Rate Of Temperature Increase Research Articles

Experimental and Numerical Investigation of Thermal Performance of an Air-Cooled Battery Module Under High Ambient Temperature Conditions

Abstract Lithium-ion batteries (LiBs) are widely used in electric vehicles due to their high energy and power density. The operating temperature has a significant impact on the thermal performance and longevity of LiBs. The thermal performance of an air-cooled battery module containing 16 (4S4P) high-energy density LiBs has been investigated through a series of experiments and numerical simulations. At varying transverse and longitudinal cell spacing, airflow rates, ambient temperatures, and discharge C-rates, the thermal performance of a battery module with aligned battery cells was analyzed. For the thermal performance evaluation, the average temperature rise, temperature non-uniformity, and maximum temperature of the module’s battery cells are utilized. During discharge cycles, the rate of temperature increase is linear but becomes nonlinear at the end of the discharge cycle. In the current architecture of the battery module, a minimum space utilization ratio of 0.38 is necessary to limit maximum temperature and temperature non-uniformity to safe battery thermal management temperatures. The thermal performance was significantly affected by the airflow rate. Increasing airflow rate decreases temperature but increases pressure drop substantially. The maximum cell temperature is greatly affected by the inlet air temperature, increasing from 62.8 °C to 76.6 °C when the inlet air temperature is increased from 30 °C to 45 °C. At high ambient temperatures (over 40 °C), LiB temperatures exceed permissible limits, and air cooling alone is inadequate. This study examines the thermal performance of an air-cooled battery module working at high temperatures.

G-OPTIMAL DESIGN OF NON-LINEAR MODEL TO INCREASE PURITY LEVELS OF SILICON DIOXIDE

Silicon Dioxide (SiO2) is one of the most abundant minerals found on earth. SiO2 is widely used in various fields, so its availability as a finite natural resource diminishes. A purity procedure can raise the purity of low-quality silica by altering the temperature and rate of temperature rise. This study aims to obtain the best design for increasing SiO2 levels—the G-optimal design on a non-linear model using the Variable Neighborhood Search (VNS) algorithm. The VNS algorithm employs two types of neighborhoods, one acquired by replacing one design point with a candidate set and the other by replacing two design points with two points in the candidate set. The model used to increase silicon dioxide's purity is a non-linear model that follows the exponential decay distribution. The best design points obtained from the G-optimal design on the relationship between temperature (oC) and the rate of temperature increase (oC/min) 800 oC to 900 oC is a pair of points 800 oC and 1,67 oC /min, 800 oC and 2,17 oC/min, 815 oC and 2,50 oC/min, 825 oC and 2,00 oC/min, 845 oC and 2,34 oC/min, 895 oC and 3,34 oC/min 900 oC and 3,50 oC/min with a G-efficiency of 96,41%.

Dielectric relaxation response of electrical insulating liquids under different natures of thermal stress

This study focuses on the dielectric relaxation response of insulating liquids based on mineral oil and synthetic ester in a thermal field.The research also offers the dielectric relaxation response of the magnetic nanofluid based on the investigated synthetic ester. The reason for investigating the synthetic ester-based nanofluid is that the temperature characteristics of the mineral oil-based magnetic nanofluid have already been investigated in several studies. Nanofluid based on synthetic ester is not sufficiently explored in this regard. The behavior of insulating liquids in the thermal field is divided into two parts. The first one points to the effect of temperature on the dielectric properties of the insulating liquids in the range from 293.15 K to 363.15 K. The insulating liquids show relaxation processes in the investigated frequency spectrum (1 mHz–3 kHz), which are dependent on temperature. The logarithm of the relaxation frequency decreases linearly with decreasing temperature according to Arrhenius' law. Mineral oil has the highest value of activation energy. In the second part, the results are focused on the influence of the rate of temperature increase on the dielectric parameters and moisture content of the investigated fluids. A slower increase in temperature causes an increase in polarization losses and a reduction in the distribution of relaxation times. In the case of base oils, also a reduction in activation energy. The change in the heating rate of the investigated liquids does not affect their moisture. Changes in dielectric parameters are not caused by changes in the moisture of insulating liquids, but by thermal aging.

