Extreme Cold Research Articles

Modulating the internal porosity of organogel electrolyte via pore-forming agent for low temperature resistant and flexible quasi-solid supercapacitors

The widely applicable gel polymer electrolytes (GPEs) hold significant promise for the commercialization of low-temperature flexible quasi-solid-state supercapacitors (FQSCs). However, their flexibility and electrochemical performance are compromised under extreme cold conditions, severely limiting their practical applications. Inspired by the novel effects of “pore-form agents (PFA)”in hydrogel-controlled drug release & delivery, polyvinyl alcohol (PVA) hydrogel electrolytes with optimized internal porosity (polymeric structure) were prepared by introducing PFA as pore-regulator and in-situ leaching process, hereby enhancing the hydrogel's electrical conductivity and low-temperature performance. Furthermore, in order to further enhance its low-temperature tolerance, the composition of the electrolyte was adjusted via binary solvent replacement method. FQSCs composed of PVA-PFA30-EG exhibited significantly improved high specific capacitances of 131.72 F g−1 at 25 °C and 72.90 F g−1 at −40 °C when tested at 1 A g−1, with only a 6.36 % capacitance decay after 10,000 cycles at −40 °C. This performance surpasses that of most previously reported low-temperature FQSCs. The novel approach proposed in this paper provides a new avenue for flexible energy storage devices in extremely cold conditions.

Among- and within-population variation in germination response shapes ecological resilience in the Mediterranean cliff species Brassica incana Ten.

Understanding how plant species respond to extreme conditions is crucial for predicting their ecological resilience under climate change. Here, we aim to forecast the ecological resilience of the Mediterranean cliff species Brassica incana (Brassicaceae) by estimating population variation in germination response under novel extreme environmental conditions. We investigated the thermal germination responses in 14 populations of B. incana by exposing seeds to temperatures within and outside conditions experienced in their local environment. Then, we quantified among- and within-population variation in germination response to extreme temperatures, estimated genotype-by-environment interactions (G × E) and tested if population performance at extreme temperatures is explained by local climate. We found significant among-population differences in germination response, a different level of within-population variability, and different mechanisms underlying G × E patterns. Also, populations experiencing warmer temperatures in their local environment showed a better performance at both cold and hot extremes while populations experiencing colder temperatures showed a limited ability to germinate under extreme conditions. Our results suggest that populations experiencing warmer temperatures in their local environment have a higher potential to face future thermal extreme conditions and their role is thus crucial to promote species ecological resilience.

Projections of Extreme Temperature–Related Deaths in the US

ImportanceExtreme heat in the US is increasing due to climate change, while extreme cold is projected to decline. Understanding how extreme temperature along with demographic changes will affect population health is important for devising policies to mitigate the health outcome of climate change.ObjectiveTo assess the burden of extreme temperature–related deaths in the contiguous US currently (2008-2019) and estimate the burden in the mid–21st century (2036-2065).Design, Setting, and ParticipantsThis cross-sectional study used historical (1979-2000) daily mean temperatures to calculate monthly extreme heat (>97.5th percentile value) and extreme cold days (<2.5th percentile value) for all contiguous US counties for 2008 to 2019 (current period). Temperature projections from 20 climate models and county population projections were used to estimate extreme temperature–related deaths for 2036 to 2065 (mid–21st century period). Data were analyzed from November 2023 to July 2024.ExposureCurrent monthly frequency of extreme heat days and projected mid–21st century frequency using 2 greenhouse gas emissions scenarios: Shared Socioeconomic Pathway (SSP)2-4.5, representing socioeconomic development with a lower emissions increase, and SSP5-8.5, representing higher emissions increase.Main Outcomes and MeasuresMean annual estimated number of extreme temperature–related excess deaths. Poisson regression model with county, month, and year fixed effects was used to estimate the association between extreme temperature and monthly all-cause mortality for older adults (aged ≥65 years) and younger adults (aged 18-64 years).ResultsAcross the contiguous US, extreme temperature days were associated with 8248.6 (95% CI, 4242.6-12 254.6) deaths annually in the current period and with 19 348.7 (95% CI, 11 388.7-27 308.6) projected deaths in the SSP2-4.5 scenario and 26 574.0 (95% CI, 15 408.0-37 740.1) in the SSP5-8.5 scenario. The mortality data included 30 924 133 decedents, of whom 15 573 699 were males (50.4%), with 6.3% of Hispanic ethnicity, 11.5% of non-Hispanic Black race, and 79.3% of non-Hispanic White race. Non-Hispanic Black adults (278.2%; 95% CI, 158.9%-397.5%) and Hispanic adults (537.5%; 95% CI, 261.6%-813.4%) were projected to have greater increases in extreme temperature–related deaths from the current period to the mid–21st century period compared with non-Hispanic White adults (70.8%; 95% CI, −5.8% to 147.3%).Conclusions and RelevanceThis cross-sectional study found that extreme temperature–related deaths in the contiguous US were projected to increase substantially by mid–21st century, with certain populations, such as non-Hispanic Black and Hispanic adults, projected to disproportionately experience this increase. The results point to the need to mitigate the adverse outcome of extreme temperatures for population health.

