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Abstract Global primary energy consumption will continue to increase with a high rate to 2050, which will be a big challenge for countries to meet both global and regional energy demand. Pumped storage stations (PSS) integrated to a hybrid power system (HPS) with solar and wind power for China are under construction to tussle with this challenge. Historically, modeling of a PSS integrated HPS has been ignored the interaction effect between the shaft vibration and the governing strategies, which will increase the dynamic risk of PSS disconnected immediately to HPS. Here we unify the models of the hydro-turbine governing system and hydro-turbine generator units with a novel expression of hydraulic forces. We quantize all the parameter’s interaction contributions of PSS integration to HPS and validate this model with the existing models. Finally, we show the feasibility of PSS’s model in integrating of a HPS under steady and fault scenarios.

AbstractA metal-organic framework, UiO-66, has been evaluated as adsorbent in a post-combustion vacuum swing adsorption (VSA) process. Equilibrium isotherms of the most relevant gases (CO2 and N2) as well as breakthrough curves measured using synthetic flue gas containing 15 mol% CO2 without and with 9 mol% water vapor are reported. Based on the breakthrough data, a six step one-column VSA cycle is designed and the effects of adsorption and CO2 rinse times used on the CO2 recovery and CO2 purity are examined. With the chosen process configuration and cycle design CO2 purities around 60% and CO2 recoveries up to 70% are achieved. 50 cycle adsorption-desorption experiments show that the cyclic CO2 capacity is reduced by approximately 25% in the presence of water vapor. No reduction in cyclic capacity is observed with increased cycle number; there is rather a slight increase in cyclic capacity with cycle number indicating that a cyclic steady state still not has been reached after 50 cycles.

Abstract European and Italian standards establish high levels of energy performance of buildings that have to be designed considering their energy balance near zero. To achieve this goal, the reduction of energy demand, attainable by improving energy efficiency of the construction, and the use of renewable energy available both on site and off site are effective solutions to be applied. In particular, in buildings that use energy produced from renewable sources, due to their unstable and unpredictable nature, having the right strategy to compensate the variations is essential. A technical solution reevaluated as a consequence of passive design principles, is to provide an adequate thermal inertia in order to store energy when it is offered and to use it when the source is not available. In these cases, the ability of construction elements to retain heat becomes fundamental as they contribute to maintain internal comfort conditions. This paper aims to investigate how various types of heating and cooling systems, based on different modes of heat transfer, are able to interact differently with the thermal mass of the building, producing a different level of its activation. The investigation considers a case study used to carry out dynamic simulation by means of DesignBuilder which is a user interface of EnergyPlus. The model consists of a building with elementary geometry and a single thermal zone, delimited by walls with outside thermal insulation and a heat accumulation layer inside. The variation of the internal temperature by using different types of conditioning system is analyzed in order to individuate the technology that takes the greatest advantages from the thermal mass.

Abstract In present study, the concentrated photovoltaic thermal (PVT) has been proposed for higher thermal gain. The compound parabolic concentrator (CPC) has been also implemented with photovoltaic thermal (PVT) to increase higher input energy or solar radiation to get higher temperature. Here, water and dimethyl‐diphenyl silicone fluid (DMDP) have been considered as a fluid for proposed system. The comparative study of two fluids: water and DMDP has been presented. The maximum outlet fluid temperature of PVT (25% of collector area covered by PV module) - CPC collector have been optimized for 190 0C at mass flow rate=0.06 kg/s of this fluid. The area of receiver and aperture are 2 m2 and 4m2. The concentration ratio is 2. The area of semi-transparent (glass to glass) PV module is 0.5m2. The annual analysis has been carried out for a clear day condition for each month, New Delhi, India. Here, the net annual overall thermal energy and exergy have been found 304.46 kWh and 50.58 kWh, respectively. The electrical gain has also been found as 12.97 kWh. The proposed system has been designed for space heating or drying for many applications with self-sustainability feature.

Abstract A state feedback nonlinear control design approach for the stabilization of chaotic phenomenon of Chua's circuit is presented in this paper. Following the feedback linearization based dynamic inversion method, the nonlinear dynamic behavior of the Chua's circuit is projected into an equivalent linearize dynamic error framework. Such design mechanism inherently suppresses the chaotic nature of Chua's circuit dynamics and enforces the system states (essentially capacitive voltage and inductive current) to asymptotically stabilize around equilibrium conditions. The stability of the controlled Chua's circuit is theoretically proven with Lyapunov theory. The simulation results show the effectiveness of the proposed method.

AbstractIn Rajasthan, the received solar irradiation is high, however, dry and dusty atmosphere are issues for harnessing of solar energy. The high speed wind characteristic of Rajasthan can initiate the saltation process, which in turn removes and carries dust from ground and deposit on collecting surfaces, such as, heliostats. This in turn reduces the collection and therefore the overall efficiency of concentrating solar thermal system. Dust deposition on flat mirror plates depends on various factors like heliostat field density, soil composition, atmospheric condition, mirror orientation, wind speed, plate material, height and structure of heliostat etc.In this article, experiments on dust deposition by wind onto a mirror simulating a heliostat model in wind tunnel are presented. Further, the performed analyses of dust deposition on single and multiple heliostats are described. These clearly indicate the influence of flow and position of heliostat. Furthermore, the obtained observations indicate a possible way of mitigating cleaning effort with localized deposition.

Abstract This paper presents three correlation based models developed based on, design of experiments (DOE), identified parameters and dimensionless groups, for estimating the performances of air cooled and water cooled condensers of a vapour compression screw chiller with capacities of about 300 TR. The correlations were developed using the experimental data obtained from chillers at various operating conditions. A comparison of experimental data and the data obtained from correlation based models found to have good agreement between them. Predictions from the developed correlation based models were compared with the condenser's (ACC and WCC) performance of three different screw chiller manufacturers and they match within ±8% and ±11% for ACC and WCC at 70 – 100% load.

AbstractLow Voltage Ride-Through (LVRT) is one of the most dominant grid connection requirements to be met by Wind Energy Conversion Systems (WECS). In presence of grid voltage dips, a mismatch is produced between the generated active power and the active power delivered to the grid. Low voltage ride through requirement demands management of this mismatch, which is a challenge for the WECS. In this paper, LVRT requirements provided by Wind Grid Codes have been reviewed. This paper discusses the standards for interconnection of wind generators to local grid during healthy and fault conditions. As per LVRT requirement, during dip occurrence, the wind power generation plant must remain connected to the grid and in addition, it has to deliver reactive power into the grid to aid the utility to hold the grid voltage. Voltage sag proves to be the most prominent power quality issue and the effect of voltage sag on different wind generator topologies has been investigated. Several methods for LVRT fulfillment have been explored and the LVRT scheme has been validated based on MATLAB-SIMULINK simulation.