Experimental and numerical investigation of fast preheating of lithium ion pouch cell via low-power inductive heating in cold climate

The fast preheating of lithium ion batteries (LIBs) is a challenge hindering its wide application in cold climate. This study proposes a new preheating method that employs an inductive heating operation. The performance of inductive heating on LIB is evaluated and compared with conventional heating methods using metal resistance film (MRF) and positive temperature coefficient (PTC) elements. Subsequently, an inductive heating numerical model is established to investigate the influence of critical factors, including current frequency and battery thickness, on the inductive heating performance. Results show that conventional MRF and PTC heating cannot provide safe fast preheating of LIBs owing to significant temperature difference inside battery. In comparison, inductive heating offers a better battery preheating performance with fast temperature increment, uniform temperature distribution and high efficiency. The battery utilizing sandwich inductive heating achieves a temperature increase rate up to 71.4 °C/min, an insignificant temperature deviation less than 6 °C, and a heating efficiency of 79.2% in the experimental test. The higher temperature uniformity of inductive heating is attributed to the fact that heat is generated within the battery electrode layers and that the contact thermal resistance induced by battery case can be eliminated. Moreover, the inductive heating performance is highly related with current frequency and battery thickness. The inductive heating of LIB is more suitable for operations at low frequencies, such as 10 kHz, as the skin effect of inductive heating can be decreased, and the temperature uniformity is increased. The battery thickness less than 4 mm is recommended as the maximum temperature deviation is less than 2 °C. This paper provides a preliminary investigation into the feasibility of LIB inductive preheating technology and offers new insights into the thermal management design of LIB application in cold climates.

Recent Active Fires in Indonesia’s Southern Papua Province Caused by El Niño Conditions

This study was conducted to identify the fire weather conditions needed to assess future peatland fires under climate change. Recent peatland fires in Indonesia have resulted in globally significant environmental impacts. Nevertheless, diurnal fire weather in the peatlands has not been clarified. The objective of this study was to determine the fire weather conditions needed to assess future peatland fires under climate change. An analysis of fire weather using diurnal weather data during the most active fire period in 2015 showed a strong wind speed of 35.7 km h−1 at 3 p.m. that continued to blow for about two weeks, suggesting that peatland fires in 2015 became very active under these very strong wind conditions. The temperature increase rate (ΔT), the RH decrease rate (ΔRH), and the wind speed increase rate (ΔWS) during morning hours from 6:00 a.m. to 9:00 a.m. were 2.3 °C h−1, −10.3% h−1, and 5.2 (km h−1) h−1 respectively. These weather parameters will be used to predict occurrences of active fires. The results of this report may help to predict fire activity under high temperatures in the future based on predictions of global warming made by other researchers. The rapid air temperature increase rate from morning will be useful for fire forecast in Papua.

Comparison of winding configurations of a 3-phase system for generating a rotating magnetic field powered by rectangular signals

The article compares two versions of 3-phase system for generating a rotating high-frequency magnetic field f = 100 kHz powered by rectangular signals with appropriately shifted phases. Obtaining sinusoidal signals from square waveforms was obtained using passive filters consisting of capacitors and inductors. The magnetic system was housed in a ferrite torus. In one version the filter branches were connected in a delta-system (Δ) and in the other version they were connected in a (Y)-system. The delta-system delivered a 72% higher magnetic field strength than the (Y)-system at the same supply voltage. Similarly, it turned out that the delta-system gives more than 3.5 times the temperature increase rate dT/dt compared to the (Y)-system. The advantage of the delta-system is its high efficiency, which can be used in magnetic hyperthermia as a treatment supporting radio- or chemo-therapy.

Numerical simulation of trans-/near-/supercritical injection characteristics based on real fluid properties

In this paper, the trans-/near-/supercritical jet models were established using a combination of large eddy numerical simulations and real fluid equations of state (EOS) in order to systematically investigate the heat and mass transfer mixing process of the jet at supercritical pressure. The effects of EOS, injection temperature (Tinj), ambient pressure (Pamb), and the pseudo-boiling phenomena on the density field, temperature increase rate, spray penetration, spray area, spreading angle, and mixing layer thickness of the spray were investigated. The results reveal that the initial shape of the spray is connected to its thermodynamic and transport characteristics. The correctness of fuel characteristic parameters impacts the development of the jet. For trans-/near-critical sprays, the temperature rise rate, spreading angle, spray area, and mixing layer thickness are enhanced, indicating the mixing efficiency is improved by increasing the Pamb and Tinj. However, raising the Pamb has a detrimental impact if both the Tinj and the Pamb exceed the critical parameters. This is owing to the link between Tinj and pseudo-boiling temperature, which results in a trade-off between Pamb and the objects discussed above for supercritical sprays. This research is essential to comprehend the heat and mass transfer mixing process of the supercritical jet.

