Design, fabrication and testing of a coated conductor magnet for electrodynamic suspension

Coated conductor magnet, as the onboard magnet of the electrodynamic suspension (EDS) train, is deemed promising due to its relatively high operating temperature, low cooling cost, and good mechanical tolerance, making the liquid-helium-free high-temperature superconducting (HTS) EDS train possible. In order to promote the progress of the HTS EDS train, this work aims at designing, fabricating and testing a coated conductor magnet as the onboard magnet of EDS train. The HTS magnet is designed with the comprehensive considerations of the electromagnetic calculation, thermal-mechanical coupling analysis, as well as the heat load estimation. The magnet is conduction-cooled without any coolant. A radiation shield was used to reduce the heat leakage, enabling the cryogenic system to provide a better low-temperature environment for the magnet. Through a deliberate design, the magnet was fabricated, including two HTS coils and the tailored cryogenic system. Afterwards, the electromagnetic and thermal performances of this magnet were tested and analysed in detail. It was proven that the magnet can be cooled to below 15 K; besides, the magnet has been successfully charged to 240 A. Further increase in the current is possible because of the high safe margin of the critical currents for both the HTS magnet and its current lead, although a slight performance degradation was observed on two double-pancake coils inside the magnet. The present study will provide useful implications for the design and application of onboard HTS magnets in EDS train.

The qutrit as a heat diode and circulator

We investigate the heat transport properties of a three-level system coupled to three thermal baths, assuming a model based on superconducting circuit implementations. The system-bath coupling is mediated by resonators which serve as frequency filters for the different qutrit transitions. Taking into account the finite quality factors of the resonators, we find thermal rectification and circulation effects not expected in configurations with perfectly-filtered couplings. Heat leakage in off-resonant transitions can be exploited to make the system work as an ideal diode where heat flows in the same direction between two baths irrespective of the sign of the temperature difference, as well as a perfect heat circulator whose state is phase-reversible.

Performance Analysis of Channels in Adiabatic and Non-adiabatic Spiral Plate Heat Exchangers: A Thermodynamic Study

This paper presents a systematic analysis of the thermodynamic performance of spiral turns in spiral plate heat exchangers (SPHEs), with and without heat leakage to the environment. An optimal design algorithm for SPHEs is developed to find higher compactness and overall heat transfer coefficient by increasing channels' pressure drops, maintaining geometric aspect ratio and minimizing the total costs. To specify the rate of heat loss to the environment, rate of internal heat transfer and channel temperature distribution, a mathematical model is proposed based on mass and energy balance equations to model the SPHE as a hypothetical heat exchanger network (HENs). Entropy-based and entransy-based performance evaluation methods in Heat Exchangers (HEs) are also examined to investigate the impact of heat leakage on the performance and irreversibility of the SPHEs. A single-phase counter-current SPHE is then designed as a case study, to examine the proposed mathematical and performance assessment models. The case study is defined and analyzed based on heat leakage to the environment. Three scenarios are then introduced namely heat leakage and no heat leakage to the environment and transferring the net heat between the streams. Results highlight the applicability of the proposed mathematical modelling and temperature distributions of channels in thermodynamics analysis of SPHEs with/without heat leakage to the environment. The findings also suggest that smaller adiabatic SPHEs can be a suitable substitute for non-adiabatic SPHEs providing appropriate insulation that covers outermost channels and prevent the leakage of the heat to the environment.

The heat leakage measurement of dewars for infrared detector arrays

Consideration is given to the analysis of a number of implementation of calorimetry method of infrared detector array dewar’s heat leakage measurements. The heat leakage measurements were made both with and without nitrogen vapor heat capacity consideration. The heat exchange process between nitrogen vapor and Dewar’s well walls was analyzed. The most reliable results were achieved by means of approach with calibration.

Onset and termination of Heinrich Stadial 4 and the underlying climate dynamics

Heinrich Stadial 4 during the last glacial period was marked by severe cooling at northern high latitudes along with the attendant changes in Asian Monsoon (Chinese Stadial 4) and South American Monsoon (South American Stadial 4). Here we present improved constraints on timings of Heinrich/Chinese/South American Stadial 4 onset and termination at sub-centennial precision based on speleothem records. We show that their initial onsets were essentially synchronous (40.20 ± 0.08 thousand years ago) and led the Antarctic warming by ~300 years. The Heinrich/Chinese Stadial 4 termination commenced at 38.34 ± 0.07 thousand years ago following a centennial-scale reduction in the Amazon River runoff and a poleward shift of the Southern Westerly wind belt. These two precursor events may have contributed to a reduced Amazon Plume Region and an enhanced Agulhas salt/heat leakage that led to an abrupt resumption of the Atlantic Meridional Ocean Circulation eventually triggering the Heinrich/Chinese Stadial 4 termination.

