Coolant Temperature Research Articles

The interactive effects between far-red light and temperature on lettuce growth and morphology diminish at high light intensity

Phytochromes (PHYs) play a dual role in sensing light spectral quality and temperature. PHYs can interconvert between the active Pfr form and inactive Pr form upon absorption of red (R) and far-red (FR) light (Photoconversion). In addition, active Pfr can be converted to inactive Pr in a temperature-dependent manner (Thermal Reversion). Recent studies have shown that FR light and temperature can interactively affect plant growth and morphology through co-regulating phytochrome activities. These studies were primarily conducted under relatively low light intensities. As light intensity increases, the impact of thermal reversion on phytochrome dynamics decreases. However, the light intensity dependency of the interactive effects between FR light and temperature on plant growth and morphology has not been characterized. In this study, lettuce (Lactuca sativa L.) ‘Rex’ was grown under two total photon flux densities (TPFD; 400-800 nm) (150 and 300 μmol m-2 s-1) x three temperatures (20, 24, and 28°C) x two light spectra (0 and 20% of FR light in TPFD). Our results showed that the effects of FR light on leaf, stem, and root elongation, leaf number, and leaf expansion were dependent on temperature at lower TPFD. However, the magnitude of the interactive effects between FR light and temperature on plant morphology decreased at higher TPFD. Particularly, at a lower TPFD, FR light stimulated leaf expansion and canopy photon capture only under a cooler temperature of 20°C. However, at a higher TPFD, FR light consistently increased total leaf area across all three temperatures. Plant biomass was more strongly correlated with the total number of photons intercepted by the leaves than with the photosynthetic activities of individual leaves. FR light decreased the contents of chlorophylls, carotenoids, flavonoids, and phenolics, as well as the total antioxidant capacity. In contrast, warmer temperatures and high light intensity increased the values of these parameters. We concluded that the interactive effects between FR light and temperature on plant growth and morphology diminished as total light intensity increased. Additionally, the combination of high light intensity, warm temperature, and FR light resulted in the highest crop yield and antioxidant capacity in lettuce.

Experimental & Modelling Studies on Novel Scraped Surface Falling Film Crystallizer for Freeze Desalination

Freeze Desalination (FD) is a low-temperature thermal desalination technique that uses freezing. FD requires seven times less energy than evaporation-based desalination processes in addition to reduced corrosion and scaling issues. However, commercial adoption is limited by issues like incomplete salt removal, scaling of heat transfer surfaces with ice. Recently, the availability of 'cold energy' at -162°C during LNG regasification has increased the potential application of FD at LNG terminals, particularly in coastal areas facing water stress. This paper introduces a new equipment called the Scraped Surface Falling Film Crystallizer (SSFFC), specifically designed for the FD process. The SSFFC uses falling film freeze crystallization and a mechanism for in-situ ice crystal harvesting through scraping and filtration. Experiments were conducted using brackish water to evaluate the performance of the SSFFC unit, focusing on ice production and salt rejection at various feed salinities and coolant temperatures. The unit achieved ice production rates of 2.7kg/h and 3.9kg/h with coolant temperatures of -9°C and -12°C, respectively, for a feed salinity of 10,000 ppm. A mathematical model of the SSFFC unit was developed, validated with experimental results and used in parametric studies to investigate the impact of different operating conditions on its performance.

COMPARATIVE ANALYSIS OF TECHNICAL, ECONOMIC, WEIGHT, AND SIZE CHARACTERISTICS OF HORIZONTAL AND VERTICAL STEAM GENERATORS FOR 1000 MW NUCLEAR POWER PLANT UNITS

