1,720,960 research outputs found
Achieving off-grid refrigeration in remote areas: A solar-powered vapor compression refrigerator prototype with PCM integration
No full textThe availability of vaccines, medicines, and perishable goods in remote or off-grid areas remains a formidable challenge. Integrating solar photovoltaic (PV) systems with refrigeration technology has emerged as a promising solution to address this critical need. This paper presents an autonomous solar-powered refrigerator prototype for off-grid refrigeration in remote areas utilising renewable energy. The system comprises a 160 W photovoltaic module, a 12/24 V DC compressor refrigerator, a lead-acid battery, and a Maximum Power Point Tracking (MPPT) controller. Its main feature is complete autonomy from the electricity grid, thanks to its standalone configuration. An experimental campaign evaluated the system's behaviour in the laboratory for 24 h at different set-point temperatures. A water-based Phase Change Material (PCM) was implemented to improve its autonomy in severe outdoor conditions. A further experimental campaign emulated the functioning of the prototype while managing the temperature of a sample solution whose melting temperature was equal to – 21 °C to ensure its liquid state during the tests. The target range for preserving the sample was defined at ± 1 °C. Several real conditions have been considered, such as higher cooling loads realised through 21 litres of additional thermal mass in the refrigerator and pick and place conditions for simulating the opening and closing of the door. The results demonstrate that the solar refrigerator prototype achieves complete autonomy from the electricity grid, paving the way for solutions for preserving perishable goods such as medicines and food in unelectrified areas
Sun-Powered Refrigerator: Design, Testing, and Limitations
No full textThe availability of vaccines, medicines, and perishable goods in remote or off-grid areas remains a formidable challenge. Integrating solar photovoltaic (PV) systems with refrigeration technology has emerged as a promising solution to address this critical need. This paper comprehensively explores a sun-powered refrigerator capable of maintaining temperatures between +2 degrees C and -20 degrees C, essential for preserving vaccines, medicines and perishable products in remote areas. A solar PV panel is mounted on the refrigerator's top surface, harnessing renewable energy to power the refrigerator. This solution also enhances portability, making it well-suited to remote and resource-constrained regions. The results of initial experimental tests aim at validating feasibility and efficacy of the sun-powered refrigerator and assessing the refrigerator's performance under varying operating conditions. Detailed insights into the design, construction and limitations are provided, shedding light on its potential as a sustainable solution for vaccines and medicines storage in underserved areas. Solar availability, storage capacity, and backup power sources are carefully examined to provide a comprehensive understanding of the practical considerations and constraints involved. This paper contributes to scientific literature on renewable energy applications and aims to inform policymakers, healthcare practitioners, and technology developers about the potential and challenges of solar-powered refrigeration solutions for resource-limited areas
Performance evaluation of a hybrid photovoltaic-vapor compression system serving a refrigerated van
No full textThe refrigerated transportation industry's growth necessitates addressing energy consumption and greenhouse gas emissions. This study estimates a photovoltaic system's energy and environmental benefits to power a vapour compression refrigeration (VCR) system serving a light-duty commercial refrigerated van. A comprehensive energy model encompassing thermal, electrical, and battery sub-models simulating the system's dynamic behaviour is calibrated with real-world data referring to an urban single-delivery mission. The potential benefits are estimated for a long-distance single-delivery mission starting from the University of Salerno (Italy) and ending at the Jaume I University in Castellon de la Plana (Spain). The results have shown that the system can reduce fuel consumption for refrigeration by more than 88 % during summer months and allows neutral refrigeration during winter months, leading to on-wheel emission savings between 4 and 8 gCO2,e/km. When considering total emissions, including electrical energy from the power grid and the increased weight due to the PV system, a 33-47 % reduction is obtained, corresponding to 1-5 gCO2,e/km. In detail, PV panels can cover up to 19 % of the total energy requirements. In economic terms, the system allows a cost-saving between 0.1 and 0.3 c/km. The low complexity and promising results suggest the hybrid PV solution is a viable path towards decarbonising refrigerated transport
Solar-Powered Refrigeration for Sustainable Refrigerated Transport
No full textSolar-powered refrigeration systems offer a feasible and promising solution for enhancing the sustainability of refrigerated transportation. This paper provides a comprehensive overview of the design and construction of a solar-powered refrigeration unit tailored for a refrigerated van, featuring photovoltaic (PV) panels mounted on the rooftop of the refrigerated box. The key components and operational mechanisms of the unit are also highlighted. The study reports on five preliminary experimental tests conducted to validate the feasibility and efficacy of a transport refrigeration unit (TRU) powered by solar energy. These tests demonstrate the impact of the PV solar system on the energy balance of the refrigerated unit under various environmental and operational conditions. The results indicate that the photovoltaic system enables autonomous operation of the refrigeration unit for 2.5 hours at a set point of -18°C (suitable for frozen products) and over 5 hours at +4°C (suitable for fresh products), assuming afternoon deliveries starting at 14:00 with climatic conditions typical of June and July in Fisciano, Salerno, Italy. These findings support the feasibility of sustainable regional and inter-regional transportation. The study also evaluates the effect of different starting times, revealing an increase in the duration of autonomous operation by up to 35% for transportation at 0°C when the start time is shifted from 14:00 to 11:00. Furthermore, the research assesses emission savings, identifying reductions between 4.1 and 4.4 kgCO2,e per delivery at set point temperatures of -18 °C and +4 °C, respectively. This range is even wider when considering earlier starting time (up to 5.4 kgCO2,e per delivery in the tests performed). This underscores the significant potential of solar-powered solutions in advancing the decarbonization of the cold chain. This research aims to inform policymakers and technology developers about the potential of deploying solar-based solutions in the refrigerated transport sector
A review on thermal management of battery packs for electric vehicles
Full text linkThe development of efficient Electric Vehicles (EVs) is related to the management of different parts of the powertrain, as the Lithium-ion (Li-ion) batteries. An important feature which affects their safety, performance, and useful life is the average temperature which must be included in an optimal range to prevent several dangerous phenomena. For this reason, Thermal Management Systems (TMSs) of battery packs of EVs are necessary to guarantee correct functioning in all environments and operating conditions. This review has the intention to divulge the recent developments in the thermal management of Li-ion batteries of EVs reached by researchers and car manufacturers to compare academic studies to the state of the art of the automotive industry from a thermal engineering point of view. Several experimental and numerical studies published in literature have been reported, and nine EV models have been analysed to explain how car manufacturers have developed their new models launched on the market. The choice of the models has been made since the quantity and the quality of data available on the official sites of manufacturers and specialist journals. In conclusion, the future perspectives of thermal management of battery packs are resumed to understand which path research and car manufacturers are following for the next generation of EVs
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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