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Urban Sustainability and Resilience of the Built Environments

A special issue of Applied Sciences (ISSN 2076-3417). This special issue belongs to the section "Environmental Sciences".

Deadline for manuscript submissions: closed (30 November 2022) | Viewed by 57839

Special Issue Editors


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Guest Editor
Building Services Engineering Faculty, Technical University of Civil Engineering of Bucharest, Bd. Pache Protopopescu no. 66, 021412 Bucharest, Romania
Interests: passive control of jet flows; experimental fluid mechanics; thermal comfort; optical measurement techniques; laser diagnostic
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Guest Editor
Department of Thermal Machines and Equipment , Universitatea Tehnica Cluj-Napoca, 400114 Cluj-Napoca, Romania
Interests: fluid mechanics; numerical simulation; turbulence; turbulence modeling; fluid flow; CFD simulation; turbulent flow; mechanical engineering
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Urbanization and urban areas are profoundly altering the relationship between society and the environment. It aims at understanding existing urban dynamics and responding to the challenges of creating livable urban futures. The built environment includes human-made building and infrastructure stocks that constitute the physical, natural, economic, social and cultural capital. Even with elevated scholarly attention, strategies for bridging between research and practice remain elusive, and efforts to understand and affect change towards more sustainable and resilient urban centers in the built environment have often fallen short.

This Special Issue seeks to showcase recent developments, disruptive new concepts, validated simulations and creative applications of urban sustainability and resilience of the built environment. Submissions are expected to focus on urban governance, urban planning, sustainable development and resilience, environmental and hazard governance, climate risk adaptation and mitigation, including energy-efficient solutions, and the built environment in general.

We hope this Special Issue will bring together diverse ideas in the field of urban sustainability and resilience of the built environment, demonstrating exiting new practices and pointing out future directions in research and development.

Dr. Ilinca Nastase
Dr. Florin Ioan Bode
Guest Editors

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Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2400 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Published Papers (21 papers)

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Editorial

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8 pages, 216 KiB  
Editorial
Special Issue “Urban Sustainability and Resilience of the Built Environments”
by Ilinca Nastase and Florin Ioan Bode
Appl. Sci. 2023, 13(1), 524; https://doi.org/10.3390/app13010524 - 30 Dec 2022
Viewed by 818
Abstract
Urbanization and the development of urban areas are profoundly altering the relationship between society and the environment [...] Full article
(This article belongs to the Special Issue Urban Sustainability and Resilience of the Built Environments)

Research

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19 pages, 5965 KiB  
Article
GIS-Based Urban Traffic Assessment in a Historical European City under the Influence of Infrastructure Works and COVID-19
by Gabriela Droj, Laurențiu Droj, Ana-Cornelia Badea and Petre Iuliu Dragomir
Appl. Sci. 2023, 13(3), 1355; https://doi.org/10.3390/app13031355 - 19 Jan 2023
Cited by 5 | Viewed by 2347
Abstract
Urban areas have developed organically over time, driven by the economic success of cities. However, this development has usually been accompanied by the side effects of urbanization, such as increased traffic and its associated problems: traffic congestion, increased accident rates and pollution. As [...] Read more.
Urban areas have developed organically over time, driven by the economic success of cities. However, this development has usually been accompanied by the side effects of urbanization, such as increased traffic and its associated problems: traffic congestion, increased accident rates and pollution. As urban populations grow and expand, the importance of GIS lies in its ability to collect a large amount of geospatial data, including human-generated data. This data is necessary to understand the complexity of the city, set priorities, solve complicated planning problems and perform a variety of spatial analysis, which shows not only the feasibility but also the consistency of the proposed infrastructure with the requirements of a sustainable city. In this paper, we demonstrate the benefits of integrating real-time traffic data with GIS technology and remote sensing data for analyzing the impact of infrastructure works and COVID-19 on traffic in Oradea, Romania. The case study was focused on the historical center of Oradea and was based on remote sensing data collected before, during, and after traffic restrictions. The study also shows the need for using GIS and crowdsourcing-based applications in traffic analysis and planning. Full article
(This article belongs to the Special Issue Urban Sustainability and Resilience of the Built Environments)
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18 pages, 5488 KiB  
Article
Experimental Investigation and Optimization of a Glazed Transpired Solar Collector
by Catalin Ioan Teodosiu, Catalin Sima, Cristiana Croitoru and Florin Bode
Appl. Sci. 2022, 12(22), 11392; https://doi.org/10.3390/app122211392 - 10 Nov 2022
Cited by 1 | Viewed by 1011
Abstract
Solar air collectors are increasingly used nowadays due to their important potential in reducing the energy consumption of buildings. In this context, glazed transpired solar collectors (GTCs) represent an interesting solution, but this type of solar air collector is less studied. Consequently, the [...] Read more.
