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The proper design and installation of systems that enable the efficient control and removal of smoke and hot gases in underground parking facilities are necessary for protecting the public and property in the event of a fire. This paper discusses how studies using Computational Fluid Dynamics (CFD) related to smoke venting have contributed to improving fire safety in underground parking facilities. As vehicle fire incidents continue to rise globally, particularly in regions with a high density of underground parking, the need for comprehensive measures to mitigate these incidents has become increasingly urgent. This paper examines the applicability of CFD as a tool to address the challenges of smoke control in underground car parks, including those caused by fires involving electric vehicles. CFD application under various fire scenarios and ventilation strategies allows for identifying more effective smoke removal solutions, improving the protection of occupants and property. However, despite the potential of CFD simulations to enhance fire safety and smoke exhaust efficiency in underground parking, it is important to recognize the limitations of these simulations, particularly in dealing with the complex challenges posed by electric vehicle fires. [ABSTRACT FROM AUTHOR]

In the actual context of growing concerns over sustainability and energy efficiency, Phase Change Materials (PCMs) have gained attention as promising solutions for enhancing energy storage and release efficiency. On another hand, materials based on graphene oxide (GO) have proven antibacterial activity, biocompatibility, efficiency in microbial growth inhibition, and pollutant removal. Integrating nanoparticles into PCMs and creating Nano-Enhanced Phase Change Materials (NEPCMs) have opened new horizons for optimizing the performance of these systems and sustainable development. The key objective of this work is to gain insight into NECPMs, which are used in solar wall systems to enhance solar energy storage. Paraffin RT31 was mixed with Cu nanoparticles, graphene oxide (GO), and Cu-decorated GO (Cu@GO) at loading ratios ranging from 1% to 4% (w/w nanoparticles with respect to RT31). The compositions were characterized through Differential Scanning Calorimetry (DSC) and rheology tests. The decoration of the carbon-based nanoparticles was performed using the ultrasonication procedure, and the decoration efficiency was confirmed through X-ray Photoelectron Spectroscopy (XPS). The rheologic measurements were performed to correlate the flow behavior of the NEPCM with their composition at various temperatures. The study methodically investigated these composites' latent heat values, phase change peak temperatures, and solidification phase change temperatures. Compared to pure paraffin, the solidification of the formulations obtained using Cu@GO exhibits the largest increase in latent heat, with a 12.07% growth at a concentration of 2%. Additionally, at a 4% concentration of NEPCM, the largest increase in thermal conductivity was attained, namely 12.5%. [ABSTRACT FROM AUTHOR]

Fire simulation is a crucial tool in modern engineering for improving fire safety in constructions, especially in complex compartmental designs. It provides practical insights into structural fire behavior, the impact of combustible materials, and fire development, aiding in the formulation of effective fire safety measures. PyroSim, a graphical interface based on the Fire Dynamics Simulator (FDS), simplifies the creation and management of complex fire models. It supports file imports from AutoCAD DXF and DWG formats, offers background options from GIF, JPG, or PNG drawings, and includes tools for creating and validating multiple meshes. These simulations are essential for obtaining comprehensive data on various fire-related properties, such as temperatures, gas concentrations, smoke volume, pressures, and more, to ensure alignment with real-world conditions. [ABSTRACT FROM AUTHOR]