A comparative analysis of the technical characteristics and parameters of horizontal and vertical steam generators for reactorinstallations with water coolant in modern 1000 MW NPP power units has been conducted. It is noted that the peculiarities of thedesign schemes and constructions of steam generators in NPP power units with water coolants are significantly influenced by thestrong dependence between the coolant temperature at the steam generator inlet and the pressure in the reactor circuit. Thedependencies of coolant and working substance temperature changes and the amount of heat transferred in steam generatorelements have been considered. The t-Q diagram of a steam generator with a water coolant featuring a non-boiling economizer,evaporator, and superheater is presented. The parameters of water coolants and working substances in nuclear power plant steamgenerators are provided. The t-Q diagram for steam generators without a superheater section is shown, because in modern 1000MW nuclear power plant units with steam generators which use water as the working substance in the steam-turbine cycle,saturated steam without superheating is used. This is because minor superheating of the steam does not significantly increase theefficiency of the steam-turbine cycle but requires significant complexity in the design of the steam generators. It is noted that thecorrect choice of their structural schemes is crucial in the creation of steam generators with water coolants. It has been proven thatthe characteristics determining the structural schemes of steam generators with water coolants are: the scheme of washing the heatexchange surface with the coolant, the form of the heat exchange surface, the layout of steam generator elements, the principle ofworking substance movement, and others. The technical characteristics of a horizontal-type steam generator for 1000 MW nuclearpower plant units are presented, which have proven to be quite effective in operation. However, their designs and characteristicslimit the potential for further improvement of the technical and economic indicators of nuclear power plants. It is noted thatimproving the technical and economic efficiency of 1000 MW nuclear power plant units while simultaneously reducing capitalcosts for their construction is possible by increasing the unit capacity of powerful vertical-type steam generators installed on them.Compared to horizontal steam generators, vertical steam generators allow for a more rational layout of the primary circuitequipment in the reactor department, thus reducing the volume and cost of construction and installation works. The maindimensions and weight characteristics of possible designs of vertical steam generators for nuclear power plants with VVER-1000reactors are provided. It is concluded that once-through vertical steam generators with spiral wound heat exchange tubes and watercoolant in the first circuit tubes weigh approximately 1.5 to 2 times less than vertical steam generators with natural circulation. It isdetermined that once-through vertical steam generators with a hydraulic scheme involving the movement of the working substancein the tubes and the water coolant in the inter-tube space significantly lag behind once-through vertical steam generators with watercoolant in the tubes in terms of dimensional and weight characteristics and also vertical steam generators with natural circulation interms of weight. It is concluded that for VVER-1000 nuclear power plants, the most promising of all options are vertical once-through steam generators with the movement of the water coolant in spiral wound heat exchanger tube bundles. These steamgenerators occupy approximately four times less area in the reactor department than horizontal ones with the same steamproduction, which significantly reduces construction costs for nuclear power plants.

Soil-associated fungal and prokaryotic diversity influenced by stoniness, depth and vintage in a high-altitude vineyard

Soil microbes are increasingly recognised as key contributors to wine terroir, playing crucial roles in soil health and nutrient cycling. Fungi and prokaryotes interact with soils, influencing physical and chemical properties and mediating nutrient availability for roots. These microorganisms also impact vine performance and wine quality. Viticulture is expanding to higher elevations due to their cooler temperatures; Mendoza's mountainous regions are of particular interest being, characterised by vineyards with heterogenous soil stoniness. However, the effect of this variability on soil-associated microbial communities remains unclear. This study explores microbial populations (alpha and beta diversity, taxonomical composition, and their relationship with soil physicochemical properties) in soils of contrasting stoniness, at different depths, vintages and sample types. A Malbec vineyard with heterogenous soil stoniness was selected, with two experimental sites 30 m apart containing stony soil (SS; 77 % stoniness) and non-stony soil (NS; 0 % stoniness), respectively, and which were managed identically. Samples were collected from two depths (0.3 m and 0.6 m) during two vintages (2017 and 2018), from bulk and rhizosphere. Amplicon sequencing targeted the V3-V4 region of the 16S rRNA gene (prokaryotes) and the ITS1 region (fungi). Results showed that soil type significantly influences fungal populations, with less effect on prokaryotes. Vintage, reflecting annual changes in weather and viticultural practices, was the most significant factor affecting microbial communities. Depth was particularly important for fungi, while the sampling type (bulk or rhizosphere) had no significant impact on the microbiome within the same soil profile. Certain soil components were found to influence microbial communities: pH affected prokaryotes, while calcareous content specifically influenced the Proteobacteria phylum. Additionally, five fungal orders were more abundant in the stony soils, though some remained unidentified. These findings provide a baseline for understanding microorganisms in contrasting soils types of a high-elevation vineyard, and they highlight the role of microbial diversity in supporting unique soil-plant-environment interactions.

