Student Team Challenges on specific topics are growing in popularity as efficient ways to stimulate students’ independent work, technical and management learning as well as socialization and internationalization. Many competitions are focused on ground vehicles (SAE Formula, Motostudent, Shell Eco Marathon, Solar Challenge), with different focuses on performance, fuel consumption or other depending on the aim of the event. An interesting approach is proposed in the United States by the ASME HPV Challenge, which is focused on Human Powered Vehicles. This class of vehicles allows not only to set-up a classical competition in terms of design, innovation, presentation, manufacturing and racing, but also to grow the student awareness about speed-energy relation. An HPV gives to the rider a direct feedback on a “human-scale” about energy quantities involved in personal mobility. The main returns by the use of this specific topic for a student challenge are: better understanding of the sustainable mobility problem, awareness about the potential and the limits of human muscular power, development of technical skills about design and engineering of lightweight and efficient vehicles, stimulation of the HPVs market development (the students are both potential future designers/manufacturers and/or customers), promotion of healthy and engaging physical activities. In this context, while Europe is rich of HPVs amateurs and manufacturers and is the usual location of the WHPVA World Championship, there is a lack of an educational framework involving students and teachers. Starting from the end of ZEV-HPV Erasmus Intensive Program 2011–2013, the proposal of creating a specific HPV challenge for the European students was developed by the authors. In particular, it was evaluated that by integrating the Student Challenge in the WHPVA World Championship as a special “Educational” category, many reciprocal advantages could be obtained: logistic and organizational support from the WHPVA and its national representatives, in particular for racing and timing, reciprocal technical and cultural exchange between students, academics and the hundred of amateur rider/designer/builder that were attending the event in the last decade, growth and renewal of the European HPVs community by aggregating young people around the subject and by stimulating the research of innovative solutions. After an in-depth analysis of the arguments reported above, an overview of the rules for the 1st edition of EU HPV Student Challenge will be presented and compared to analogous international competitions from an educational perspective.

Solar chimney is a new method to produce electrical power. It employs solar radiation to raise the temperature of the air and the buoyancy of warm air to accelerate the air stream flowing through the system. By converting thermal energy into the kinetic energy of air movement, solar chimneys have a number of different applications such as ventilation, passive solar heating and cooling of buildings, solar-energy drying, and power generation. Moreover, it can be employed as an energy conversion system from solar to mechanical. A component, such as a turbine or piezoelectric component, set in the path of the air current, converts the kinetic energy of the flowing air into electricity. In this paper, a numerical investigation on a prototypal solar chimney system integrated in a south facade of a building is presented. The chimney is 4.0 m high, 1.5 m wide whereas the thickness is 0.20 m for the vertical parallel walls configuration and at the inlet 0.34 m and at the outlet 0.20 m for convergent configuration. The chimney consists of a converging channel with one vertical wall and one inclined of 2°. The analysis is carried out on a three-dimensional model in airflow and the governing equations are given in terms of k-ε turbulence model. The problem is solved by means of the commercial code Ansys-Fluent. The numerical analysis was intended to examine the effect of the solar chimney’s height and spacing. Further, comparison between radiative and non-radiative model is examined and discussed. Results are given in terms of wall temperature distributions, air velocity and temperature fields and transversal profiles for a uniform wall heat flux on the vertical wall equal to 300 W/m 2 . Thermal and fluid dynamics behaviors are evaluated in order to have some indications to improve the energy efficiency of the system.