The effect of extreme temperatures on evictions

Using data on evictions in the United States, we estimate the relationship between temperature and eviction filings. We find that extreme heat days result in a statistically significant increase in filings, while extreme cold days do not have the same relationship. To explain these findings, we show that residential energy expenditures are more sensitive to extreme heat than extreme cold, and that energy assistance programs in the United States prioritize funding for heating rather than cooling. These findings suggest that relative to today, future climate change scenarios with more hot days and fewer cold days will increase eviction filings without other policy or private adaptation.

Outcome of recycle bone reconstruction using liquid nitrogen in primary malignant bone tumor

Primary malignant bone tumors constitute a small but significant portion, accounting for 3–5% of childhood cancers. Cryosurgery, utilizing liquid nitrogen to induce tumor necrosis through extreme cold, emerges as a favorable surgical technique for bone tumor. This study delves into the clinical and radiological outcomes of individuals underwent cryosurgery. This descriptive study focused on patients with primary malignant bone tumors subjected to wide resection and cryosurgery with follow-up period from 6 up to 48 months from year 2018 - 2023. The data was collected from medical records and database, we evaluated the demographic data, clinical with Musculoskeletal Tumor Society (MSTS), radiological outcome with International Society of Limb Salvage (ISOLS) score, and the complications of cryosurgery observed. Among the 37 patients examined, 20 males and 17 females were averaging 21.7 years of age. 29 of 37 (78%) cases identified as osteosarcoma most common location in the epimetaphyseal of the long bone with Grade Enneking IIB. MSTS score averaged 25.35 ± 5.54, with more than 68% achieving excellent and good score. ISOLS for radiological score revealed 37.8% with an excellent score, 48.6% with a good score. The most common complication, reccurence, occurs in 6 cases (16.2%). Patients with primary malignant bone tumors who underwent cryosurgery showed successful clinical and radiological outcomes, as measured by MSTS and ISOLS scores. This underscores the significance of cryosurgery in primary malignant bone tumor as favorable and cost-effective treatment, showcasing improved functionality and positive radiological results.

Whole genome re-sequencing reveals high altitude adaptation signatures and admixture in Ladakhi cattle

Ladakhi cattle, native to the high-altitude region of Ladakh in northern India (ranging from 3,000 to 5,000 m above sea level), have evolved unique genetic adaptations to thrive in harsh environmental conditions, such as hypoxia, extreme cold, and low humidity. This study explored the genome of Ladakhi cattle to investigate genetic structure, selection signatures, and adaptive mechanisms. Whole genome sequencing reads, generated on Illumina NovaSeq 6000 platform, were aligned to the Bos taurus reference genome with BWA-MEM. SNPs were identified and filtered using GATK and bcftools, and functionally annotated with SnpEff. For population genomic analysis, PCA and admixture modeling assessed genetic structure, while Neighbor-Joining trees, LD decay, nucleotide diversity (π), and FST evaluated phylogenetic relationships and genetic variation. Selective sweeps were detected using RAiSD, and gene-set enrichment and protein–protein interaction analyses were conducted to explore functional pathways related to adaptation. The study revealed 3,759,279 unique SNPs and demonstrated that Ladakhi cattle form a distinct genetic cluster with an estimated admixture of 68 % Bos indicus and 32 % Bos taurus ancestry. Key findings include rapid linkage disequilibrium decay, low inbreeding level, and the identification of selection signatures and genes associated with hypoxia response, energy metabolism, and cold adaptation. Mean nucleotide diversity (π, 0.0037) and FST values indicated moderate genetic differentiation from other breeds. The analysis highlighted selection signatures for genes like HIF1A, ENO4, ANGPT1, EPO, NOS3, MAPK3, HMOX1, BCL2,CAMK2D, MTOR, AKT2,PIK3CB, and MAP2K1, among others, including various keratin and heat shock proteins. The interaction between genes associated with hypoxia signaling (HIF-1) and other enriched pathways such as PI3K, mTOR, NFκB, ERK, and ER stress, reveals a complex mechanism for managing hypoxic stress in Ladakhi cattle. These findings offer valuable insights for breeding programs aimed at enhancing livestock resilience in extreme environments and enhance understanding of mammalian adaptation to high-altitude conditions.

