Abstract

In this paper, the thermal performance of an all SiC 650 V, 116 A MOSFET power module has been studied by numerical simulation. Aiming at the heat dissipation problem of the SiC power devices in the inverter, three integrated liquid cooling heat sinks with different channel structures were designed. Results showed that compared with the other two cooling structures, the serpentine flow channel cooling structure can provide the best cooling effect. For the serpentine flow channel cooling structure, the heat source maximum temperature increases as the fin thickness increases, and the pressure drop decreases as the fin thickness increase when the coolant flow rate is constant. The improved heat sink has been numerical tested up to 110 A showing the device maximum temperature of 39.8°C, which can well meet the design requirements.

Abstract

Convergence analysis in carbon intensity is a critical tool to decide the CO2 emission reduction targets. Accurately estimating convergence behavior on a finer scale is generally more effective and practical to address spatial-temporal heterogeneity. However, little research has focused on convergence in carbon intensity across the prefecture-level cities in China. Here, we tested the convergence hypothesis in carbon intensity across 264 prefecture-level cities in China from 1992 to 2013 using convergence analysis, cross-section regressions, and dynamic spatial panel econometric techniques. We also compared different time periods and regions to explore the spatial-temporal heterogeneity of convergence behavior. Findings reveal converging CO2 intensities across cities and significant spatial effects in this convergence process. In addition, carbon intensity convergence rates for 1992–2013 show an overall decline over time. Furthermore, the analysis of spatial dynamic panel data shows significant conditional β-convergence after controlling for economic growth, population density, urbanization, and finance. We further provide significant evidence that population density, urbanization, and finance had significant negative effects on carbon intensity, while GDP per capita significantly facilitated carbon intensity. By controlling dynamic temporal effects, we find larger long-term, compared to short-term, effects of control variables on carbon intensity. Finally, carbon intensity convergence differs in regional heterogeneity, suggesting the necessity of designing different carbon intensity reduction polices.

Abstract

The multi-year wastewater-related energy in the Beijing-Tianjin-Hebei (BTH) region are calculated. The Logarithmic Mean Divisia Index (LMDI) method is used to analyze the driving factors of energy consumption for industrial wastewater treatment (wastewater-related energy). The results of driving force analysis illustrate that: From 2010 to 2018, the energy consumptions related to industrial wastewater in the BTH increase by 1.91, 1.50, and 1.11 times, respectively. The power consumption intensity and economic activity are the main drivers for the increase of industrial wastewater-related energy consumption. In contrast, the industrial structure is the main driver for its decrease. A significant increase in industrial wastewater-related energy consumption occurred between 2014 and 2018 (increased by 37.42 million kWh), while the decrease occurred from 2011 to 2014 (decreased by 11.02 million kWh). By identifying the critical driving factors of energy consumption change for wastewater treatment, this study aims to provide energy saving strategy to boost the synergies of energy-water nexus in industrial wastewater treatment.The multi-year wastewater-related energy in the Beijing-Tianjin-Hebei (BTH) region are calculated. The Logarithmic Mean Divisia Index (LMDI) method is used to analyze the driving factors of energy consumption for industrial wastewater treatment (wastewater-related energy). The results of driving force analysis illustrate that: From 2010 to 2018, the energy consumptions related to industrial wastewater in the BTH increase by 1.91, 1.50, and 1.11 times, respectively. The power consumption intensity and economic activity are the main drivers for the increase of industrial wastewater-related energy consumption. In contrast, the industrial structure is the main driver for its decrease. A significant increase in industrial wastewater-related energy consumption occurred between 2014 and 2018 (increased by 37.42 million kWh), while the decrease occurred from 2011 to 2014 (decreased by 11.02 million kWh). By identifying the critical driving factors of energy consumption change for wastewater treatment, this study aims to provide energy saving strategy to boost the synergies of energy-water nexus in industrial wastewater treatment.

Abstract

From the perspective of industrial agglomeration, this paper attempts to explore how much energy used is transformed into effective work affecting steel production and consumption. Using panel data of Chinese provinces from 1997 to 2016, we measure industrial agglomeration and effective energy service of the iron and steel industry. The panel threshold model is utilized with GDP per capita as the threshold variable, and a nonlinear framework is constructed to identify the relationship between agglomeration and effective energy service. The results show that the iron and steel industry exhibit agglomeration characteristics, with the average location entropy index exceeding 1. The effective energy service experiences a rise from 1997 to 2013, but declines from 2014 to 2016. The effective energy service in central and western regions lag behind that in eastern region. And with the economic growth, the influence of agglomeration on effective energy service is increasing. Finally, the paper suggests some policy priorities to improve the effective energy service of the iron and steel industry.

