Fenwicks Shombe Musonye^1,*, Hiram Ndiritu², Robert Kinyua³

Energy Engineering, Vol.118, No.2, pp. 211-224, 2021, DOI:10.32604/EE.2021.013890

Abstract Pinch Analysis is an attractive solution for reduction of thermal energy costs in thermo-chemical industries. In this approach, maximum internally recoverable heat is determined and a heat exchange network is designed to meet the recovery targets. The thermal performance of a heat exchanger over its lifetime is however a concern to industries. Thermal performance of a heat exchanger is affected by many factors which include the physical properties of the shell and tube materials, and the chemical properties of the heat transfer fluid. In this study, thermal performance of shell and tube heat exchangers designed to meet heat recovery targets… More >

Yu Liu¹, Ruiting Jiao¹, Liyao Zhao¹, Kai Liu^1,2,*

Energy Engineering, Vol.118, No.2, pp. 363-378, 2021, DOI:10.32604/EE.2021.013472

Abstract The impact of greenization on the marginal utility of the intensity of carbon emissions in China and factors influencing this relationship are explored in this study. China’s level of greenization is evaluated by using an index system developed based on the comprehensive index method. The intensity of carbon emissions is determined by using the standards for the coefficients of conversion of coal equivalent and coefficients of carbon emission. The impact of greenization on the marginal utility of the intensity of carbon emissions is then evaluated by using an elastic formula and factors affecting this relationship are verified by regression analysis.… More >

Chi Zhang, Yong Shi^*, Xuwei Gui

Energy Engineering, Vol.118, No.2, pp. 341-361, 2021, DOI:10.32604/EE.2021.014229

Abstract To realize effective utilization of renewable energy sources, a novel polymorphic topology with hybrid control strategy based LLC resonant converter was analyzed and designed in this paper. By combining the merits of a full bridge LLC resonant converter, three-level half bridge LLC resonant converter, and variable frequency control mode, the converter realizes an intelligent estimation of input voltage by automatically changing its internal circuit topology. Under this control strategy, different input voltages determine different operation modes. This is achieved in full bridge LLC mode when the input voltage is low. If the input voltage rises to a certain level, it… More >

Lian Zhang^1,2,3,*, Linjun Fan⁴, Xin Xu⁵, Baowen Cao¹, Heng Zhang², Lihong Song³

Energy Engineering, Vol.118, No.2, pp. 399-410, 2021, DOI:10.32604/EE.2021.012647

Abstract Radiator thermal performance test equipment plays a key role in the processing of developing a new type of heat radiator and its application products. The precise of temperature controlling, temperature measuring and flow measuring are the vital factors for a radiator thermal performance test equipment. Based on the above background, this paper improves the measurement and control system of radiator thermal performance test equipment, which improves the accuracy of the radiator thermal performance test equipment. This paper also optimizes the software and hardware system simultaneously so as to improve the precision of the auto-test system of test equipment. The flow… More >

Pulin Cao, Haoran Fan, Zilong Cai^*

Energy Engineering, Vol.118, No.2, pp. 265-284, 2021, DOI:10.32604/EE.2021.014513

Abstract Since the voltage source converter based high voltage direct current (VSC-HVDC) systems owns the features of nonlinearity, strong coupling and multivariable, the classical proportional integral (PI) control is hard to obtain content control effect. Hence, a new perturbation observer based fractional-order PID (PoFoPID) control strategy is designed in this paper for (VSC-HVDC) systems with offshore wind integration, which can efficiently boost the robustness and control performance of entire system. Particularly, it employs a fractional-order PID (FoPID) framework for the sake of compensating the perturbation estimate, which dramatically boost the dynamical responds of the closed-loop system, and the cooperative beetle antennae… More >

Shuowang Zhang¹, Lingxiang Huang^1,*, Dongran Song^2,*, Ke Xu¹, Xuebing Yang¹, Xiaoping Song¹

Energy Engineering, Vol.118, No.2, pp. 237-250, 2021, DOI:10.32604/EE.2021.014269

Abstract Yaw control system plays an important role in helping large-scale horizontal wind turbines capture the wind energy. To track the stochastic and fast-changing wind direction, the nacelle is rotated by the yaw control system. Therein, a difficulty consists in the variation speed of the wind direction much faster than the rotation speed of the nacelle. To deal with this difficulty, model predictive control has been recently proposed in the literature, in which the previewed wind direction is employed into the predictive model, and the estimated captured energy and yaw actuator usage are two contradictive objectives. Since the performance of the… More >

Jia Zhu^*

Energy Engineering, Vol.118, No.2, pp. 379-397, 2021, DOI:10.32604/EE.2021.014178

Abstract In order to solve the problems of poor information flow, low energy utilization rate and energy consumption data reuse in the heavy equipment industrial park, the Internet of Things (IoT) technology is applied to construct the intelligent energy management and control system (IEMCS). The application architecture and function module planning are analyzed and designed. Furthermore, the IEMCS scheme is not unique due to the fuzziness of customer demand and the understanding deviation of designer to customer demand in the design stage. Scheme assessment is of great significance for the normal subsequent implementation of the system. A fuzzy assessment method for… More >

Jungang Wang^1,*, Liqun Qian¹, Shuairui Xu¹, Ruina Mo²

Energy Engineering, Vol.118, No.2, pp. 251-264, 2021, DOI:10.32604/EE.2021.014143

Abstract Wind turbine is a key device to realize the utilization of wind energy, and it has been highly valued by all countries. But the mechanical gear transmission of the existing wind power device has the disadvantages of high vibration and noise, high failure rate, and short service time. Magnetic field modulation electromagnetic gear transmission is a new non-contact transmission method. However, the conventional modulation magnetic gear has low torque density and torque defects with large fluctuations. In order to overcome the gear transmission problems of the existing semi-direct drive wind power generation machinery and improve the electromagnetic performance of the… More >

Hongming Yang^1,*, Qian Yu¹, Xiao Huang¹, Ben Niu², Min Qi³

Energy Engineering, Vol.118, No.2, pp. 285-301, 2021, DOI:10.32604/EE.2021.013734

Abstract The two-way interaction between smart grid and customers will continuously play an important role in enhancing the overall efficiency of the green and low-carbon electric power industry and properly accommodating intermittent renewable energy resources. Thus far, the existing electricity pricing mechanisms hardly match the technical properties of smart grid; neither can they facilitate increasing end users participating in the electricity market. In this paper, several relevant models and novel methods are proposed for pricing scheme design as well as to achieve optimal decision-makings for market participants, in which the mechanisms behind are compatible with demand response operation of end users… More >

Quanjia Zuo¹, Fanyi Meng^1,*, Yang Bai²

Energy Engineering, Vol.118, No.2, pp. 303-322, 2021, DOI:10.32604/EE.2021.013239

Abstract As one of the most important commodity futures, the price forecasting of natural gas futures is of great significance for hedging and risk aversion. This paper mainly focuses on natural gas futures pricing which considers seasonality fluctuations. In order to study this issue, we propose a modified approach called six-factor model, in which the influence of seasonal fluctuations are eliminated in every random factor. Using Monte Carlo method, we first assess and comparative analyze the fitting ability of three-factor model and six-factor model for the out of sample data. It is found that six-factor model has better performance than three-factor… More >