Silica aerogel has remarkable properties, particularly its translucence/transparency, extremely low thermal conductivity and density. Due to these properties, it can be used for the thermal insulation of buildings for energy saving, cost saving, and enhanced comfort. In this context, aerogel products such as aerogel blankets have already started to demonstrate their effectiveness in retrofitting projects and the development and adoption of aerogel glazing systems and aerogel-enhanced renders is promising. Other products, for example, through the incorporation of silica aerogel granules in cement and lime renders were obtained, with high thermal insulation properties, to achieve energy efficiency on buildings facades. This research aims to come up with new aerogel particle composition insulation plasters at cost-effective rates for application in building insulation. Their physical apparent mass density, mechanical–flexural and compressive strengths, thermal conductivity, and properties were investigated. As an experimental study, the thermal conductivities of six sets of cement and lime plasters with aerogel particles (0.1–4.0 mm) were investigated and it was concluded that the thermal conductivity of cement and lime plasters with 80% aerogel was 0.2287 W·m−1·K−1, about 3.4 times smaller than the respective value of traditional lightweight plasters of 0.76 W·m−1·K−1, while the cement and lime plasters with less than 40% aerogel showed a thermal conductivity value as low as 0.3172 W·m−1·K−1. It was confirmed that the end product plasters' mechanical qualities included low apparent mass densities, no apparent shrinkage, and mechanical strength values that matched those of the prepared compositions. This suggests that the obtained plasters are suitable for use in both new constructions and renovation projects. [ABSTRACT FROM AUTHOR]

This study aimed to obtain and characterize a mortar with perlite aggregate and thermal-treated materials that could substitute for Portland cement. First, the thermally treated materials were obtained by calcinating old Portland cement (OC-tt) and concrete demolition waste (CC-tt) at 550 °C, for 3 h. Second, plastic mortars with a perlite: cement volume ratio of 3:1 were prepared and tested for water absorption, mechanical strength, and thermal conductivity. The microstructure was also analyzed. Portland cement (R) was partially substituted with 10%, 30%, and 50% OC-tt. Thermal-treated materials negatively influenced the compressive and flexural strengths at 7 and 28 days. With an increase in the substitution percentage to 50%, the decrease in the compressive strength was 40% for OC-tt and 62.5% for CC-tt. The presence of 10% OC-tt/CC-tt positively influenced the water absorption. The thermal conductivity of the tested mortars was in the range of 0.37–0.48 W/m·K. SEM analysis shows the expanded perlite pores remained unbroken. [ABSTRACT FROM AUTHOR]

The increasing concerns about CO2 emissions and climate change have pointed out the urgency of promoting sustainability in the building sector. One promising solution to enhance the energy efficiency of buildings and diminish environmental impact is the integration of phase-change materials (PCMs) into ventilated façade systems. This review article critically examines the current state of research on this innovative approach, with a particular focus on fire safety considerations. The paper explores the integration of PCM into ventilated façades, highlighting the potential for significant improvements in energy consumption, thermal comfort, and reductions in CO2 emissions. However, the flammability of PCMs introduces substantial fire safety challenges that must be addressed to ensure the safe application of this solution. The fire safety of both ventilated façades and PCMs is approached, followed by specific fire safety concerns when PCMs are integrated into ventilated façade systems. The conclusion states that while the integration of PCMs into ventilated façades offers substantial environmental benefits, attention to fire safety is essential. This necessitates the implementation of rigorous fire protection measures during the design and construction phases. By addressing both the environmental advantages and fire safety challenges, this review aims to provide a comprehensive understanding of the potential and limitations of PCM-integrated ventilated façades, offering valuable insights for researchers, engineers, and policymakers in the field of sustainable buildings. [ABSTRACT FROM AUTHOR]

The current trends converge towards minimizing the carbon footprint on the environment in the operation of all thermal equipment and need finding alternative solutions compared to what the market offers at the moment. Utilizing hydrogen in combustible mixtures with methane gas to fuel condensing boilers is one solution. The benefit is that it reduces carbon dioxide emissions into the atmosphere as only water vapor is produced when hydrogen undergoes combustion. The effects of adding hydrogen at percentages of 23%, 30%, 35% and 45%, respectively, to the combustible gas mixture are examined in the paper. [ABSTRACT FROM AUTHOR]

Maximizing the quantity of heat delivered to the air is one of the difficulties dealt with by solar collectors used for air heating. In order to increase the quantity of heat delivered by the phase change materials with integrated nano materials, a thermal insulation solution is investigated in this work to reduce losses to the adjacent regions. A mobile insulating blanket that is fully mechanized is the solution. The time of day or the season determines where to set the insulating blanket. [ABSTRACT FROM AUTHOR]

