Table of Contents

The most important parameter in the design of the building envelope is the insulation thickness, because it dramatically influences the heating and cooling loads. The objective of this study is the investigation of different insulation scenarios for the four climate zones of Greece and, more specifically, the cities Heraklion, Athens, Thessaloniki, and Florina. The insulation thickness is examined up to 8 cm and the optimum thickness is determined by the minimization of the simple payback period in order to design a cost-effective system. Moreover, the primary energy consumption, the heating/cooling loads, and the equivalent CO₂ emissions are calculated. Furthermore, a multi-objective evaluation procedure of the various insulated scenarios is conducted in order to show the relationship between the energetic and the financial optimization. Generally, it is found that the optimum insulation thickness is around 4 cm for all the climate zones using financial criteria, while the energy criteria indicate higher thicknesses. These results can be applied to the suitable design of Greek residential buildings. Full article

There are high numbers of remote villages that still need electrification in some countries. Extension of the central electrical power network to these villages is not viable owing to the high costs and power losses involved. Isolated power systems such as rural microgrids based on renewables could be a potential solution. Photovoltaics (PV) technology is particularly suited for countries like India due to factors such as the available solar resource, the modularity of the technology and low technology costs. It was identified that unlike larger isolated power systems, rural microgrids have a low energy demand as the loads are mainly residential and street lighting. Hence, these microgrids could be of a single-phase configuration. At present, the typical procedure followed by planners of rural networks does not consider the importance of PV source siting and optimisation of network structure. An improved design procedure is introduced in this work based on the use of centres of moments for central PV system sizing, simulated annealing for network structure optimisation and load flow based parametric analysis for confirming the PV microgrid structure before detailed software-based PV design. Case studies of two remote villages are used to inform and illustrate the design procedure. Full article

It is well known that the major constraints to the efficiency of photovoltaic devices come from the generation of heat. In this context, thermoelectric generators have been proposed as a viable heat recovery solution, leading to an increase of the overall efficiency. Within this kind of hybrid solution, the photovoltaic and thermoelectric parts can be either electrically separated or connected in the same circuit. In the latter case, the presence of the thermoelectric generator in series to the solar cell may lead to electrical losses. In this work, we analyze the effect of several parameters on the output power of electrically hybridized thermoelectric-photovoltaic systems. Both electrical measurements and simulations are used. The results show that while an electrical lossless condition exists (as also reported in previous works), it does not necessarily lead to significant power gains compared to the sole photovoltaic case. In addition, the strong temperature sensitivity of the lossless condition makes electrical hybridization difficult to implement. Since solar irradiation varies over time, such sensitivity would make the system work mostly in a suboptimal regime. Therefore, this study provides clues on the actual applicability of electrically hybridized devices. Full article

Concerning the robust model predictive control (MPC) for constrained systems with polytopic model characterization, some approaches have already been given in the literature. One famous approach is an off-line MPC, which off-line finds a state-feedback law sequence with corresponding ellipsoidal domains of attraction. Originally, each law in the sequence was calculated by fixing the infinite horizon control moves as a single state feedback law. This paper optimizes the feedback law in the larger ellipsoid, foreseeing that, if it is applied at the current instant, then better feedback laws in the smaller ellipsoids will be applied at the following time. In this way, the new approach achieves a larger domain of attraction and better control performance. A simulation example shows the effectiveness of the new technique. Full article

Most European cities are facing urban densification issues. In this context, a solution to create usable spaces without additional pressure on land consists in the vertical extension of existing buildings. Given their abundance in the building stock, tertiary buildings offer an important potential. The paper introduces the Working Space project, which aims to develop an innovative, modular and prefabricated timber construction system adapted to the vertical extension of existing office buildings. The dimensions of the system can be adjusted to a great variety of structural grids and allows for any new typological organisation. Based on the principles of bioclimatic architecture, the extension’s envelope provides high-performance insulation, a smart management of passive solar gains, natural ventilation and free cooling, but also offers large surfaces dedicated to photovoltaic energy production and urban biodiversity. The system is made up of eco-friendly, local materials with very low environmental impact. The project’s outcomes are presented at a variety of scales, from urban design to construction details, as well as the outputs of an extensive life cycle assessment including the induced mobility impacts. Finally, the paper introduces a first application of this innovative architectural concept, which is currently being completed in Lausanne, Switzerland. Full article

