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Photoconductive antennas (PCAs) are among the most conventional devices used for emission as well as detection of terahertz (THz) radiation. However, due to their low optical-to-THz conversion efficiencies, applications of these devices in out-of-laboratory conditions are limited. In this paper, we report several factors of enhancement in THz emission efficiency from conventional PCAs by coating a nano-layer of dielectric (TiO2) on the active area between the electrodes of a semi-insulating GaAs-based device. Extensive experiments were done to show the effect of thicknesses of the TiO2 layer on the THz power enhancement with different applied optical power and bias voltages. Multiphysics simulations were performed to elucidate the underlying physics behind the enhancement of efficiency of the PCA. Additionally, this layer increases the robustness of the electrode gaps of the PCAs with high electrical insulation as well as protect it from external dust particles.

Nowadays, increasing population, widespread urbanization, rise in living standards together with versatile use of polymers have caused non-biodegradable polymeric wastes affecting the environment a chronic global problem, simultaneously, the existing high energy demand in our society is a matter of great concern. Hence forth, this review article provides an insight into the technological approach of pyrolysis emphasizing catalytic pyrolysis for conversion of polymeric wastes into energy products and presents an alternative waste management technique which is a leap towards developing sustainable environment. Pyrolysis of waste non-biodegradable polymer materials involves controlled thermal decomposition in the absence of oxygen, cracking their macromolecules into lower molecular weight ones, resulting into the formation of a wide range of products from hydrogen, hydrocarbons to coke. Nanocatalyzed pyrolysis is a recommended solution to the low thermal conductivity of polymers, promoting faster reactions in breaking the C-C bonds at lower temperatures, denoting less energy consumption and enabling enhancement in the process selectivity, whereby higher value added products are generated with increased yield. Nanotechnology plays an indispensable role in academic research as well as in industrial applications. Existing reviews illustrate that one of the oldest application field of nanotechnology is in the arena of nanocatalysis. Nanocatalysis closes the gap between homo and heterogeneous catalyses while combines their advantageous characteristics and positive aspects, reducing the respective drawbacks. During the current nanohype, nanostructured catalysts are esteemed materials and their exploration provide promising solutions for challenges from the perspective of cost and factors influencing catalytic activity, due to their featured high surface area to volume ratio which render enhanced properties with respect to the bulk catalyst.

Abstract In this communication, an analysis of multipass air heating system has been carried out bv incorporating the effect of reflector, duct length, thermal storage and movable insulation for various applications. The analysis is based on energy balance equations for different component of the system. In order to have the parametric study, numerical computation has been done for a typical day of the month of June and December for Delhi climatic conditions. It has been observed that design parameters can be optimized by the proposed theory

Abstract Based on the periodic solution of the heat conduction equation, an analysis has been developed to study the thermal performance of a simple domestic solar water-heating system consisting of a thermal-trap solar-energy collector, connected to a water tank. To study the effects of typical parameters such as the thickness of the trap material and the presence/absence of the glass cover on the thermal performance, numerical calculations have been performed to correspond to the daily variations of the ambient temperature and solar intensity on a typical cold winter day in New Delhi.

Abstract We present an analytical model of a ground collector which uses thermal trap material instead of glazing on its top. The effects of different parameters e.g., the depth of the heat retrieval plane, thickness of the thermal trap material and the use of various materials such as concrete, sand and bricks above the heat retrieval plane are studied. The proposed system is compared with a conventional system.

A periodic analysis of a matrix air heater has been carried out to study the capacity effect of various storage materials such as concrete, fire bricks, glass and coal. The storage effect is, however, not significant in such systems. Higher conducting and low heat capacity materials, such as iron, copper and aluminium used in the form of scraps, result in a good performance of the system. Coal is also found to give as good a performance as metallic materials. The efficiency of the system increases with increased mass flow rate but the rise in the inlet air temperature is correspondingly smaller. The temperature distribution inside the system is seen to be almost linear.

Abstract In this study, three novel biomass gasification based tetra-generation systems for syngas, heating, cooling and power generations have been proposed and theoretically assessed for selected biomass materials. The systems, instead of using the chemical energy of the gasification products, use the thermal energy to operate both Rankine and Refrigeration cycles in three configurations, namely, steam Rankine cycle with organic Rankine Cycle and ejector refrigeration cycle (Cycle-1), binary Rankine cycle with ejector refrigeration cycle (Cycle-2) and steam Rankine cycle with combined power ejector refrigeration cycle (Cycle-3). Syngas (a mixture of hydrogen and carbon monoxide gas), which has the potential for various domestic applications, has been obtained as the gasification product. The effects of different operating parameters such as water to biomass ratio, total biomass-water mass flow rate, mass flow rate of refrigerant, generator pressure, gasification temperature and types of biomass material have been studied on the syngas and hydrogen yields, as well as coefficient of performance and overall performance index of the system. The study shows that Cycle-2 is more effective in terms of coefficient of performance and refrigeration effect whereas Cycle-1 is best for higher performance index. Hence, either Cycle-1 or Cycle-2 can be preferred depending on the requirement.

We present performance studies of an earth air tunnel cum greenhouse technology in terms of instantaneous thermal efficiency. Analytical expressions have been obtained for heating/cooling conditions of a greenhouse. The results are in accordance with the experimental results obtained for the same system in Greece.

An HVDC transmission system has a converter transformer as one of its main components. The failure of the converter transformer is one of the major concerns for electric power utilities all over the world. Invariably, the top portions of the secondary windings of the converter transformers fail whereas the primaries are left unaffected. In this paper, an effort has been made to analyze the causes for these failures by means of modeling a practical HVDC system existing in India which ties up Talcher and Kolar and has a length of 1368 km. The modeling and analysis have been carried out in the MATLAB/SIMULINK environment. Based on the analysis, possible solutions for this problem have been suggested, such as providing passive filters on the secondary windings of the converter transformer, connecting a parallel capacitor on the dc side of the converter and R-C snubbers across the secondary windings. The suggested solutions have been compared to bring out their relative merits and demerits.

Photovoltaic (PV) system is one of the reliable alternative sources of energy and its contribution in energy sector is growing rapidly. The performance of PV system depends upon the solar insolation, which will be varying throughout the day, season and year. The biggest challenge is to obtain the maximum power from PV array at varying insolation levels. The maximum power point tracking (MPPT) controller, in association with tracking algorithm will act as a principal element in driving the PV system at maximum power point (MPP). In this paper, the simulation model has been developed and the results were compared for perturb and observe, incremental conductance, extremum seeking control and fuzzy logic controller based MPPT algorithms at different irradiation levels on a 10 KW PV array. The results obtained were analysed in terms of convergence rate and their efficiency to track the MPP.Article History: Received 3rd Oct 2016; Received in revised form 6th January 2017; Accepted 10th February 2017; Available onlineHow to Cite This Article: Naick, B. K., Chatterjee, T. K. & Chatterjee, K. (2017) Performance Analysis of Maximum Power Point Tracking Algorithms Under Varying Irradiation. Int Journal of Renewable Energy Development, 6(1), 65-74.http://dx.doi.org/10.14710/ijred.6.1.65-74