International Journal of Power and Energy Research

16

Authors: Mohammad Aman Yaqobi, Hidehito Matayoshi, Mir Sayed Shah Danish, Naomitsu Urasaki, Abdul Motin Howlader, Tomonobu Senjyu

The recent evolution in technology and lifestyle has been led to a dramatic increase in electricity demand so that the local communities are encountered with challenges of huge initial costs, and sustainable extension to a national grid. Here in this paper, a DC microgrid cluster with three small areas (A, B and C) is proposed. Control and power stability of small-scale electrical system using renewable resources is a big challenge. In this study, the operation of DC microgrid and behavior of the system at different operating conditions is evaluated under different condition of the solar radiation and temperature changes for specific time periods. The DC Converters with PI control strategies are integrated to control the system performance and load-power balancing. The DC bus voltage level is employed as an information carrier for controller to maintain operation stability, improve efficiency, and enhance the redundancy of a system. At the meanwhile, the Maximum Power Point Trucking Incremental Conductance (MPPT-IC) algorithm is applied to maximize the efficiency and regulate the output voltage of the PV system to desired DC bus voltage. The PV arrays with battery and bidirectional converter are simulated to overcome the intermittency problems of PV outputs. Some typical operation modes are simulated using MATLABR /Simulink to confirm the proposed model preference compared to the literature.

9

Authors: Denver F. Cheddie

Two recent trends in fuel cell development are the use of ammonia as a fuel, and the preference for intermediate temperature operation of solid oxide fuel cells. There have been a few mathematical models of ammonia-fed solid oxide fuel cells reported in the literature, all of which are for high temperature operation where Tamaru kinetics applies. To date, there have been no models reported for intermediate temperature operation. At intermediate temperatures, hydrogen inhibition of ammonia decomposition occurs and hence the Temkin-Pyzhev model of ammonia decomposition must be employed. This paper is the first to present a two-dimensional computational model of an intermediate temperature ammonia-fed solid oxide fuel cell with Temkin-Pyzhev ammonia decomposition kinetics. The results show that the problem of thermal shock associated with high temperature ammonia-fed fuel cells is alleviated at intermediate temperature operation.

17

Authors: Issoufou Tahirou Halidou, Mohamed Elsayed Lotfy, Atsushi Yona, Tomonobu Senjyu, Abdoul Aziz Ibrahim

This paper presents a novel real multi-objective approach for thermal unit commitment (UC) problem solution in Niamey (Niger). The proposed methodology consists of four conventional thermal generating units and imported power from a neighboring country in addition to future inclusion of Photovoltaic (PV) power, Wind Turbine Generators (WTGs), and Pumped Hydro Energy Storage (PHES). Minimization of total daily operating cost and decreasing the maximum daily mismatch between load demand and generation are considered as two objective functions in two cases. In the first case, UC with thermal units considering the imported power (IMP), PV and PHES is determined. In the second case, WTGs are introduced and the IMP is removed in order to get rid of its economical and political problems. ε-MOGA (epsilon Multi-Objective Genetic Algorithm) is used to obtain an optimal unit commitment problem solution with consideration of PV, WTGs and PHES. The effectiveness and robustness of the proposed scheme is verified by numerical simulations using MATLAB environment.

9

Authors: Batan Le, Vanmanh Nguyen, Thanhtrung Dang

The effects of microchannel geometry on the phase transition between liquid and vapour for the two phase flow were investigated both numerically and experimentally. In the study the rounded edge rectangular microchannel heat sink was found to have the phase transition earlier than the rectangular one in both numerical simulation and experimental data by about 1.5 seconds. The outlet temperature and vapour quality of the rounded edge rectangular microchannel heat sink was higher than those obtained from the rectangular microchannel heat sink. Also, the phase transition curves achieved in the evaporation were parabolic in shape. The output vapour temperature achieved a steady state with the maximum value at around 2 minutes, 30 seconds. In addition the numerical results matched well with the experimental data. These numerical results have not yet been seen in literature reviews.