Average Surface Temperature Research Articles

Integrated Assessment of the Runoff and Heat Mitigation Effects of Vegetation in an Urban Residential Area

Urban vegetation has an essential role in maintaining the hydrological and energy balance. These processes in urban areas have been long overlooked due to the fragmentation and uneven feature of land use and vegetation distribution. Recent advances in remote sensing and the ease of data acquisition have allowed a more precise mapping of vegetation and land cover, making it possible to simulate the above processes at micro scales. This research selects a small typical residential catchment in Japan as the study area and the purpose of this research is to investigate the impact of urban vegetation on mitigating urban runoff and the heat island effect. The remote-sensed Normalized Difference Vegetation Index (NDVI) data were used to represent vegetation spatial distribution and seasonal variation. A single layer canopy model and the Storm Water Management Model were coupled to simulate interception, evapotranspiration, and runoff generation processes. The effects of vegetation amount and landscape patterns on the above processes were also considered. The results showed that the coupled model had a satisfactory performance in the modeling of these processes. When the vegetation amount was set to 1.4 times its original value, the summer total runoff had a 10.7% reduction and the average surface temperature had a 2.5 °C reduction. While the vegetation amount was 0.8 times its original value, the total runoff increased by 6%, and the average surface temperature in summer increased by 1.5 °C. The combination of green roof and dense street trees showed the best mitigation performance among the different landscape patterns. The results of this study could be used as a reference for future green infrastructure development in areas with similar climate and vegetation characteristics.

Performance of interstitial thermal barrier materials on containing sidewall rupture and thermal runaway propagation in a lithium-ion battery module

Containing thermal runaway propagation in lithium-ion battery packs is a pertinent problem that is exacerbated when considering high energy density batteries and severe battery failure modes, such as sidewall rupture. This work investigates five different passive thermal barrier materials for their performance with respect to containing sidewall rupture and mitigating thermal runaway propagation between high energy density 21,700 cells. Along with propagation rate and total count of sidewall rupture failures, two new key performance indicators are introduced, the temperature reduction value and the sidewall rupture ratio, to quantify a material's performance. Overall, a stainless steel thermal barrier coated with an intumescent flame-retardant fabric performs best out of the five materials investigated. Evidence is given for the count of sidewall ruptures being linearly correlated to the propagation rate. It is shown that cells that fail with sidewall rupture have an average maximum surface temperature of 919 °C compared to 653 °C for cells that fail with top cap rupture. Evidence is also presented that sidewall rupture propagates to adjacent cells in a module. This work aims to provide battery pack designers with information to aid them in determining a strategy for containing thermal runaway propagation and sidewall rupture, including a method to evaluate the performance of thermal barrier materials against this objective.

Deep reinforcement learning based fast charging and thermal management optimization of an electric vehicle battery pack

Existing optimal strategies for fast-charging electric vehicle batteries are predominantly at the cell level. The proposed high-fidelity methods for extending available cell models to pack level are associated with a large computational burden, making real-world implementation impossible. Further, fast charging optimization and thermal management problems are dependent. That is, the cooling system reduces battery temperature, allowing for higher charging current, while optimal current minimizes the need for cooling and, in turn, reduces thermal system power consumption. There is a lack of studies where fast charging optimization and battery thermal management problems are jointly solved. Therefore, this paper proposes a simulation study using a deep reinforcement learning (RL) approach that concurrently solves fast charging and thermal management problems for a battery pack with low computational complexity. In this regard, we formulate each cell using an electro-thermal-aging model, which accounts for the heat exchange between adjacent cells. The electro-thermal-aging model plays the role of the environment for RL and is not the focus of novelty in this work. The RL agent is then trained to output the optimal charging current and coolant mass flow rate. Moreover, the proposed methodology is examined through a numerical study where the outperformance of our model is showcased by comparing it with baseline algorithms of model predictive control (MPC) and CC–CV. Consequently, three battery packs comprising 20, 444, and 7104 cells are used, respectively. We demonstrate that RL requires less than a second to finish the simulation for 20 cells, while MPC requires more than 80 min. In addition, RL keeps the cells’ core temperature below 33 °C, but MPC results reach 40 °C. The RL performance in charging packs with 444 and 7104 cells is then compared with that of CC–CV. In terms of computation time, RL and CC–CV are nearly the same, while regarding the average core and surface temperature of the cells as well as the cell aging, RL attains better outcomes, extending the battery pack’s life by up to two years after 1000 fast charging cycles.

