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We investigated changes in the hydrological cycle in inner East Asia during the boreal summer (June-to-August) from 1979 to 2020 by analyzing climate variables including latent heat flux, precipitation and soil moisture. We found that the correlation between latent heat flux (LH) and precipitation varies across East Asia, with a negative correlation dominating over the summer monsoon region. In contrast, LH is positively correlated with precipitation in inner East Asia. Additional analyses indicate a positive correlation of LH-precipitation, implying a coupling of land and atmosphere that becomes strong in inner East Asia across the late 1990s. Soil moisture is also consistently and significantly reduced in inner East Asia after the late 1990s, which could be associated with the strengthening of a positive correlation of LH-precipitation. A tripole-like sea surface temperature (SST) in the North Atlantic Ocean causes anomalous anticyclonic circulation in inner East Asia through zonal wave propagation, resulting in a significant reduction of soil moisture. Our results indicate that the hydrological cycle in inner East Asia is influenced remotely by North Atlantic SST through soil moisture – precipitation feedback. [ABSTRACT FROM AUTHOR]

Diurnal variations in precipitation, clouds and other related fields are of interest for many applications. Here I analyze surface and satellite observations and ERA5 data to quantify these variations and evaluate ERA5's performance. Results show that ERA5 captures the observed seasonal climatology of precipitation and cloud amount remarkably well. Surface observations show that warm-season precipitation exhibits a robust diurnal cycle with an amplitude of ~ 20 to 50% of the daily mean and a peak around 14–18 local solar time (LST) over most land areas and 04–08 LST over most oceans. ERA5 approximately reproduces these features with a slightly earlier peak (by ~ 2 h) over both land and ocean and a stronger amplitude over land, mainly due to biases in its convective precipitation. The IMERG satellite product captures mainly the diurnal cycle of convective precipitation with a peak around 16–20 LST during the warm season. ERA5 oceanic precipitation shows robust diurnal variations that are comparable to observations despite its dampened marine surface diurnal cycle due to its use of daily-mean SST. This suggests a free-tropospheric control of oceanic precipitation diurnal cycle. Surface and satellite observations show more clouds (mainly from low clouds) during daytime (nighttime) over land (ocean). ERA5 total cloud diurnal anomalies are more comparable to surface observations than to ISCCP satellite product. Cloud base height shows a minimum in early afternoon and a maximum around midnight with a diurnal amplitude of ~ 150 m over warm-season land in surface observations; ERA5 approximately captures this diurnal cycle with a slightly stronger amplitude and earlier phase. Land planetary boundary layer height (PBLH) in ERA5 is around 250 m at night but increases after sunrise to a peak around 14–15 LST of about 1500–1900 m in the warm season and ~ 650 to 1100 m in the cold season, with largest diurnal amplitudes over summer drylands. ERA5 marine PBLH is higher in the cold season (~ 1000 m) than in the warm season (~ 530 m) in the extra-tropics, suggesting a dominant role by low-level wind-induced mixing. ERA5 CAPE shows out-of-phase diurnal variations over land and ocean, with near-noontime peak (minimum) and an early morning minimum (peak) over land (ocean). ERA5 CIN's diurnal cycle is approximately out of phase with CAPE. ERA5 captures well the diurnal cycles and their land–ocean and seasonal differences in surface net shortwave and longwave (LWnet) radiation seen in CERES satellite product, with a near-noontime peak in land LWnet. A near-noontime peak is also seen in ERA surface sensible and latent heat fluxes over land, while oceanic PBLH, LWnet and heat fluxes show little diurnal variation in ERA5, which may be partly due to its use of daily-mean SST. [ABSTRACT FROM AUTHOR]

This study provides a simple and effective decision-making method to choose the best phase-change material for different energy storage applications. Three case studies are provided to demonstrate the proposed decision-making method. The first case study addresses the problem of best phase-change material selection for a domestic water heating latent heat storage system by considering 15 different phase-change materials and 8 selection attributes; the second case study addresses the problem of selecting the best phase-change material for a triple tube heat exchanger unit by considering 12 different phasechange materials and 5 selection attributes; the third case study addresses the problem of best phase-change material selection for latent heat thermal energy storage within the walls of Trombe to enhance performance considering 11 phase-change materials and 4 selection attributes. The results of the proposed decision-making method are compared with those of other well-known multi-attribute decision-making methods. The proposed method is shown to be simple to implement, providing a logical way for allocating weights to the selection attributes and adaptable to phase-change material selection problems in different energy storage contexts. [ABSTRACT FROM AUTHOR]

This study investigates the variations in air–sea heat fluxes and temperatures in two ocean front regions, the Southwestern Atlantic Ocean (SWA) and the Drake Passage, widely recognized as hotspot areas with significant influences on South America weather and climate. We analyse means and trends of latent and sensible heat fluxes (LHF and SHF) and their associated air–sea temperatures (SAT and SST), based on monthly ERA5 (1985–2014) and eight CMIP6 models, for historical and long‐term simulations (2015–2099). The ERA5 trend for all parameters was positive over SWA, contrasting with the negative values observed in the Drake Passage, indicating surface warming and cooling, respectively. In the SWA, the ERA5 and CMIP6 multi‐model ensemble (MME) align in SST and SAT values, with a historical trend of 0.1°C·decade−1 and a significantly increasing trend in warming estimated by 0.4°C·decade−1 up to 2099. The ERA5 LHF and SHF trends were 4 and 0.6 W·m−2·decade−1, respectively. The MME shows historical (SSP5‐8.5) trends of 0.2 (1.3) W·m−2·decade−1 for LHF and −0.2 (−0.1) W·m−2·decade−1 for SHF. In the Drake Passage, the models accurately reproduced the air–sea mean temperatures; however, they failed to simulate negative trends observed in SAT and SST. Under the high emissions scenario, all CMIP6 models predict an increasing warming trends of 0.1–0.4°C·decade−1 and ocean heat gain of −0.2 to −1.2 (−1 to −2) W·m−2·decade−1 for LHF (SHF). For both regions, spatial analyses of SST and SAT highlight the coupling between the ocean and the atmosphere, alongside changes in air–sea heat fluxes. Our findings reveal inhomogeneous patterns of SST warming trends by the end of the 21st century, which are approximately 2–4 times greater than historical trends. The results suggest the persistence and enhancement of these regions as hotspots with significant potential to influence oceanic and atmospheric dynamics. [ABSTRACT FROM AUTHOR]

The East Asian winter monsoon (EAWM) is an important climate pattern in Southeast Asia. This study delved into the aerosol effects on the EAWM by analysing simulations conducted with the Taiwan Earth System Model version 1 (TaiESM1) model, part of the Coupled Model Intercomparison Project Phase 6 (CMIP6). Our assessment, validated against observational and reanalysis data, revealed that TaiESM1 effectively replicates the robust circulation of the EAWM and aerosol concentrations, placing its performance above average level among CMIP6 models. Notably, the simulated global mean aerosol optical thickness exhibited an approximately 20% increase from 1850 to 2014. The increased aerosols corresponded to a weakened Aleutian Low and an intensified Siberian High, leading to a weakened EAWM in the lower atmosphere over extratropical areas. In addition, the cooling across the Northern Hemisphere might affect enhanced northerly winds at approximately 10°N, which are situated in the southern part of the EAWM. An analysis of the near‐surface temperature budget indicated that the aerosol‐induced cooling in East China and India was primarily driven by changes in shortwave and longwave radiation fluxes, albeit slightly offset by sensible heat and latent heat fluxes. Furthermore, our study also reveals that while the mechanisms through which anthropogenic aerosols affect the northern portion of the EAWM vary across most CMIP6 models, their impacts on the tropical region remain consistent. [ABSTRACT FROM AUTHOR]

Accurate air temperature measurements are essential in eddy covariance systems, not only for determining sensible heat flux but also for applying density effect corrections (DECs) to water vapor and CO2 fluxes. However, the influence of wind-induced vibrations of mounting structures on temperature fluctuations remains a subject of investigation. This study examines 30 min average temperature variances and fluxes using eddy covariance systems, combining Campbell Scientific sonic anemometers with closely co-located fine-wire thermocouples alongside LI-COR CO2 – H2O gas analyzers at multiple heights above a sagebrush ecosystem. The variances of sonic temperature after humidity corrections (Ts) and sensible heat fluxes derived from Ts are underestimated (e.g., by approximately 5 % for temperature variances and 4 % for sensible heat fluxes at 40.2 m , respectively) as compared with those measured by a fine-wire thermocouple (Tc). Spectral analysis illustrates that these underestimated variances and fluxes are caused by the lower energy levels in the Ts spectra than the Tc spectra in the low-frequency range (natural frequency < 0.02 Hz). These underestimated Ts spectra in the low-frequency range become more pronounced with increasing wind speeds, especially when wind speed exceeds 10 ms-1. Moreover, the underestimated temperature variances and fluxes cause overestimated water vapor and CO2 fluxes through DEC. Our analysis suggests that these underestimations when using Ts are likely due to wind-induced vibrations affecting the tower and mounting arms, altering the time of flight of ultrasonic signals along three sonic measurement paths. This study underscores the importance of further investigations to develop corrections for these errors. [ABSTRACT FROM AUTHOR]