Solar air collectors are increasingly used nowadays due to their important potential in reducing the energy consumption of buildings. In this context, glazed transpired solar collectors (GTCs) represent an interesting solution, but this type of solar air collector is less studied. Consequently, the objective of this work is to thoroughly assess the performance of a GTC prototype under real long-term climatic conditions. First, the design of the GTC is optimized based on methodically experimental tests. The results show that the GTC configuration with a 30 mm air gap among the absorber and the glazing leads to improved heat transfer efficiency and superior global effectiveness, regardless of airflow rates through the solar air collector. This optimized GTC configuration is further studied by integration within the façade of a full-scale experimental building (container-type, light structure). Comparative experimental studies are then carried out concerning the heating energy consumption and ventilation load of the experimental building without/with GTC implemented in the ventilation system, under Bucharest real weather conditions. The data achieved indicate that the GTC prototype is capable of substantially reducing the ventilation load: up to 25% for low solar radiation (below 200 W/m2) and over 50% (achieving even 90%) for moderate solar radiation (between 250 and 380 W/m2). Finally, for high solar radiation (over 400 W/m2), the GTC outlet air temperature exceeds the interior temperature set-point (22 °C) of the experimental building. Full article
(This article belongs to the Special Issue Urban Sustainability and Resilience of the Built Environments)
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22 pages, 6451 KiB  
Article
Design and Simulation of a Solar Tracking System for PV
by Fatima Zohra Baouche, Bilal Abderezzak, Abdennour Ladmi, Karim Arbaoui, George Suciu, Traian Candin Mihaltan, Maria Simona Raboaca, Sebastian Valeriu Hudișteanu and Florin Emilian Țurcanu
Appl. Sci. 2022, 12(19), 9682; https://doi.org/10.3390/app12199682 - 27 Sep 2022
Cited by 18 | Viewed by 13543
Abstract
After installing a solar panel system, the orientation problem arises because of the sun’s position variation relative to a collection point throughout the day. It is, therefore, necessary to change the position of the photovoltaic panels to follow the sun and capture the [...] Read more.
After installing a solar panel system, the orientation problem arises because of the sun’s position variation relative to a collection point throughout the day. It is, therefore, necessary to change the position of the photovoltaic panels to follow the sun and capture the maximum incident beam. This work describes our methodology for the simulation and the design of a solar tracker system using the advantages that the orientation and efficiency of the PV panel offer due to the latitude and the number of hours of sunshine in the testing area. This proposed methodology is experimentally validated through the implementation of a single-axis solar tracker at a specific location (36.261° latitude), which allowed the incorporation of a high-availability tracking mechanism, low precision, and low cost. Based on the results, the feasibility of this type of solar tracker for latitudes close to 36° was demonstrated, as this tracking system costs less than traditional commercial systems. Furthermore, this system increased the collection efficiency compared to a fixed device. Our results provide an excellent platform for engineering technology researchers and students to study the design theory of a sun-tracking solar system. Full article
(This article belongs to the Special Issue Urban Sustainability and Resilience of the Built Environments)
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19 pages, 8763 KiB  
Article
Effect of Wind Direction and Velocity on PV Panels Cooling with Perforated Heat Sinks
by Sebastian Valeriu Hudișteanu, Florin Emilian Țurcanu, Nelu-Cristian Cherecheș, Cătălin-George Popovici, Marina Verdeș, Diana-Ana Ancaș and Iuliana Hudișteanu
Appl. Sci. 2022, 12(19), 9665; https://doi.org/10.3390/app12199665 - 26 Sep 2022
Cited by 5 | Viewed by 1554
Abstract
The numerical modeling of the effect of wind direction and velocity over the air cooling of PV panels with heat sinks is realized. During the study, a random PV panel with typical characteristics was analyzed for three different wind directions—towards its back, towards [...] Read more.
The numerical modeling of the effect of wind direction and velocity over the air cooling of PV panels with heat sinks is realized. During the study, a random PV panel with typical characteristics was analyzed for three different wind directions—towards its back, towards its front and from the side. The analysis was realized on a fixed PV panel, oriented to the south, with an inclination of 45 degrees from the horizontal position. The accuracy of the numerical simulation was achieved by comparison with the experimental studies presented in the literature and by comparing the NOCT conditions. The numerical study is focused on different types of heat sinks attached to a typical PV panel. The fins were distributed both horizontally and vertically. A challenging task consisted in simulation of the real wind conditions around the PV panel by taking into account the entire air domain. The simulations were realized for air velocity vair from 1 m/s to 5 m/s, solar radiation of G = 1000 W/m2 and ambient temperature tair = 35 °C. The output parameters analyzed were the average temperature of PV panels and their power production. Although the lowest temperatures were achieved for the back wind, the cooling effect was more intense for the side wind. The other direction studied also determined the cooling of PV panels. The passive cooling solutions analyzed introduced a rise of maximum power production between 1.85% and 7.71% above the base case, depending on the wind direction and velocity. Full article
(This article belongs to the Special Issue Urban Sustainability and Resilience of the Built Environments)
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29 pages, 13301 KiB  
Article
Numerical Study on the Impact of Platform Screen Doors in a Subway Station with a Train on Fire
by Catalin Ioan Teodosiu and Vladimir Francisc Kubinyecz
Appl. Sci. 2022, 12(16), 8296; https://doi.org/10.3390/app12168296 - 19 Aug 2022
Cited by 3 | Viewed by 2279
Abstract
Almost all recently built subway stations are equipped with Platform Screen Doors (PSDs) due to the numerous proven benefits of these systems. In addition, PSDs are now being introduced in existing subway stations, but their operation in conjunction with previously designed ventilation systems [...] Read more.