Evaluating Food Production, Cooling Potential, and Gardener Perspectives in Urban Allotment Gardens of Valladolid, Spain

The renaissance in urban agriculture is driven by its contributions to fostering more sustainable, healthy, and renaturalized cities. While urban gardens are usually designed to improve food security or serve social purposes, they also offer additional benefits. The aim of this research is to study the urban allotment gardens in Valladolid, Spain, highlighting their capacity to support low-income populations and their potential contribution to urban cooling. As a result of research in twelve plots across four gardens, we found that crop selection in Valladolid aligns with broader urban gardening trends in the Global North, with production adapted to limited plot space and varying significantly by season. In addition, we observed that urban allotment gardens provide more stable and cooler temperatures compared to urban gray spaces, although not as significantly as urban parks. The cooling effect was most pronounced during the summer, a season with the highest number of crops and the warmest temperatures. The study identified that greater crop cover above soil had a more significant cooling effect at the plot level. Surprisingly, crop abundance and crop diversity showed a weak correlation with cooling benefits. As a complement, survey questionnaires conducted with gardeners revealed their awareness of climate change and its perceived direct threat to their crops, health, and city. The future concerns of gardeners regarding the availability of water for both crop growth and the development of urban allotment gardens are emphasized. The findings provide results on self-produced food, urban cooling, and the opinion of gardeners, underscoring the multifunctional contributions of urban gardens to cities.

ZTF SN Ia DR2: The spectral diversity of Type Ia supernovae in a volume-limited sample

More than 3000 spectroscopically confirmed Type Ia supernovae (SNe Ia) are presented in the second data release (DR2) of the Zwicky Transient Facility survey. In this paper we detail the spectral properties of 482 SNe Ia near maximum light, up to a redshift limit of z leq 0.06. We measured the velocities and pseudo-equivalent widths (pEW) of key spectral features ( and and investigated the relation between the properties of the spectral features and the photometric properties from the SALT2 light-curve parameters as a function of spectroscopic sub-class. We discuss the non-negligible impact of host galaxy contamination on SN Ia spectral classifications, and we investigate the accuracy of spectral template matching of the DR2 sample. We define a new subclass of underluminous SNe Ia (04gs-like) that lie spectroscopically between normal SNe Ia and transitional 86G-like SNe Ia (stronger than normal SNe Ia, but significantly weaker features than 86G-like SNe). We model these 04gs-like SN Ia spectra using the radiative-transfer spectral synthesis code tardis and show that cooler temperatures alone are unable to explain their spectra; some changes in elemental abundances are also required. However, the broad continuity in spectral properties seen from bright (91T-like) to faint normal SN Ia, including the transitional and 91bg-like SNe Ia, suggests that variations within a single explosion model may be able to explain their behaviour.

Friction factor and heat transfer prediction of rocket engine cooling channels in numerical simulations with high roughness Reynolds number

In literature, it is widely recognized that surface roughness significantly influences friction and heat transfer. This effect is especially pronounced in additive manufactured components, which are increasingly important in the space sector. However, using numerical approaches to predict their performances is challenging because the correlations and the numerical models available for high roughness conditions have to be tuned with respect to the specific case. This study aims to benchmark existing modeling strategies and to compare the results against the experimental results of additively manufactured rocket engine cooling channels. To achieve this, the Spalart–Allmaras model equipped with the Boeing roughness correction was implemented in ANSYS Fluent and tested on various test conditions. The goal is to determine the best-fitting sand-grain parameter values that match experimental data in terms of friction factor and compare the heat transfer predictions regarding coolant temperature, wall temperature, and Nusselt number. Eventually, a correction of the turbulent Prandtl number was demonstrated to be needed. Data from literature and empirical correlations for high values of roughness Reynolds number are gathered and compared with the outcomes from this work, giving satisfying results.