The porous layer of snow and firn on the Greenland Ice Sheet stores meltwater and limits the rate at which the ice sheet contributes to sea level rise. This buffer is threatened in a warming climate. To better understand the nature and timescales of firn's response to air temperature change on the Greenland Ice Sheet, we use a physics-based model to assess the effects of atmospheric warming and cooling on Greenland's firn air content in idealized climate experiments. We identify an asymmetric response of Greenland's firn to air temperature: firn loses more air content due to warming compared to the amount gained from commensurate cooling. 100 years after a 1 °C temperature perturbation, warming decreases the spatially integrated air content by 9.7 %, and cooling increases it by 8.3 %. In dry firn, this asymmetry is driven by the highly nonlinear relationship between temperature and firn compaction, as well as the dependence of thermal conductivity on the composition of the firn. The influence of liquid water accentuates this asymmetry. In wet firn areas, melt increases nonlinearly with atmospheric warming, thus enhancing firn refreezing and further warming the snowpack through increased latent heat release. Our results highlight the vulnerability of Greenland firn to temperature change and demonstrate that firn air content is more efficiently depleted than generated. This asymmetry in the temperature–firn relationship may contribute to the overall temporally asymmetric mass change of the Greenland Ice Sheet in a changing climate across many timescales. [ABSTRACT FROM AUTHOR]

To reduce the influence of unfrozen water content and thermal parameter variations caused by freeze–thaw cycles on temperature field predictions, the water content of unfrozen sand and clay was measured during freeze and thaw. The specific heat capacity, apparent specific heat capacity, and thermal conductivity of frozen soil were calculated using the mass-weighted average, equivalent latent heat, and geometric average methods, respectively. On this basis, the hysteresis behaviors of unfrozen water content and the variations of thermal parameters of frozen soil with temperature and temperature pathways were analyzed. [ABSTRACT FROM AUTHOR]

The study inspects the elevation dependency of temperature and precipitation across northeast India. Various gridded observations and outputs from high-resolution Regional Climate Models under the CORDEX-CORE framework have been employed. The better representation of the topography leads to higher orographic precipitation in the model environment. Positive vorticity led to strong convergence of the moisture-laden air resulting in high precipitation along the slopes of the mountains, which is more intense above 1800 m. The variance in the magnitude of precipitation at different elevations indicates the role of other factors, such as the difference in the convection processes. The latitudinal and longitudinal analysis reflects that the precipitation follows the topography leading to higher orographic precipitation along the slopes of the Meghalaya Plateau and the mountains. The change of temperature with elevation is very shallow till 3000 m, particularly during monsoon and pre-monsoon, which can be attributed to the release of a huge amount of latent heat due to the condensation of water vapour during the convection process. Interestingly, all the model experiments indicate towards a higher warming signal between the elevation range 4000–5000 m. The temperature also shows a strong association with the elevation, with a decline in temperature over the Meghalaya plateau and higher elevations. The variability among model experiments as well as the decline of temperature with elevation is highest above 5000 m. Precipitation and temperature changes are found to be higher for fast-changing elevation profiles, while precipitation distribution is also dependent upon the local processes influencing the convection processes such as the vorticity, CAPE etc. [ABSTRACT FROM AUTHOR]

Achieving simultaneous control over temperature and humidity through a single direct expansion air conditioner would be advantageous, especially considering its widespread use in residential buildings. Traditional control strategies fail to achieve satisfactory control performance due to the nature of complexity and cross-decoupling of the system. Therefore, this research paper presents the advancement of a feedforward decoupling control scheme designed for a direct expansion air conditioning unit to effectively control both temperature and humidity. To facilitate the controller design, a dynamic model considering both sensible and latent heat transfers was developed and verified. The thermal responses of the coupled system were analyzed and their correlation coefficients also examined. Through identifying the transfer function model of the coupled system, a feedforward decoupling controller with two compensators was designed. The proposed decoupling control scheme was tested using the developed model as the plant to be controlled. Test results showed that, in comparison to the transitional PID based dual single-input and single-output controller, the proposed decoupling control scheme was capable of eliminating the interactions between indoor air temperature and humidity under variable speed operation, and realizing the simultaneous control over indoor air temperature and humidity with a desirable control performance. [ABSTRACT FROM AUTHOR]

Tropical cyclones are known to expand to an equilibrium size on the f plane, but the expansion process is not understood. In this study, an analytical model for tropical cyclone outer-size expansion on the f plane is proposed. Conceptually, the storm expands because the imbalance between latent heating and radiative cooling drives a lateral inflow that imports absolute vorticity. Volume-integrated latent heating increases more slowly with size than radiative cooling, and hence, the storm expands toward an equilibrium size. The predicted expansion rate is given by the ratio of the difference in size from its equilibrium value rt,eq to an environmentally determined time scale τrt of 10–15 days. The model is fully predictive if given a constant rt,eq, which can also be estimated environmentally. The model successfully captures the first-order size evolution across a range of numerical simulation experiments in which the potential intensity and f are varied. The model predictions of the dependencies of lateral inflow velocity and expansion rate on latent heating rate are also compared well with numerical simulations. This model provides a useful foundation for understanding storm size dynamics in nature. [ABSTRACT FROM AUTHOR]

Using a reanalysis dataset and large‐ensemble simulation results, this study examines a possible factor of increasing trend in early winter precipitation in recent decades in the Hokuriku region of Japan. Monthly precipitation in December has a significant increasing trend after the early 1990s, which is different from those in January and February. The increasing precipitation in December is related to that in the sea surface upward latent heat flux due to intensified winter monsoon circulation and warming sea surface temperatures (SSTs) over the Sea of Japan. December averaged SSTs show a trend pattern in recent decades that is similar to the negative phase of the interdecadal Pacific oscillation (IPO), accompanied by positive trends from the eastern Indian Ocean to the western tropical Pacific. The enhanced trend of convection over the Bay of Bengal is seen; suggesting a combined effect of climatologically high SSTs and IPO‐related warmed SSTs over the region. Trends in recent decades of an upper‐level wavy pattern from South Asia to near Japan along the subtropical jet associated with enhanced convection near the Bay of Bengal and the related pressure drop from Japan to the north are seen, which contribute to intensified winter monsoon circulation. [ABSTRACT FROM AUTHOR]

We extend the parametric method developed for the van der Waals model by Lekner [Am. J. Phys. 50(2), 161–163 (1982)] to other equations of state, particularly the Berthelot model, thereby making the testing of these equations of state much faster and simpler. We systematically investigate important properties of first-order phase transitions in the Berthelot model. Thermodynamic properties near the critical point are discussed and the predictions of the Berthelot and van der Waals models are compared with experimental data. The Berthelot equation affords an improved fit to the density–temperature coexistence curve for many substances when compared to the van der Waals equation. A failure of the Berthelot model is its prediction of latent heat and heat capacities that are convex functions at lower temperatures. We also examine two modifications of the Berthelot equation of state that, like the van der Waals model, are also solvable by the parameter method. These, which we call the cPF and dPF models, reduce to the van der Waals and Berthelot models in different limits of their parameters. They give improved fits to the experimental data away from the critical point but involve an additional fitting parameter. Editor's note: While the van der Waals equation of state provides a simple model for phase transitions, it fails to achieve a good quantitative fit for properties near phase transitions in most substances. A closely related model, the Berthelot model, still has only two free parameters, but it allows the attraction between molecules to depend not only on volume but also on temperature. This paper builds on the parametric expressions for the van der Waals gas derived in a 1982 paper in this journal by John Lekner. It shows that similar expressions derived from the Berthelot model provide a much better fit to the data. This derivation could be shared with students in intermediate or advanced thermodynamics courses. [ABSTRACT FROM AUTHOR]

