Full-scale model to predict borehole fluid temperature with groundwater advection

Ground source heat pump (GSHP) system is one of the major techniques that utilize shallow geothermal energy and borehole heat exchangers (BHEs) is the key component in GSHP system. Although most proposed analytical models for the thermal analysis of vertical BHEs take into account of the effects of either groundwater flow or axial heat conduction in the soil, the time scale of heat transfer in the BHEs is not well treated. In this study, an analytical full-scale model was developed to efficiently include the effects of the coupled transient heat transfer in the borehole, the axial heat conduction along the borehole and the effect of horizontal flow of groundwater. Results derived from the new model were compared with solutions of other traditional analytical and numerical models with the same configuration. The impacts of axial heat transfer and groundwater flow on the thermal response in the full time scale were also analyzed based on the proposed model

Structural Engineering of Hierarchical Micro‐nanostructured Ge-C Framework by Controlling the Nucleation for Ultralong Life Li Storage

The rational design of a proper electrode structure with high energy and power densities, long cycling lifespan, and low cost still remains a significant challenge for developing advanced energy storage systems. Germanium is a highly promising anode material for high-performance lithium ion batteries due to its large specific capacity and remarkable rate capability. Nevertheless, poor cycling stability and high price significantly limit its practical application. Herein, a facile and scalable structural engineering strategy is proposed by controlling the nucleation to fabricate a unique hierarchical micro-nanostructured Ge-C framework, featuring high tap density, reduced Ge content, superb structural stability, and a 3D conductive network. The constructed architecture has demonstrated outstanding reversible capacity of 1541.1 mA h g −1 after 3000 cycles at 1000 mA g −1 (with 99.6% capacity retention), markedly exceeding all the reported Ge-C electrodes regarding long cycling stability. Notably, the assembled full cell exhibits superior performance as well. The work paves the way to constructing novel metal-carbon materials with high performance and low cost for energy-related applications

The Effect of Spiritual Leadership on Employee Effectiveness: An Intrinsic Motivation Perspective

Drawing on spiritual leadership theory and intrinsic motivation theory, we proposed a homologous multilevel model to explore the effectiveness of spiritual leadership on employees’ task performance, knowledge sharing behaviors and innovation behaviors at the individual level. With questionnaires rated by 306 pairs of employees and their supervisors in 26 teams from the energy industry in mainland China, we conduct multilevel analysis to examine our hypotheses. The results show that spiritual leadership was positively related to employee task performance, knowledge sharing behaviors and innovation behavior, when we controlled for possible confounding effects of moral leadership and benevolent leadership, and ruled out alternative explanation of ethical leadership. The theoretical and practical implications are discussed

Randomly fractal approach to calculate the thermal conductivity of moist soil

Ground coupled heat pump (GCHP) is an energy saving technology that uses the shallow geothermal energy for the building heating and refrigeration systems. An optimized design of ground heat exchangers (GHEs) is the key to minimize the installation fee of GCHP systems. The effective thermal conductivity of soil is an important input parameter in the design of GHEs. This paper proposed a randomly fractal approach to predict the effective thermal conductivity of soil-like materials (quartz sand). The fractal Monte-Carlo method combined with the Quartet Structure Generation Set (QSGS) method was used to reconstruct the random structure of the soil-like materials. Lattice Boltzmann method (LBM) was further applied to the complicated porous structure and compute the effective thermal conductivity. The simulation results were compared to the findings from experiments and other similar models. The impacts of porosity, fractal dimension, size ratio and accumulation structure on the effective thermal conductivity were also analyzed in detail

Research on Consumers’ Preferences for the Self-Service Mode of Express Cabinets in Stations Based on the Subway Distribution to Promote Sustainability

With the explosive growth in the express delivery business, last-mile delivery issues have come to the forefront in China. Subway-based distribution has been demonstrated and practiced. The self-service mode of express cabinets in stations based on the subway distribution can effectively reduce the last-mile delivery costs, increase the utilization rate of public transportation resources, and reduce traffic congestion and carbon emissions. This paper designed self–service mode of express cabinets in stations and discussed the feasibility by investigating consumers’ preferences. The consumers’ preferences and influencing factors were examined by using the multicategorical logit model. The results show that consumers’ gender, education level and number of online purchases per month have an impact on consumers’ preferences. The majority of consumers are willing to actively engage in green consumer behavior. Meanwhile, consumers are more concerned about whether the express mode is convenient to conduct and the queuing of an express cabinet. Some suggestions and recommendations on promoting this self-service mode were put forward, such as pushing different advertisements for different groups of consumers, designing efficient and multi-function express cabinets, and adopting a reward system. This research provides guidance for decision making regarding the promotion of a new self–service mode based on the subway distribution, which can promote sustainable consumption and improve the efficient operation of urban last-mile delivery and the low-carbon development of urban transportation. Document type: Articl