Power lithium-ion batteries are widely utilized in electric vehicles (EVs) and hybrid electric vehicles (HEVs) for their high energy densities and long service-life. However, thermal safety problems mainly resulting from thermal runaway (TR) must be solved. In general, temperature directly influences the performance of lithium-ion batteries. Hence, an efficient thermal management system is very necessary for battery modules/packs. One particular approach, phase change material (PCM)-based cooling, has exhibited promising applicability due to prominent controlling-temperature and stretching-temperature capacities. However, poor thermal conductivity performance, as the main technical bottleneck, is limiting the practical application. Nevertheless, only promoting the thermal conductivity is far from enough considering the practical application in EVs/HEVs. To fix these flaws, firstly, the heat generation/transfer mechanisms of lithium-ion power batteries were macro- and microscopically reviewed. Following that, the thermal conductivity, structural stability, and flame retardancy of PCM are thoroughly discussed, to which solutions to the aforementioned performances are systematically reviewed. In addition, battery thermal management system (BTMS) employing PCM is illustrated and compared. Eventually, the existing challenges and future directions of PCM-based BTMS are discussed. In summary, this review presents effective approaches to upgrade the PCM performances for high-density lithium-ion BTMS. These strategies furtherly accelerate the commercialization process of PCM BTMS.

In this article, a deep artificial neural network (ANN) model has been proposed to predict the boiling heat transfer in helical coils under high gravity conditions, which is compared with experimental data. A test rig is set up to provide high gravity up to 11 g with a heat flux up to 15100 W/m2 and the mass velocity range from 40 to 2000 kg m−2 s−1. In the current work, a total 531 data samples have been used in the ANN model. The proposed model was developed in a Python Keras environment with Feed-forward Back-propagation (FFBP) Multi-layer Perceptron (MLP) using eight features (mass flow rate, thermal power, inlet temperature, inlet pressure, direction, acceleration, tube inner surface area, helical coil diameter) as the inputs and two features (wall temperature, heat transfer coefficient) as the outputs. The deep ANN model composed of three hidden layers with a total number of 1098 neurons and 300,266 trainable parameters has been found as optimal according to statistical error analysis. Performance evaluation is conducted based on six verification statistic metrics (R2, MSE, MAE, MAPE, RMSE and cosine proximity) between the experimental data and predicted values. The results demonstrate that a 8-512-512-64-2 neural network has the best performance in predicting the helical coil characteristics with (R2=0.853, MSE=0.018, MAE=0.074, MAPE=1.110, RMSE=0.136, cosine proximity=1.000) in the testing stage. It is indicated that with the utilisation of deep learning, the proposed model is able to successfully predict the heat transfer performance in helical coils, and especially achieved excellent performance in predicting outputs that have a very large range of value differences.

Air quality and thermal environment of mine refuge chamber (MRC) are very important to determine the physical safety of refugees. Accurately assessing the environmental load and taking reasonable measures are critical to achieve the environmental control goals of MRC. In order to evaluate the metabolic parameters of occupants and the effectiveness of environmental control measures in a MRC, in this research, 50 adult men entered a MRC laboratory for an 8-h test. During the test, the compressed O2 cylinders and air purification devices were used to ensure the indoor air quality. The possibility of using chemical adsorbents to passively scrub CO2 and the performance of dehumidification by mine compressed air (MCA) were also investigated by simulation experiments. The results indicated that: (1) The per capita metabolic rates of O2, CO2 and heat during the refuge process are 0.34-0.37 L/min, 0.34 L/min and 117-128 W, respectively. (2) When Ca(OH)2 particles are used as CO2 adsorbent, the air purification device has both dehumidification and CO2 scrubbing functions, and three air purification devices could make the CO2 concentration below 0.8% with the relative humidity below 76%. When Ca(OH)2 particles are packaged to passively scrub CO2, the amount of adsorbent may increase significantly. (3) When MCA is used for dehumidification in a MRC, the air volume of 0.15 m3/min per capita could maintain the relative humidity close to 60%. (4) In the early stage of disaster avoidance, the indoor ambient temperature rises rapidly within 1 h followed by a slight increase.