Application of the infrared scanning method for optimizing the microclimate of the winter garden for bees

The article discusses the practical significance of using the infrared scanning method to optimize the microclimate of wintering grounds for bee colonies in extreme conditions of the cryolithozone. When monitoring the microclimate by generally accepted zoohygienic methods, the devices record specific indicators of a particular parameter (temperature, humidity, air velocity, pressure, noise, light), while the reason for the deviation from the standard indicators for optimizing the microclimate is not always possible to find out. When using the infrared scanning method with the Irtis 2000SN thermal imager to determine the reasons for the deviation of the microclimate parameters from the standards, the following results were obtained: defects of enclosing structures were found: joints of walls and floor and joints of floor boards with a minus temperature of up to -21°C; the entrance group with a defect of heat leakage, warming the outdoor air to -36°C at an outdoor temperature of -48°C; the reason for the deviation of the air velocity of 0.18 m/s deviation from the standard by 0.08 m/s are defects of enclosing structures (Fig.7,8,12). The targeted elimination of the defects of the enclosing structures detected by infrared scanning made it possible to quickly optimize the parameters of the microclimate of the winter garden, thereby increasing the results of successful wintering of bee colonies. The analysis of the wintering results showed that the proportion of successful wintering in 2019 was 90%, which is 20% more than in 2018 and 30% more than in 2017

Additive Manufacturing as a Means of Gas Sensor Development for Battery Health Monitoring

Lithium-ion batteries (LIBs) still need continuous safety monitoring based on their intrinsic properties, as well as due to the increase in their sizes and device requirements. The main causes of fires and explosions in LIBs are heat leakage and the presence of highly inflammable components. Therefore, it is necessary to improve the safety of the batteries by preventing the generation of these gases and/or their early detection with sensors. The improvement of such safety sensors requires new approaches in their manufacturing. There is a growing role for research of nanostructured sensor’s durability in the field of ionizing radiation that also can induce structural changes in the LIB’s component materials, thus contributing to the elucidation of fundamental physicochemical processes; catalytic reactions or inhibitions of the chemical reactions on which the work of the sensors is based. A current method widely used in various fields, Direct Ink Writing (DIW), has been used to manufacture heterostructures of Al2O3/CuO and CuO:Fe2O3, followed by an additional ALD and thermal annealing step. The detection properties of these 3D-DIW printed heterostructures showed responses to 1,3-dioxolan (DOL), 1,2-dimethoxyethane (DME) vapors, as well as to typically used LIB electrolytes containing LiTFSI and LiNO3 salts in a mixture of DOL:DME, as well also to LiPF6 salts in a mixture of ethylene carbonate (EC) and dimethyl carbonate (DMC) at operating temperatures of 200 °C–350 °C with relatively high responses. The combination of the possibility to detect electrolyte vapors used in LIBs and size control by the 3D-DIW printing method makes these heterostructures extremely attractive in controlling the safety of batteries.

Comparative study on thermodynamic characteristics of composite thermal insulation systems with liquid methane, oxygen, and hydrogen

Composite passive insulation technology has been proved to be an effective method to reduce heat leakage into the cryogenic storage tank. However, the current related research mainly focused on liquid hydrogen (LH2). The thermophysical properties of different cryogenic liquids and the thermal insulation materials at different temperatures are significantly different, so whether the results related to LH2 are applicable to other cryogenic liquids remains to be further determined. In fact, the insulation technology of LH2 itself also needs further study. In this paper, a thermodynamic calculation model of a composite insulation system including hollow glass microspheres (HGMs), multilayer insulation (MLI), and self-evaporating vapor cold shield (VCS) has been established. The accuracy of the calculation model was verified by the experimental results, and a comparative study on thermodynamic characteristics of the composite thermal insulation system with liquid methane, liquid oxygen (LO2), and LH2 was carried out. The results show that the heat leakage reduction of the proposed system for liquid methane, LO2 and LH2 is 25.6%, 29.7% and 64.9% respectively compared to the traditional SOFI+MLI system (1*10−3 Pa). The type of liquid and the insulation system structure has a relatively large influence on the VCS optimal position. While for a specific insulation system structure, the insulation material thickness, storage pressure, and hot boundary temperature have a weak influence on the VCS optimal position.