, ont récemment uni leurs forces dans le but d'éloigner du secteur dit « informel » de l'économie de précieux flux de biens de consommation, en érigeant notamment d'importantes barrières à l'entrée. Ils s'efforcent de se distinguer des petits recycleurs en s'appuyant abondamment sur une propagande écologiste et sur des discours centrés sur le progrès technologique. Cependant, le « système de gestion » du recyclage des « e-déchets » approuvé par le gouvernement chinois n'est pas aussi écologique que ses défenseurs le prétendent. Il promeut un régime en matière de déchets centré sur des « ressources », et non des produits, et contribue ainsi à accélérer et à allonger les cycles matériels. Afin de pleinement saisir sa nature et son impact, il faut comprendre les liens qu'il entretient avec d'autres politiques nationales, en particulier celles qui promeuvent la croissance. [ABSTRACT FROM AUTHOR]

The paper presents a review on recent development of possible substitutes for non-ecological refrigerants from HVAC&R equipment based on thermodynamic, physical and environmental properties and TEWI (Total Equivalent Warming Impact) analysis. This review contains a good amount of information regarding the environmental pollution produced by the working fluids of the air-conditioning, heat pump and commercial refrigeration applications and the ecological refrigerant trend. Overall, it is useful for those readers who are interested in current status of alternative refrigerant development related to vapour compression-based refrigeration, air-conditioning and heat pump units. The study describes the selection of refrigerants adapted to each utilisation based on the thermodynamic, physical and environmental properties and explores the studies reported with new refrigerants in domestic refrigerators, commercial refrigeration systems, air-conditioners, heat pumps, chillers and in automobile air-conditioners. Additionally, a comparative analysis of the TEWI for possible substitutes of refrigerant R22 used in various air-conditioning, heat pump and refrigeration systems is performed. [ABSTRACT FROM AUTHOR]

Les rejets sulfurés de la mine abandonnée de Kettara, située à 30 km au Nord-Nord-Ouest de Marrakech, sont directement entreposés sur un substratum schisto-gréseux fracturé. D'une superficie d'environ 16 ha, ils constituent une réelle source de pollution pour l'écosystème local en particulier à cause du Drainage Minier Acide (DMA) vers les eaux de surface et de la nappe phréatique. Le projet de réhabilitation du site minier de Kettara prévoit dans l'un de ses axes de minimiser l'effet DMA par neutralisation à l'aide de dépôts stériles riches en carbonates issus de l'extraction des phosphates de la mine de Youssoufia voisine. Ces derniers seront utilisés à la fois comme amendement des rejets miniers acides et comme couverture évapo-transpirante (barrière capillaire). Notre étude a permis d'une part, de mieux appréhender la nature et la structure du parc à résidus et de son substratum et d'autre part, de caractériser l'impact de ces résidus sur la qualité des ressources en eau souterraine. Les résultats issus de cette étude vont contribuer à la réussite du projet de réhabilitation du site. Editeur Z.W. Kundzewicz Citation Lghoul, M., Kchikach, A., Hakkou, R., Zouhri, L., Guerin, R., Bendjoudi, H., Teíxido, T., Antonio Penã, J., Enriqué, L., Jaffal, M. et Hanich, L., 2012. Etude géophysique et hydrogéologique du site minier abandonné de Kettara (région de Marrakech, Maroc): contribution au projet de réhabilitation. Hydrological Sciences Journal, 57 (2), 370–381. [ABSTRACT FROM PUBLISHER]

Climate change is likely to exacerbate the dry conditions already experienced in southern Africa. When rainfall does come, it is likely to be in bursts of greater intensity, leading to erosion and flood damage. However, these predictions have had very little influence on policy in southern African countries. Computable general equilibrium (CGE) model simulations for Namibia indicate that over 20 years, annual losses to the Namibian economy could be up to 5% of GDP, due to the impact that climate change will have on its natural resources alone. This will affect the poorest people the most, with resulting constraints on employment opportunities and declining wages, especially for unskilled labour in rural areas. Namibia must take steps to ensure that all its policies and activities are `climate proofed' and that it has a strategy to deal with displaced farmers and farm workers. The need to mainstream climate change into policies and planning is clear, and it is the responsibility of industrialized nations, who have largely created the problem of climate change, to help Namibia and other vulnerable countries cope with climate change impacts and plan for a climate-constrained future. [ABSTRACT FROM AUTHOR]

Recent case studies for individual locations and on individual urban challenges reveal the growing complexity of managing interrelations among population, infrastructure and institutions. Climate change is increasing the pressures on many urban systems and adding to this complexity. Many of the case studies investigating urban dynamics in the light of climate change have chosen narrow, sector-specific approaches. Few projects have built on insights from complexity theory and related bodies of knowledge which are more consistent with the perspective that urban infrastructure systems are tightly coupled with one another and must respond to often subtle, long-term changes of technological, social and environmental conditions. Drawing on that knowledge, and building on insights from previous case studies, this article explores the potential roles of complexity theory in guiding investment and policy decisions in the urban context. Policy and management that are consistent with insights from complexity theory will need to anticipate a wide array of potential trajectories for urban dynamics, identify and implement strategies that are robust under a range of potential developments, continuously innovate the policy-making and management institutions, and intensify the exchange of knowledge between science and society. [ABSTRACT FROM AUTHOR]