In the paper the authors analyze the possibility of using the energy recovered from combustion gases, for air cooling. The objective is to evaluate the thermal potential of combustion gases from a cogeneration plant with a 3 MW electric power, located in Buzau. The monitoring data for the cogeneration system shows that the average flue gas temperature at the exit to the atmosphere is 125° C and the mass flow rate of the combustion gases is 18351 kg/h. The thermal potential of combustion gases isused for the preparation of hot water at 85°C for the operation of a LiBr-H2O solution absorption plant. Finally, the authors present a comparative study between the classic cooling system using chiller with mechanical vapor compression (VCM) and the absorption plant supplied by recovered energy from the cogeneration system, high lighting the advantage of the proposed trigeneration system.

The article presents a theoretical and experimental analysis that highlights how the employment of a hydrogen- methane mixture influences the variation of the fuel flow for wall-mounted boilers and also aims to evaluate whether fuel economy may be achieved. For a 28 kW condensing boiler, at 50/30 °C water outlet/inlet operating regime and for 2800 h functioning, 431 m3 of methane gas were saved when using a 23% hydrogenmethane combustible. Correspondingly, at 80/60 °C working regime 599.3 m3 of methane economy was achieved. The theoretical increasing of the combustible flow of 23,2% is validated by the value obtained experimentally of 22.84% respectively, when the mixture is utilized [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

This paper presents a technical study on energy consumption and performance of a refrigeration system used for food products refrigeration and congelation. The authors compared the two-stage refrigeration system with the cascade refrigeration system. The analysis was based on the thermodynamic cycles corresponding to each one of the proposed solutions. For the booster system several refrigerants were considered in the analysis for the upper loop, respectively R717, R404A, R407C and R417A. Based on the total energy consumption of the installation (compressor, fans, recirculation pumps), the overall performance coefficient of the installation was determined. The study showed that the lowest electrical energy consumption corresponds to the cascade refrigeration system with R717-R744 and the two-stage compression refrigeration system with R717. The difference between the 2 optimal variants is only 4.6%. Therefore, it is recommended that the choice of the final scheme to be made on the basis of an LCC (Life cycle cost) analyze, which takes into account the refrigerant charge, the initial investment cost, the operating costs and the electricity cost. [ABSTRACT FROM AUTHOR]

Copyright of Romanian Journal of Civil Engineering / Revista Română de Inginerie Civilă is the property of Matrix Rom 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.)

Copyright of Romanian Journal of Civil Engineering / Revista Română de Inginerie Civilă is the property of Matrix Rom 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.)

Copyright of Romanian Journal of Civil Engineering / Revista Română de Inginerie Civilă is the property of Matrix Rom 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.)

This paper develops a theoretical and experimental study on convective heat transfer characteristics in a mini-channel type air-cooler, operating with ice-slurry. Although ice slurry is usually employed as a secondary fluid in air conditioning systems, this paper investigates its behaviour as a primary fluid. Furthermore, since previous investigations on ice slurry mostly referred to plate heat exchangers, little information is yet available in the literature regarding ice slurry use in mini-channel heat exchangers, this study employed several correlations recommended by the open literature for binary mediums, such as ice-slurry, in order to identify the best fitted correlation in terms of best agreement with the experimental results obtained for the given geometrical configuration of the heat exchanger, ice mass fraction, and specific operating conditions. Besides the theoretical study, the authors have also developed an experimental study and a comparative analysis of theoretical vs. experimental results with respect to the heat transfer coefficient on ice-slurry side as a function of ice mass fraction, of ice-slurry flow rate and air flow rate. [ABSTRACT FROM AUTHOR]

Copyright of Romanian Journal of Civil Engineering / Revista Română de Inginerie Civilă is the property of Matrix Rom 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.)

Copyright of Romanian Journal of Civil Engineering / Revista Română de Inginerie Civilă is the property of Matrix Rom 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.)