Almost all recently built subway stations are equipped with Platform Screen Doors (PSDs) due to the numerous proven benefits of these systems. In addition, PSDs are now being introduced in existing subway stations, but their operation in conjunction with previously designed ventilation systems in case of emergency should be deeply studied. In this context, the objective of this study is to assess the efficiency of the planned emergency strategy (coupled operation, ventilation systems–PSDs system) in the case of trains on fire stopped at the platform of a subway station retrofitted with PSDs. The approach is based on Computational Fluid Dynamics (CFD) full-scale simulations to predict the airflow, temperature, and pollutant (carbon monoxide—CO and carbon dioxide—CO2) concentrations caused by the fire. The results show the evident contribution of PSDs in stopping the dispersion of hot and polluted air in the subway station during the entire simulation time (20 min from the arrival of the train on fire). Consequently, the investigated emergency strategy (exhausting air both through the “over track system” and the “under platform system”, simultaneously with the opening of the PSDs on the side with the train on fire) assures the safe evacuation of passengers as soon as they have left the subway train. The results indicate that access to the platform is not perturbed by high temperatures or dangerous concentrations of CO and CO2. Full article
(This article belongs to the Special Issue Urban Sustainability and Resilience of the Built Environments)
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14 pages, 3076 KiB  
Article
CO2 Emissions Reduction through Increasing H2 Participation in Gaseous Combustible—Condensing Boilers Functional Response
by Nicolae N. Antonescu, Dan-Paul Stănescu and Răzvan Calotă
Appl. Sci. 2022, 12(8), 3831; https://doi.org/10.3390/app12083831 - 11 Apr 2022
Cited by 8 | Viewed by 1422
Abstract
Considering the imperative reduction in CO2 emissions, both from household heating and hot water producing facilities, one of the mainstream directions is to reduce hydrocarbons in combustibles by replacing them with hydrogen. The authors analyze condensing boilers operating when hydrogen is mixed [...] Read more.
Considering the imperative reduction in CO2 emissions, both from household heating and hot water producing facilities, one of the mainstream directions is to reduce hydrocarbons in combustibles by replacing them with hydrogen. The authors analyze condensing boilers operating when hydrogen is mixed with standard gaseous fuel (CH4). The hydrogen (H2) volumetric participation in the mixture is considered to vary in the range of 0 to 20%. The operation of the condensing boilers will be numerically modeled by computational programs and prior validated by experimental studies concluded in a European Certified Laboratory. The study concluded that an increase in the combustible flow with 16% will compensate the maximum H2 concentration situation with no other implications on the boiler’s thermal efficiency, together with a decrease in CO2 emissions by approximately 7%. By assuming 0.9 (to/year/boiler), the value of CO2 emissions reduction for the condensing boiler determined in the paper, and extrapolating it for the estimated number of boilers to be sold for the period 2019–2024, a 254,700-ton CO2/year reduction resulted. Full article
(This article belongs to the Special Issue Urban Sustainability and Resilience of the Built Environments)
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21 pages, 12915 KiB  
Article
Delineation of the Flooded Areas in Urban Environments Based on a Simplified Approach
by Cristian Dinu, Nicolai Sîrbu and Radu Drobot
Appl. Sci. 2022, 12(6), 3174; https://doi.org/10.3390/app12063174 - 20 Mar 2022
Cited by 3 | Viewed by 2062
Abstract
The Tulcea municipality is frequently exposed to rainfall-generated floods, with its lower downtown area (located in the Danube’ former meadow, now protected by dikes) being flooded two to three times per year. In this study, our objective was to understand the generation mechanism [...] Read more.