Internal Variability Dominated the Extreme Cold Wave Over North America in December 2022

AbstractIn December 2022, North America experienced an unprecedented extreme cold event. However, the underlying physical mechanisms of this cold wave, and the extent to which it is driven by internal variability or external forcing, are not fully understood. Using ERA5 reanalysis data and the HadGEM3‐A‐N216 attribution simulations, we identified internal variability as the main cause, contributing −5.14 K to surface air temperature (SAT) anomalies in North America. External forcing slightly mitigated the cold by 0.42 K. An internally generated wave train from the North Pacific, influenced in combination by Pacific‐North American (PNA) and North Pacific Oscillation (NPO) teleconnection patterns, initiated this intense cyclonic event, contributing −2.18 K and −2.12 K to SAT anomalies, respectively. La Niña‐like sea surface temperature anomalies amplified this wave train and resultant cold wave. Additionally, excessive snow cover in the previous November also intensified the December cold anomalies by enhancing surface albedo and reducing solar radiation.

Odorless Probiotic Chicken of Eco-Smart Poultry Coop

The smell of chicken waste has become a serious problem in Malaysia. Flies and an unpleasant odor from poultry coop plague the locals. To decrease the disagreeable odor of chicken manure, the approach used in this study is charcoal as an adsorption method to adsorb an ammonia gas. The sawdust is used as a drying agent for the chicken waste to ensure it produces no smell, and it also contains EM (Effective Microorganisms) as a decomposition mechanism for the bacteria in the chicken waste. The research result obtained positive results based on the number of flies, the odor examined through human surveys, the difference between probiotic and normal chicken waste, and the difference in fat content identified in probiotic chicken. It has been demonstrated by studies that while using wood dust and charcoal can aid in eliminating the odor of chicken droppings, processing chicken droppings with an EM solution is crucial before the droppings start to smell bad. Implementing an automatic system to manage chicken feed and drink is a recommended approach to ensure the project's success. This will ensure that the chickens obtain the proper amount of food and drink at the time specified. Given that chickens are highly susceptible to extreme heat or cold, the following recommendation is to monitor the cage's temperature and humidity levels. The ammonia odor associated with poultry farming affects not only the environment but also people. People who live close to the area where chickens are raised will feel uncomfortable because of this issue. The probiotic approach is the problem-solving strategy, according to the research. The chickens' digestive tract will be aided using EM solution as a drink and meal, resulting in less offensive chicken faeces.

Thermal resiliency of single-family housing stock under extreme hot and cold conditions

The building sector has gained attention due to its vulnerability to hazards such as heat waves in summer and power outages in winter, which have led to significant human health issues, including deaths. Thermal resiliency, which refers to a building’s capacity to cope and recover from weather-related events affecting indoor thermal conditions, lacks a systematic assessment approach considering future climate changes. This paper presents a framework for thermal resiliency assessment of buildings under future climatic conditions. The framework evaluates passive survivability under both hot and cold extreme events during a power outage or an HVAC system failure. A case study was conducted by considering code-compliant residential buildings located in different climatic regions. The study indicates that code-compliant buildings may overheat during hot extreme events without air conditioning in the future climate; however, severe indoor conditions can be avoided with passive measures like natural ventilation. The thermal resiliency of buildings under extreme conditions in cold regions is not adequate, as the buildings can reach severe indoor conditions within a four-day power outage, even with passive measures such as movable insulations. The proposed framework and study’s findings can serve as a valuable resource for policy-makers and researchers in developing climate adaptation measures.