Microstructural modeling of temperature distribution and heat transfer of 3-D carbon fiber braided circular composite tubes under direct current

Temperature distribution and heat transfer of carbon fiber composites under direct current are key factors to thermal-electric behavior design in aircraft. Here we report the effect of circular braided tubular structure on temperature distribution and heat transfer of carbon fiber braided composites with a microstructure finite element analysis (FEA) model. From the test and FEA results, we found that surface temperature distribution depends on surface braided texture and temperature decreases from the end part to the middle region because of the two heat sources including carbon fiber resistance and contact resistance. The surface temperature distribution has regular high-temperature zone correlated with braided structure. The temperature at the tube internal surface is slightly lower than that at the outside surface due to current distribution difference. The influence of braiding angle on heat generation and temperature distribution was also revealed. The temperature level and increase rate of the braided tube with a greater braiding angle are higher than that with a lower braiding angle.

Arctic Amplification in the Community Earth System Models (CESM1 and CESM2)

We compare the Arctic amplification (AA) produced by the two Community Earth System Models CESM1 and CESM2, members of the CEMIP5 (Coupled Models Intercomparison Project phase 5) and CEMIP6 collections, respectively. We find that the CESM1 model reproduces the recent high values of the AA deduced from the observed temperature much better than the CESM2. The correlation coefficient within the 1970–2012 time period between CESM1-simulated AA and the observed one is 0.47, while the CESM2 simulation leads to an anticorrelation of r = −0.53. Even the more successful model (CESM1) is not able to reproduce recent high AA values of 4–5. The main cause of this failure is the model’s overestimate of the rate of increase in the mean global temperature in years post 1990. When the CESM1 model’s simulated trend of the mean global temperature is replaced in the expression for the AA by the observed temperature trend, the correlation coefficient increases from 0.47 to 0.75. The CESM1 model is among the best north American models in AA simulation while the CESM2 model is among the least successful.

Experimental study of the temperature distribution in long tubular bones with a periossal arrangement of heaters

Purpose: to study the changes in the temperature outside and inside the long tubular bones of animals under the influence of different temperature regimes for a given time.Material and Methods. The experiments were conducted using fresh frozen pig long bones. The heating was carried out using surface heaters, the temperature of which was determined by the selected mode for 1 hour; fixation of temperature values was carried out every minute. Four heating modes were used: 3 modes of constant heating (60, 70, 80 °C) and the maximum heating mode, in which no special temperature limit was set, so heating was carried out up to 120 °C.Results. During the first 10 min of heating, a rapid rise in temperature occurred. The temperature increase rate on the outer surface outstripped the temperature increase rate on the inner surface of the bone, thus leading to a significant temperature difference. Further, there was a slowdown in the rate of temperature increase, which led to a gradual convergence of the temperature values inside and outside the bone, followed by temperature stabilization at a stable level (plateau), which was different for the studied areas. During this period, the temperature difference was 3.5–6 °C and it remained at this level until the end of the study. At a constant heating mode (60/70/80 °C), temperature stabilization occurred at the level of 55/61/70 °C in the center of the medullary canal and at the level of 58/67/75 °C under the heater, respectively. The period before reaching the stabilization temperature was 30–40 min. The stable temperature levels both inside and outside the bone were below the temperature stabilization level of the heater. Therefore, to achieve the planned temperature in the center of the bone to its outer surface, it is necessary to apply a high temperature, i.e., a downward temperature gradient is formed: the heater stabilization temperature – the temperature on the outer surface – the temperature inside the medullary canal. Increasing the exposure temperature can shorten the heating period, but increase the temperature difference during the heating period (up to 25 °C in the fifth minute of heating when using the maximum heating mode).Conclusion. To ensure reaching the required temperature (60°C) within a short time (15–20 min) while maintaining optimal temperature parameters, it was proposed to develop variable temperature modes that would combine the initial use of the maximum heating mode until reaching the desired temperature in medullary cavity, followed by switching to a constant temperature mode, which allowed maintaining the achieved temperature level during therapeutic exposure.