The Tulcea municipality is frequently exposed to rainfall-generated floods, with its lower downtown area (located in the Danube’ former meadow, now protected by dikes) being flooded two to three times per year. In this study, our objective was to understand the generation mechanism of these rainfall-triggered urban floods and to identify tailored mitigation options. Due to the lack of reliable information on the sewage network (diameters, slope, material) and the uncertain sewage outflows during heavy rain events, a rather simplified approach was preferred by the authors of this paper. The data processing was performed using GIS tools, with appropriate accounting of the digital terrain modelling, ortho-photos, administrative boundaries of the Tulcea municipality, delineation of the urban catchments, imagery of the frequently flooded areas, and the urban sewage network. Subsequently, a fast hydrological modelling and a volume-based flooding approach were developed in order to identify and evaluate the flooded urban areas under extreme rainfall events. Upon the completion of the calibration and validation processes, numerical simulations were run that considered the design storms of different return periods. Due to the high slopes of the hills, hence the short concentration time of the pluvial waters, a Sponge City approach does not seem as though it would be easy to implement. A more efficient solution utilising large-capacity buried urban retention tanks in the lower part of the municipality was alternatively identified. Further on, this solution will be supported by a set of green measures. Full article
(This article belongs to the Special Issue Urban Sustainability and Resilience of the Built Environments)
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24 pages, 110920 KiB  
Article
Personalized Ventilation as a Possible Strategy for Reducing Airborne Infectious Disease Transmission on Commercial Aircraft
by Paul Danca, Costin Ioan Coşoiu, Ilinca Nastase, Florin Bode and Matei Razvan Georgescu
Appl. Sci. 2022, 12(4), 2088; https://doi.org/10.3390/app12042088 - 17 Feb 2022
Cited by 8 | Viewed by 2579
Abstract
In the last decade, there has been an increase in ease and affordability of air travel in terms of mobility for people all around the world. Airplane passengers may experience different risks of contracting airborne infectious diseases onboard aircraft, such as influenza or [...] Read more.
In the last decade, there has been an increase in ease and affordability of air travel in terms of mobility for people all around the world. Airplane passengers may experience different risks of contracting airborne infectious diseases onboard aircraft, such as influenza or severe acute respiratory syndrome (SARS-CoV-1 and SARS-CoV-2), due to nonuniform airflow patterns inside the airplane cabin or proximity to an infected person. In this paper, a novel approach for reducing the risk of contracting airborne infectious diseases is presented that uses a low-momentum personalized ventilation system with a protective role against airborne pathogens. Numerical simulations, supported by nonintrusive experimental measurements for validation purposes, were used to demonstrate the effectiveness of the proposed system. Simulation and experimental results of the low-momentum personalized ventilation system showed the formation of a microclimate around each passenger with cleaner and fresher air than produced by the general mixing ventilation systems. Full article
(This article belongs to the Special Issue Urban Sustainability and Resilience of the Built Environments)
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24 pages, 22486 KiB  
Article
Advanced Thermal Manikin for Thermal Comfort Assessment in Vehicles and Buildings
by Dragoş Daniel Ion-Guţă, Ioan Ursu, Adrian Toader, Daniela Enciu, Paul Alexandru Dancă, Ilinca Nastase, Cristiana Verona Croitoru, Florin Ioan Bode and Mihnea Sandu
Appl. Sci. 2022, 12(4), 1826; https://doi.org/10.3390/app12041826 - 10 Feb 2022
Cited by 7 | Viewed by 2710
Abstract
Among the factors that influence the resilience and sustainability of cities in general, and of inhabited spaces in particular, there are extreme temperatures and, in particular, for people, thermal comfort is something that should be considered. This problem includes all aspects of comfort [...] Read more.
Among the factors that influence the resilience and sustainability of cities in general, and of inhabited spaces in particular, there are extreme temperatures and, in particular, for people, thermal comfort is something that should be considered. This problem includes all aspects of comfort for users of inhabited spaces in both buildings and vehicles. The purpose of this paper is to present the details of a recently designed and created thermal manikin that comprises 79 superficial zones with independent neuro-fuzzy temperature regulation. Both the component parts of the manikin and the acceptance strategy are described. Flexible heating elements were used to control the temperature, on which five digital sensors are positioned. In order to establish the relationship between heat loss and ambient temperature, the thermal manikin was calibrated in a climatic chamber. The thermal manikin was able to predict local sensations through the equivalent temperature concept of the so-called Predicted Mean Vote. Full article
(This article belongs to the Special Issue Urban Sustainability and Resilience of the Built Environments)
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10 pages, 3878 KiB  
Article
Asphalt Heat Recovery Application for Sustainable Green Energy
by Angel Dogeanu, Laurentiu Tacutu, Elena Iatan, Alin-Marius Nicolae and Catalin Ioan Lungu
Appl. Sci. 2022, 12(3), 1196; https://doi.org/10.3390/app12031196 - 24 Jan 2022
Cited by 5 | Viewed by 2419
Abstract
Increasing demand for energy due to comfort requirements in the built environment coupled with development of road networks and amplifying heat island effect call for a comprehensive approach that can answer both issues. The lifespan of an asphalt layer is affected by surface [...] Read more.