The aim of this work is to present the energy, exergy and thermoeconomic analysis of a hypothetical solar air heating plant located in Zaragoza, Spain. The plant consists mainly of four parts: 1) a field of solar collectors, 2) a water tank storage, 3) a heat exchanger where heat energy is transferred from the collectors to the water storage tank, and 4) a water to air heater heat exchanger. Circulating pumps, pipes and fan have also been considered. In a previous work of the authors the design variables of the system were optimally determined from a conventional economic approach. In this paper, a productive structure for the plant has been proposed and energy losses and exergy destructions (or irreversibility) have been calculated. Energy and exergy efficiencies have also been determined for each of the components and the whole system. Moreover, the costs of internal flows have been dynamically calculated for the time period under consideration. The very specific features of solar heating systems: thermal energy storage as well as continuous variation of solar radiation and energy demand (seasonal and throughout the day) impose important difficulties, which in our opinion have not been deeply studied yet in current methodologies. The major conclusions are: i) energy, exergy and thermoeconomic analyses following a dynamic approach is very sensitive to the reference environment (ambient air temperature), ii) the same productive structure can and must be used for all of them, iii) solar energy should be considered as a high quality source and thermodynamic efficiency of solar heating plants is very low (2.5% in our case), and iv) a dynamic analysis of the process of cost formation through the different components reveals interesting and valuable information about the physics and economics of solar energy conversion systems.

The present work concerns a prototype implementation and an experimental study of a new design of water heating using parabolic troughs equipped with solar tracking system. Combining the two techniques of parabolic troughs and solar tracking permits to enhance the water heating by solar energy. A prototype is implemented to test the proposed approach. An experimental study is carried-out to test the performance of the system as well as the effect of the weather conditions on the system. The effect of each technique is evaluated separately by performing experiments with and without solar tracking and with/without parabolic mirrors. It is shown that with a parabolic trough of 0.6 m 2 area, water can be heated from 23 to 57 °C. Moreover, the temperature can reach 69 °C when the tracking system is activated.

This paper proposes a new kind of system for effective indirect solar cooking by utilizing a novel Fresnel lens. A semi-cylindrical vessel (solar boiler) for producing steam and a jacketed cooker was designed, fabricated and tested experimentally for cooking applications. The solar boiler produced high temperature steam of 146°C and pressure of 3.15 bar g which was used for cooking purposes. The international standard for evaluating cooker performance was implemented on this system and heating power was determined to be 51.2 Watt at a temperature difference of 50°C. The maximum energy and exergy efficiencies for boiler were found to be 30.18 % and 2.86%, respectively. This represents a 92% increment in energy efficiency and 128.8% increment in exergy efficiency as compared to solar parabolic cookers. The maximum energy efficiency of 5.02% and maximum exergy efficiency of 0.378% were achieved in this cooking system.

Two new Sliding Mode Control (SMC) design methods for nonlinear systems are presented in order to eliminate the reaching phase in the SMC. The sliding surface design approaches are based on optimal sliding surface selection methods for Linear Time Invariant (LTI) and Linear Time Varying (LTV) systems. The reaching phase is eliminated by confining the LTI/LTV system on a predefined linear level surface that moves to the designed optimal sliding hyperplane exponentially. The methodology is extended to nonlinear systems by using two approaches; the “State Dependent Riccati Equation” (SDRE) and “Approximating Sequence of Riccati equations” (ASRE) methods. Systematic ways are defined to eliminate the reaching phase and to design optimal sliding surface for the nonlinear system. The proposed methods are then applied to a spacecraft model with flexible solar panels in order to control the attitude and to suppress some of the vibration modes of the flexible panels. Numerical simulations are used to illustrate the application of proposed methods which are also compared with each other to reveal the effectiveness in coping with uncertainty and vibration suppression and minimization of the energy cost.

Solar Heating and Cooling systems are a virtuous alternative to conventional air conditioning plants, as a renewable energy source (solar energy) is exploited. In this paper the coupling of low temperature solar devices with an innovative desiccant-based air handling unit, which meets the sensible and latent loads of a simulated lecture room, is analyzed through TRNSYS dynamic simulation software. The components have been characterized by means of experimental tests carried out at the test facility of Università degli Studi del Sannio. The desiccant-based air handling unit current set-up allows summer operation only. However, heating operation is also simulated, as comfort conditions can be maintained in the conditioned space exploiting solar thermal energy also in winter, with some modifications to the air handling unit. A parametric analysis is performed to compare different technical solutions (collector types, surface, tilt angle) and to identify the optimal one, taking into account energy, economic and environmental performance with respect to a reference system. The best case in terms of energy and environmental performance is represented by evacuated collectors, achieving a primary energy saving of 64% and a CO 2 emissions reduction of 61%; flat-plate collectors are instead the best solution in terms of pay-back period (6 years).