Multi-objective decoupling control of thermal management system for PEM fuel cell

Operating temperature is an important factor that affects the efficiency, durability, and safety of proton exchange membrane fuel cells (PEMFC). Thus, a thermal management system is necessary for controlling the appropriate temperature. In this paper, a novel thermal management system based on two-stage utilization of cooling air is first established, whose core characteristic is utilizing the temperature difference between the cooling air leaving the main radiator and the auxiliary radiator. The novel thermal management system can reduce the parasitic power of the fan by 59.27 % and improve the temperature control effect to a certain extent. The traditional feedforward decoupling control based on system identification is first adopted to control the temperature and surpasses dual-PID on all the 5 indexes, which are Integral Absolute Error Criterion (IAE) of temperature difference, IAE of inlet coolant temperature, parasitic power of fan, average overshoot of temperature difference and average overshoot of inlet coolant temperature. The multi-objective decoupling control based on multi-objective optimization is then proposed to further improve the temperature control effect on the basis of traditional feedforward decoupling control. The above 5 indexes are chosen as the optimization objectives, the decoupling coefficients are chosen as the decision variables, and the Pareto set is obtained by NSGAⅡ and NSGAⅢ. The results show that the proposed multi-objective decoupling control has the main advantages as follows: (1) It can provide comprehensive optimization options for different design preferences; (2) It can significantly optimize a certain objective while other objectives are not too extreme; (3) It has the ability to surpass traditional feedforward decoupling control on all the 5 indexes; (4) It does not rely on the system identification.

Risk factors for spotted fever group rickettsioses in Kilimanjaro Region, Tanzania

Abstract Background Knowledge gaps exist on risk factors for spotted fever group rickettsioses (SFGR) in sub-Saharan Africa. We sought to identify SFGR risk factors in Kilimanjaro Region, Tanzania. Methods We recruited febrile patients presenting at two hospitals in Moshi from February 2012 through May 2014. Standardised clinical and risk factor questionnaires were administered. SFGR exposure was defined as a Rickettsia africae immunofluorescence antibody reciprocal titer ≥64, and acute SFGR as a ≥four-fold rise between paired sera. Logistitic regression was used to identify associations. Results Of 1,190 participants providing ≥1 serum sample, median (range) age was 21.8 (0.3, 100.2) years, 545 (54.3%) were female, and 650 (54.6%) had SFGR exposure. Of 731 participants with paired sera, 67 (9.2%) had acute SFGR. On multivariable analysis, odds of acute SFGR were higher in age group 0-2 years (adjusted odds ratios [aOR] for older age groups <0.36, p<0.011), rural residence (aOR 4.1, p=0.007), and areas with maximum daily temperature <26°C (aORs for higher temperature groups <0.42, p-values<0.035). Odds of SFGR exposure were higher in those working in the garden (aOR 1.8, p=0.010), and seeing a dog (aOR 1.5, p=0.010). Odds of SFGR exposure were lower in age group 0-2 years (aORs for older age groups >1.5, p<0.026), female sex (aOR 0.62, p<0.001), and being from Chaga tribe (aOR 0.68, p=0.003). Conclusion Those aged <2 years, rural residents, and persons residing in areas with cooler temperatures had increased odds of SFGR. Our results identify groups for further research on tick exposure and for targeted prevention interventions.

Migratory birds have a distinct haemosporidian community and are temporally decoupled from vector abundance at a stopover site.