A crossed compound parabolic concentrator (CCPC) is a non-imaging concentrator which is a modified form of a circular 3D compound parabolic concentrator (CPC) obtained by orthogonal intersection of two 2D CPCs that have an optical efficiency in line with that of 3D CPC. The present work is about the design and fabrication of a new generation of solar concentrator: the hybrid photovoltaic (PV)/thermal absorptive/reflective CCPC module. The module has a 4× CCPC structure truncated to have a concentration of 3.6× with a half acceptance angle of 30°. Furthermore, an experimental rig was also fabricated to test the performance of the module and its feasibility in real applications such as building-integrated photovoltaic (BIPV). 3D printing and Computer Numerical Control (CNC) milling technologies were utilized to manufacture the absorber and reflective parts of the module. Full article

This paper presents the contemporary metaheuristic optimization algorithm named the Spotted Hyena Optimizer (SHO). The proposed technique is based on the law of gravitation and simulates the social behavior of spotted hyenas. The three basic steps of SHO, namely, searching for prey, encircling, and attacking prey, are mathematically modelled and discussed. The main concept of this work is to apply the recently developed SHO algorithm to two real-life design problems, namely optical buffer design and airfoil design. Experimental results reveal the supremacy of the SHO algorithm for solving the engineering design problems as compared to other competitor algorithms. Full article

A crucial step in the biomimicry process is the search and identification of biological models relevant to the design challenge. Anecdotal observations from case studies in authentic business contexts, as well as emerging literature on biomimicry methods, suggest that tools, which focus the search for biological models, could help research and development (R&D) professionals execute this step more effectively. We prototyped one such tool, a set of four frames of inquiry, to test whether it helped R&D professionals identify a greater quantity and variety of biological models. The tool we prototyped did not significantly improve biological model identification; however, its use was associated with a trend of higher quantity and variety of biological models. Our study, as well as previous work, both empirical and theoretical, suggests that tools, like ours, could improve the search and identification of biological models. We encourage further tests using larger samples sizes and/or conditions that maximize potential effect sizes. Full article

Sustainable buildings are often considered expensive alternatives to conventional designs. However, a decline in costs associated with materials, technology, labor and whole building approaches make green homes realistic to construct even within low-income neighborhoods. This can address the critical shortage of affordable housing in cities, and the emerging recognition of their impact on healthy communities. This study proposes an affordable and energy-efficient design for a low-income rowhouse in Philadelphia as a city having the highest poverty rate in the U.S. The design can be replicated as an investment in the future where people live with net zero energy and zero emissions. Furthermore, residents have the opportunity to create a more vibrant and healthy neighborhood economy by investing their savings locally. The results showed that the proposed prototype has a payback of approximately just over 16 years. Although this seems long, the building is affordable since the ongoing operating expenses are significantly less than a typical house. This is achieved by the combination of an efficient building design, onsite power generation, water conservation and rainwater harvesting. The payback period may suggest that larger-scale projects than just a single urban residence (two residences and larger) are needed to improve investment paybacks. This is discussed. Considering the added benefits (energy and water) that will continue after the payback period, the design can be a pioneer for low-income neighborhoods. Full article

This paper presents a low-cost temperature-controlled chamber based on the natural radiation principle. The temperature-controlled chamber assembled using a 1.0 mm thick aluminum sheet equipped with expanded polystyrene lagging material, temperature controller, K-type thermocouple and solid-state relay. A high precision temperature sensor (K-type thermocouple) attached to the sample under test (SUT) near the instrument’s measuring point gives a feedback signal to the temperature integrated derivative (TID) controller. The accuracy of temperature readings from the chamber investigated and the chamber itself, calibrated with temperature sensor by Fluke, show temperature readings that correspond to the set temperature values. In addition, perovskite thin film deposited on a glass substrate of 75 × 25 mm was tested and the temperature readings equally correspond to the temperature set values. This low-cost and low-energy-consumption chamber could use in laboratories in the developing world where there is scarce power supply. Full article