In recent years with the exacerbation of energy shortage around the world and the continuous increase in the level of greenhouse gas emissions, the use of various sources of renewable energy is increasingly becoming important for sustainable development. Solar energy is considered to be one of the most promising sources of energy, owing to its clean and renewable characteristics. Thermal energy storage (TES) is used to assist in the effective utilization of thermal energy in wide number of industrial and domestic applications. Thermal energy is stored as sensible heat (SHS) or latent heat (LHS). Sensible heat storage (SHS) materials are combination of materials (both solids and liquids) which undergo no phase change in the defined temperature range of the storage process. Example concrete, cast steel, cast iron etc. The use of a latent heat storage system (LHS) using phase change materials (PCMs) is an effective way of storing thermal energy and has the advantages of high energy storage density, narrow operating temperature range and the isothermal nature of the storage process. The phase change materials are more energy dense than sensible energy storage when the temperature difference between heat source and sink are low. Phase change material can store or release energy through its morphology change mechanism. These advantages lead to small volume and less heat loss, which attract attention of researchers in different fields. Ex: Sodium acetate trihydrate, NaNO 3 . There are large numbers of PCMs that melt and solidify at a wide range of temperatures, making them attractive in a number of applications. PCMs have been widely used in latent heat thermal storage systems for heat pumps, solar engineering and spacecraft thermal control applications. The uses of PCMs for heating and cooling applications for buildings have been investigated within the past decade. The experimental results computed in the field of water distillation process using solar energy in the presence of energy storage materials are discussed in this paper.

The paper describes a new kind of solar tracker intended to satisfy the precision requirements of high concentration photovoltaic systems. The tracker is designed according to a Delta type parallel kinematic schematics. The paper describes the kinematic schematics, the sensor chain and the control algorithm. Finally results obtained in functional tests are shown.

In this paper, a solar cooling installation is analyzed with the aim of optimizing its performances. The system consists of vacuum solar collectors, which supply hot water to a LiBr absorption chiller. A boiler can be used to supply an additional amount of hot water in the case of insufficient solar radiation. In addition, a vapor compression chiller operates as a backup system and integrates the solar driven system in the case of large cooling request. Such system gives multiple operating options, especially at partial load. A model of the system is presented and applied to the real plant. It is shown that if a multi-objective optimization is performed, considering minimum primary energy consumption from fossil fuel and maximum utilization of the absorption system, a Pareto front is obtained. This occurs because the two objective functions are competing. A control strategy based on the use of neural networks is presented. Input variables are the solar radiation, ambient temperature and the cooling request. In this work the control strategy is adjusted in order to reach the minimum fossil energy consumption, but the same approach can be applied with other objective functions.

The electrical efficiency and reliability of photovoltaic (PV) modules are severely limited by elevated cell operating temperature in high solar irradiation and ambient air temperature environments, such as in the Middle East. In this study the potential of water-cooling to improve the electrical performance of stationary south facing and sun-tracked flat-type PV modules is experimentally investigated for application at oil and gas facilities in the Persian Gulf. The cooling design is based on gravity-assisted water trickling over the module active surface. In parallel with measurements of PV module electrical characteristics, global solar irradiation, ambient air and cooling water temperatures are also recorded. From the results obtained, the following initial guidelines are derived for the operation of PV modules in late winter to early spring conditions (G ≈ 485–900 W/m 2 , T∞ ≈ 26–40°C) in the United Arab Emirates (24.43°N, 54.45°E), which would correspond to summer at for example mid European latitudes: i) vertical single-axis sun tracking improves module peak electrical power output by 6% to 10% compared to operation in stationary, geographical south facing orientation, for both passively- or water-cooled modules; ii) for cooling water temperatures ranging from 26 to 33°C, water-cooling enhances the power output of stationary south facing and sun-tracked modules for a significant portion of the day, up to 19.8 W (21%) at solar noon; iii) the integration of water-cooling and sun-tracking increases power output by 22 W (26%) at for example 10:30 a.m. relative to a stationary, passively-cooled module. For the latitude and seasonal conditions considered, water-cooling a stationary PV module is 9 to 15% more effective than sun-tracking a passively-cooled module in terms of peak power output. Higher performance improvements could be obtained using either chilled or underground water at a temperature below ambient air temperature, particularly in Middle East summer conditions.