Increasing demand for energy due to comfort requirements in the built environment coupled with development of road networks and amplifying heat island effect call for a comprehensive approach that can answer both issues. The lifespan of an asphalt layer is affected by surface temperature. In this paper, we aim to study the feasibility of heat recovery and its effects in terms of energy harvesting efficiency and asphalt surface temperature by creating a numerical model and validating the model based on onsite measurements at laboratory scale. The experimental setup was developed at Technical University of Civil Engineering in Bucharest, and measurements were monitored during the summer. The heat recovery system used for this study was made of copper pipes, and material cost and layout optimization need to be addressed in future studies. The numerical model was validated using measured data. During this study, we obtained favorable results in terms of heat recovery, reducing surface temperature and selection of system materials. Further research is required for heat recovery system and pump automation (based on the surface temperature), in order to optimize energy consumption and improve overall efficiency. Full article
(This article belongs to the Special Issue Urban Sustainability and Resilience of the Built Environments)
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19 pages, 5609 KiB  
Article
Experimental and Numerical Study for a Novel Arrangement of a SuperCapacitors Stack to Improve Heat Transfer
by Ionut Victor Voicu, Florin Bode, Wassim Abboud, Hasna Louahlia, Hamid Gualous, Mihnea Sandu and Ilinca Nastase
Appl. Sci. 2022, 12(2), 662; https://doi.org/10.3390/app12020662 - 10 Jan 2022
Cited by 3 | Viewed by 1619
Abstract
Supercapacitors (SCs) are electrical energy storage devices which have the peculiarity of storing more electrical energy than capacitors and supply it at higher power outputs than batteries. This, together with the fact that the SCs have high cyclability and long-term stability, make them [...] Read more.
Supercapacitors (SCs) are electrical energy storage devices which have the peculiarity of storing more electrical energy than capacitors and supply it at higher power outputs than batteries. This, together with the fact that the SCs have high cyclability and long-term stability, make them very attractive devices for electrical energy storage. Thermal transfer around a novel arrangement of a module of five rows of SCs is approached in this paper. A mixed aligned/staggered configuration is studied, aiming to explore a new possibility that can improve heat transfer more than other configurations studied before in the literature. The maximum SC current rate current is 84 A and the maximum temperature is 65 °C. The module undergoes charge and discharge cycles. The current tests are performed up to 50 A for natural convection and up to 70 A in forced convection. For the natural convection case, the SC located in the center of module is the most critical from the temperature point of view and the temperature evolution shows the necessity of a cooling system. The relative temperature reaches 27 °C for 50 A and the permanent regime cannot be reached with a current greater than 50 A. Thereafter, the impact of position and current on the temperature of SCs in forced convection is examined. The airflow mean air velocity is 0.69 m/s. The temperature of the SCs located on the third and fourth row are very close. However, the last row is the least cooled. This low temperature rise can be explained by the change from an aligned to a staggered arrangement between these rows. Compared to the natural convection case, a significant decrease is observed for the relative temperatures. The difference between the highest and lowest temperature augmentation also decrease but remain high. The temperature difference becomes greater than 5 °C if continuous current exceeds 39 A. CFD numerical simulation is performed for steady state at maximum experimental current rate in order to better understand the thermal and flow behavior. Numerical and experimental results are in good agreement, with a temperature deviation of less than 10%. Full article
(This article belongs to the Special Issue Urban Sustainability and Resilience of the Built Environments)
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17 pages, 3002 KiB  
Article
Numerical and Parametric Analysis for Enhancing Performances of Water Photovoltaic/Thermal System
by Chaimae El Fouas, Nelu Cristian Cherecheș, Sebastian Valeriu Hudișteanu, Bekkay Hajji, Emilian Florin Țurcanu and Monica Lilioara Cherecheș
Appl. Sci. 2022, 12(2), 646; https://doi.org/10.3390/app12020646 - 10 Jan 2022
Cited by 7 | Viewed by 2025
Abstract
Photovoltaic/thermal (PV/T) systems are innovative cogeneration systems that ensure the cooling of photovoltaic (PV) backside and simultaneous production of electricity and heat. However, an effective cooling of the PV back is still a challenge that affects electrical and thermal performance of the PV/T [...] Read more.
