Current Issue : July - September Volume : 2020 Issue Number : 3 Articles : 5 Articles
This article presents the results of an eco --efficiency assessment of the application of large --\nscale rechargeable battery technology in electricity generation from coal. ...................................
This work is devoted to an experimental study of metallic pressure cooker\ninsulated with kapok wool, a vegetal biodegradable fiber. Experiments conducted\non the cooling of hot water in the equipment revealed very low heat\nlosses and a time constant of 60 hours on average. As a result, the equipment\nmakes it possible to finish cooking meals only thanks to the heat stored at the\nbeginning of cooking and keeps cooked dishes warm for long hours. The\nthermal phase shift of the pressure cooker is around 7 h. Cooking tests conducted\non some local dishes revealed about 70% butane gas savings for cooking\ncowpea and white rice, 38% for cooking fatty rice, 75% for pasta and\ncouscous, and 30% for cooking potato stew. These results show that this\ntechnology can contribute to minimizing energy consumption in the restaurant\nsector....
Steel industry is high energy-consuming industry, and its waste heat recovery\nis critically important for energy utilization. In this study, pipeline bundle is\nused to enhance heat transfer in waste heat recovery device, and associated\ngas-solid heat transfer and energy utilization performance with different\npipeline arrangement, pipe diameter and shape of internal component are\nfurther analyzed. The temperatures of gas and particle in device with pipeline\nbundle periodically fluctuate in horizontal direction, and those in staggered\nsystem distribute more uniformly than those in paralleled system. Compared\nwith paralleled device, exergy and waste heat utilization efficiency of staggered\ndevice have been improved, and they are both higher than those without\npipeline. As pipe diameter increases, exergy and waste heat utilization efficiency\nfirst increases and then decreases, and they reach the maxima with\noptimal pipe diameter. As the width of internal component keeps constant,\ninfluence of its shape on heat transfer is very little....
In this paper, stochastic fractal search method (SFS) is employed for solving the optimal reactive power flow (ORPF) problem with\na target of optimizing total active power losses (TPL), voltage deviation (VD), and voltage stability index (VSI). SFS is an effective\nmetaheuristic algorithm consisting of diffusion process and two update processes. ORPF is a complex problem giving challenges\nto applied algorithms by taking into account many complex constraints such as operating voltage from generators and loads,\nactive and reactive power generation of generators, limit of capacitors, apparent power limit from branches, and tap setting of\ntransformers. For verifying the performance, solutions of IEEE 30 and 118-bus system with TPL, VD, and VSI objectives are found\nby the SFS method with different control parameter settings. Result comparisons indicate that SFS is more favorable than other\nmethods about finding effective solutions and having faster speed. As a result, it is suggested that SFS should be used for ORPF\nproblem, and modifications performed on SFS are encouraged for better results....
In recent years, power generation using renewable energy sources has been\ndeveloped as a solution to the global warming problem. Among these power\ngeneration methods, wind power generation is increasing. However, as the\npenetration level of wind power generation increases, the low inertia and lack\nof synchronous power characteristics of the penetrated power system can\nhave a significant impact on the transient stability of the grid. The virtual\nsynchronous generator provides the ability of virtual inertia and synchronous\npower to interconnected inverters. The interconnected inverter with the virtual\nsynchronous generator ability uses, in general, PI control based current\ncontroller. This paper proposes a new current-control method and compares\nit with conventional methods. The proposed current control is a method that\nfollows virtual synchronous generator model that changes every moment by\nsolving the discrete-time linear quadratic optimal control problem for each\nsampling time interval. The new method follows the conventional method,\nand therefore the reactive power fluctuation can be suppressed and the interconnected\ninverter will be downsized....
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