Cryoablation in Chronic Pain Management: A Narrative Review

Abstract Cryoneurolysis is a technique of applying extreme cold temperatures to specific sensory nerves, causing a prolonged period of loss of conduction through that nerve. This technique has found widespread application in the field of interventional pain medicine in a variety of conditions including chronic postsurgical pain, phantom limb pain (PLP), and cancer pain. Its use in chronic pain states has been aided further by the advent of handheld cryoneurolysis devices and the widespread use of ultrasonographic imaging to guide and target nerves accurately. Chronic pain states – chronic knee pain from osteoarthritis, refractory PLP, temporomandibular disorders, cervicogenic headaches, low back pain, different peripheral neuropathies, and metastatic bone tumor pain – are some of the conditions where cryoneurolysis has been proven to benefit patients in cases where the symptoms were refractory to other conventionally used modalities. Chronic pain is a complex and multifaceted condition and hence requires a variety of individualized treatment approaches. Current research on this treatment method for chronic pain indicates that it carries low risk and, when used correctly, offers extended pain relief without causing motor function loss. This narrative review includes all types of scientific studies, published between 2010 and 2023, which were selected using a specific set of keywords through two different literature search engines. In conclusion, it explains how cryoneurolysis works to provide long-term pain relief and summarizes the latest evidence supporting its use in chronic pain management.

Future changes in agrometeorological extremes in the southern Mediterranean region: When and where will they affect croplands and wheatlands?

Climate change and extremes are increasingly threatening food security, especially in the Global South. Here, we examine how croplands and wheatlands of the southern Mediterranean region could be affected by projected changes in agrometeorological extremes over the 21st century. We use 17 bias-corrected climate models from the sixth phase of the Coupled Model Intercomparison Project (CMIP6) to identify potential trends and assess the time of emergence of significant changes in agrometeorological extremes under the Shared Socioeconomic Pathway (SSP3–7.0). We note that simulated historical trends in agrometeorological extremes closely match observed trends, here derived from ERA5land, over croplands. Our analysis of CMIP6 projected scenarios reveals a consistent rise in heat intensity, drought intensity, and the frequency of compound dry and hot (D5/H95) days. While a reduction in frost intensity, combined with fewer wet and cold (W95/C5) and dry and cold (D5/C5) events offer some mitigation potential, concerns about water scarcity due to heightened heat and drought stresses may overshadow these benefits. These changes in agrometeorological extremes are projected to emerge in the near- and mid-term future (by 2030 and 2050). We also note that the projected decreases in cold extremes affect smaller agricultural regions than the increases in extreme heat. We find higher likelihoods of negative agrometeorological impacts over croplands and wheatlands throughout the 21st century, which could significantly challenge crop yields and agricultural sustainability. Without proactive adaptation and mitigation strategies, food security could come increasingly under threat in a changing climate in the southern Mediterranean region.

Grey correlation analysis of asphalt-aggregate adhesion with high and low-temperature performance of asphalt mixtures

The adhesion work and force of the five types of asphalt to andesite were measured using surface energy and pull-out tests, respectively. Various tests were operated to estimate the high and low-temperature characteristics of the five types of asphalt mixtures: high-temperature rutting, low-temperature bending, indirect tensile creep, and thermal stress restrained specimen tests. Furthermore, the high and low-temperature evaluation index, adhesion work, and adhesion force of these asphalt mixtures were analyzed using grey correlation analysis. The results show that compared with the adhesion work, the actual contact between mineral aggregate and asphalt in the pull-out test leads to the difference in adhesion force and work measured by SBS-modified, SBR-modified, and extreme cold asphalt. The correlation degree of adhesion work and force to the evaluation indexes of high and low-temperature properties in asphalt mixture is roughly the same, and the adhesion work has a more momentous impact on the high and low-temperature properties in asphalt mixtures. The adhesion work and force correlate best with low-temperature bending test parameters and thermal stress restrained specimen test (TSRST) parameters related to fracture failure of asphalt mixture, followed by the indirect tensile creep test parameters. It shows that the adhesion work and force significantly impact the low-temperature characteristics of asphalt mixture more than their high-temperature stability.