Comparative analysis of combustion characteristics and economy between air assisted combustion and oxy-fuel combustion in glass furnaces

The oxy-fuel combustion is an effective means to improve the high energy consumption, pollution, and economic cost of glass furnaces. In this paper, the combustion characteristics in the flame spaces of traditional natural gas/air assisted combustion glass furnace (GF-NAC) and reformed natural gas/oxy-fuel combustion glass furnace (GF-NOC) are analyzed and compared by means of numerical calculation. More importantly, a systematic quantitative comparative analysis is conducted on the economic performance of the two glass furnaces from the perspectives of fixed and operating costs. The results show that enhanced combustion performance of GF-NOC over GF-NAC is found with flames being extended across the entire width of the furnace in GF-NOC. A more uniform temperature distribution within the furnace is consequently accomplished in GF-NOC. The flame center temperature, the average furnace temperature, and the average glass surface temperature in GF-NOC are increased by 7.42 %, 1.17 %, and 7.96 %, respectively, compared to GF-NAC. Furthermore, a reduction in gas velocity by 50 % at the arch in GF-NOC is observed to mitigate the erosive effects of high-temperature gas flows on the furnace crown. According to the service life of glass furnace of 15 years, the GF-NOC can save 420 M (million yuan) (12.8 %) compared to the GF-NAC. Although the fixed cost of GF-NOC is 9.82 M (5.43 %) higher than that of GF-NAC due to the expenditure on oxygen production equipment, the difference is offset by operating costs. Compared to GF-NAC, GF-NOC can save operating costs of 28.7 M (15.87 %) per year.

Design and fabrication of porous three‐dimensional Ag-doped reduced graphene oxide (3D Ag@rGO) composite for interfacial solar desalination

Solar-driven interfacial desalination technology has shown great promise in tackling the urgent global water scarcity crisis due to its ability to localize heat and its high solar-to-thermal energy conversion efficiency. For the realization of sustainable saline water desalination, the exploration of novel photothermal materials with higher water vapor generation and photothermal conversion efficiency is indispensable. In the current study, a novel 3D interconnected monolithic Ag-doped rGO network was synthesized for efficient photothermal application. The Ultraviolet–Visible-Near Infrared (UV–Vis-NIR) and FTIR analyses demonstrated that the controlled hydrothermal reduction of GO enabled the restoration of the conjugated sp2 bonded carbon network and the subsequent electrical and thermal conductivity through a significant reduction of oxygen-containing functional groups while maintaining the hydrophilicity of the composite photothermal material. In the solar simulated interfacial desalination study conducted using 3.5 wt.% saline water, the average surface temperatures of the 3D material increased from 27.1 to 54.7 °C in an hour, achieving an average net dark-excluded evaporation rate of 1.40 kg m−2 h−1 and a photothermal conversion efficiency of ~ 97.54% under 1 sun solar irradiance. In the outdoor real-world application test carried out, the surface temperature of the 3D solar evaporator reached up to 60 °C and achieved a net water evaporation rate of 1.50 kg m−2 h−1 under actual solar irradiation. The 3D interwoven porous hierarchical evaporator displayed no salt precipitation over the 54-h period monitored, demonstrating the promising salt rejection and real-world application potential for efficient desalination of saline water.

