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This paper aims to present energy extraction behavior of multi stage Micro Hydro Turbine (MHT), particularly when it operates in a low velocity In-Stream water body. Development a MHT with multi stage blade (runner) for water velocity ranges from 0.5 m/s to 1.0 m/s is the novelty of this research. Findings of literature review on MHT and simulation results of ANSYS CFD software are the basis of designing this research project. The vital parameters involved in designing the turbine were blade area, blade stage, blades position against water flow direction, spacing between blades, blade materials; and other technical factors associated with turbine operations. The study revealed that the turbine had started to extract energy at water velocity 0.3 m/s at 35 RPM turbine speed. At water inlet velocity 1.1 m/s, the velocity drop across blade was 25.6% and the energy extraction efficiency was 48.3%. The findings demonstrated that the energy extraction capacity of turbine blade had been greatly influenced by the blade stages and water velocity. The study concludes that the developed turbine is useful in low velocity In-stream water body for energy extraction and would be able to contribute to achieve energy and environmental sustainability. [ABSTRACT FROM AUTHOR]

The phenomenon that involves direct contact of steam with water is called Direct Contact Condensation (DCC). This phenomenon has been observed/prevailed in most of the power and process industries. The phenomenon of direct contact condensation involves heat, mass and momentum transfer across the highly fluctuating interface between steam jet and surrounding water giving this process an intricate nature to be studied. More recently the observation of hydrodynamic instabilities at the interface between supersonic steam jet and water has given a new facet to the study of DCC. In the current study the equivalent von-Mises Stress, equivalent elastic strain and total deformation in the Perspex vessel that has been incurred due to the pressure stresses has been studied. These pressure stresses have been generated due to the condensing supersonic steam jet induced hydrodynamic instabilities. It has been investigated first by experimentally observing the temperature fluctuations in axial and radial directions across supersonic steam jet which actually depicts these instabilities. Then Direct Contact Condensation (DCC) model has been used to conduct the CFD study using a commercial code Ansys ® . Accompanied with this a mock up study has been done in which the pressure loads computed using DCC model have been coupled to the Perspex vessel structure using one way Fluid Structure Interaction (FSI) analysis in Ansys ® to compute the true scale equivalent von-Mises Stress, equivalent elastic strain and total deformation generated by hydrodynamic instabilities induced pressure stresses. On true scale, hundreds of Pico scale deformation has been computed in the Perspex vessel confinement. [ABSTRACT FROM AUTHOR]

Hydrodynamic instabilities are regarded as important but are undesirable occurrences for the systems used in process industries, which involve steam. These instabilities affect to a great extent the life line of the safe operation of their systems by inducing thermal stresses and steam induced water hammers. On the basis of system operational analysis, it was found that condensation induced hydrodynamic instabilities were responsible for one third of the destructive events in steam driven systems and their attributes in power and process industry. Thus it becomes vital to investigate the influence of critical parameter such as sub-cooling to curb the destructive effects due to hydrodynamic instabilities on to the process equipment. Here for steam water two phase flows, the attenuation of hydrodynamic instabilities due to sub-cooling and inlet pressure has been investigated. It was found that sub-cooling has more pronounced and notable effect on the attenuation of these instabilities. [ABSTRACT FROM AUTHOR]

As distributed renewable energy sources (RES) continue to expand, the necessity arises for more robust coordination approaches and conversion techniques to tackle the challenges introduced by uncertainties in renewable generation. Increasing concerns about energy efficiency and power grid security, such as the significant number of conversion stages for energy production from renewable resources and the bidirectional power flow in the distribution system, have attracted attention to the topic. The presented comprehensive review in this paper discusses the merits and weaknesses of different integration strategies as supported by the literature review. In particular, the focus is placed on the challenges of interconnection and opportunities for direct current (DC) systems. The ultimate objective of this paper is to explore the most important power grid-wide effects due to the expected renewable energy expansion and to gain insights on the availability characteristics of DC microgrids to facilitate their integration with the power grid. The idea behind this is to establish inferences that energy conversion based DC microgrids can be a possible solution to mitigate the negative effect of renewable energy expansion. This is accomplished by systematically reviewing studies on power grid integration as well as providing technical analysis of the resulting outcomes in relation to the general impact of renewable energy production, and then, conducting a comparative study on renewable energy conversion based DC and alternating current (AC) systems. The types of bus topologies and control of DC distribution systems are also intensively reviewed and discussed. Moreover, the protection design considerations, control classifications and standards of DC microgrids are highlighted to explore the future research trends to be undertaken. The review concluded that the impact of interconnection on power grid can be eliminated through the use of intelligent control with advance communication technologies and the implementation of DC microgrids powered by sustainable resources in the distribution system. • Energy production from renewable sources is reviewed by discussing the merits and weaknesses of grid integration. • Renewable energy conversion based DC system is the possible solution to overcome the issues of generation expansion. • The standards of DC microgrids need to be enhanced to ensure the security during different operating conditions. • The review confirms that efficient protective devices of DC systems have not been developed as compared to AC systems. [ABSTRACT FROM AUTHOR]