Exposure to acute ambient temperature extremes and neonatal intensive care unit admissions: A case-crossover study

BackgroundExtreme in utero temperatures have been associated with adverse birth outcomes, including preterm birth and low birthweight. However, there is limited evidence on associations with neonatal intensive care unit (NICU) admissions, which reflect a range of poor neonatal health outcomes. MethodsThis case-crossover study assesses the associations between ambient temperature changes during the week of delivery and risk of NICU admission. Data from the Consortium on Safe Labor (2002–2008) were linked to ambient temperature at hospital referral regions. Adjusted hazard ratios (HR) and 95 % confidence intervals (CI) estimated NICU admission risk with a 1 °C increase on each day of the week of delivery and of the average weekly temperature, adjusted for particulate matter ≤2.5 μm (PM2.5) and relative humidity. We also estimated associations with 1 °C increases and 1 °C decreases in temperatures during weeks of site-specific extreme heat (>90th and 95th percentiles) and cold (<5th and 10th percentiles), respectively. ResultsThere were 27,188 NICU admissions with median (25th, 75th) temperature of 16.4 °C (5.8, 23.0) during the week before delivery. A 1 °C increase in temperature during the week of delivery was not associated with risk of NICU admission. However, analyses of extreme temperatures found that a 1 °C decrease in weekly average temperatures below the 10th and 5th percentiles was associated with 30 % (aHR = 1.30, 95 % CI 1.28, 1.31) and 47 % (aHR = 1.47, 95 % CI 1.45, 1.50) increased risk of NICU admissions, while a 1 °C increase in weekly average temperatures above the 90th and 95th percentiles was associated with more than two- (aHR = 2.29, 95 % CI 2.17, 2.42) and four-fold (aHR = 4.30, 95 % CI 3.68, 5.03) higher risk of NICU admission, respectively. ConclusionsOur study found temperature extremes in the week before delivery increased NICU admission risk, particularly during extreme heat, which may translate to more adverse neonatal outcomes as extreme temperatures persist.

Harsh Environment-Tolerant, High Performance Soft Pressure Sensors Enabled by Fiber-Segment Structure and Plasma Treatment.

As the demand for specialized and diversified pressure sensors continues to increase, excellent performance and multi-applicability have become necessary for pressure sensors. Currently, flexible pressure sensors are primarily utilized in fields such as health monitoring and human-computer interaction. However, numerous complex extreme environments in reality, including deep sea, corrosive conditions, extreme cold, and high temperatures, urgently require the services of flexible devices. Here, a piezoresistive flexible pressure sensor based on expanded polytetrafluoroethylene/functionalized carbon nanotubes (EPTFE/FCNT) is proposed. Benefiting from the unique fiber-segment architecture, chemical stability, and strong chemical binding force between EPTFE and FCNT, the fabricated sensor exhibits remarkable sensing capabilities and can be employed in multifarious extreme environments. It demonstrates a sensitivity of 862.28kPa-1, a response time of 6-7ms, and a detection limit below 1Pa. Furthermore, it possesses a pressure resolution of 0.0018% under 111kPa and can withstand over 10,000 loading and unloading cycles under 1MPa. Additionally, the EPTFE/FCNT sensor retains its outstanding pressure response and work efficiency in extreme conditions such as an ultra-low temperature of -80°C, high temperature (200°C), acidic and alkaline corrosion, and underwater. These notable attributes enormously broaden the sensors' real-world application range.

Lost in translation? Evidence for a muted proteomic response to thermal stress in a stenothermal Antarctic fish and possible evolutionary mechanisms.