Cryogenic opto-electronic interconnects are gaining increasing interest as a means to control and readout cryogenic electronic components. The challenge is to achieve sufficient signal integrity with low heat load processing. In this context, we demonstrate the opto-electronic bias and readout of a commercial four-pixel superconducting nanowire single-photon detector array using a cryogenic photodiode and laser. We show that this approach has a similar system detection efficiency to a conventional bias. Furthermore, multi-pixel detection events are faithfully converted between the optical and electrical domains, which allows reliable extraction of amplitude multiplexed photon statistics. Our device has a latent heat load of 2.6 mW, maintains a signal rise time of 3 ns, and operates in free-running (self-resetting) mode at a repetition rate of 600 kHz. This demonstrates the potential of high-bandwidth, low noise, and low heat load opto-electronic interconnects for scalable cryogenic signal processing and transmission. [ABSTRACT FROM AUTHOR]

Reconstructing historical climate change from deep ground temperature measurements in cold regions is often complicated by the presence of permafrost. Existing methods are typically unable to account for latent heat effects due to the freezing and thawing of the active layer. In this work, we propose a novel method for reconstructing historical ground surface temperature (GST) from borehole temperature measurements that accounts for seasonal thawing and refreezing of the active layer. Our method couples a recently developed fast numerical modeling scheme for two‐phase heat transport in permafrost soils with an ensemble‐based method for approximate Bayesian inference. We evaluate our method on two synthetic test cases covering both cold and warm permafrost conditions as well as using real data from a 100 m deep borehole on Sardakh Island in northeastern Siberia. Our analysis of the Sardakh Island borehole data confirms previous findings that GST in the region have likely risen by 5–9°C between the pre‐industrial period of 1750–1855 and 2012. We also show that latent heat effects due to seasonal freeze‐thaw have a substantial impact on the resulting reconstructed surface temperatures. We find that neglecting the thermal dynamics of the active layer can result in biases of roughly −1°C in cold conditions (i.e., mean annual ground temperature below −5°C) and as much as −2.6°C in warmer conditions where substantial active layer thickening (>200 cm) has occurred. Our results highlight the importance of considering seasonal freeze‐thaw in GST reconstructions from permafrost boreholes. Plain Language Summary: Long‐term changes in the temperature of the atmosphere are recorded in the solid Earth due to the insulating properties of soil and rock. As a result, it is possible to estimate past changes in temperature at the interface between the ground and the atmosphere by measuring ground temperatures deep below Earth's surface. In cold regions, the presence of permafrost, that is, ground that remains frozen throughout the year, complicates such analyses due to the effects of water freezing and thawing in the soil. In this work, we present a new method for reconstructing past changes in ground surface temperature from boreholes situated in permafrost using a computational model of heat flow that accounts for these effects. We evaluate our method on both synthetic test cases as well as real data from a 100 m deep borehole in northeastern Siberia. Our results demonstrate that annual freezing and thawing of water near the surface has a substantial impact on the reconstructed ground surface temperature (GST), especially in regions where permafrost is thawing. The proposed method is the first to be widely applicable to ground temperatures measured in permafrost and thus constitutes a valuable new tool for understanding past and present climate change in cold regions. Key Points: We propose a new method to estimate historical ground surface temperatures from boreholes in permafrost using Bayesian inverse modelingWe evaluate our method on both synthetic test cases for cold and warm conditions as well as real data from a 100 m deep borehole in SiberiaWe find that seasonal freezing and thawing of the active layer has a significant impact on the reconstructed ground surface temperatures [ABSTRACT FROM AUTHOR]

The power battery is a key component of electric vehicles and its performance is greatly affected by temperature. Battery thermal management systems based on phase change materials can effectively control the battery temperature and at the same time have the advantages of simple structures, energy savings, and good temperature uniformity, and has broad development prospects. In this paper, expanded graphite–paraffin composite phase change materials were prepared, phase change material cooling experiments were carried out, and a phase change material cooling simulation model was also established using the Fluent software to study the influence of phase change material thermophysical parameters on thermal management performance. The results show that the phase change material thermal management method has excellent cooling performance. The best thermal management performance is achieved at the 3C discharge rate, with a phase change material filling thickness of 4 mm, a melting point of 40 °C above ambient temperature, and a thermal conductivity of 3 W/(m·K). When the phase change latent heat was increased from 150 J/g to 250 J/g, the liquid phase ratio decreased from 0.84 to 0.51, and the subsequent cooling performance was greatly improved, so the phase change latent heat should be increased as much as possible. [ABSTRACT FROM AUTHOR]

The adoption of phase change materials (PCMs) for thermal energy storage in low‐ and medium‐temperature settings is witnessing a notable surge. However, the lesser thermal conductivity (TC) poses a noteworthy challenge to PCM's heat transfer and storage capabilities. One of the noteworthy solutions to augment the TC is incorporating nanoparticles in the PCM. Nevertheless, nanoparticles often clump together after several cycles due to poor compatibility and weak interfacial strength. Functionalization methods have been proposed to address this issue, offering improved performance for energy storage applications. Herein, graphene nanoplatelets (GNP) and functionalized graphene nanoplatelets (FGNP) are dispersed into A70 PCM at mass fractions ranging from 0.1 to 1.0 wt% using two‐step method. Fourier transform infrared analysis confirms the successful integration of FGNP into A70 PCM without altering its chemical characteristics. Adding 1.0 wt% FGNP to A70 PCM increases its TC by 140.88%, with just a 3.02% decrease in latent heat enthalpy. However, incorporating pure GNP (1.0 wt%) improves TC by 48.83%. The engineered nano‐PCMs exhibit robust thermal and chemical stability even after undergoing 1000 thermal cycles, remaining unchanged up to 414.64 °C. This exceptional stability makes the formulated nanoenhanced PCM suitable for sustainable thermal applications. [ABSTRACT FROM AUTHOR]

Precipitation changes in northern China are projected to increase in the Coupled Model Inter‐comparison Project Phase 6 (CMIP6) multi‐model ensemble. However, these projections are accompanied by notable inter‐model uncertainty, and the sources of this uncertainty remain largely unexplored. By analyzing 30 CMIP6 models, this research explores the source of inter‐model uncertainty in projected precipitation change and reveals the fundamental mechanism driving uncertainty spread. Following the empirical orthogonal function of inter‐model projected precipitation change, the leading mode displays a seesaw spatial pattern between northwest and north China. This phenomenon predominantly stems from the inter‐model divergence of projected sea surface temperature (SST) warming in the North Atlantic. Further scrutinizing the ocean mixed layer heat budget, we discover that the combined effect of surface sensible heat flux, net surface shortwave radiation flux, and ocean heat transport convergence influences heat flux and SST change of North Atlantic. The multi‐model projections indicate that localized increases in solar radiation and heat convergence warm sea surface, raising SST and initiating convective motion. This convective motion subsequently transforms the 200 hPa teleconnection wave train, leading to an anti‐phase pattern over northern China. This wave pattern modulates total cloud cover percentage, influences surface upward latent heat flux, and adjusts the top of atmosphere outgoing longwave radiation, collectively resulting in the seesaw pattern. Our study underscores the pivotal role of inter‐model disparities in North Atlantic SST warming projection, which is a primary driver of precipitation uncertainty in northern China. These insights offer an essential foundation for refining and diminishing inter‐model uncertainty. Plain Language Summary: The Coupled Model Inter‐comparison Project Phase 6 multi‐model ensemble projects significant precipitation uncertainty due to differences in couplers and components of the global system model. This study identifies the discrepancies in projected North Atlantic sea surface temperature (SST) warming as the primary source of inter‐model uncertainty for projected precipitation changes in northern China. The projected SST warming amplifies heat transfer from the ocean surface to the atmosphere, intensifying upward air motion. This process alters the teleconnection wave trains at 200 hPa, propagating downstream to form an anti‐phase pattern in northern China. These upper atmospheric shifts regulate upward and subsiding motions, influence total cloud cover percentage, modify the top of atmosphere outgoing longwave radiation, and impact surface upward latent heat flux. Together, these atmospheric dynamics forge a seesaw spatial precipitation pattern in northern China. The combined effect of surface sensible heat flux, net surface shortwave radiation flux, and ocean heat transport convergence influence heat flux and SST change in the North Atlantic. Our findings elucidate the complex spread process of inter‐model uncertainty in precipitation projection, setting the stage for more precise projection in northern China. Key Points: The leading precipitation pattern exhibits a seesaw in northern China due to inter‐model differences in North Atlantic sea surface temperature (SST) warmingThe model with a higher SST warming tends to induce a strong teleconnection wave train, resulting in a more pronounced seesaw patternSurface sensible heat flux, net surface shortwave radiation flux, and ocean heat transport convergence influence heat flux and SST change [ABSTRACT FROM AUTHOR]