Loop heat pipe has a wide application in the fields of airborne electronics cooling and thermal management. However, the pertinent temperature oscillation of the loop heat pipe could lead to adverse effects on the electronics. In the current study, an ammonia-stainless steel dual compensation chamber loop heat pipe was developed to experimentally investigate the temperature oscillation under different acceleration conditions. The impact of several control parameters such as different heat loads, loading modes, acceleration directions and magnitudes on the operational performance of the loop heat pipe was analyzed in a systematic manner. The heat load applied on the evaporator ranged from 25 W to 300 W. The acceleration magnitude varied from 1 g to 9 g and four different acceleration direction, i.e. configurations A, B, C and D, were taken into account. Two different loading modes were applied with different heat load and acceleration force. Experimental results show that (i) the loop temperature will change and oscillate as the acceleration force was applied under all test conditions. It can be easily found that the temperature oscillation occurred at both heat loads of 250 W and 300 W. (ii) for the case of the first loading mode, periodic temperature oscillation is observed on the liquid line, whereas for the second loading mode, periodic temperature oscillation can be easily appeared on the entire loop. (iii) the loop temperature under both configurations A and B with acceleration of 7 g does not oscillate at heat load of 150 W, 200 W and 250 W when the first loading mode is applied. Especially under configuration B, the acceleration could contribute to repress the temperature oscillation. Under the current heat loads for almost all cases, the temperature oscillation can be observed for configurations A, C and D with acceleration of 5 g. (iv) the amplitude of evaporator at heat load of 300 W under configuration C are 0.6 degrees C, 0.3 degrees C, 0.2 degrees C and 0.3 degrees C with acceleration of 3 g, 5 g, 7 g and 9 g. The corresponding period is 66 s, 36 s, 34 s and 36 s, respectively.

Nitrogen used for pressurization in the extinguisher can be partially dissolved in the fire extinguishing agent. Consequently, the evolution of the dissolved nitrogen has a significant effect on the release behavior of the fire extinguishing agent in a rapid process. In this article, a new model was developed to predict the critical pressure of the nitrogen evolution and the release process of the fire extinguishing agent was described in detail. According to the Peng–Robinson equation of state and van der Waals mixing rule, the effect of the dissolved nitrogen on the surface tension of the fire extinguishant was analyzed by considering surface phase and fugacity coefficient. A method to calculate the surface tension of the liquid agent dissolved with nitrogen was proposed. The results showed that the proposed model can determine the accurate critical pressure of the evolution of the dissolved nitrogen and further evaluated whether nitrogen escapes. At different initial filling pressures, in addition, the release process of the nitrogen extinguishant such as CF3I, FC218 (C3F8), HFC125 (C2HF5) and Halon1301 (CF3Br) was well predicted by the fluid release model when taking the surface tension and adiabatic index of the mixture into account. Compared with the previously obtained experimental data, the predictions obtained indicated that the present model can adequately describe the liquid and the gas mixture release stage in the release process of the nitrogen extinguishant.

In this article, the development of the energy separation for the vortex tube has been briefly reviewed. This review mainly focuses on three aspects, they are the energy separation principle, the design criteria of vortex tubes, and practical application. First, the research progress on the energy separation principle of the vortex tube from several aspects has been introduced, such as friction, pressure gradient, acoustic streaming, secondary circulation and multi-circulation theory. In addition, the control factors that affecting the performance of the vortex tube were summarized. Furthermore, due to its simple structure, safety and stability, the vortex tube is widely used in the field of refrigerating and heating, mixture separation. This survey, while extensive cannot cover all papers, some selection is necessary. The purpose of this review aims to summarize the important works of literature on the energy separation of vortex tube as well as identify limitations to existing studies and directions for future research.

This paper investigated the dynamic coupling heat transfer characteristics of rock and air in a Mine Refuge Chamber (MRC) under ventilation. In the current work, a comprehensive fifty-person MRC model combining human-body heat sources and ventilation is established, the proposed model is validated against available experimental data with deviation less than 4%. Furthermore, sensitivity analysis is performed to investigate the influence of several control parameters such as heating rate, ventilation and wall area in a MRC through using numerical simulation. Results indicated that: (i) the heat transfer process in a MRC will reach a stage of air temperature slow increase (ATSI) in less than 0.5 h. The air temperature rises linearly with the square root of time during the ATSI stage; (ii) for a MRC built in a sandstone seam with an initial rock temperature of less than 27 degrees C, the average air temperature will not exceed 35 degrees C in 96 h when the ventilation volume rate is 0.3 m(3)/min per person; (iii) the rate of temperature rise in MRC is proportional to the rate of heat generation, but it is inversely proportional to the thermal conductivity, density and thermal capacity of the rock, as well as the ventilation volume rate and the wall area; (iv) an empirical correlation for the MRC average air temperature is developed while the supply air temperature equals to the initial rock temperature.

A combined experimental and numerical study was performed to improve the performance of the ventilation system in a mine refuge chamber (MRC). In the experiment, CO2 cylinders and dispersion pipes were used to simulate the CO2 release of 50 people, and 0.1 L/min per person of fresh air was provided by an air compressor. A new analytical model for a 50-person MRC was proposed and validated against the experimental data. Sensitivity analysis was carried out to investigate the effects of several control factors. The results indicated the following: (1) The ventilation system layout has a significant influence on the CO2 concentration distribution in an MRC, while the uniformity of the CO2 concentration distribution in the MRC may not be effective with increased number of air inlets. (2) Under a well-arranged ventilation system in the 50-person MRC, the average CO2 concentration can be controlled at less than 0.5 % with a ventilation rate of 0.1 m(3) /min per person, and less than 0.2 % with a ventilation rate of 0.3 m(3) /min per person. (3) A quantitative correlation exists between the CO2 concentration and ventilation volume rate, as well as the CO2 release rate, for an MRC under a well-arranged ventilation system. (C) 2019 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.