Development of a compact high-power density air-cooled proton exchange membrane fuel cell stack with ultrathin steel bipolar plates

Air-cooled fuel cells used in portable stacks are required to reduce the size and weight while ensuring a high-power output. In this study, the 0.1 mm stainless steel sheet was used to form the ultrathin bipolar plates (BPs), by the reasonable flow field design and material selection, the mass of single bipolar plate is as low as 44.6 g and the thickness is only 1.9 mm with 180 cm−2 active area. The 2.8 kW air-cooled stack has efficient heat dissipation, small voltage over/undershoot, rapid temperature dynamic response, and compact structure, moreover, the mass of the stack core is 3203 g and the volume of the stack is 3.36 L. The designed stack has an excellent voltage consistency, fast temperature response, and high power density. The maximum voltage overshoot is 0.035 V with a current step/drop of 10 A. The maximum temperature drop rate reaches 0.12 K s−1 in a 10% fan duty cycle step when the load current is 72 A. At 50% fan duty cycle, the temperature increase rate reaches its peak of 0.27 K s−1 when the load current steps from 70 A to 80 A. The mass power density of the designed air-cooled 56-cell stack is 0.885 kW kg−1 and the volumetric power density is 0.751 kW L−1.

Peatland Fire Weather Conditions in Central Kalimantan, Indonesia

Peatland fires in Central Kalimantan emit thick smoke and large amounts of greenhouse gases and have an impact on the environment globally, but studies on fire weather have not been carried out due to lack of diurnal weather data. The aim of this study is to identify the fire weather conditions during active fires that is needed to mitigate future occurrences of peat fires in Indonesia. The available diurnal weather data was used to analyze the fire weather conditions. Based on meteorological data on active fires (11 days), there was a significant increase in air temperature due to the sea breeze that started blowing in the morning. The average values for the 11-day period around 15:00 are a maximum air temperature of 36 °C, minimum humidity of 37%, wind speed of 21 km h−1, and a rate of increase of 2.7 °C h−1 from 8:00. The difference in sea and land temperatures causes strong winds to blow and triggers an increase in land temperatures. The results of this report can help predict fire activity at high temperatures in the future based on global warming predictions made by other researchers. The rapid rate of increase in air temperature from the morning will be useful in anticipating fires in Central Indonesia.

Urban Surface Thermal Runoff Generation Mechanism and Scenario Simulation

AbstractWhen precipitation happens in summer, the thermal runoff from impervious surfaces flow into urban lakes, causing the rise of the surface water temperature. Such a process eventually leads to the short‐term effects of cyanobacteria blooms in eutrophic lakes and the long‐term effects of changes in the structure and quantity of lake species. It is of great scientific significance to understand the heat exchange process between surface air, underlying surface, and surface runoff and reveal the thermal runoff formation mechanism. In this study, the heat transfer models between land, surface‐air, and surface‐water were implemented, aiming to quantify the heating process of surface runoff caused by surface heat load under real conditions. The results show that the two established models can accurately simulate the heat exchange process. Based on our model simulations and field measurements, we analyzed the impact of weather conditions, hydrological conditions, and underlying surface types on runoff temperature. The study finds that the initial surface temperature, wind speed, rainfall intensity, thermal conductivity, and the underlying surface's water permeability can explain 95.4% and 91.9% of the observed differences in surface runoff heating and temperature increase rate, respectively. The initial surface temperature is the most critical factor in the heat exchange process. The reduction of urban ventilation will aggravate the heat effect of surface runoff. Compared with the underlying permeable surface, the impervious surface is the main driving force for the formation of surface thermal runoff pollution.

PD45-05 TURNING UP THE HEAT: THERMAL PROFILE OF HOLMIUM:YAG (HL) AND THULIUM (TLF) LASER LITHOTRIPSY IN A PELVICALYCEAL SYSTEM (PCS) ANATOMIC HYDROGEL MODEL