Photovoltaic/thermal (PV/T) systems are innovative cogeneration systems that ensure the cooling of photovoltaic (PV) backside and simultaneous production of electricity and heat. However, an effective cooling of the PV back is still a challenge that affects electrical and thermal performance of the PV/T system. In the present work, a PV/T numerical model is developed to simulate the heat flux based on energy balance implemented in MATLAB software. The numerical model is validated through the comparison of the three-layer PV model with the NOCT model and tested under the operation conditions of continental temperate climate. Moreover, the effect of velocity and water film thickness as important flow parameters on heat exchange and PV/T production is numerically investigated. Results revealed that the PV model is in good agreement with the NOCT one. An efficient heat transfer is obtained while increasing the velocity and water film thickness with optimal values of 0.035 m/s and 7 mm, respectively, at an inlet temperature of 20 °C. The PV/T system ensures a maximum thermal power of 1334.5 W and electrical power of 316.56 W (258.8 W for the PV). Finally, the comparison between the PV and PV/T system under real weather conditions showed the advantage of using the PV/T. Full article
(This article belongs to the Special Issue Urban Sustainability and Resilience of the Built Environments)
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18 pages, 25723 KiB  
Article
Numerical Simulation Investigation of a Double Skin Transpired Solar Air Collector
by Charles Berville, Florin Bode and Cristiana Croitoru
Appl. Sci. 2022, 12(1), 520; https://doi.org/10.3390/app12010520 - 5 Jan 2022
Cited by 7 | Viewed by 2229
Abstract
Transpired solar collectors (TSC) are one of the most popular solar thermal technologies for building façades. TSC use solar energy to heat the absorber surface, which transmits thermal energy to the ambient air. A variant of TSC, namely, a double skin transpired solar [...] Read more.
Transpired solar collectors (TSC) are one of the most popular solar thermal technologies for building façades. TSC use solar energy to heat the absorber surface, which transmits thermal energy to the ambient air. A variant of TSC, namely, a double skin transpired solar collector (DSTSC), has been analyzed in this paper, thus providing guide values and a technical point of view for engineers, architects, and constructors when designing such transpired solar collectors. Three important parameters were addressed in this study through numerical simulation: the influence of a separation plate introduced in a TSC, turning it into a DSTSC; the air layer thickness influence on the performance of the collector; and the influence of the used absorber materials for the separation plate material. Greater heat exchange efficiency was noticed for the DSTSC at every imposed airflow rate compared with the TSC. Regarding the thickness of the collector, the efficiency gradually increased when increasing the solar collector thickness until it reached a value of 20 cm, though not varying significantly at a thickness of 30 cm. Full article
(This article belongs to the Special Issue Urban Sustainability and Resilience of the Built Environments)
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22 pages, 13947 KiB  
Article
Experimental Study on Airflow and Temperature Predicting in a Double Skin Façade in Hot and Cold Seasons in Romania
by Monica Lilioara Cherecheș, Nelu Cristian Cherecheș, Adrian Alexandru Ciobanu, Sebastian Valeriu Hudișteanu, Emilian Florin Țurcanu, Aurelia Bradu and Cătălin George Popovici
Appl. Sci. 2021, 11(24), 12139; https://doi.org/10.3390/app112412139 - 20 Dec 2021
Cited by 4 | Viewed by 1926
Abstract
In the context of energy conservation and sustainable development, building design should take into account the energy efficiency criteria by using renewable energy sources. Double-skin facades (DSF) represent innovative energy-efficient techniques that have gained increasing interest worldwide. The present study reports the results [...] Read more.
In the context of energy conservation and sustainable development, building design should take into account the energy efficiency criteria by using renewable energy sources. Double-skin facades (DSF) represent innovative energy-efficient techniques that have gained increasing interest worldwide. The present study reports the results of an experimental campaign performed on a full-scale double-skin façade using the in-situ measurement methodology. The thermodynamic behavior of the façade is studied under real exterior climatic conditions in Romania in hot and cold seasons, and performance indicators in terms of pre-heating efficiency and dynamic insulation efficiency were determined. Three summer periods are analyzed corresponding to the outdoor air curtain scenario for three ventilation modes in naturally or mechanically ventilated single-story DSF. Results revealed that the third ventilation scenario, which combines horizontal and vertical openings, gives the best efficiency of 71.3% in the double skin façade functioning. During the cold season, the channel façade behaved like a thermal buffer between the building and the exterior air, ensuring the thermal energy for partial or integral heating of the building. Full article
(This article belongs to the Special Issue Urban Sustainability and Resilience of the Built Environments)
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20 pages, 6797 KiB  
Article
Numerical Model Development of the Air Temperature Variation in a Room Set on Fire for Different Ventilation Scenarios
by Marius Dorin Lulea, Vlad Iordache and Ilinca Năstase
Appl. Sci. 2021, 11(24), 11698; https://doi.org/10.3390/app112411698 - 9 Dec 2021
Cited by 3 | Viewed by 1510
Abstract
Statistics show that most fires occur in civil residential buildings. Most casualties are due to the inhalation of hot air loaded with smoke, leading to intoxication with substances harmful to the human body. This research aimed to develop a CFD model that relates [...] Read more.