The photoswitchable MOlecular Solar Thermal (MOST) energy storage systems that are capable of exhibiting high energy storage densities are found to suffer from the poor cyclability, the use of less abundant UV light of the solar spectrum, or reduced charging/discharging rates and poor photoconversions in solid states. Herein, we have designed and readily synthesized a novel set of para-thioalkyl substituted arylazoisoxazoles, that undergo high trans-cis and cis-trans photoconversions under visible light, and show fast charging/discharging and impressive cyclability. Remarkably, the presence of C6-or C10-thioalkyl chainin photochromes permitted reversible solid-liquid phase transition with the formation of cis-enriched charged states by 400 nm light irradiation and trans-enriched discharged states by 530 nm light at various temperatures (10-35 °C). The solid-to-liquid phase transition enabled storage of the latent heat in addition to the isomerization energy, resulting in a high net energy storage density of 189-196 J/g, which are substantially higher than that of many recently reported azobenzenebased MOST compounds (100-161 J/g). Using a high-resolution infrared camera, we further demonstrated that a brief irradiation of green light can be employed to readily release the trapped photon energy as heat. Our results suggest that the arylazoisoxazole with C6-thioalkyl chain at para-position can serve as an effective and eco-friendly photoliquefiable MOST material. [ABSTRACT FROM AUTHOR]

This paper evaluates Indo-Pacific warm pool (IPWP) sea surface temperature (SST) warming biases of Coupled Model Intercomparison Project Phase 5 (CMIP5) and CMIP6. The IPWP warming trend in the CMIP5 multi-model ensemble (MME) is closer to observation than in CMIP6 MME, but the IPWP expanding trend is the opposite. There is no qualitative improvement in the simulation of IPWP warming from CMIP5 to CMIP6. In addition, four metrics were used to investigate the performance of Indo-Pacific region warming trends in all models. CMIP6 models perform better than CMIP5 with smaller root mean square error and bias in MME and higher skill scores in MME and top models, which is tightly linked to their better performance in simulating associated physical processes in CMIP6 models. IPWP warming biases are mainly attributed to the combined effects of positive atmospheric process biases and negative ocean dynamics term biases. The positive atmospheric process biases are primarily related to the shortwave radiation and latent heat flux from atmospheric forcing, the latter of which can be attributed to the biases in surface wind fields. Compared with CMIP5 models, the IPWP warming simulated by CMIP6 models is weaker, related to the less robust atmospheric processes and the shallower thermocline anomalies simulated by CMIP6. [ABSTRACT FROM AUTHOR]

This study aims to quantify the magnitude of latent heat release by strong typhoons in the Northwest Pacific region and to identify the key cloud microphysical processes that affect the release of latent heat. The Weather Research and Forecasting mesoscale numerical model was used to simulate Typhoon Songda from 2011. Single‐ and double‐moment 6‐class (WSM6 and WDM6) cloud microphysics schemes were used to simulate the 3D structure and evolution of latent heat release. Simulations show that condensation of cloud water is the main source of latent heat release, while the main sources of latent heat absorption are evaporation of rain and cloud water. Depositional heating in cold cloud processes in the upper troposphere also plays an important role in the evolution of typhoon intensity. Latent heat release and absorption simulated by both schemes evolve through the phases of intensifying, maintaining, and weakening during the lifetime of the typhoon. The largest latent heat release occurs at altitudes between 5 and 10 km; condensational heating plays a major role at altitudes below 6 km, while depositional heating is the dominant process at altitudes from 6 to 12 km. Compared with WSM6, the WDM6 scheme produces smaller absolute values of latent heating from condensation and evaporation of cloud water and a more reasonable vertical distribution of cloud water mixing ratio. Positive latent heating from WDM6 is larger than that from WSM6. However, because of stronger processes of evaporation of rainwater and sublimation of cloud ice, total net latent heat release is lower in WDM6, and hence, simulated typhoon intensity is higher in WSM6. [ABSTRACT FROM AUTHOR]

This study investigates the responses of the urban atmospheric thermal environment to two distinct heat waves in Hefei, China, and explores potential changes associated with future urban expansion. During the Event 1, characterized by clear and dry conditions, the western Pacific subtropical high limits water vapor influx, resulting in a significant cooling effect in rural area due to higher surface latent heat flux. The urban heat island (UHI) intensity, calculated using surface temperature and 2‐m temperature, reaches 5.2°C and 1.7°C during the Event 1, respectively. Although Event 2, characterized by cloudy and humid conditions, exhibits weaker UHI and urban dry island effects, it remains highly unfavorable for human comfort. During distinct heat waves, the vertical extent of the warming effect induced by future urban expansion varies, which can be attributed to environmental factors, such as atmospheric stability and near‐surface wind speed. Plain Language Summary: The study investigates the interactions between the urban atmospheric thermal environment and two distinct heat waves in Hefei, China, as well as the changes induced by future urban expansion. During the first event, which has clear and dry weather conditions, the influx of water vapor is limited by a high‐pressure system. Consequently, rural area experiences a significant cooling effect due to higher surface latent heat flux. The urban heat island (UHI) intensity, measured by surface temperature and 2‐m temperature, reaches 5.2°C and 1.7°C, respectively, during this event. In contrast, the second event, characterized by cloudy and humid weather conditions, exhibits weaker UHI and urban dry island effects but remains highly uncomfortable for humans. The vertical extent of the warming effect caused by future urban expansion varies during distinct heat waves. This variation can be attributed to environmental factors, such as atmospheric stability and near‐surface wind speed. Key Points: The underlying mechanisms of the different responses of the urban atmospheric thermal environment to distinct heat wave events are analyzedThe limitation of water vapor influx by a high‐pressure system and intense solar radiation jointly enhance the urban heat island effectAtmospheric stability and wind speed could influence the vertical extent of the warming effect induced by future urban expansion [ABSTRACT FROM AUTHOR]

AbstractAn innovative tree-shaped fin is proposed to address the problem of low thermal conductivity of phase change materials (PCMs) in latent heat energy storage units. Numerical methods are applied to investigate the thermal properties of the melting process of PCMs. This paper investigates the effects of fin arrangement, fin geometry parameters, and temperature of the heat source on melting characteristics of PCMs in the latent heat energy storage unit. Results show that the melting time of PCMs with the inwardly-tilted fins at the top increases by 21.3% compared to the outwardly-tilted fins at the bottom. The response surface methodology is adopted to obtain the fin parameter combination with lower quality and better performance. The optimal fin dimensions are a thickness of 1.06 mm, a length of 3.38 mm, and a spacing of 12.61 mm. The reduction of the ambient temperature from 35 °C to 30 °C increases the melting time of the latent heat energy storage unit by 85%, and from 35 °C to 40 °C decreases the melting time by 29%. [ABSTRACT FROM AUTHOR]

This study presents a one-dimensional mathematical model developed to simulate multi-zone thermal storage systems using phase change materials (PCMs). The model enables precise analysis of temperature distribution in the layered storage based on several PCM configurations and properties. It is distinguished by its adaptability to various tank geometries and the number of PCM capsules, enabling its application under diverse operating conditions. By simplifying the implementation of heat transfer processes that depend on the shape of the capsule and the thermal properties of the PCM, the computation time can be reduced to a level that makes simulations over longer periods feasible. Experimental validation confirmed the accuracy of the model, with deviations below 6%, underscoring its practical applicability. The study demonstrates that individual layering in the storage tank can be achieved by filling it with PCMs of different melting points without compromising the maximum storage capacity. It is shown that including a PCM layer can maintain the outlet temperature 20% longer while storing 14% more energy. The results point out the model's potential to improve the performance of thermal storage systems through targeted PCM layer configurations. The model serves as the basis for the planning and optimization of these systems. [ABSTRACT FROM AUTHOR]

Seasonal storage of solar thermal energy through supercooled phase change materials (PCM) offers a promising solution for decarbonizing space and water heating in winter. Despite the high energy density and adaptability, natural PCMs often lack the necessary supercooling for stable, long-term storage. Leveraging erythritol, a sustainable mid-temperature PCM with high latent heat, we introduce a straightforward method to stabilize its supercooling by incorporating carrageenan (CG), a bio-derived food thickener. By improving the solid-liquid interfacial energy with the addition of CG the latent heat of erythritol can be effectively locked at a very low temperature. We show that the composite PCM can sustain an ultrastable supercooled state below −30 °C, which guarantees no accidental loss of the latent heat in severe cold regions on Earth. We further demonstrate that the common ultrasonication method can be used as the key to unlocking the latent heat stored in the CG-thickened erythritol, showing its great potential to serve as a high-performance, eco-friendly PCM for long-term seasonal solar energy storage. To enable high-performance seasonal thermal energy storage for decarbonized solar heating, the authors propose an effective method to realize ultrastable supercooled erythritol, with an ultrahigh supercooling >150 ˚C, by making it more viscous. [ABSTRACT FROM AUTHOR]