Migratory animals likely play an important role in the geographic spread of parasites. In fact, a common assumption is that parasites are potentially transmitted by migratory animals at temporary stopover sites along migratory routes, yet very few studies have assessed whether transmission at stopover sites can or does occur. We investigated the potential for a group of vector-transmitted parasites, the avian haemosporidians, to be transmitted during migratory stopover periods at Rushton Woods Preserve in Pennsylvania, USA. Using an analysis of 1454 sampled avian hosts, we found that while a core group of abundant haemosporidians was shared between local breeding birds and passing migrants, the parasite community of migratory birds at Rushton was distinct from that of local breeding birds and showed similarity to a previously sampled boreal forest haemosporidian community. Haemosporidians that were unique to passing migratory birds were associated with sampling sites in North America with cooler summer temperatures than haemosporidians that are transmitted at Rushton, suggesting that the transmission of these parasites may be restricted to high-latitude regions outside of our temperate stopover site. We also found that the abundance of mosquitoes in our study region is offset from that of migratory bird abundance during avian migratory periods, with the peak period of bird migration occurring during periods of low mosquito activity. Collectively, these findings suggest that although abundant haemosporidians are possibly transmitted between local and passing migratory birds, a combination of biotic and abiotic factors may constrain haemosporidian transmission during avian stopover at our study site.

Why Is It Too Cold? Towards a Mechanistic Understanding of Cold-Water Pollution Effects on Recruitment of an Imperiled Warmwater Fish.

Environmental temperature shapes the ontogeny of ectotherms by influencing rates of growth and development which can be key determinants of survival. Whereas the escalating impacts of water management on freshwater ecosystems is well documented, the effects of cold-water releases from dams-which can alter downstream temperatures-remains relatively underexplored but may present novel challenges to endemic ectotherms. Specifically, little is known about how thermal depressions reshape phenotypic and genetic patterns during larval metamorphosis for fishes that evolved in warmwater systems. We assessed the effects of thermal shifts on larval ontogeny of the endangered razorback sucker (Xyrauchen texanus), which evolved in the warm waters of the Colorado River Basin, USA. We hypothesised that development is more sensitive to cold-water influences than growth and that temperature would influence patterns in gene expression related to development. Our results supported these hypotheses and showed that both wild and laboratory-reared larvae in slightly cooler temperatures exhibited delayed development, but similar growth compared to larvae reared in warmer conditions. These findings suggest growth and development in early ectotherm life stages can be decoupled, which follows patterns more like the temperature-size rule than allometric scaling of development by size. We also observed transcriptional differences related to genes associated with stress responses and development in our laboratory-reared fish; here, gene expression of fish from the coldest conditions at the end of the experiment was more similar to fish reared in warmer temperatures at the midpoint. Our findings suggest that modest temperature reductions can delay ontogeny and alter the transcriptional landscape while not necessarily limiting growth. This finding highlights the need for conservation practitioners to consider cascading impacts that even small temperature reductions can cause in riverine ecosystems.

Performance and Durability of Heavy-Duty Fuel Cell Systems with an Advanced Ordered Intermetallic ORR Alloy Catalyst and Novel Support

Abstract Ordered PtCo intermetallic (OIM) catalyst (L10-PtCo/C) is a promising candidate as the oxygen reduction reaction (ORR) catalyst in hybrid fuel cell systems (FCS) for class-8 heavy duty (HD) trucks. Compared to a baseline annealed Pt on high surface area carbon (a-Pt/HSC) catalyst, its mass activity (MA) is 71% higher initially and 144% higher after 90,000 potential cycles in an accelerated stress test (AST). Analysis of the AST data indicates that the ORR kinetic constants do not change with aging and the degradation in the OIM catalyst activity is linearly proportional to the loss in the electrochemically active surface area (ECSA). Several operational strategies are investigated to mitigate catalyst degradation and achieve 25,000-h electrode lifetime and 2.5 kW/g Pt utilization on a HD truck duty cycle including load sharing with the hybrid battery, regulating the radiator fan power to maintain the coolant temperature close to 60oC, clipping the maximum cell voltage below 850 mV, limiting the ECSA loss to 55%, and oversizing the membrane active area by 20%. Drive cycle simulations indicate that the lifetime average voltage degradation rate is about 1.8 V/h and the integrated stack and FCS drive cycle efficiencies decrease by 3.5 to 3.9%.

