Journal of Renewable Energy and Environment
Volume:6 Issue: 1, Winter 2019

In this paper, on the basis of Green Comprehensive Plan at Hakim Sabzevari University of Sabzevar, Iran, the application of active solar  systems for the dining hall is evaluated. The impact of solar systems and energy management designed for this hall on energy consumption and environment was investigated.This study measures the electricity and thermal energy consumption of the dining hall , proposes some new efficient lighting systems for rational usage and calculates energy consumption based on new technologies. Further, it evaluates renewable energies available in the region such as solar energy that includes hybrid photovoltaic/thermal panel and one ended evacuated tube collector systems for providing energy requirement. Then roof top and façade installation for solar collector and photovoltaic/thermal panel are chosen. Modified Angstrom equation, sunshine hours, mathematical relations and models are used to determine solar insolation. For these systems, the required area, rate of energy saving, pollutant reduction, and payback time are calculated. Results show that 85 photovoltaic panels are needed for providing 9898.2 Kwh/year electric energy. In addition, 36683 Nm3/year natural gas saving and 87.6 tone/year pollutants are reduced. The payback time for the system based on internal energy carrier and export electricity price is 21.3 years  and 3.9 years respectively.

In this study, an unsteady aerodynamic simulation is performed to realize the influences of platform surge motion on the aerodynamic performance of a high capacity offshore floating wind turbine. A dynamic model with pitch angle control system is utilized to propose a more realistic model of wind turbine and also achieve the rated condition of the rotor. The transient effect of platform surge motion on power coefficient, thrust coefficient and blade pitch angle also is investigated. The 5 MW NREL wind turbine is selected for the simulations. The unsteady aerodynamic model contains unsteady blade element momentum method, dynamic stall and dynamic inflow models. The in-home aerodynamic code and the control system model are implemented in MATLAB/SIMULINK software. It is revealed that reduction in mean power coefficient at tip speed ratios less that 7 is expected by amount of 12-15 % at surge amplitude of 2m and frequency of 0.1 Hz. For high tip speed ratios, the trend is reverse with respect to fixed-platform case. The mean thrust coefficient is also reduced for many tip speed ratios with maximum loss of 32 %. The mean blade control pitch angle is increased due to the surge motion. Since the influence of changing amplitude and frequency of disturbances depends on the tip speed ratio, therefore the special bound of this parameter is being proposed.

The present study investigates the effectiveness of thermostat control strategy in cooling energy consumption in residential buildings. To evaluate the energy consumption, two scenarios including a residential zone with and without the thermostat control system are assumed. The TRNSYS software provides an efficient numerical tool to model and evaluate a cooling system. Furthermore, since solar-powered cooling systems for residential air-conditioning are receiving growing and significant interest, a hot-water fired absorption chiller coupled with evacuated tube collectors is considered as the cooling system. The results reveal that the cooling systems consume a large amount of energy in hot climate zones without employing the thermostatic control. Therefore, cooling energy has great potential for a significant saving in hot climates. It is illustrated that the thermostat strategy has an obvious impact on such energy saving. In the current study, employing the thermostat in 90m2 residential building results in saving energy by up to 36%.

The effect of the thickness of ceramic membrane on the productivity of microbial fuel cells (MFCs) was investigated with respect to the electricity generation and domestic wastewater treatment efficiencies. The thickest ceramic membrane (9 mm) gained the highest coulombic efficiency (27.58±4.2 %), voltage (681.15±33.1 mV), and current and power densities (447.11±21.37 mA/m2, 63.82±10.42 mW/m2) compared to the 6- and 3-mm thick separators. The results of electrochemical impedance spectroscopy (EIS) analysis were investigated to identify the internal resistance constituents by proposing the appropriate equivalent electrical circuit. The Gerischer element was modeled as the coupled reaction, and diffusion in the porous carbon electrodes and the constant phase element was assimilated into the electrical double-layer capacitance. The thickest ceramic (9 mm) was found to have the largest ohmic resistance; however, owing to its superior barrier capability, it provided more anoxic conditions for better accommodation of exoelectrogenic bacteria in the anode chamber. Therefore, lower charge transfer, fewer diffusional impedances, and higher rates of anodic reactions were achieved. Excessive oxygen and substrate crossover through the thinner ceramics (of 6 and 3 mm) resulted in the suppressed development of anaerobic anodic biofilm and the accomplishment of aerobic substrate respiration without electricity generation.

In this study, the effects of hydrogen and hydroxygen additions and oxygen enrichment on the emission characteristics of a gasoline engine (EF7) were investigated and compared with each other. The simulation was launched by GT-Power at different engine speeds with 5 % to 15 % volume fractions for both of oxygen and hydrogen enrichment and 4.5 % to 9 % volume fractions of hydroxygen addition in the intake gas, respectively. In addition, the model was validated by experimental data. The results showed that CO emission decreased from 11 % to 28 % in the hydrogen-enrichment condition. Moreover, carbon monoxide production was reduced from 28 % to 42 % for hydroxygen addition, and this pollutant emission experienced a reduction of 51 % to 67 % for oxygen enrichment. According to the results, HC emission decreased up to 13% in the hydrogen-enriched air condition, and it was reduced from 30 % to 43 % during hydroxygen addition. In addition, HC emission experienced maximum reduction of 47 % to 68 % during oxygen addition. On the other hand, there was an opposite trend for NOx emission. It was observed that NOx emission increased by around 40 % and 75 % for hydrogen and hydroxygen enrichment, respectively. Moreover, nitrogen oxides enhanced 2 to 5 times during oxygen enrichment, compared to that in the normal condition of the engine. Results showed that 15 % oxygen enrichment and 9 % hydroxygen enrichment had significant effect on the reduction of HC and CO emissions, and oxygen enrichment had greater effect on the rise of NOx emissions than hydrogen and hydroxygen additions.

The effective utilization of wind energy conversion system )WECS( is one of the most crucial concerns for the development of renewable energy systems. In order to achieve appropriate wind power, different pitch angle methods are used. Recurrent Adaptive Neuro-Fuzzy Inference System (RANFIS) is utilized in this paper in a new effective design to improve the performance of classical and adaptive Proportional Integral (PI) controllers applied for the pitch control purposes. Adaptive-online performance and high robustness coverage are the main advantages of the suggested controller. The effectiveness of the proposed method is verified by a simplified two-mass wind turbine model and a detailed aero-elastic wind turbine simulator (FAST7). At any given wind speed, the proposed controller has outperformed PI, Adaptive Neuro-Fuzzy Inference System (ANFIS), and RANFIS based controllers, reducing the mechanical stress of drive train while presenting suitable aerodynamic power tracking and maintaining the rotational speed of the rotor under the rated value.