The objective of this work is the investigation of a solar heat industry process with parabolic trough solar collectors. The analysis is conducted for the climate conditions of Athens (Greece) and for five load temperature levels (100 °C, 150 °C, 200 °C, 250 °C, and 300 °C). The examined configuration combines parabolic trough solar collectors coupled to a storage tank and an auxiliary heat source for covering the thermal need of 100 kW. The solar thermal system was optimized using the collecting area and the storage tank volume as the optimization variables. There are three different optimization procedures, using different criteria in every case. More specifically, the solar coverage maximization, the net present value maximization, and the payback period minimization are the goals of the three different optimization procedures. Generally, it is found that the payback period is between five and six years, the net present value is between 500–600 k€, and the solar coverage is close to 60%. For the case of the 200 °C temperature level, the optimum design using the net present value criterion indicates 840 m² of solar collectors coupled to a storage tank of 15.3 m³. The optimization using the solar cover indicates the use of 980 m² of solar collectors with a tank of 28 m³, while the payback period minimization is found for a 560 m² collecting area and an 8-m³ storage tank volume. The results of this work can be used for the proper design of solar heat industry process systems with parabolic trough collectors. Full article

The categorization of cell culture chiefly includes two aspects; one is the dimensionality and another regards the dynamicity. Referring to knowledge of “engineering system evolution”, 2D toward 3D cell culture follows the direction of evolution in dimensionality, and 3D scaffolds with 3DP as its popular fabrication tools has played a role in 3D cell culture applications. Dynamic methods of cell culturing, compared with traditional static means, generally follow the evolution line “static to motional or dynamic”, and vibration has been selected frequently as the suitable tool to achieve the dynamicity of cell culture. Although such a scaffold plus vibration approach has benefited cell culture, there exist significant defects. To mitigate some existing gaps, as well as following further evolutionary trends, the concept of the 3D printed vibratory scaffold (3DPVS) used in cell culture applications is firstly brought out in this study. With 3DPVS, a 3D scaffold in traditional scaffold engineering could potentially evolve into a novel vibratory scaffold which will play significant role in future bioengineering and scaffold engineering. Since 3DPVS’s development remains blank, designers firstly need to propose a high-quality conceptual design; the process of identifying design methodology is challenging since there has been no formal methodology applied for scaffold design. To address these issues, a new design approach is proposed in this paper, which includes an integral development process and focuses on the 3DPVS conceptual stage. The possible methodology and tools to achieve the established conceptual design in following step will be also be discussed. Full article

The current extraction process in the Oil and Gas Industry today takes 10–32 h for 2 tonnes of refined crude, incurs 16–25% of the total volume spill, has an extraction efficiency of 50–74%, experiences $820—$4250 CAD of revenue loss for every 1% spilled and costs $280,000–$650,000 CAD to clean up a single percent. The Automated Crude Constituent Extractor extracts constituents from 2 tonnes of refined crude in 34–46 min, incurs no volume spill, has an extraction efficiency of 76–98%, results in no revenue loss and no remediation cost. This system needs to be implemented immediately in the Oil and Gas Industry today so that oil producing nations can start enjoying these benefits. Full article

There has been constant growth in the wind energy market. A study conducted in January 2018 by Global Market Insights Inc. predicted that the global wind energy market will surpass USD 170 billion by 2024. Before installation of a wind turbine, wind data must be collected from a prospective site for a minimum of one year. This has compelled the high demand for instruments used for collecting wind data. Various commercial cup anemometers and wind vanes have been manufactured for sale, some of which lack proper calibration or are not affordable for small-scale wind farmers, especially in developing countries. Wind data are a big data affair and call for instruments that handle them as such, unlike most commercial wind data collection instruments. This paper presents the design and calibration of a wireless 3D-printed cup-vane instrument for collecting wind data. This instrument represents a Wireless Sensor Node (WSN) in the Internet of Things (IoT). This study gave rise to an instrument system that was able to acquire wind data within a mean fitting deviation of $\pm 0.063398$ m/s, store them and present them wirelessly to an IEEE 802.15.4 protocol sink node. This was verified in the lab using 1 m/s to 16 m/s wind speeds at the Armfield™ wind tunnel and outside in an open field with 1 m/s to 5 m/s wind speeds. Full article

The paper presents a historical overview of the developments of aerodynamic design methods for low-speed axial-flow fans. This historical overview starts from the first fan applications, dating back to the 16th century, and arrives to the modern times of computer-based design techniques, passing through the pioneering times of aerodynamic theories and the times of designing before computers. The overview shows that the major achievements in the axial fan design discipline have actually been related to other technological fields, such as marine and aeronautical propulsion, as well as to the development of wind tunnels. At the end of the paper, the reader will have acquired a complete panorama of how the historical developments of the discipline have brought us to the current state of the art. Full article