Currently, solar heating systems face several challenges in winter cold conditions, including low heat collection temperature, high heat collection loss, low thermal storage density, and unstable storage temperature, making it difficult to meet heating quality requirements. Taking the heating of a driving school building in the suburbs of Baiyin, Gansu as a case study, and using typical meteorological data for the local heating season, we simulated the indoor thermal load of the building using DEST software. We then designed a focused solar heating system with phase change thermal storage, coupling focused solar thermal technology with latent heat storage technology. The thermal storage performance of Ba(OH)2-8H2O composite phase change material in an oil-sealed environment was verified. Mathematical models of the major components of the focused solar heating system with phase change storage were developed, along with a TRNSYS system model. An objective function was established using the annualized cost method, with the area of the collector and the mass of PCM as variables. Optimization was performed using Genopt software, invoking the Hooke-Jeeves algorithm to optimize the heat collection area S and mass m of phase change material in the focused solar heating system. The optimized results showed a collector area of 4.11 m2, and a PCM mass of 130 kg, resulting in a 10.04% improvement in the solar assurance rate. Over the system's entire lifecycle, the cost decreased by 1025 RMB, and the carbon emission reduction increased from 10,838 to 16,101 kg. [ABSTRACT FROM AUTHOR]

The application of phase change material (PCM) has shown great potential in the fabrication of PCM-integrated cloth (PCMIC) due to its numerous advantages, including latent heat storage, narrow temperature range, energy storage density, longevity, and compatibility with textile processing. PCMs can lessen the demand for mechanical heating and cooling systems, which can save energy and assist the environment towards sustainability. PCM-integrated cloth provides new opportunities to enhance thermal comfort, energy efficiency, and functionality across a range of applications. The advancement of PCMIC has shown promise in the past decade. This review covers the fundamentals, latest advancements, characterization methods, and advanced applications of PCMIC in detail. Progresses, challenges, and opportunities of versatile applications of PCMIC in space wear, medical textiles, sportswear, bedding, thermoregulating buildings, flame-retardant textiles, automotive textiles, and footwear are critically summarized. Space agencies like NASA, and ESA used PCM-based products for comfortable space exploration while surgical gauges, bandages, and other clinical products incorporated with PCM comfort much in patients. Moreover, sportswear brands like Nike and Adidas utilized PCM in their products for better wearability. Through an analysis of the foundations, current developments, and challenges, this thorough overview is a valuable resource for further innovation and progress in the field of PCM-integrated textiles. [ABSTRACT FROM AUTHOR]

This study examines the impact of different circular shell and tube heat exchanger configurations on the system charging time. Various configurations will be evaluated, namely A, B, C, and D, with 1, 2, 3, and 4 tubes, respectively. The shell contains a phase change material (N‐eicosane), and the location of tubes changes in each configuration, forming a new case. A total of 38 numerical experiments were conducted using a commercial software to investigate various tube locations and arrangements. While previous studies have primarily focused on total charging time as the fitness measure for different configurations, this study considers the need to achieve high charging levels within limited time windows. Therefore, a configuration that takes longer to charge completely may have a shorter time to reach 90% of charging, making it more reliable. The top configurations were assessed with gold, silver, and bronze rankings based on their agility to reach milestones (at every level of 50%, 80%, and 90% charging). For instance, case C6 achieved a golden ranking for reaching 90% of full charge in about 328 seconds, 12.5% faster (41 seconds) than the efficient configuration (C5) with the minimum total time. However, C6 has a longer total charge time of 516 seconds (about 20% extra time). On the other hand, C5 also has the fastest time for reaching milestones at 50% and 80% of charging, which shows that it responds to the thermal source very rapidly. The results also demonstrate that increasing the tubes significantly decreases total melting time. For instance, the efficient case of type D, D7, takes only about one‐fifth (80% improvement) of the total charging time compared to the base case, A1. Finally, the performance of various cases during the discharge process is also evaluated. [ABSTRACT FROM AUTHOR]

Phase change material (PCM) is an ideal heat storage material with huge latent heat and nearly constant phase change temperature, but there are serious problems in application such as leakage and low thermal conductivity. Porous ceramic is widely used in PCM packaging because of its advantages of controllable porosity and high thermal conductivity. Porous Al 2 O 3 ceramics were prepared by foaming injection coagulation method. In order to improve the thermal conductivity of porous ceramic matrix, Porous Al 2 O 3 @Graphite Ceramics (PAGC) were prepared by sucrose decomposition. Form-Stable Phase Change Materials (FSPCMs) were prepared by adsorption of Lauric Acid/Myristic Acid (LA/MA) in PAGC by vacuum impregnation method. SEM showed that the prepared PAGC had a three-dimensional interpenetrating structure and high porosity. TEM and XPS showed that alumina skeleton were uniformly coated with graphite. After PAGC impregnated by LA/MA, the maximum PCM storage reached 62.11 wt %. The maximum latent heat of FSPCMs reaches 83.33 J/g. Thermogravimetric analysis, thermal cycling test and Fourier transform infrared spectroscopy show that the prepared FSPCMs has good thermal stability, thermal reliability, chemical stability and compressive strength. More importantly, the thermal conductivity of the prepared FSPCMs is greatly improved, reaching up to 3.73 W/mK. It is 20.72 times the original PCM, mainly due to the synergistic effect of the Al 2 O 3 skeleton and the graphite coating to build a continuous highway for heat transfer. This study provides a practical means to greatly improve the thermal conductivity of FSPCMs, which will promote the practical application of FSPCMs. [ABSTRACT FROM AUTHOR]

In the present work, lauric acid was taken as a phase change material (PCM), and different nanoparticles (NPs) such as SiO2, TiO2, CuO, and ZnO were taken as the supporting materials. CuO NPs were prepared through the co-precipitation technique; SiO2, TiO2, and ZnO NPs were synthesized via the sol-gel technique. These NPs with different weight fractions were dispersed into molten lauric acid, individually. The variations in thermal properties (phase change temperature and latent heat for solid and liquid) of the prepared composite PCMs due to the dispersion of NPs were observed by DSC analyses. An increase in thermal conductivity of the composite PCMs was observed with the increasing weight fraction of NPs. In order to ascertain the long-term utility, a thermal reliability test was conducted on the composite PCMs with repeated heating and cooling cycles. Also, the specific heats of the pure PCM and the composite PCMs were determined as a function of temperature. Further, the experimental investigation was performed on the pure PCM and the prepared composite PCMs to assess their phase change behavior, and the test results clearly proved that the time required for the complete melting and freezing process of the composite PCMs was less when compared to pure PCM. By considering the above facts, the newly prepared composite PCMs can be recommended as a potential candidate for low-temperature solar heating applications. [ABSTRACT FROM AUTHOR]

Heat‐storage materials are important for energy saving to protect the environment. Here, we show a long‐term heat‐storage material based on zirconium‐substituted lambda‐trititanium‐pentoxide (λ‐ZrxTi3−xO5, 0 < x≤0.06). λ‐ZrxTi3−xO5 exhibits a phase transition to zirconium‐substituted beta‐trititanium‐pentoxide (β‐ZrxTi3−xO5) upon application of pressure. The transition pressures were 600 MPa (x=0.04) and about 1 GPa (x=0.06). When the pressure‐produced β‐phase is heated, the β‐phase returns to λ‐phase. The phase transition temperatures (i. e., heat‐storage temperatures) were 185 °C (458 K) and 183 °C (453 K) for x=0.04 and 0.06, respectively. These heat‐storage temperatures are suitable for the reuse of low‐temperature industrial waste heat, which is considered to be a difficult temperature region to be efficiently collected and reused. The present pressure‐sensitive heat‐storage ceramic, which can store the latent heat energy for a prolonged period, is effective for the sustainable reuse of heat energy that are wasted in power plants and industrial factories. [ABSTRACT FROM AUTHOR]

