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Abstract Various assumptions are often made to model turbomachinery bladed assemblies. In particular, the cyclic symmetry of single rotor stages, and dynamically independence of isolated rotor stages are frequently used. The first assumption enables a drastic reduction of the required computational resources by considering only one sector instead of the entire assembly to model and analyze the dynamic behavior of the complete structure. However, small random blade-to-blade structural variations, known as mistuning, exist due to manufacturing tolerances, etc. and significantly affect the dynamic behavior of bladed disks. The second assumption also reduces the needed computational resources and time. However, ignore inter-stage coupling does not always describe accurately the disk or drum flexibility especially at the inter-stage boundaries. In this work, the component mode mistuning method is used for multi-stage assemblies to create a mistuning identification approach. An experimental modal analysis is performed on a two-stage monobloc academic bladed drum. The frequency response function is measured using a base excitation with an electrodynamic shaker and one measurement point per blade of each stage is used. The approach is used to identify mistuning in a multi-stage rotor. Numerical and experimental results are presented. Results show that the proposed approach is effective even for modes which are multi-stage.

Abstract This paper presents some research activities conducted at the Centre Spatial de Liege (CSL) in the field of space solar arrays and concentration. With the new generation of high efficiency solar cells, solar concentration brings new insights for future high power spacecrafts. A trade-off study is presented in this paper. Two different trough concentrators, and a linear Fresnel lens concentrator are compared to rigid arrays. Thermal and optical behaviors are included in the analysis. Several technical aspects are discussed: • Off-pointing with concentrators induces collection loss and illumination non uniformity, reducing the PV efficiency. • Concentrator deployment increases the mission risk. • Reflective trough concentrators are attractive and already proven. Coating is made of VDA (Aluminum). A comprehensive analysis of PV conversion increase with protected silver is presented. • Solar concentration increases the heat load on solar cells, while the conversion efficiency is significantly decreasing at warm temperatures. To conclude, this paper will point out the new trends and the key factors to be addressed for the next generation of solar generators.

Abstract The present work focuses on the numerical simulation of Moderate or Intense Low oxygen Dilution combustion condition, using the Partially-Stirred Reactor model for turbulence-chemistry interactions. The Partially-Stirred Reactor model assumes that reactions are confined in a specific region of the computational cell, whose mass fraction depends both on the mixing and the chemical time scales. Therefore, the appropriate choice of mixing and chemical time scales becomes crucial to ensure the accuracy of the numerical simulation prediction. Results show that the most appropriate choice for mixing time scale in Moderate or Intense Low oxygen Dilution combustion regime is to use a dynamic evaluation, in which the ratio between the variance of mixture fraction and its dissipation rate is adopted, rather than global estimations based on Kolmogorov or integral mixing scales. This is supported by the validation of the numerical results against experimental profiles of temperature and species mass fractions, available from measurements on the Adelaide Jet in Hot Co-flow burner. Different approaches for chemical time scale evaluation are also compared, using the species formation rates, the reaction rates and the eigenvalues of the formation rate Jacobian matrix. Different co-flow oxygen dilution levels and Reynolds numbers are considered in the validation work, to evaluate the applicability of Partially-Stirred Reactor approach over a wide range of operating conditions. Moreover, the influence of specifying uniform and non-uniform boundary conditions for the chemical scalars is assessed. The present work sheds light on the key mechanisms of turbulence-chemistry interactions in advanced combustion regimes. At the same time, it provides essential information to advance the predictive nature of computational tools used by scientists and engineers, to support the development of new technologies.

Abstract This paper investigates the impact of urbanization on energy consumption by applying the Stochastic Impacts by Regression on Population, Affluence and Technology (STIRPAT) in case of Malaysia. The study covers the time period of 1970Q1–2011Q4. The unit root test and the ARDL bounds testing approach have been applied to examine integrating properties and long run relationship in the presence of structural breaks. Our results validated the existence of cointegration and exposed that urbanization is a major contributor in energy consumption. Affluence raises energy demand. Capital stock boosts energy consumption. Trade openness leads to affluence and hence increases energy consumption. The causality analysis finds that urbanization Granger causes energy consumption. The feedback effect is found between energy consumption and affluence and, energy consumption and capital. The bidirectional causality exists between trade openness and energy consumption.

Abstract The work discusses a problem of harvesting and upgrading of ultra-low grade heat with thermochemical energy storage technology for space and domestic water heating in residential area. The laboratory scale prototype, operating on the principle of an open packed bed sorption reactor and using moist air as a heat/mass transfer fluid, is experimented. The range of experimental air temperature was set to 17–40 °C, which corresponds to the typical range of domestic waste thermal energy. The tested sorbent was a salt-in-matrix composite material composed of a silica gel containing 43 wt.% of calcium chloride (CaCl2) salt. Hygrothermal behavior and energy performances of the prototype control volume filled with 245 g of material, representing the reactive front of a thermal wave, were analyzed at constant inlet hydration conditions (water vapor pressure of 12.5 mbar). The average temperature lift was recorded as 9–13 °C, representing the amplification of a supplied heat on 23% – 75% depending on the inlet temperature. The average specific thermal power inside the material bed was measured to be 168–267 W kg-1. The apparent energy density, based on the prototype control volume, ranged between 1.0 and 1.6 GJ m-3. Taking into account the heat of water vaporization, the coefficient of performance of the process was determined to be 0.96–1.57.

Water is an essential requirement for agricultural productivity. In the agriculture sector, electricity generated by conventional sources contributes to a substantial amount of carbon footprints for pumping water through tube wells. Over the past few decades, a transitional shift towards renewable resources has increased leading to decarbonizing the environment and is considered as a viable solution for electricity production. To assist and provide a road map for this paradigm shift, the proposed study presents a techno-economic and environmental analysis of irrigation systems by carrying comparative analysis of both standalone and grid-connected systems based on four independent sites in a developing country. PV system integrated with grid enabling both energy purchase and sale (PV + G(P+S)), proved to be the most optimal configuration with cost of energy (COE) of $0.056/kWh, $0.059/kWh, $0.061/kWh, and $0.068/kWh while having net present cost (NPC) of $7,908, $20,186, $25,826, and $34,487 for Peshawar, Khyber Agency, Mardan, and Charsadda respectively, over a useful life span of 25 years. Furthermore, sensitivity analysis has been carried out based on uncertain variables such as Grid power purchase (GPP) and average solar radiation (GHI) to check the optimality behavior of the system. Results from environmental analysis revealed that (PV+ G(P+S)) system has a relatively low carbon impact as compared with conventional sources. This configuration also has the ability to prevent excess water extraction by selling any excessive solar PV energy to the grid. This study provides a policy framework insight for the entities for future optimization.