You have accessJournal of UrologyCME1 Apr 2023PD45-05 TURNING UP THE HEAT: THERMAL PROFILE OF HOLMIUM:YAG (HL) AND THULIUM (TLF) LASER LITHOTRIPSY IN A PELVICALYCEAL SYSTEM (PCS) ANATOMIC HYDROGEL MODEL Christopher Wanderling, Aaron Saxton, Dennis Phan, Karen Doersch, Lauren Shepard, Nathan Schuler, Andrew Cook, Timothy Campbell, Stephen Hassig, and Ahmed Ghazi Christopher WanderlingChristopher Wanderling More articles by this author , Aaron SaxtonAaron Saxton More articles by this author , Dennis PhanDennis Phan More articles by this author , Karen DoerschKaren Doersch More articles by this author , Lauren ShepardLauren Shepard More articles by this author , Nathan SchulerNathan Schuler More articles by this author , Andrew CookAndrew Cook More articles by this author , Timothy CampbellTimothy Campbell More articles by this author , Stephen HassigStephen Hassig More articles by this author , and Ahmed GhaziAhmed Ghazi More articles by this author View All Author Informationhttps://doi.org/10.1097/JU.0000000000003358.05AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookLinked InTwitterEmail Abstract INTRODUCTION AND OBJECTIVE: Introduction of high-powered HL and TLF have raised the concerns of temperature generation during lithotripsy. In-vitro studies have yet to define the contributing factors in temperature profiles for these lasers. We sought to evaluate the thermal profiles for the HL and TLF in two 40w laser settings- fragmentation (2J x 20Hz) and dusting (0.4J x 100Hz). Each evaluated at 3 operator duty cycles (ODC); 50%, 75%, and 100% with different lasering on- and off- times (times on- 30s, 60s, 120s) in a realistic experimental setting METHODS: In an anatomical hydrogel model of a human PCS validated with mechanical and computational fluid dynamics testing containing a 2cm pelvic BegoStone, lithotripsy using the Moses 2.0 and Soltive Premium (200um laser fiber, short pulse for both) via a flexible ureteroscope with standardized irrigation. Two laser settings were tested at 3 ODCs and 3 laser-on times. Temperature was recorded using a K-type thermocouple probes (Omega, Norwalk, CT). Statistical analysis was a non-linear regression in a third-order polynomial model (Prism 9). RESULTS: 30 experiments were completed. At 100% ODC a significant difference in temperature profile was found comparing HL and TFL for each 40W setting (p<0.0001). Higher temperatures were generated at 2J x 20Hz for HL vs 0.4J x 100Hz for TFL (Fig 1). For all ODCs and on/off iterations, TFL was hotter during dusting while HL was hotter during fragmentation except at 2J x 20Hz for 120s on (75% ODC) where TFL temp>HL. The rate of temperature increase for both lasers was greatest in Q1 after which temperature rise for HL plateaued compared to TLF which steadily increased (Fig 1b). Critical temperature (51°C) was reached for 2J x 20Hz at 100% ODC (HL at 280s, TFL at 550s) and both 75% ODC (60s on: HL at 540s, TFL at 750s) (120s on: HL at 580s, TFL at 880s). At 0.4J x 100Hz, only TFL reached critical temperature at 100% (at 300s) and 75% ODCs (60s on- at 510s, 120s on- at 430s). There was significant difference between HL and TFL for each cycle in 50% and 75% ODC (p<0.0001) CONCLUSIONS: TFL generated higher temperatures during dusting vs HL during fragmentation that remained consistent for ODC and laser on iterations except during fragmentation with>60 sec laser-on times (TLF >HL). TLF heat generation occurs steadily vs HL generates heat initially during fragmentation. Source of Funding: Internal Funding © 2023 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 209Issue Supplement 4April 2023Page: e1164 Advertisement Copyright & Permissions© 2023 by American Urological Association Education and Research, Inc.MetricsAuthor Information Christopher Wanderling More articles by this author Aaron Saxton More articles by this author Dennis Phan More articles by this author Karen Doersch More articles by this author Lauren Shepard More articles by this author Nathan Schuler More articles by this author Andrew Cook More articles by this author Timothy Campbell More articles by this author Stephen Hassig More articles by this author Ahmed Ghazi More articles by this author Expand All Advertisement PDF downloadLoading ...

Spatial–temporal variation and temperature effect of urbanization in Guangdong Province from 1951 to 2018