A novel passive thermal management system (TMS) based on copper foam and paraffin composite phase change material (PCM) was designed for a lithium-ion battery pack in this work, where the phase change storage energy unit (PCSEU) was indirectly in contact with the cell. A combined experimental and numerical study was performed to investigate the thermal performance of the battery pack with the novel TMS and air cooling system (ACS). The effects of the PCSEU casing, composite PCM effective thermal conductivity, geometric structure parameters of the TMS, charge discharge rate and ambient temperature were systematically evaluated, as well as the battery thermal behaviors during charge and discharge cycles. Results showed that the passive TMS could keep the battery temperature in a desirable range even under 4C discharge rate at 42 degrees C and the PCSEU casing could remarkably improve its heat absorption efficiency. The thickness of the heat conducting sheet demonstrated the greatest impact on the battery temperature. Pure ACS with an air flow rate <= 200 m m(3)/h could not meet the battery cooling demands. The passive TMS could achieve up to 3 cycles of 4C charge and discharge at 35 degrees C while keeping the maximum temperature of the battery pack below 52 degrees C. (C) 2018 Elsevier Ltd. All rights reserved.

In this article, a combined experimental and numerical study has been performed to investigate the thermal performance of a mine refuge chamber (MRC) under natural convection. In the current study, a 20-hour heating experiment is carried out in a fifty-person MRC laboratory and the heat lamps are utilized to simulate the human heat loss. A new analytical model is proposed to predict the air temperature and validated against the experimental data. Sensitivity analysis is performed to further investigate the effects of the thermal parameters of the rock. Results indicated that: (1) two different air temperature increase stages, rapid and slow increase stages, are observed in the MRC; (2) A new analytical method for predicting the air temperature in MRC under natural convection is proposed, it shows that the air temperature increasing trend becomes slow with the increase of the thermal conductivity, density and specific heat capacity of the rock; (3) the surface heat transfer coefficient on the vertical walls reaches the largest and it increases linearly with air temperature.

The present work introduces a new technology for converting energy from steps into electricity. It starts with a study of the mechanical energy available from steps in a busy corridor. The subsequent development efforts and devices are presented, with an iterative approach to prototyping. Methods for enhancing the piezoelectric conversion efficiency have been determined as a part of the process and are introduced in the present article. Capitalizing on these findings, we have fabricated energy-harvesting devices for stairs that power embedded emergency lighting. The typical working unit comprises an energy-harvesting stair nosing, a power management circuit, and an embedded light-emitting diode that lights the tread in front of the user with an illuminance corresponding to emergency standards. The stair nosing generates up to 17.7 mJ of useful electrical energy per activation to provide up to 10.6 seconds of light. The corresponding energy density is 0.49 J per meter square and per step, with an 8.5 mm thick active layer.

— This paper identifies five key design characteristics of production scheduling software systems in printed circuit board (PCB) manufacturing. The authors consider that, in addition to an effective scheduling engine, a scheduling system should be able to process a preventative maintenance calendar, to give the user the flexibility to handle data using a variety of electronic sources, to run simulations to support decision-making, and to have simple and customisable graphical user interfaces. These design considerations were the result of a review of academic literature, the evaluation of commercial applications and a compilation of requirements of a PCB manufacturer. It was found that, from those systems that were evaluated, those that effectively addressed all five characteristics outlined in this paper were the most robust of all and could be used in PCB manufacturing.

ABSTRACT In three studies employing over 350 community adults and college students, participants wrote or told narratives of personally important scenes in their lives. The autobiographical accounts were coded for themes of agency and communion, the two general content dimensions in lives and life stories that have been identified by many theorists and researchers. The four agentic themes of self‐mastery, status, achievement/responsibility, and empowerment were positively associated with Thematic Apperception Test (TAT) measures of achievement and power motivation, self‐report scales of dominance and achievement, and personal strivings concerning being successful and feeling strong. Similarly, the four communal themes of love/friendship, dialogue, care/help, and community were positively associated with intimacy motivation, needs for affiliation and nurturance, and personal strivings concerned with warm and close relationships. The results suggest a thematic coherence in personality across the arenas of key autobiographical memories, social motives, and daily goals.

This study tested the hypothesis that when processing negative emotional material, psychopaths, compared with nonpsychopaths, would rely less on connotative-emotional processes based in the right hemisphere and more on denotative-linguistic processes based in the left hemisphere. Psychopathic and nonpsychopathic inmate groups, defined by their scores on the Psychopathy Checklist-Revised (R. D. Hare 1985), completed 2 analogous tachistoscopic tasks (words and faces). Accuracy and reaction times of inmates' responses in identifying which of 2 bilaterally presented stimuli (1 neutral and 1 emotional) was the emotional stimulus were measured. significant lateral processing differences between the 2 groups emerged on the word task but not on the face task, providing partial support for the experimental hypothesis. Psychopaths also showed lower generalized emotional responsivity than nonpsychopaths on the Affect Intensity Measure.