Photovoltaic (PV) technology provides a direct method to convert solar energy into electricity. In recent years, the use of PV systems has increased greatly with many applications of PV devices in systems as small as battery chargers to large scale electricity generation systems and satellite power systems. An important factor that influences the reliability of photovoltaic modules is their ability to withstand high thermal stresses which develop in PV modules due to the different coefficients of thermal expansion of the different module materials. PV modules also experience thermal cycles which can lead to failure of the module. In the present work, three dimensional numerical thermal and structural models of a PV module were developed and sequentially coupled together to calculate the temperature distribution in the PV module and the thermal stresses developing in it. The model is also capable of simulating PV module cooling. Using the model, a study was conducted to evaluate the thermal and structural performance of the module with and without cooling and the variation in thermal stress magnitudes with changing environmental conditions (solar radiation and ambient temperature) and operating conditions (heat exchanger inlet temperature and velocity).

The increasing engineering accreditation program requirements for outcome based assessment, combined with emphasis on green energy and other sustainable technologies, prompted introduction of a solar panel tracking project within a senior product design course. Recognizing that the course is offered to students with mechanical engineering as well as software engineering (mechatronics) backgrounds, technical aspects emphasized three dimensional Computer Aided Design (CAD), rapid prototyping, and basic microcontroller interface electronics and programming. Mixed teams including students from both backgrounds were mandatory. This paper reports observations after three course offerings. In particular, it is noted that a paradigm shift away from lectures to hands-on development laboratories is needed, but formal laboratory milestones and submission deadlines remain essential for successful team project completion.

The aim of this paper is the optimization of Solar Absorption Cooling (SAC) system’s performances. Over the past decade the electricity consumption has significantly increased in Reunion Island during the summer months, which is mainly due to the use of standard air conditioning systems. SAC systems present a good alternative for reducing this consumption. Solar cooling systems are environmentally friendly as they use water and lithium bromide solution as the working fluid. The purpose of this work is to undertake a sensitivity analysis to identify parameters which have a significant influence on the SAC systems performances. The sensitivity analysis has been carried out on numerical models developed at the PIMENT laboratory and validated using RAFSOL experimental data (experimental plant is set up at the IUT in St-Pierre). The results of the sensitivity analysis are used to establish the design and create the control rules to allow for the optimization and ensure the performance of future SAC systems. Firstly, this paper presents the modelization of the SAC system and the sensitivity analysis method used. Secondly, it displays the results from the sensitivity analysis that has been applied to all main components of the plant separately (solar collector field, solar loop and absorption chiller) and to the entire system. Finally, the results are analyzed and discussed. Two types of influential parameters have been distinguished: variables factors and geometrical properties of the plant. This study highlights that the compactness of the installation, the quality of the solar collector, and the control of the temperature at the output of the distribution loop are essential.

The paper describes a 2-DOF parallel kinematic machine designed to achieve precise solar tracking. The mechanism has been developed keeping in mind that solar concentration technology requires a precise alignment of photovoltaic modules and sun radiation, with error allowance much lower than those ensured by traditional sun trackers. The paper describes the kinematic structure and discusses its forward and inverse kinematic, providing the tools to design a system that satisfies the requirements for dexterity and workspace.

Hydrogen is regarded as the potential bearer of energy of the future. Solar hydrogen is the hydrogen produced using renewable energy, particularly solar energy [15,8]. The availability of water and hours of sunshine make Algeria a place of choice for solar hydrogen production. In this work, solar hydrogen production by electrolysis of water is considered. The required energy for water dissociation is supplied by a photovoltaic system. A design and operation study of a photovoltaic system has been done for three different regions in Algeria. The production potential is highly significant particularly in the south parts of this country.