The discovery of the cyanobiphenyl and related compounds in 1973 not only played a significant role in important innovations in displays and related technologies but also opened opportunities for testing of novel insights in understanding phase transitions and critical phenomena. In the study of these phenomena, high-resolution calorimetry made substantial contributions. In this paper, we present an overview of the high-resolution calorimetry results obtained during the past 50 years on the phase transitions that occur in the cyanobiphenyl compounds. For the isotropic–nematic and isotropic–smectic A transitions, their (weakly) first-order nature is well established and the temperature dependence of the pretransitional-specific heat capacity strongly points in the direction of a nearby tricritical point. For the nematic-smectic A transition, precise latent heat values of several binary liquid crystal (mainly of cyanobiphenyl type) mixtures give significant evidence on the Halperin, Lubensky and Ma prediction of the always weakly first-order nature of this transition. The dependence of the specific heat capacity critical exponent α on the width of the nematic range, resulting from coupling between the nematic and the smectic order parameters as pointed out by de Gennes, is well confirmed. [ABSTRACT FROM AUTHOR]

The summer changes in the vertical heat and moisture fluxes in Russian landscape zones were analyzed in connection with the changes in the indices of the leading modes of general atmospheric circulation, sea surface temperature, and air temperature. The series of the circulation indices and ERA5 and ERA5-Land reanalysis data were used. The contribution of the general circulation modes, sea surface temperature, and air temperature to the changes in heat and moisture fluxes on Russian plain territories can vary from 40 to 90% depending on a landscape zone. The vertical fluxes of heat and moisture in European Russia and Western Siberia are largely dependent on the SCAND and EA/WR regional modes of atmospheric circulation. With a change in the phases of SCAND and EA/WR from positive to negative, a significant increase in the areas of influence of these modes on heat fluxes occurred in subarctic and boreal landscapes, and a decrease in the areas of influence on moisture divergence was registered in boreal and subboreal landscapes. In the summers of 1950–2021, trends in upward sensible heat fluxes were evident in subboreal landscapes of eastern European Russia (4–6%/10 years). The trends in upward latent heat fluxes in subarctic and boreal landscapes of Western Siberia were about 3%, and the ones in downward latent heat fluxes in subboreal landscapes made up about 5%. The trends in upward moisture fluxes in subarctic and northern boreal landscapes were registered at the level of 5–7%, and an increase in downward moisture fluxes by 10% was observed in subboreal landscapes. [ABSTRACT FROM AUTHOR]

Elastocaloric cooling is emerging as a promising alternative to conventional vapor compression systems due to its potential for energy savings and significant temperature lift compared to other solid-state cooling technologies. This technology harnesses the latent heat associated with the martensitic phase transition of shape memory alloys to generate the desired cooling or heating effect. This paper comprehensively reviews the fundamentals of elastocaloric cooling systems, including the thermodynamics cycle and various materials used. It also presents the latest advancements in elastocaloric systems, focusing on heat transfer enhancement, actuator development, and prototype summaries. Additionally, this paper introduces a new non-dimensional performance parameter to evaluate different elastocaloric prototypes and discusses key aspects necessary to achieve potentially high-performance elastocaloric devices. Finally, we propose an approach for future elastocaloric device development. [ABSTRACT FROM AUTHOR]

Ice melting front thickness has been estimated by studying the kinetics of thawed water accumulation during melting of ice balls with different sizes at room temperature (≈22°C) taking into account the temperature measured both on the surface and inside of the balls. The supplied heat flux is absorbed as the latent heat of fusion by an ice layer, which we define as the melting front. A model of this process has been formulated to describe the kinetics of ice ball melting. It has been assumed that the heat is supplied through the entire ice ball surface, the area of which decreases in the course of melting. The temperatures measured on the surface and inside of the balls have turned out to be ~0.4 and 0°С, respectively. Corrections associated with water evaporation have been taken into account. The fit of the experimental data according to the proposed model has made it possible to estimate the thickness of the ice melting front at room temperature. It has appeared to be approximately 3.2–3.6 mm. [ABSTRACT FROM AUTHOR]

The heat storage system (HHS) still faces the problem of void formation as a result of the supercooling phenomenon caused by the use of paraffin. This study was conducted to analyze the effect of HTF discharge variation in the HHS system on the increase of heat storage efficiency in both the charging and discharging processes. The prototype helical coil heat exchanger is designed, fabricated, and experimentally analyzed on 4 types of helical coils with different models of fin designs: finless helical coil, straight fin, branched fin, and crossed fin. The phase change material (PCM) used is 9 kg of commercial paraffin type. The heat transfer fluid (HTF) is SAE 20W40 oil which is heated to a temperature of 210 °C with the heat source coming from the heating element. The pump is used to circulate the HTF with an output of 10 mL·s−1, 11 mL·s−1, and 12 mL·s−1. The experimental results show that the variation of the HTF flow rate affects the melting temperature, the paraffin freezing temperature, and the power efficiency of the LHS. The highest temperature absorption by paraffin was achieved by the branch fin model at 124 °C with a discharge of 11 mL·s−1, and the highest temperature release in the Branch Fin at 90 °C with a discharge of 12 mL·s−1. The highest effective power achieved by the branched fin model with effective power of 73 % charge and 53 % discharge occurred at a discharge of 12 mL·s−1. Varying the HTF discharge makes a positive contribution to the charge/discharge pattern, so it can be used as a reference for latent heat storage models. [ABSTRACT FROM AUTHOR]

Amputees who use prosthetic limbs suffer from the problem of high contact temperature between the socket of the prosthetic limb and the amputated part and lack of evaporation of sweat. These conditions lead to discomfort and failure to perform functions properly. In addition, these conditions help generate ulcers and accumulate harmful bacteria in this area. This paper presents a heatsink design to extract heat from the contact area. A cylindrical heat sink is designed for phase‐changing materials with three branched tubes in two stages. The current heat sink is used to cool the contact area between the amputated part and the socket in the lower prostheses. Three distributions of pipe branches are proposed. The distribution and pipe lengths were obtained using a constructal design method. In the constructal design, the lengths of the branched tubes were the degrees of freedom, the objective function was the minimization of the inlet temperature to the heat sink, and the constraint was the volume of the cylindrical heat sink. The metabolic heat transfer during exercise was estimated and its value was used to calculate the size of the cylindrical heatsink and the selection of the phase change material by testing three of them: water, tridecane, and dodecane. It was found that water gives the highest latent heat of melting and the lowest volume in addition to its availability. On the other hand, two cooling fluids were tested: water and air. It was found that water as a cooling fluid gave the lowest flow and the largest heat capacity. Constructal theory was used to design a cylindrical heat sink using branched tubes for the coolant in two steps: the first with three branches, and the second with nine branches. The degree of freedom for constructal theory was the length of the branches through the choice of their end locations. It was found that the branches of the highest length led to a reduction in temperature from 40°C to 15.48°C compared with the single tube, which reduced the temperature to 23.87°C. All tests recorded a pressure drop within the acceptable range of 3.1–5.43 Pa for the branches examined. The research demonstrated that using constructal theory achieved the best thermal dissipation within a restricted volume. [ABSTRACT FROM AUTHOR]

The Archean–Proterozoic transition in the Earth's history is marked by significant changes in the mantle dynamics and temperature regimes. A notable consequence is the disappearance of Al-depleted komatiites in the Late Archean and an almost complete absence of Archean-typical peridotitic komatiites since the Proterozoic. This work presents a study of the 2.41 Ga komatiitic basalts from the Vetrenyi Belt, dating back to the early Proterozoic. Unique data on the compositions of olivine and chromite, as well as on the crystallization temperatures based on Al-in-olivine geothermometry for komatiitic basalts from the Vetrenyi Belt are provided. The temperatures of the earliest stages of crystallization were approximately 1240 ± 25°C, which indicates the occurrence of water in the melt and is consistent with measured water contents of 0.4 ± 0.2 wt % H2O in the melt inclusions. However, during crystallization, the komatiitic basalt melt underwent degassing, resulting in mass crystallization of the system and a temperature rise by ~20°C due to the release of the latent heat of crystallization. The degassing of water from the melt suggests crystallization under surface conditions. [ABSTRACT FROM AUTHOR]