Dynamic thermal and mass transport in PEM fuel cells at elevated temperatures and pressures: A 3D model study

Next-generation proton-exchange membrane fuel cells (PEMFCs) encounter significant challenges at elevated temperatures (OTs) and pressures (OPs) due to local thermal and mass fluctuations. In this study, a three-dimensional transient model was developed to analyze these dynamics by incorporating the effects of the microporous layer and variations in the coolant temperature along the channel. The results indicate that increasing the OT from 80 °C to 90 °C decreases the output voltage by 34–78 mV, increases voltage undershoot/overshoot by 0.2–16.6 mV, and raises the temperature difference between the cathode catalyst layer (cCL) and coolant from 1.2 to 2.1 °C, leading to more irregular temperature fluctuations in the cCL. These effects stem from the increased gas–liquid water outflow within the cCL that induces membrane dehydration, particularly in the electrolyte near the channel. Consequently, the lag in proton conduction relative to the oxygen reduction reaction (ORR), as quantified by the newly introduced Damköhler number, has emerged as a critical factor that influences both heat transfer and reaction kinetics. Conversely, increasing OPs from 130 kPa [anode]/120 kPa [cathode] to 400 kPa [anode]/390 kPa [cathode] improves output voltage by 50–150 mV and reduces proton conduction hysteresis by 12–54 % under dynamic loads. This improvement is linked to higher O2 concentration and membrane water facilitated by a 0.6–2 °C decrease in cCL temperature. However, the rise in OPs also results in an increased voltage undershoot/overshoot due to greater fluctuations in the membrane water content, ultimately leading to additional power loss. These findings are crucial for optimizing PEMFC performance under extreme conditions and advancing fuel cell technology.

Walking on sunshine: Application of a choice experiment to understand impacts of climate change on tourism attractions

Summer destinations and local attractions in Western European countries are increasingly affected by climate change, predominantly high temperatures and impacts by thunderstorms. In order to assist practitioners, this study investigates the trade-offs visitors make under different expected weather conditions and develops recommendations for adaptation strategies. A survey containing a discrete choice experiment including different types of attractions, accessibility and weather conditions, was conducted (N = 5544). The results show that the impacts of heavy rainfall, thunderstorms and heat as a result of climate change cannot be assessed in a blanket manner. Visitors are less sensitive to high temperatures than to the probability of thunderstorms and cooler temperatures are preferred, especially for outdoor activities. Furthermore, the survey revealed that the majority of respondents would rather travel further (spatial substitution) than change the desired activity (activity substitution).We expected that steering instruments such as higher parking fees or the enhanced accessibility by public transportation are able to change mobility patterns and enhance mitigation strategies. However. parking fees, meant to influence behavior and enhance the shift from private car to public transportation, showed limited effects. Finally, the results underline that the perceived utility of sustainability certifications remains low, and that certification has a very limited influence on the decision-making process.

Upper Ocean Thermodynamic Response to Coupling Currents to Wind Stress over the Gulf Stream

We use high-resolution coupled atmosphere–ocean model simulations over the Gulf Stream extension region during a winter season to examine the upper ocean thermodynamic response to including current feedback to atmospheric wind stress. We demonstrate that a model that includes current feedback leads to significant changes in the structure and transport of heat throughout the upper ocean in comparison to the same model without current feedback. We find that including the current feedback leads to changes in the upper ocean temperature pattern that match the vorticity pattern. Areas with cyclonic ocean vorticity, typically north of the Gulf Stream extension, correspond to areas with warmer temperatures throughout the water column. Areas with anticyclonic ocean vorticity, typically south of the Gulf Stream extension, correspond to areas with cooler temperatures throughout the water column. We also find that including current feedback leads to an overall reduction in the submesoscale vertical heat flux spectra across all spatial scales, with differences in the submesoscale vertical heat flux corresponding to SST minus mixed layer temperature differences. The direct impact of current feedback on the thermodynamic structure within the upper ocean also has indirect impacts on other aspects of the ocean, such as the energy transfer between the ocean and the atmosphere, ocean stratification, and acoustic parameters.