“Green tribology” is the concept that was introduced in 2009 by the founder of Tribology, Prof. P. Jost, who defined it as “ the science and technology of the tribological aspects of ecological balance and of environmental and biological impacts .” This includes tribological technology that mimics living nature (biomimetic surfaces) and thus is expected to be environment-friendly, the control of friction and wear that is of importance for energy conservation and conversion, environmental aspects of lubrication and surface modification techniques, and tribological aspects of green applications such as the wind-power turbines, tidal turbines, or solar panels. It is clear that a number of tribological problems could be put under the umbrella of “green tribology” and is of mutual benefit to one another. Biomimetic applications are of particular interest for the Green Tribology, because of their environment-friendliness. Nosonovsky and Bhushan suggested the “12 principles of the Green Tribology.” The common feature in various biomimetic surfaces is their hierarchical structure and the ability for self-organization. I will discuss the principles of self-organization in hierarchical tribological systems on the basis of the concepts of the non-equilibrium thermodynamics (the Onsager formalism). In particular, I will show that the thermodynamic approach in tribology can yield new and practically important results.

Thermoeconomic analyses of any thermal system design are always based on the economic objectives. However, knowledge of economic optimization may not be sufficient for decision making process, since solutions with higher thermodynamic efficiency, in spite of small increases in total costs, may result in much more interesting designs due to changes in the energy market prices or in the energy policies. In this paper a multi-objective optimization scheme is developed and applied for an Integrated Solar Combined Cycle System (ISCCS) that produces 400 MW of electricity to find solutions that simultaneously satisfy exergetic as well as economic objectives. This corresponds to search for a set of Pareto optimal solutions with respect to the two competing objectives. The optimization process is carried out by a particular class of search algorithms known as multi-objective evolutionary algorithms (MOEAs). For such MOEAs, an example of decision-making is presented and a final optimal solution has been introduced. The final optimal solution that is selected in this analysis belongs to the region of Pareto Frontier with significant sensitivity to the costing parameters. However, the region with lower sensitivity to the costing parameter is not reasonable for the final optimum solution due to a weak equilibrium of Pareto Frontier in which a small changes in exergetic efficiency of plant due to variation of operating parameters may lead to the danger of increasing the cost rate of product, drastically. The analysis shows that optimization process leads to 3.2% increasing in the exergetic efficiency and 3.82% decreasing of the rate of product cost. Also optimization leads to the 2.73% reduction on the fuel exergy, 5.71% reductions in the total exergy destruction and also 3.46% and 7.32% reductions in the fuel cost rate and cost rate relating to the exergy destruction, respectively.

A cross-corrugated portable forced-convection solar air heater has been designed, fabricated, and developed. A wavelike bottom plate has been positioned crosswise to the air flow while rectangular baffles have been attached to the flat-plate absorber. The relative corrugation height, ( e/D h ) ranges between 0.24 and 0.4, and relative baffles distance ( l/L ) varies between 0.21 and 0.48. The air flow rate in the heater duct has been varied in the range of 0.001 kgs −1 to 0.01 kgs −1 (Reynolds number ranges from 350 to 3500), while other thermal specifications such as inlet, outlet, and plate temperatures have varied due to weather changes. Results of this study have been compared with those related to smooth ducts and other literatures, and the maximum enhancement in Nusselt number is observed to be approximately five times of that of the smooth duct under similar flow conditions. Finally, thermal efficiency of the device for different case studies has been determined and compared with other researches.

Spectacular missions to the moon, the Mars and to other planets of our solar system has boosted public attention to the outer space for the last five decades. During the same period mankind has also conquered the inner space — with fantastic innovations and fabulous inventions — however, hidden under the sea surface, and hence widely unnoticed. While searching for new promising oil and gas fields the offshore industry operates in water depths that have never been explored before. Production systems already reach down to 2000 m, and will probably conquer greater water depths during the next years. Extreme environmental conditions in addition to these enormous water depths call for special solutions. This paper deals with recent developments of offshore deepwater production technology, e.g. SPARs, TLPs, Compliant Towers and huge mono-buoys. After a short survey of the development in ocean engineering from the first shallow water platforms in the Gulf of Mexico in 1947 to today’s deepwater production systems off the Brasilian coast the paper summarizes the principles of platform dynamics in waves to illustrate the advantages of specific design characteristics.