Stenothermal Antarctic notothenioid fishes are noteworthy for their history of isolation in extreme cold and their corresponding lack of the canonical heat shock response. Despite extensive transcriptomic studies, the mechanistic basis for stenothermy has not been fully elucidated. Given that the proteome better represents an organism's physiology, the possibility exists that some aspects of stenothermy arise posttranscriptionally. Here, Antarctic emerald rockcod (Trematomus bernacchii) were sampled after exposure to chronic and/or acute high temperatures, followed by a thorough assessment of proteomic responses in the brain, gill, and kidney. Few cellular stress response proteins were induced, and overall responses were modest in terms of the numbers of differentially expressed proteins and their fold changes. Inconsistencies in protein induction across treatments and tissues are suggestive of dysregulation, rather than an adaptive response. Changes in regulation of the translational machinery in Antarctic notothenioids could explain these patterns. Some components of translational regulatory pathways are highly conserved [e.g., Ser-52, eukaryotic translation initiation factor 2α (eIF2α)], but other proteins comprising the cellular "integrated stress response," specifically, the eIF2α kinases general control nonderepressible 2 (GCN2) and PKR-like endoplasmic reticulum kinase (PERK), may have evolved along different trajectories in Antarctic fishes. Taken together, these observations suggest a novel hypothesis for stenothermy and the absence of a coordinated cellular stress response in Antarctic fishes.NEW & NOTEWORTHY Antarctic fishes have some of the lowest known heat tolerances among vertebrates, but the molecular mechanisms underlying this pattern are not fully understood. By combining detailed analyses of protein expression patterns in several tissues under various heat treatments with a broader evolutionary perspective, this study offers a novel hypothesis to explain the narrow range of temperature tolerance in this extraordinary group of fishes.

The Study of Synergistic Changes in Extreme Cold and Warm Events in the Sanjiang Plain

Extreme climate events are occurring frequently under global warming. Previous studies primarily focused on isolated extreme climate events, whereas research on the synergistic changes between extreme cold (EC) and extreme warm (EW) events remains limited. This study conducted trend, correlation, and dispersion analyses on EC and EW, as well as their synergistic changes, in the Sanjiang Plain from 1960 to 2019, using inverse distance weighting, statistical methods, and the Mann–Kendall test. The results indicated that cold-to-warm (C2W) and warm-to-cold (W2C) events were significantly and positively correlated with elevation, with correlation coefficients (r) of 0.76 and 0.84, respectively. Meanwhile, C2W showed a significant negative correlation with latitude (r = −0.55), while W2C also exhibited a significant negative correlation with latitude (r = −0.71). However, there was a significant positive correlation between (EC) and latitude (r = 0.65). After 1980, both the declining trend of EC and the increasing trend of EW slowed down, and the trends in C2W and W2C changed from decline to increase. The dispersion of EC and EW shows an increasing trend, while the dispersion of C2W and W2C exhibits a decreasing trend. This study provides important references for studying temperature fluctuations and addressing extreme climate changes.

Quantifying and Rating the Energy Resilience Performance of Buildings Integrated with Renewables in the Nordics under Typical and Extreme Climatic Conditions

The future buildings and society need to be resilient. This article aims to propose a novel concept of the energy resilience framework and implement a color-based rating system to quantify and rate the energy resilience performance of buildings in Nordic climates. The objective is to conduct a comparative analysis between old (1970s) and new (2020s) single-family buildings integrated with renewable energy sources and storage, assessing their energy resilience performance for heating during power outages, under extreme and typical climatic conditions. The study utilizes dynamic simulation of the buildings and renewable energy systems, conducting parametric studies to calculate proposed resilience indicators and rate their resilience performance, employing both passive and active methods. The total costs of the design variables are also calculated for economic evaluation. Given the complexities arising from climate change, the article uses a simplified method to synthesize regional climate to consider extreme climate change impacts on energy resilience performance. For the old building lacking PV, the robustness duration increased from 1 h to 3 h, and the degree of disruption (DoD) varied from 0.545 to 0.3 in extreme cold to warm climate scenarios, with the higher DoD number indicating worse performance. The impact of the season within the same climate scenario is also evident, as the habitability and robustness durations increased during spring compared to winter. The resilience improved with PV and battery. The new building showed that the robustness duration increased from 3 to 15 h, habitability durations increased, and the DoD varied from 0.496 to 0.22 from extreme cold to warm climates without renewables and storage. With the integration of PV and battery, the new building was able to achieve a lower DoD and better performance with lower PV and battery capacity, compared to the old building. Furthermore, utilizing the color grading method (red to green), optimal technical solutions and corresponding design variables were identified for each building type and climate scenario that could support decision-making. The total cost of the optimal solutions varied, as new buildings required lower costs to reach optimal performance. However, for optimal resilience performance during extreme cold climate scenarios, higher costs are required for each building type. The proposed resilience framework, indicators, color grading system, and costing could potentially support improvements in building regulations, ensuring the development of optimally resilient buildings, particularly in the face of extreme climatic conditions.