In this paper, we focus on Guangdong province, which is a frontier area of Reform and Opening up, and analyze the variation of urban and rural temperature to detect the urbanization warming effect from 1951 to 2018, based on the daily temperature data of 85 weather stations. We classified the metrological stations into urban and rural stations according to the urbanization population size, population density and urban built-up area data. The combined methodology of mathematical statistics, trend analysis, urban/rural station comparison and spatial analysis was adopted to reveal the urbanization warming and its spatial–temporal heterogeneity. The results show that the warming process in Guangdong Province is very complex and has high temporal and spatial heterogeneity. From 1951 to 2018, the average temperature in the coldest month in Guangdong Province increased with the fastest (0.27 °C/10a) rate, and the annual average temperature increased slightly faster than the average temperature in the warmest month (0.15 °C/10a vs. 0.12 °C/10a). The comparative study on the temperature of urban and rural stations shows that the temperature increase rate of urban stations is faster than that of rural stations (0.30 °C/10a vs. 0.23 °C/10a), especially the average temperature in the coldest month, which is most significantly driven by urbanization, and the contribution rate of urbanization is about 24.09% in general. Affected by the background climate and the stages of urbanization, the warming effect of urbanization fluctuates obviously in different periods. Stronger urbanization effect can be witnessed during 1980–2000, when the urbanization developed into mid-level with highest rate. The spatial differentiation of urbanization warming effect is prominent. The temperature of urban stations in Eastern Guangdong increases most rapidly. The urbanization contribution rates to the coldest month average, annual average and the warmest month average temperature reach 33.86%, 25.70% and 17.64%, respectively, which are around 1.69, 1.50 and 1.19 times that of the Pearl River Delta. The average temperature of the warmest month in Western Guangdong shows a weak cooling effect. Multi-faceted, multi-level regulation of sustainable urbanization is the key to mitigating the warming caused by urbanization.

Neural Network PID-Based Preheating Control and Optimization for a Li-Ion Battery Module at Low Temperatures

Low temperatures induce limited charging ability and lifespan in lithium-ion batteries, and may even cause accidents. Therefore, a reliable preheating strategy is needed to address this issue. This study proposes a low-temperature preheating strategy based on neural network PID control, considering temperature increase rate and consistency. In this strategy, electrothermal films are placed between cells for preheating; battery module areas are differentiated according to the convective heat transfer rate; a controller regulates heating power to control the maximum temperature difference during the preheating process; and a co-simulation model is established to verify the proposed warm-up strategy. The numerical calculation results indicate that the battery module can be preheated to the target temperature under different ambient temperatures and control targets. The coupling relationship between the preheating time and the maximum temperature difference during the preheating process is studied and multi-objective optimization is carried out based on the temperature increase rate and thermal uniformity. The optimal preheating strategy is proven to ensure the temperature increase rate and effectively suppress temperature inconsistency of the module during the preheating process. Although preheating time is extended by 17%, the temperature difference remains within the safety threshold, and the maximum temperature difference is reduced by 49.6%.

Response of soil hydrothermal processes within the active layer to variable alpine vegetation conditions on the Qinghai‒Tibet Plateau

Alpine vegetation plays an important role in the thermal stability of the permafrost under a warming climate, as it affects ground hydrothermal dynamics. The response of soil hydrothermal dynamics in the active layer to permafrost degradation under different alpine grassland types is unclear on the Qinghai‒Tibet Plateau. In this study, long-term soil temperature and soil water content in the active layer were monitored in situ from October 2010 to December 2018 at five sites in the Kaixinling permafrost region on the interior Qinghai‒Tibet Plateau along the Qinghai–Tibet Railway. The sites included an alpine steppe (AS), three alpine meadows (AM) with different degrees of degraded vegetation, and an alpine swamp meadow (ASM). Based on field-monitored data, the variations in soil temperature, soil water content, and freeze–thaw processes were examined in the active layer. The response characteristics of the soil hydrothermal processes to climate change were analysed under the different alpine grasslands. The results showed that the duration of the thawing and freezing stages of the active layer of the AMs was shorter than that of the ASM and the AS. The average mean annual soil temperature (MAST) in the active layer of the AM ((−1.25 ± 0.50) °C) was lower than those in the AS ((−0.71 ± 0.39) °C) and ASM ((−0.45 ± 0.57) °C), while the AM had the highest rate of soil temperature increase ((0.2 ± 0.06) °C per year). The annual amplitude of ground temperature in the active layer increased with the transition direction of the alpine vegetation type from ASM to AM to AS. The small surface offset (SO) and thermal offset (TO) (absolute values) indicated that the ground thermal state of the AM was more unstable, as it was more sensitive to the increase in air temperature than the ASM or the AS. Soil properties controlled the distribution of soil water content within the active layer, but vegetation improved the shallow soil structure by producing more belowground phytomass, thus, enhancing soil water content in the 0–30 cm layer. The average soil water content at depths of 0–30 cm was directly proportional (p < 0.05) to the phytomass. Soil water contents at depths of 0–30 cm in the ASM ((37.7 ± 5.3)%) and the AM ((40.8 ± 5.9)%) were significantly higher than those in the AS ((22.7 ± 3.2)%). These results provide valuable insight into the hydrothermal interactions between the degradation of permafrost and alpine vegetation under a warming climate.