Hibernation reduces GABA signaling in the brainstem to enhance motor activity of breathing at cool temperatures

BackgroundNeural circuits produce reliable activity patterns despite disturbances in the environment. For this to occur, neurons elicit synaptic plasticity during perturbations. However, recent work suggests that plasticity not only regulates circuit activity during disturbances, but these modifications may also linger to stabilize circuits during future perturbations. The implementation of such a regulation scheme for real-life environmental challenges of animals remains unclear. Amphibians provide insight into this problem in a rather extreme way, as circuits that generate breathing are inactive for several months during underwater hibernation and use compensatory plasticity to promote ventilation upon emergence.ResultsUsing ex vivo brainstem preparations and electrophysiology, we find that hibernation in American bullfrogs reduces GABAA receptor (GABAAR) inhibition in respiratory rhythm generating circuits and motor neurons, consistent with a compensatory response to chronic inactivity. Although GABAARs are normally critical for breathing, baseline network output at warm temperatures was not affected. However, when assessed across a range of temperatures, hibernators with reduced GABAAR signaling had greater activity at cooler temperatures, enhancing respiratory motor output under conditions that otherwise strongly depress breathing.ConclusionsHibernation reduces GABAAR signaling to promote robust respiratory output only at cooler temperatures. Although frogs do not ventilate lungs during underwater hibernation, we suggest this would be beneficial for stabilizing breathing when the animal passes through a large temperature range during emergence in the spring. More broadly, these results demonstrate that compensatory synaptic plasticity can increase the operating range of circuits in harsh environments, thereby promoting adaptive behavior in conditions that suppress activity.

Experimental and numerical investigations of liquid cooling plates for pouch lithium-ion batteries considering non-uniform heat generation

Ensuring the thermal safety of lithium-ion batteries requires efficient and reliable thermal management systems. However, the non-uniform heat generation of lithium-ion batteries results in uneven temperature distribution, which complicates the comprehension of the flow pattern design and operating parameter optimization in liquid-based battery thermal management, especially under extreme conditions. This study evaluates the thermal management performance of four classic liquid cooling plate designs for pouch batteries by considering their non-uniform heat generation through the electrochemical-thermal coupled model. Through experiment and numerical simulation, the optimal flow pattern is identified. Subsequently, the capability of the thermal management system, utilizing the best flow design, is further assessed under varying operating conditions. The results indicate that while a higher flow rate marginally enhances cooling, the coolant inlet temperature exerts a more substantial impact on the cooling performance. In addition, the recommended parameter settings for cell-level liquid cooling systems are outlined under extreme conditions. With a 5 C discharge rate and an initial temperature of 35 °C, the recommended coolant temperature range and coolant flow rate range are 20–30 °C and 60–100 mL min−1, respectively. As a typical example of computer-aided engineering, this study reveals the impact of battery non-uniform heat generation on battery temperature performance and provides a critical reference for the optimization of liquid-based battery thermal management systems.