Abstract

Plug-in hybrid vehicles will become a major part of urban transportation before 2030. The hybrid powertrain is a micro energy system that needs to be managed to achieve low carbon emission. Dynamic programming is widely adopted to optimize the energy efficiency, but it cannot be directly used for real-time control. This paper proposes a new Global K-fold Fuzzy Learning (GKFL) scheme to implement the offline optimization results in real-time control with adaptive neuro-fuzzy inference system (ANFIS). It aims to obtain an ANFIS network that can robustly achieve the optimum control utility which is defined as a function of the vehicle’s energy efficiency and the battery state-of-charge (SoC). The performances of the 2 ANFIS network systems developed by both standard method and the GKFL method respectively are evaluated through experimental studies. GKFL is shown effective in knowledge implementation. Compared to the default solver in the MATLAB ANFIS toolbox, GKFL can increase the control utility of the studied vehicle by 8% in the Worldwide-harmonized Light-duty Testing Cycle.

Abstract

Mitigating global warming is the responsibility of all countries. Moreover, the role of forests in sequestrating carbon is very crucial. Most environmental organizations are active in protecting the environment according to their objectives. This paper investigates the relationship between institutional freedom and forest carbon sinks by using a panel threshold model with 139 countries to verify the U-shaped relationship between forest carbon sinks and economic development. The U-shaped curve between forest carbon sinks and economic development is the same as the environmental Kuznets curve. The impact of institutional freedom on forest carbon sinks under different economic development thresholds is analyzed. Institutional freedom harms forest carbon sinks when the country experiences lower economic growth. Further analysis shows that when economic development is high, there are positive effects, and the beneficial effects of institutional freedom on the forest carbon sink gradually enhance as the threshold value increases. The article clarifies the relationship between institutional freedom and forest carbon sinks and also provides implications for making forest management strategies and climate mitigation policies.

Abstract

In order to show the significance of Distributed Generation (DG) based on renewable energy and energy storage units in Regional Integrated Energy System (RIES), a model of RIES including power system, gas network system, and heating network system is presented in this paper. Furthermore, an intelligent recognition energy hub model considering energy utilization priority is used to describe the coupling of multi-energy. Finally, a case study of three scenarios is employed to examine the feasibility of the proposed model.

Abstract

Latent heat storage (LHS) can improve the imbalance of energy supply and demand. However, the relatively low thermal conductivity of phase change materials (PCMs) may weaken the advantage of latent heat storage. In this paper, seven different fin combinations are designed for LHS device filling with paraffin wax RT56 as PCM. The fins are composed of straight and Y-shaped ones. For the same volume ratio of fins to PCMs, the width and height of fin are changed to study their effect on melting phase change. A 2D model is established and is solved numerically. Comparing of phase interface evolution verifies the established numerical model. Results show that the melting speed of PCM at the bottom of LHS device is slow, and the Y-shaped fin with longer part in the lower region for PCM can help heat penetrate into the interior of PCM, and promote the heat conduction inside the lower PCM, thus improving the overall melting performance. The PCM melting time of the unit with increasing fin height is shorter than that of the device with increasing fin width.

Abstract

Latent heat thermal energy storage is used to solve the problem for the intermittency of time and space for solar energy. To improve the energy storage efficiency, metal fins are typically further added to the shell side to increase thermal conductivity of phase change materials. In this paper, a novel shell-and-tube latent heat thermal energy storage unit with angled fins was designed. A two-dimensional simulation model for an angled-fin tube was established and its melting characteristics were studied, including melting fraction, melting front evolution and complete melting time. Results demonstrated that a 55.41% reduction in full melting time was obtained for the unit with angled-fins. Except too big angles, the melting speed increased. Angled-fin tube can give a perspective to optimization of traditional finned tubes for practical applications with thermal energy storage.

Abstract

With the continuous increase in residential electricity consumption, attention should be paid to the issue of renewable energy power consumed by residents. Rethinking residents’ willingness to pay for renewable energy electricity is of great significance to the long-term development goal of renewable energy. This paper finds that residents’ willingness to support the development of renewable energy is growing. Respondents with the more participation in renewable energy planning, and the more satisfaction with the implementation of renewable energy policies, as well as a higher recognition of the high cost of renewable energy, are willing to use renewable energy and are willing to pay more for renewable energy power. Moreover, respondents who are willing to use renewable energy are willing to pay more for renewable energy electricity. Although respondents are more willing to use voluntary payment mechanisms for payment, they are more likely to pay more for renewable energy power under the mandatory payment mechanism. At present, there is a large gap between the actual green power purchase behavior of Chinese residents and the expected WTP, mainly because there are many problems in the voluntary subscription mechanism for green power certificates.