Optimized cabinet parameters for drying lithium-ion batteries based on coupled fluid–thermal field analysis

Hot-airflow desiccation is a commonly applied technique for drying lithium-ion batteries. However, most drying cabinet designs currently suffer from poor efficiency because they evacuate steam by ejecting the hot air in the cabinet to the open air continuously. This can be addressed by closing and opening the cabinet periodically, where the temperature of the heating zone is increased as quickly as possible through internal air recirculation in the closed position, and the steam is ejected with the hot air only during the open period. Nonetheless, drying cabinet designs of this nature have been rarely subjected to numerical analysis based on computational fluid dynamics and heat transfer, and the design factors enhancing the rate of temperature increase during the closed period remain poorly understood. The present work addresses these issues by outlining a detailed numerical approach for simulating the airflow temperature of a drying cabinet during internal air recirculation in its closed position, and the characteristics of the airflow and the temperature distribution in the dryer are evaluated via transient fluid–thermal coupling analysis. The results of the numerical investigation indicate that the heating efficiency is substantially influenced by the inlet airflow velocity, the distance between the trays holding the batteries, and the size of the free space between the front door and the trays. The results demonstrate that the developed model provides a useful means of evaluating and optimizing the heating efficiency of these types of drying cabinets.

Mechanically induced thermal runaway severity analysis for Li-ion batteries

Thermal runaway is one of the most important safety concerns in the deployment of Li-ion batteries. We developed a standardized single-side indentation test protocol to induce an internal short-circuit. Cell voltage, temperature, and applied compressive force are monitored as a function of time. Each cell is given an observed hazard severity (OHS in five categories) modified from the EUCAR table. Meanwhile a calculated hazard severity (CHS) is obtained solely based on temperature and voltage curves. The calculation formula considers the cell temperature, rate of temperature increase, cell capacity, state of charge (SOC), voltage drop, and voltage drop rate. Each term is assigned with an appropriate weight to scale the calculated score from 0 to100. This method was applied to >100 Li-ion batteries with various SOCs and chemistries, and their OHS and CHS were displayed against SOC. The purpose is to provide battery designers, manufacturers, and end-users a clear comparison of thermal runaway severity of different batteries.

Study on water and heat transport of different types of vegetations and fields in Pengbo alpine irrigation district of Qinghai Tibet Plateau

Many water-saving projects have been initiated in the typical alpine irrigation district in Tibet, which resulted in dramatic changes to the hydrothermal conversion process. There is an urgent need to fully understand the hydrothermal transport process and to clarify the mechanism under which agricultural hydrology evolves in the alpine irrigation district of Tibet. This study selected highland barley field, oat field, wasteland (Natural herbage field without irrigation) in Pengbo irrigation district of Tibet as study objects to study soil water and heat dynamics and soil water balance. Observed water and temperature data were used to calibrate and validate simulations of the HYDRUS_1D model for 2019 and 2020, respectively. Simulations of soil water and temperature were in good agreement with the measured values, with determination coefficient of 0.69–0.91.This study proposes a set of hydrothermal parameters to fill the gap in the hydrothermal research of Tibet. The results showed that the variation of soil temperature was approximately sinusoidal, with a lag effect. The temperatures of the 0–20 cm and 30–50 cm soil layers lagged by about 1–2 h and 3–5 h, respectively. The highest rate of soil temperature increase occurred from the initial growth period to the rapid growth period during which the soil temperature of each layer increased by an average of 2 °C, however, the soil temperature in this period was not the most suitable for crop growth. Soil evaporation of highland barley field, oat field, and wasteland during the growth period accounted for 20 % – 29 %, 20 % – 29 %, 10 % – 18 % of the rainfall and irrigation, whereas transpiration accounted for 33 % – 43 %, 42 % – 50 %, and 36 % – 57 %, and percolation accounted for 42 %, 35–39 %, and 16–45 %, respectively. Implementation of water-saving projects resulted in reductions in irrigation volume and percolation rate. This study can provide a reference for clarifying the hydrothermal transport process and allocating agricultural water resources in the alpine irrigation district of Tibet.