By utilizing the significant amount of energy absorbed and released during their phase transitions, phase change materials (PCMs) can capture and store thermal energy to fill gaps between supply and demand. Due to their many favorable properties, organic PCMs have gained attention in a wide range of applications. Nevertheless, their inherent low thermal conductivity has limited the direct use of organic PCMs in thermal energy storage (TES). Extensive research has been conducted on enhancing organic PCM thermal conductivity by incorporating high thermal conductivity materials. Owing to their high thermal conductivity and low density, carbon-based materials have been extensively used for thermal conductivity enhancement in phase change composites (PCCs). Carbon-based organic PCCs, which incorporate highly thermally conductive carbon allotropes and their direct chemical derivatives with organic PCMs, are a group of diverse PCCs with highly promising potential for TES applications. Adequate latent heat and shape stability performances are crucial to the success of the applicational performances of these PCCs. Much empirical research has pushed efforts to enhance these phase change properties, yet a logical understanding of these enhancement efforts based on the thermodynamics and intermolecular interactions of carbon-based organic PCCs has been elusive. In particular, the effect of characterization methods on the evaluation of phase change properties has been largely understudied. This review strives to provide novel physical and chemical insights into latent heat and shape stabilization evaluation processes and enhancement efforts in carbon-based organic PCCs through a detailed review and analysis of recent literature. The review provides an unprecedented comprehension of newly developed PCCs that challenge the traditional understanding that the latent heat of PCCs cannot exceed that of its base PCM. Efforts on phase change property enhancement driven by these new insights have the potential for carbon-based organic PCCs to succeed in a variety of TES applications, including solar-thermal harvesting, thermal management of batteries and electronics, thermoregulating textiles, and infrared stealth and infrared responsive materials. [ABSTRACT FROM AUTHOR]

The objective of the current study is to investigate the importance of entropy generation and thermal radiation on the patterns of velocity, isentropic lines, and temperature contours within a thermal energy storage device filled with magnetic nano-encapsulated phase change materials (NEPCMs). The versatile finite element method (FEM) is implemented to numerically solve the governing equations. The effects of various parameters, including the viscosity parameter, ranging from 1 to 3, the thermal conductivity parameter, ranging from 1 to 3, the Rayleigh parameter, ranging from 102 to 3 × 102, the radiation number, ranging from 0.1 to 0.5, the fusion temperature, ranging from 1.0 to 1.2, the volume fraction of NEPCMs, ranging from 2% to 6%, the Stefan number, ranging from 1 to 5, the magnetic number, ranging from 0.1 to 0.5, and the irreversibility parameter, ranging from 0.1 to 0.5, are examined in detail on the temperature contours, isentropic lines, heat capacity ratio, and velocity fields. Furthermore, the heat transfer rates at both the cold and hot walls are analyzed, and the findings are presented graphically. The results indicate that the time taken by the NEPCMs to transition from solid to liquid is prolonged inside the chamber region as the fusion temperature θf increases. Additionally, the contours of the heat capacity ratio Cr decrease with the increase in the Stefan number Ste. [ABSTRACT FROM AUTHOR]

Based on ERA5 reanalysis data, the present study analyzed the thermal energy development mechanism and kinetic energy conversion characteristics of two extreme rainstorm processes in relation to the shallow southwest vortex in the warm-sector during a "rain-generated vortex" process and the deep southwest vortex in a "vortex-generated rain" process. The findings were as follows: (1) During the extreme rainstorm on August 11, 2020 (hereinafter referred to as the "8·11" process), intense surface heating and a high-energy unstable environment were observed. The mesoscale convergence system triggered convection to produce heavy rainfall, and the release of latent condensation heat generated by the rainfall promoted the formation of a southwest vortex. The significant increase (decrease) in atmospheric diabatic heating and kinetic energy preceded the increase (decrease) in vorticity. By contrast, the extreme rainstorm on August 16, 2020 (hereinafter referred to as the "8·16" process) involved the generation of southwest vortex in a low-energy and highhumidity environment. The dynamic uplift of the southwest vortex triggered rainfall, and the release of condensation latent heat from rainfall further strengthened the development of the southwest vortex. The significant increase (decrease) in atmospheric diabatic heating and kinetic energy exhibited a delayed progression compared to the increase (decrease) in vorticity. (2) The heating effect around the southwest vortex region was non-uniform, and the heating intensity varied in different stages. In the "8·11" process, the heating effect was the strongest in the initial stage, but weakened during the vortex's development. On the contrary, the heating effect was initially weak in the "8·16" process, and intensified during the development stage. (3) The available potential energy of the "8·11" process significantly increased in kinetic energy converted from rotational and divergent winds through baroclinic action, and the divergent wind energy continued to convert into rotational wind energy. By contrast, the "8·16" process involved the conversion of rotational wind energy into divergent wind energy, which in turn converted kinetic energy back into available potential energy, thereby impeding the further development and maintenance of the southwest vortex. [ABSTRACT FROM AUTHOR]

The Northeastern China cold vortex (NCCV) is one type of strong cyclonic vortex that occurs near Northeastern China (NEC), and NCCV activities are typically accompanied by a series of hazardous weather. This paper employed an automatic algorithm to identify the NCCVs from 1979 to 2018 and analyzed their circulation patterns and climatic impacts by using the defined NCCV intensity index (NCCVI). The analysis revealed that the NCCV activities in summer exhibited a strong inter-annual variability, with an obvious periodicity of 3-4 years and 6-7 years, but without significant trends. In years when the NCCVI was high, NEC experienced negative geopotential height anomalies, cyclonic circulation, and cooler temperature anomalies, which were conducive to the maintenance and development of NCCV activities. Furthermore, large amounts of water vapor converged in NEC through two transportation routes as the NCCVs intensified, leading to a significant positive (negative) correlation with the summer precipitation (surface temperature) in NEC. The Atlantic sea surface temperature (SST) anomalies were closely related to summer NCCV activities. As the Atlantic SST rose, large amounts of surface sensible and latent heat flux were transported into the lower troposphere, inducing a positive geopotential height anomaly that occurred on the east side of the heat source. As a result, an eastward diverging flow was formed in the upper troposphere and propagated downstream, i.e., the eastward propagating Rossby wave train, which eventually led to a coupled circulation in the Ural Mountains and NEC, as well as more intensive NCCV activities in summer. [ABSTRACT FROM AUTHOR]

In heating processes using superheated steam, a practical heat transfer model for predicting the change in the material temperature taking condensation/evaporation into consideration is required. This study observed the behavior of condensed water and verified a simple but practical heat transfer model to predict the heating time of materials. The one-dimensional model, which comprehensively includes the conductive, convective, radiative, and latent heat fluxes, was utilized. For simplicity, film condensation was assumed. To conduct experiments covering a wide humidity range, the humidity of the airflow was regulated by mixing superheated steam with high-temperature air. The sample material having 50 mm of length, 50 mm of width, and 10 mm of thickness was placed under this airflow, and the change in temperature over time was measured. During the initial stages of heating via superheated steam, condensation, and subsequent evaporation were observed. The time required for the evaporation of condensed water increased with the humidity, owing to the large amount of condensed water. The ending time of evaporation was successfully estimated within about −30% error. Although some modifications will be required in the future, the model is expected to be a powerful tool in various industries where superheated steam is applied. [ABSTRACT FROM AUTHOR]

The impact of global warming on lightning flash rates remains relatively unknown. In this study, the South China Sea (SCS) and the surrounding areas within Southeast Asia were selected to examine the long‐term trend and future projection of lightning activity based on the currently longest satellite‐based lightning data set available and climate models. Our study revealed a reduction in the observed lightning flash rates around the SCS, with a linear trend of −0.11 fl km−2 yr−2 during 1996–2013. In contrast, the precipitation around the SCS exhibited an increasing trend and was negatively correlated with the local lightning flash rate. The sea surface temperature gradient over equatorial Pacific Ocean, latent heat flux over the equatorial Indian Ocean, local convective available potential energy, precipitation and aerosol changes collectively accounted for 82% of the variance in the lightning fluctuations over the SCS and Southeast Asia. Multiple linear regression proxies of lightning flash rates were constructed and applied to the climate models. The models indicated that lightning activity around the SCS is projected to intensify by 10% and 12% by the end of the 21st century under SSP245 and SSP370, respectively. Plain Language Summary: The projection of future changes in lightning activity is uncertain owing to various factors, and different regions exhibit distinct trajectories. In this study, the focus was on the South China Sea (SCS) and Southeast Asia, and past variations in lightning activity was examined and used to predict future variations in lightning activity. Employing a multiple linear regression approach, we identified the large‐scale thermodynamic drivers and local environmental factors that influence lightning activity around the SCS. The research findings indicated a reduction in lightning activity over the past few decades over the SCS and Southeast Asia region. The simulation results indicate that in the future under ongoing global warming, regional lightning activity will intensify. Key Points: Lightning activity and precipitation show opposing regional trends around the South China Sea (SCS)Remote thermodynamic and local environmental factors both contribute to the variability in lightning around the SCSUnder future climate change scenarios, lightning activity around the SCS is projected to gradually increase [ABSTRACT FROM AUTHOR]