Statistics show that most fires occur in civil residential buildings. Most casualties are due to the inhalation of hot air loaded with smoke, leading to intoxication with substances harmful to the human body. This research aimed to develop a CFD model that relates the operation of the sprinkler system to the operation of the ventilation system through the air temperature in a specific point close to the sprinkler position. A real-scale experiment was carried out, and a CDF model was developed. Several parameters of the CFD model (thermal conductivity of the experimental test room walls, numerical grid elements’ dimensions, burner heat release rate variation) were imposed to the model, so that the resulting entire time variation of the temperature next to the sprinkler location corresponds to the real measured variation. Two other experiments were used to validate the numerical model. Besides the air temperature, at this point, other essential parameters were determined in the entire experimental space: indoor air temperature, visibility, oxygen concentration, and carbon dioxide concentration. We found that if the ventilation rate increases, the indoor temperatures in that specific point decrease, and the sprinkler is activated later or, in some cases, it might never be activated. However, this conclusion is not valid for the entire analyzed space, as the ventilation system alongside the natural air movement imposes specific air speed and specific temperature distribution inside the analyzed space. Full article
(This article belongs to the Special Issue Urban Sustainability and Resilience of the Built Environments)
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13 pages, 5905 KiB  
Article
Experimental and Numerical Study of Thermal Performance of an Innovative Waste Heat Recovery System
by Robert Stefan Vizitiu, Andrei Burlacu, Cherifa Abid, Marina Verdes, Marius Costel Balan and Marius Branoaea
Appl. Sci. 2021, 11(23), 11542; https://doi.org/10.3390/app112311542 - 6 Dec 2021
Cited by 4 | Viewed by 1809
Abstract
One of the biggest challenges the world is facing these days is to reduce the greenhouse gases emissions in order to prevent the global warming. Since a significant quantity of CO2 emissions is the result of the energy producing process required in [...] Read more.
One of the biggest challenges the world is facing these days is to reduce the greenhouse gases emissions in order to prevent the global warming. Since a significant quantity of CO2 emissions is the result of the energy producing process required in industry or buildings, the waste heat recovery is an important aspect in the fight for preserving the planet. In this study, an innovative waste heat recovery system which can recover waste heat energy from cooling liquids used in industry or in different processes, was designed and subjected to experimental investigations. The equipment uses heat pipes to capture thermal energy from the residual fluids transiting the evaporator zone and transfer it to the cold water transiting the condenser zone. The efficiency of the heat exchanger was tested in 9 scenarios, by varying the temperature of the primary agent to 60, 65 and 70 °C and the volume flow rate of the secondary agent to 1, 2 and 3 L/min. The temperature of the secondary agent and the volume flow rate of the primary agent were kept constant at 10 °C, respectively 24 L/min. The results were later validated through numerical simulations, and confirmed that the equipment can easily recover waste thermal energy from used water with low and medium temperatures at very low costs compared to the traditional heat exchangers. The results were promising, revealing an efficiency of the equipment up to 76.7%. Full article
(This article belongs to the Special Issue Urban Sustainability and Resilience of the Built Environments)
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10 pages, 2039 KiB  
Article
Aspects Regarding the Optimal Insulation Thickness, the Cost and Energy Savings for Cold Storage in Romania
by Alina Girip, Răzvan Calotă and Anica Ilie
Appl. Sci. 2021, 11(23), 11455; https://doi.org/10.3390/app112311455 - 3 Dec 2021
Cited by 1 | Viewed by 2599
Abstract
The paper presents a technical and economic analysis regarding the sandwich panels with polyurethane insulation layer (PUR) used in cold stores’ construction. The authors determine the optimal thickness of the insulating layer (OIT) corresponding to the 5 climatic zones in Romania. The operating [...] Read more.
The paper presents a technical and economic analysis regarding the sandwich panels with polyurethane insulation layer (PUR) used in cold stores’ construction. The authors determine the optimal thickness of the insulating layer (OIT) corresponding to the 5 climatic zones in Romania. The operating and investment costs for cold and frozen storage in these 5 climatic zones have been assessed. The results obtained from the analysis show that regardless of the climatic zone, the OIT for cold storage is 150 mm and for frozen storage is 180 mm. The investment cost increases by 41% and the expenditure on operating energy decreases by 8.3% for 180 mm for cold storage in comparison to OIT. Moreover, this tendency is maintained as well in the other case of frozen storage, where, by increasing the thickness above OIT at 200 mm the investment cost is increased by 20% and the expenditure in operating energy is decreased by 6.7%. The SEC has an average value of 54.83 kWh·m3/yr for cold storage and 74.55 kWh·m3/yr for frozen storage respectively. The average values obtained in the paper were compared with those presented in the literature and resulted in deviations of about 1.58% for refrigeration, and hence 4.1% for freezing. Full article
(This article belongs to the Special Issue Urban Sustainability and Resilience of the Built Environments)
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20 pages, 22445 KiB  
Article
Enhancement of PV Panel Power Production by Passive Cooling Using Heat Sinks with Perforated Fins
by Sebastian Valeriu Hudișteanu, Florin Emilian Țurcanu, Nelu Cristian Cherecheș, Cătălin George Popovici, Marina Verdeș and Iuliana Huditeanu
Appl. Sci. 2021, 11(23), 11323; https://doi.org/10.3390/app112311323 - 30 Nov 2021
Cited by 23 | Viewed by 3134
Abstract
This paper presents a numerical model regarding the passive cooling of PV panels through perforated and non-perforated heat sinks. A typical PV panel was studied in a fixed position, tilted at 45 degrees from the horizontal with the wind direction towards its backside. [...] Read more.
