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 >

Piyanut Saengsikhiao¹, Juntakan Taweekun^1,2,*, Kittinan Maliwan², Somchai Sae-ung², Thanansak Theppaya²

Energy Engineering, Vol.118, No.2, pp. 411-433, 2021, DOI:10.32604/EE.2021.012860

Abstract This paper presents the improvement of eco-friendly and power consumption saving refrigerants for refrigeration systems. The novel azeotropic refrigerant mixtures of HFCs and HCs can replace refrigeration systems, and using the R134, R32, R125, and R1270 refrigerants in several compositions found using the decision tree function of the RapidMiner software (which came first in the KDnuggets annual software poll). All refrigerant results are mixed of POE, which is A1 classification refrigerant, non-flammable, and innocuous refrigerant, and using REFPROP software and CYCLE_D-HX software are under the CAN/ANSI/AHRI540 standards. The boiling point of the new refrigerant mix R-No.595 is 4.58%, lower than… More >

Yanju Wei^1,*, Shengcai Deng¹, Jie Zhang¹, Yajing Yang², Hao Chen³

Energy Engineering, Vol.118, No.2, pp. 225-235, 2021, DOI:10.32604/EE.2021.012416

Abstract The aerodynamic breakup of the droplet has been intensely studied in this paper. We aim to establish a unified relationship between dimensionless kinematic parameters such as displacement, spreading diameter, Weber number, time, and so on. The breakup characteristics of the acoustic levitated ethanol droplet are experimentally investigated when exposed to an air jet flow. The breakup phenomenons were recorded with a high-speed camera. The breakup characteristics were analyzed, and the physical models of the moving and transforming behaviors were established to explain the breakup mechanisms. We found that the displacement of the windward side of the droplet follows free acceleration… More >

Xiang Xiao¹, Wei Zhao¹, Wei Wang¹, Wei Zhang¹, Xianbiao Bu², Lingbao Wang^2,*, Huashan Li²

Energy Engineering, Vol.118, No.1, pp. 89-101, 2021, DOI:10.32604/EE.2020.014016

Abstract Solar energy powered organic Rankine cycle vapor compression cycle (ORC-VCC) is a good alternative to convert solar heat into a cooling effect. In this study, an ORC-VCC system driven by solar energy combined with electric motor is proposed to ensure smooth operation under the conditions that solar radiation is unstable and discontinuous, and an office building located in Guangzhou, China is selected as a case study. The results show that beam solar radiation and generation temperature have considerable effects on the system performance. There is an optimal generation temperature at which the system achieves optimum performance. Also, as a key… More >

Mei Song^1,2,*, Liyan Zhang¹, Mingxin Zhang^1,*, Dandan Li¹, Yaxu Zhu¹

Energy Engineering, Vol.118, No.1, pp. 143-161, 2021, DOI:10.32604/EE.2020.013834

Abstract Coordinated development of new high-tech industries and traditional industries is crucially important for economic growth and environmental sustainability, and it has become a focus of academic and governmental bodies. This study establishes the comprehensive evaluation index system of high-tech industries and traditional industries, and uses the method of principal component analysis, coupling and coupling coordination degree model to determine the level of industry coordinated development. Then, Pearson correlation test is used to further analyze the correlation between regional industrial coupling coordination and carbon intensity of the seven provinces in the Bohai Rim Economic Circle (BREC). The results are as follows.… More >

Zhiqiang Pan¹, Zhiwen Lin¹, Kunle Fan², Cheng Yang^2,*, Xiaoqian Ma²

Energy Engineering, Vol.118, No.1, pp. 119-141, 2021, DOI:10.32604/EE.2020.013585

Abstract Gas turbine power units, as an effective way to cope with the severe challenge of renewable energy accommodation in power grids, arouse the interest of power enterprises in the deep peak-load regulation performance. Two common alternative load-control strategies including constant turbine inlet temperature (TIT) and constant turbine exhaust temperature (TET) regulations were taken into consideration. To comparatively investigate the part-load performance under these strategies, both mathematical and physical models were set up successively to serve as a validation and complementary to each other. For the mathematical model of compressor with inlet guide vane (IGV), combustor and turbine, stage-stacking method based… More >

L. Krambeck¹, G. A. Bartmeyer¹, D. O. Souza², D. Fusão¹, P. H. D. Santos², T. Antonini Alves^1,*

Energy Engineering, Vol.118, No.1, pp. 1-14, 2021, DOI:10.32604/EE.2020.013572

Abstract The temperature control in electronic packaging is the key in numerous applications, to avoid overheating and hardware failure. Due to high capability of heat transfer, good temperature uniformity, and no power consumption, heat pipes can be widely used for heat dissipation of electronic components. This paper reports an experimental thermal analysis of different capillary structures for heat pipes. The wicks considered are metal screens, axial microgrooves, and sintered metal powder. The heat pipes are made of copper, a 200 mm length tube and a 9.45 mm external diameter. Working fluid used was distilled water. The devices are investigated in three… More >

Shusheng Xiong¹, Qiujie Song¹, Wei Li^2,*, Lian Xie³

Energy Engineering, Vol.118, No.1, pp. 163-172, 2021, DOI:10.32604/EE.2020.013410

Abstract Based on the principles of heat transfer, an oil film model in the engine cylinder was established. Under the condition of cold state, the influence of factors such as engine fuel injection, fuel drop point, cylinder inner wall temperature, and inlet fluid on the oil film is comprehensively considered to establish an oil film quality prediction model. Based on the measurement of the compensation oil quantity in the transition conditions, the variation of the oil film during the transition is analyzed. The experimental results show that the velocity of the airflow in the intake port and the temperature and pressure… More >