Research on control strategy of electric vehicle thermal management system motor

Abstract The low efficiency and difficulty in low-temperature heating are the challenges currently faced by the thermal management system of new energy vehicles. A multi-heat source vehicle thermal management system for waste heat cascade recovery and utilization was proposed, and the performance of the vehicle thermal management system was studied through a combination of component testing and one-dimensional simulation. Based on a one-dimensional simulation model, the characteristics of the motor waste heat source are analyzed. The increase in the inlet water temperature of the motor coolant will lead to enhanced heat dissipation of the motor to the air, resulting in a waste of motor waste heat. Based on the results of the analysis, an energy cascade management strategy is constructed. The optimal heating mode is selected by collecting temperature signals such as motors, and the cut-off valve is controlled through logic gates to achieve flexible switching of different modes. The system effectively reduces the energy consumption of thermal management systems, which is of great significance for developing thermal management systems for new energy vehicles.

The SRG/eROSITA All-Sky Survey

Context. Galaxy groups lying between galaxies and galaxy clusters in the mass spectrum of dark matter halos play a crucial role in the evolution and formation of the large-scale structure. Their shallower potential wells compared to clusters of galaxies make them excellent sources to constrain non-gravitational processes such as feedback from the central active galactic nuclei (AGN). Aims. We investigate the impact of feedback, particularly from AGN, on the entropy and characteristic temperature measurements of galaxy groups detected in the SRG/eROSITA’s first All-Sky Survey (eRASS1) to shed light on the characteristics of the feedback mechanisms and help guide future AGN feedback implementations in numerical simulations. Methods. We analyzed the deeper eROSITA observations of 1178 galaxy groups detected in the eRASS1. We divided the sample into 271 subsamples based on their physical and statistical properties and extracted average thermodynamic properties, including the electron number density, temperature, and entropy, at three characteristic radii from cores to outskirts along with the integrated temperature by jointly analyzing X-ray images and spectra following a Bayesian approach. Results. We present the tightest constraints with unprecedented statistical precision on the impact of AGN feedback through our average entropy and characteristic temperature measurements of the largest group sample used in X-ray studies, incorporating major systematics in our analysis. We find that entropy shows an increasing trend with temperature in the form of a power-law-like relation at the higher intra-group medium (IGrM) temperatures, while for the low-mass groups with cooler (T < 1.44 keV) IGrM temperatures, a slight flattening is observed on the average entropy. Overall, the observed entropy measurements agree well with the earlier measurements in the literature. Additionally, comparisons with the state-of-the-art cosmological hydrodynamic simulations (MillenniumTNG, Magneticum, OWL) after applying the selection function calibrated for our galaxy groups reveal that observed entropy profiles in the cores are below the predictions of simulations. At the mid-region, the entropy measurements agree well with the Magneticum simulations, whereas the predictions of MillenniumTNG and OWL simulations fall below observations. At the outskirts, the overall agreement between the observations and simulations improves, with Magneticum simulations reproducing the observations the best. Conclusions. These measurements will pave the way for achieving more realistic AGN feedback implementations in numerical simulations. The future eROSITA Surveys will enable the extension of the entropy measurements in even cooler IGrM temperatures below 0. 5 keV, allowing for the testing of the AGN feedback models in this regime.

System Modeling-Based Investigation of SMR Operations Using Variable T-avg Control for Cost-Effective Electricity Generation in a Grid

Given the importance of nuclear power as low carbon energy source, this study conducted techno-economic evaluation of flexible use (baseload as well as load-following) of small modular reactors (SMRs) in an electric grid. The load-following operation of SMR (SMART-100) was restricted to the use of variable T-avg control, a least disruptive and cost minimizing method of load follow control. A system model was developed to describe the reactivity feedback effects of coolant temperature variations due to electric demand-based turbine load changes. Using the system model, conservative output ranges and maximum ramp rates that allow load-following operation without violating axial offset limits were derived. Assuming the introduction of SMR in Jeju Island in South Korea, a semi-independent grid region, with highly dependency on fossil fuel energy and power imports along with significant renewable energy generation (15–20 %), as a test case, this study evaluated the economic contribution of SMR using LPM to minimize the grid electricity generation costs. The results indicate that in regions with a high penetration of renewable energy in their grid systems, flexible energy generation of SMR can make a significant contribution in reducing electricity generation cost and carbon emissions.