Performance assessment of residential heat pumps operating in extreme cold climates using zeotropic mixtures

Extremely cold climates subject residential heat pumps to significant temperature differences between the heat source and the ambient being heated, which may lead to system failure and reduced compressor performance. The present study considers the possibility of improving the performance of heat pump systems that are simultaneously used for residential space and domestic water heating while subjected to climates varying from -25 °C to 5 °C by exploring the use of zeotropic mixtures. CO2-based binary mixtures composed of low-GWP (global warming potential) refrigerants are considered – R32, R1234yf, and R290 – aiming to benefit from environmentally friendly and flame suppressants characteristics of CO2, as well as the improved thermal efficiency granted by the addition of a secondary refrigerant. A thermodynamic model was developed for a standard vapor-compression heat pump cycle and used to maximize the coefficient of performance limited by the minimum pinch point in the heat exchangers. Our analysis explores the effect of several parameters, such as, the mixture components, mass fractions, space and water heating demands, and heat source temperature on the heat pump's performance. For cold climates, the mixture of R32 (90%)/CO2 (10%) yields the highest COP and CO2-rich mixtures exhibit the lowest. However, by increasing the mass fraction of CO2 within the zeotropic mixture, the pressure ratio of the heat pump was improved. When considering combined performance criteria, such as the volumetric heating effect and the total heat delivered related to heat pump size, CO2-rich mixtures tend to allow more compact systems, especially in colder climates.

Implications for extreme midlatitude weather events of secondary flow associated with polar jets

AbstractIn the Earth's general circulation, polar jets act as baroclinic pumps of angular momentum and heat. Reanalysis datasets indicate that shear changes near jets induce upward displacements of the jet cores, suggesting a weakening thermodynamic pumping over the last 50 years. From secondary flow theory, a well‐established principle in fluid dynamics, an increased frequency of heatwaves and persistent winter storms is expected. The ageostrophic wind shear between 700 and 50 hPa indicates the strength of this secondary circulation. The weakening tendency during the reanalysis period also exists in multimodel simulations under the RCP8.5 emissions scenario for the 21st century. The reduction between the periods 2005–2025 and 2081–2100 reaches 18%, 5.3% and 19%, respectively, for the North America, Mid‐Europe and East Asia sectors of the Northern Hemisphere polar jet. Within this background, cold‐surge events are the result of synergic co‐working of several factors. The occurrence trend for transitional season winter extreme events also is examined. The winter extremes seemingly have larger temperature drops. However, in a warming climate, they emerge more rapidly from extreme cold states. The storm tracks, especially over North America, have equatorward extensions, indicating that winter storms can reach lower latitudes. Due to the temperature‐dependence of air viscosity, secondary flows decrease more slowly than the main zonal flow. This imposes an important adjustment to the traditional polar amplification effects on midlatitude winter extremes. During a warmer winter (the primary manifestation of a warmer climate), spatially uniform positive trends in cold extreme events are not expected. There are, however, regions experiencing more winter extremes. These regions show consistent patterns in both the reanalysis period and the remainder of the 21st century.

Dynamic model of integrated electricity and district heating for remote communities

District heating networks offer promising solutions for remote communities, providing centralized heat supply, improved efficiency, and diverse energy sources, especially with existing diesel generation. Hence, this paper bridges gaps in the existing literature by developing comprehensive dynamic models of combined district heating networks within existing electric power networks in remote communities, which allows identifying challenges and benefits of district heating networks for these communities. It is shown that district heating networks allow utilizing waste energy to enable energy exchanges between the electricity and heating systems, enabling the provision of necessary ancillary services for remote microgrids with renewable energy sources. The presented dynamic district heating network model incorporates particular considerations in remote, northern communities such as soil limitations, extreme cold conditions, and piping insulation to minimize heat loss. It also addresses accurate sizing of heat pumps based on realistic thermal load requirements, weather conditions, and consumer profiles, proposing demand management controls to enhance frequency regulation for the integration of variable renewable energy sources. The main contributions of the paper include detailed dynamic modeling for district heating network operation, heat pump demand response control system design, and a comparative analysis between centralized district heating networks and decentralized electric thermal storage units that have been deployed for thermal supply in remote areas. The presented dynamic models are applied, tested, and validated in an existing electric microgrid at Kasabonika Lake First Nation in Northern Ontario, showcasing the role of a potential district heating network in facilitating renewable energy sources integration in isolated microgrids.