Oana Giurgiu

Bio: Oana Giurgiu is an academic researcher from Technical University of Cluj-Napoca. The author has contributed to research in topics: Plate heat exchanger & Heat transfer. The author has an hindex of 3, co-authored 8 publications receiving 80 citations.

The selection of industrial robots for military industry using ahp method: a case study

Abstract: Given the multitude of industrial robots manufacturing companies, the complex structural configuration and the automation degree, the selection of industrial robots in order to carry out specific task, is becoming more and more difficult. In this research paper, the AHP method was applied to select the most favorable configuration of an industrial robot that must perform the technological process of ARC welding of the tracked mini-robots housing, used in military applications. For this purpose, several industrial robots manufacturing companies that are producing industrial robots with different technical specifications were taken into consideration. The study highlights the usefulness in applying decision-making methods in automated technological processes, in order to facilitate and simplify the selection process of the industrial robot, to obtain the best version of industrial robot, from a set of alternatives that carry out one or more specific tasks.

Review on phase change materials for building applications

Abstract: In nowadays, the Phase Change Material (PCM) is a viable alternative for reducing the energy consumption and for increase the thermal comfort in buildings. The use of PCM in building applications provides the potential to increase the indoor thermal comfort for occupants due to the reduced indoor temperature fluctuations and lower global energy consumption. The possibility to incorporate the PCM into the material of construction for cooling and heating the buildings gained the interest of researchers from all the world because the PCM have a high heat of fusion, meaning it is capable to storing and release large amounts of energy in the form of heat during its melting and solidifying process at a specific temperature.

Review on thermal conductivity enhancement, thermal properties and applications of phase change materials in thermal energy storage

Abstract: In recent years, energy conservation and environmental protection have become most important issues for humanity. Phase change materials (PCMs) for thermal energy storage can solve the issues of energy and environment to a certain extent, as PCMs can increase the efficiency and sustainability of energy. PCMs possess large latent heat, and they store and release energy at a constant temperature during the phase change process. Thereby PCMs have gained a wide range of applications in various fields, such as buildings, solar energy systems, power systems and military industry. However, low thermal conductivity of PCMs leads to low heat transfer rate, thus, numerous studies have been carried out to improve thermal conductivity of PCMs. The main purpose of this paper is to review the methods for enhancing thermal conductivity of PCMs, which include adding additives with high thermal conductivity and encapsulating phase change materials. It is found that addition of thermal conductivity enhancement fillers is a more effective method to improve thermal conductivity of PCMs, where carbon-based material additives possess a more promising application prospect. Finally, the applications of PCMs in solar energy system, buildings, cooling system, textiles and heat recovery system are also analyzed.

A New Model for Determining Weight Coefficients of Criteria in MCDM Models: Full Consistency Method (FUCOM)

Abstract: In this paper, a new multi-criteria problem solving method—the Full Consistency Method (FUCOM)—is proposed. The model implies the definition of two groups of constraints that need to satisfy the optimal values of weight coefficients. The first group of constraints is the condition that the relations of the weight coefficients of criteria should be equal to the comparative priorities of the criteria. The second group of constraints is defined on the basis of the conditions of mathematical transitivity. After defining the constraints and solving the model, in addition to optimal weight values, a deviation from full consistency (DFC) is obtained. The degree of DFC is the deviation value of the obtained weight coefficients from the estimated comparative priorities of the criteria. In addition, DFC is also the reliability confirmation of the obtained weights of criteria. In order to illustrate the proposed model and evaluate its performance, FUCOM was tested on several numerical examples from the literature. The model validation was performed by comparing it with the other subjective models (the Best Worst Method (BWM) and Analytic Hierarchy Process (AHP)), based on the pairwise comparisons of the criteria and the validation of the results by using DFC. The results show that FUCOM provides better results than the BWM and AHP methods, when the relation between consistency and the required number of the comparisons of the criteria are taken into consideration. The main advantages of FUCOM in relation to the existing multi-criteria decision-making (MCDM) methods are as follows: (1) a significantly smaller number of pairwise comparisons (only n − 1), (2) a consistent pairwise comparison of criteria, and (3) the calculation of the reliable values of criteria weight coefficients, which contribute to rational judgment.

Critical review of latent heat storage systems for free cooling in buildings

Abstract: Buildings have a major contribution to the global energy consumption. Heating, ventilating and air conditioning systems (HVAC) are responsible for most of the energy use in buildings. Thus, clean and sustainable alternatives such as free cooling of buildings have recently gained much attention as means to reduce the operation hours and capacity of the conventional cooling and heating systems. The free cooling could be provided by collecting the natural cold energy during night time in appropriate thermal storage form and this could be retrieved when needed. Phase change materials are exploited by a number of investigators as a storage medium in free cooling applications, as these substances possess high energy densities, and absorb and release heat at a narrow temperature range, hence, the comfort temperature can be maintained day and night. The objectives of this article are to provide a comprehensive review on recent development on free cooling technologies incorporating latent heat storage and to shit lights on the most significant parameters affecting the performance of these materials in free cooling strategy. The outcomes of this review would be helpful in providing clear insight information on potential improvements that can be applied to the storage materials. All the reviewed studies demonstrated that the night cooling strategy using PCMs has the capacity to maintain the indoor temperature well within the comfort zone whilst providing a considerable reduction in cooling loads in all considered climates.

Application of MCDM method in material selection for optimal design: A review

Abstract: Purpose The principal purpose of this paper is to present a methodical review of application of Multi-Criteria Decision Making (MCDM) method in material selection. Methodology The study reviewed a total of 55 papers, published from the year 1994–2019. The papers reviewed were majorly from high ranking journals and were extracted from different databases such as Web of Science (WoS), Scopus and Google scholar. In order to have understanding of the various MCDM methods applicable for material selection, some of the MCDM tools were briefly discussed. Next, a detailed reviewed of the MCDM tools are performed and summaries in a tabular form with respect MCDM decision criteria, method utilised and application areas, year of publication and country of application. Furthermore, papers are analysed based on decision criteria, MCDM methods and application areas, year of publication, journal type and country of application. Findings The results of the analysis indicated the following: the hybrid method which is the combination of two or more MCDM methods is the most applied technique for material selection in all application areas identified; the most commonly applied decision criteria for selecting optimum alternative is cost; the highest number of articles on material selection was published in 2013; the most significant journal is materials and design and finally, the country with the highest application of MCDM method is India. It can be concluded that MCDM technique is a very useful tool in making decision with respect to material selection.