This paper presents a numerical model regarding the passive cooling of PV panels through perforated and non-perforated heat sinks. A typical PV panel was studied in a fixed position, tilted at 45 degrees from the horizontal with the wind direction towards its backside. A challenging approach was used in order to calibrate the base case of the numerical model according to the NOCT conditions. Further validation of the accuracy of the numerical simulation consisted of a comparison between the results obtained for the base case, or heat sink, with horizontal non-perforated fins and the experiments presented in the literature. Six types of heat sink attached to the backside of the PV panel were numerically studied. The analyzed configurations focused on heat sinks with both perforated and non-perforated fins that were distributed horizontally and vertically. The CFD simulation was also conducted by modeling the air volume around the PV panel in real wind conditions. The main output parameters were the average temperature and the convective heat transfer coefficient on the front and back of the PV panel. The most important effect of cooling was achieved in low wind conditions and high levels of solar radiation. For vair = 1 m/s, G = 1000 W/m2 and ambient temperature tair = 35 °C, the percentage of maximum power production achieved 83.33% for the base case, while in the best cooling scenario it reached 88.74%, assuring a rise in the power production of 6.49%. Full article
(This article belongs to the Special Issue Urban Sustainability and Resilience of the Built Environments)
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18 pages, 7924 KiB  
Article
Open Tools for Analysis of Elements Related to Public Transport Performance. Case Study: Tram Network in Bucharest
by Liliana Andrei and Oana Luca
Appl. Sci. 2021, 11(21), 10346; https://doi.org/10.3390/app112110346 - 3 Nov 2021
Cited by 2 | Viewed by 3270
Abstract
The present paper aims to be useful for public transport operators and municipalities, as it should enable them to make decisions and to optimize public transport schedules during peak hours. In this study, we outline the data and the means necessary for the [...] Read more.
The present paper aims to be useful for public transport operators and municipalities, as it should enable them to make decisions and to optimize public transport schedules during peak hours. In this study, we outline the data and the means necessary for the creation and use of a specific database for a dynamic spatial analysis of the public transportation network. This will facilitate the analysis of public transport vehicle operating programs and the simulation of new transport programs using open-source software. This paper delivers the first digital map of the public transport in Bucharest. Using the QGIS software and the PostgresSQL database, (i) we analyzed the accessibility of public transport stops for residential areas (5-min isochrones, corresponding to walking distances of 400 m), and (ii) we determined the correlation of transport vehicle programs with the existing transport network to optimize the headway of vehicles. These two elements were considered for the analysis of public transport performance. The research study was based on the tram network in Bucharest, but it can be easily upscaled for the entire public transport network and may be replicated in other large cities. Full article
(This article belongs to the Special Issue Urban Sustainability and Resilience of the Built Environments)
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Review

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24 pages, 3589 KiB  
Review
Seismic Behavior of Micropiles and Micropiled Structures Used for Increasing Resilience: A Literature Review
by Majd Abou Alhaija and Loretta Batali
Appl. Sci. 2022, 12(5), 2743; https://doi.org/10.3390/app12052743 - 7 Mar 2022
Cited by 1 | Viewed by 2703
Abstract
The aim of this paper is to present the relevant information and development available in the scientific literature regarding the seismic behavior of micropiles (MPs) and micropiled structures (MPed). The seismic behavior of MPs is not very well studied, but MPs are used [...] Read more.
The aim of this paper is to present the relevant information and development available in the scientific literature regarding the seismic behavior of micropiles (MPs) and micropiled structures (MPed). The seismic behavior of MPs is not very well studied, but MPs are used in retrofitting of old buildings and for new resilient buildings, and in terms of seismic behavior they have a high potential. Additionally, their association with seismic dampers for improving the seismic behavior of buildings is not yet fully studied and it represents a major topic of interest for both new structures and historical monuments. After the introductory part, the paper describes all relevant information regarding MPs, as types and technology, seismic behavior, applications for increasing seismic resilience, and experimental and numerical modeling. Full article
(This article belongs to the Special Issue Urban Sustainability and Resilience of the Built Environments)
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