Boiling is a phase change heat transfer process that transfers latent heat quickly, making it suitable for use in various heat transfer systems. An important worry for the boiling performance degradation is the durability of the artificial nano-/microporous interfaces concerning the bottom surface. This study therefore proposes a novel three-step surface creation process (chemical etching, electroplating, and sintering process). Wet/chemical etching is first used to form three distinct micro/nanostructured substrates (ES#1, 2, 3). The most effective etched substrate (ES#3) is again employed as a cathode for the electrochemical depositing process or next-of-surface manufacturing. To strengthen the link between the etched layer (ES#3) and the surface of the coating (copper-alumina), the electroplating produced substrate (ES#4) is sintered in a predetermined environment. The enhanced boiling efficiency obtained on ES#4 is attributable to the appropriate bonding among ES#3 and electroplated nanoparticles (Cu-Al2O3). By maintaining a consistent temperature across the heater's topmost layer and the fin tip, the reduction in resistance at the intermediate level brought on by appropriate binding increases the rate of heat transfer. The critical heat flux (CHF) and heat transfer coefficient (HTC) improvements for ES#4 over bare copper are 184% and 216%, respectively. Additionally, the impact of certain macro- and micro-scale restrictions on the occurrence of flow boiling heat transfer is examined. The ES#4 surface showed better stability during repeated thirty testing cycles, as seen by the much smaller decline in superheat temperatures (1.2 °C) and wettability (32° to 33.7°). [ABSTRACT FROM AUTHOR]

Subantarctic Mode Water is a water mass with nearly vertically homogeneous physical properties in the Southern Ocean, which exhibit variability at various time scales. This study investigates the low-frequency variability of upper-ocean temperature in the Central Pacific Subantarctic Mode Water (CPSAMW) formation region since the 1980s using an eddy-resolving ocean model and two observation-based products. It is found that the CPSAMW core layer temperature has significant low-frequency variability, with an unusually cold period around 2000 and warm periods around 2005 and 2015, respectively. This low-frequency variability is closely related to the change in local mixed layer temperature, which in turn is mainly attributed to the change in surface latent heat flux resulting from the change in wind speed. Further analysis indicates that the low-frequency variability of wind speed in the CPSAMW formation region is dominated mainly by the Interdecadal Pacific Oscillation (IPO) and to a lesser extent by the Southern Annular Mode (SAM). This study reveals the relationship in the low-frequency variability of CPSAMW temperature with the IPO and SAM, and provides insight into the remote influence of Pacific decadal variability on SAMW variability. [ABSTRACT FROM AUTHOR]

Heatwaves (HWs) are high-impact phenomena stressing both societies and ecosystems. Their intensity and frequency are expected to increase in a warmer climate over many regions of the world. While these impacts can be wide-ranging, they are potentially influenced by local to regional features such as topography, land cover, and urbanization. Here, we leverage recent advances in the very high-resolution modelling required to elucidate the impacts of heatwaves at these fine scales. Further, we aim to understand how the new generation of km-scale regional climate models (RCMs) modulates the representation of heatwaves over a well-known climate change hot spot. We analyze an ensemble of 15 convection-permitting regional climate model (CPRCM, ~ 2–4 km grid spacing) simulations and their driving, convection-parameterized regional climate model (RCM, ~ 12–15 km grid spacing) simulations from the CORDEX Flagship Pilot Study on Convection. The focus is on the evaluation experiments (2000–2009) and three subdomains with a range of climatic characteristics. During HWs, and generally in the summer season, CPRCMs exhibit warmer and drier conditions than their driving RCMs. Higher maximum temperatures arise due to an altered heat flux partitioning, with daily peaks up to ~ 150 W/m2 larger latent heat in RCMs compared to the CPRCMs. This is driven by a 5–25% lower soil moisture content in the CPRCMs, which is in turn related to longer dry spell length (up to double). It is challenging to ascertain whether these differences represent an improvement. However, a point-scale distribution-based maximum temperature evaluation, suggests that this CPRCMs warmer/drier tendency is likely more realistic compared to the RCMs, with ~ 70% of reference sites indicating an added value compared to the driving RCMs, increasing to 95% when only the distribution right tail is considered. Conversely, a CPRCMs slight detrimental effect is found according to the upscaled grid-to-grid approach over flat areas. Certainly, CPRCMs enhance dry conditions, with knock-on implications for summer season temperature overestimation. Whether this improved physical representation of HWs also has implications for future changes is under investigation. [ABSTRACT FROM AUTHOR]

When discharging latent heat thermal energy storage (LHTES) systems, performance is influenced by the formation and adherence of a solid layer of phase change material (PCM) on heat eXchange (HX) surfaces. Super‐liquid‐repellent thin films (STFs) may be able to reduce solidifying PCM adhesion on HX surfaces during discharging, delay PCM solidification to lower temperatures, and by modifying nucleation sites potentially enable long‐term seasonal thermal storage. Techniques employed previously to fabricate sintered polymeric STF coatings include chemical vapour deposition, dip‐coating, spray‐coating, spin‐coating, layer‐by‐layer (LbL) assembly, sol‐gel, anodizing, electrodeposition, electrospinning, so on. Dip‐coating is considered attractive for fabricating thin films on simple and complex surface geometries due to process maturity, scalability, flexibility and cost‐effectiveness. To identify suitable materials for preparing STFs on metal HX surfaces using the dip‐coating process, more than 200 journal articles published in English during the period 2010 to 2022 were reviewed and the potential role of STFs in LHTES applications was assessed. The review identified key areas and applications stimulating STF material developments and formulations. The dip‐coating of potential STF materials was classified under three major themes driving current research and development (R&D) activities, that is, high performance thin films, eco‐friendly thin films and fundamental research formulations. This review provides a platform from which to develop coatings and HX systems to enable the cost‐effective implementation of STFs for improved heat transfer in future mobile/stationery LHTES systems. [ABSTRACT FROM AUTHOR]

Retrogression and hydration commonly affect large swaths of Earth's crust, causing variable degrees of chloritization, sericitization, and/or serpentinization. Hydration is a strongly exothermic process that partially opens isotopic systems, thereby distorting the recorded apparent ages and cooling histories of reworked terranes. Using a simple one-dimensional numerical model involving heat released at variable temperatures to simulate exothermic hydration, we track the cooling histories for rocks that exhume from depth. The calculated cooling paths are used to quantify apparent 39Ar-40Ar ages in muscovite, biotite, and feldspar considering 40Ar production and diffusive Ar loss. For fluid incorporation relative to chloritization of ~10%, ~50 kJ of latent heat are released per kilogram of rock. For this scenario and exhumation rates between 1 mm·yr-1 and 4 mm·yr-1, muscovite grains =100 µm in diameter yield apparent ages that are younger by up to 10%, but always exceeding the typical uncertainty of Ar dating. Biotite and feldspar display a similar distortion, even for large grains of ~1 mm in size. The relative younging effect increases to >30% with enthalpy released, exhumation rate, and decreasing grain size, with younging reaching a maximum for hydration at approximately the nominal closure temperature of the respective thermochronometers. Using published data sets (from Sifnos, Greece, and Tian Shan, China), we suggest that rejuvenation of apparent mica ages is consistent with diffusive Ar loss due to exothermic hydration during exhumation. Our method applies to any thermally activated process, like element exchange in mineral thermometers or fission-track annealing, provided heat is released close to the characteristic closure temperature. This extends to processes beyond hydration, such as shear heating or localized magma emplacement, making our results pertinent for diverse thermochronometers and temperature-sensitive methods across a broad range of conditions. [ABSTRACT FROM AUTHOR]

Heat‐storage materials are important for energy saving to protect the environment. Here, we show a long‐term heat‐storage material based on zirconium‐substituted lambda‐trititanium‐pentoxide (λ‐ZrxTi3−xO5, 0 < x≤0.06). λ‐ZrxTi3−xO5 exhibits a phase transition to zirconium‐substituted beta‐trititanium‐pentoxide (β‐ZrxTi3−xO5) upon application of pressure. The transition pressures were 600 MPa (x=0.04) and about 1 GPa (x=0.06). When the pressure‐produced β‐phase is heated, the β‐phase returns to λ‐phase. The phase transition temperatures (i. e., heat‐storage temperatures) were 185 °C (458 K) and 183 °C (453 K) for x=0.04 and 0.06, respectively. These heat‐storage temperatures are suitable for the reuse of low‐temperature industrial waste heat, which is considered to be a difficult temperature region to be efficiently collected and reused. The present pressure‐sensitive heat‐storage ceramic, which can store the latent heat energy for a prolonged period, is effective for the sustainable reuse of heat energy that are wasted in power plants and industrial factories. [ABSTRACT FROM AUTHOR]