Mitigation of urban heat island in China (2000–2020) through vegetation-induced cooling

City afforestation serves as a robust strategy for thermal mitigation. Employing multisource satellite data, we explored the impact of vegetation cover on temperature dynamics across urban and rural sectors in Chinese cities. Our analysis reveals that a 1 % increase in vegetation coverage corresponds to a reduction in surface temperature by 0.099 °C to 0.102 °C in urban environments. However, the cooling effect diminishes from urban to rural areas, where increased vegetation occasionally results in warming. Further, the temperature reduction tends to stabilize at higher vegetation levels, as demonstrated in grid-based evaluations. Significantly, variations in urban population density substantially modulate these cooling effects. Over the period 2000–2020, afforestation increased vegetation coverage by 4.35 % in urban areas, which led to cooling in 67.43 % of the analyzed cities, with an average surface temperature decline of 0.58 °C. Additionally, our findings document a notable attenuation of the urban heat island (UHI) effect over time, with an average decrease of 0.56 ± 0.35 °C. This reduction primarily results from the thermoregulatory effects of changes in vegetation coverage, which cool urban areas and may warm rural ones. Our study underscores the critical role of afforestation in urban climate management and its efficacy in attenuating urban heat waves and UHI effects.

Application of thermography in the assessment of physical effort on body surface temperature distribution in racehorses

The aim of this study was to evaluate the efficacy of thermography in assessing the impact of regular physical effort on changes in the body surface temperature of the upper body parts of young racehorses. The study involved monitoring 33 racehorses aged 3 years in 3 imaging sessions over a period of 3 months. Temperature measurements of the neck and upper part of the forelimbs and hindlimbs from both sides were taken just before and after training. Three regions of interest (ROIs) located at the base of the neck, elbow and quarter on both sides of the body were analysed. Before physical effort, the average temperatures in all ROIs did not differ significantly between the right and left side of the body. After physical effort average surface temperatures of the left side of the elbow and quarter were significantly higher compared to the opposite side and the temperature at the base of the neck was higher on the right side in comparison to the left side (p<0.001). Body surface temperatures of all ROIs after physical effort significantly (p≤0.001) increased, with the greatest increase observed in the elbow (4.7°C) and the lowest in the base of the neck (3ºC). All regions demonstrated a positive correlation between average surface temperatures on the left and right side of the body, before and after training. There was a strong positive correlation between the average temperatures in the analyzed ROIs after physical effort with the strongest correlation between the elbow and quarter (r=0.773) and the weakest between the quarter and base of the neck (r=0.474). In conclusion, our study revealed that thermography remains a feasible diagnostic modality for identifying changes in upper parts of the body in response to physical effort and can therefore provide valuable insights into the assimilation of training regimes by the equine physiology.

Thermal-hydraulic performance of an imperfectly bonded ultrathin manifold micro pin-fin channel heat sink

This study numerically investigated the thermal-hydraulic performance of an ultrathin manifold microchannel heat sink (MMHS) and an ultrathin manifold micro pin-fin channel heat sink (MMPF-HS) with gaps between the manifold and microchannel layers. Unlike previous researches, the effect of the presence of gaps on flow distribution and overall heat transfer of MMHS and MMPF-HS was analyzed. The simulation results show that the presence of the gap significantly affect the heat transfer of both heat sinks but have minimal impact on pressure drop. For the MMHS with a gap of 0.05 mm in height, the bypass effect introduced by the gaps makes the uneven flow distribution worse and causes the formation of low-speed vortexes, leading to a 25.5% increase in the average temperature and 2.1-fold increase in the temperature non-uniformity of the heating surface. MMPF-HS is more effective in mitigating the effect of gap on temperature non-uniformity compared to the original MMHS due to the structural optimization. For the MMPF-HS with a 0.05 mm height gap, the average surface temperature rises from 34.3 to 40.9 °C, and the temperature non-uniformity increases from 1.1 to 5.5 °C, which remain significantly lower than those of the original MMHS without a gap.

Analysis Of The Effect Of Vegetation Density Index On Land Surface Temperature In Sukoharjo Regency In 2018 – 2022

Abstract Regional Development and population growth in Sukoharjo Regency will result in reduced land vegetation, thus giving an impact on the influence of rising ground surface temperatures. The objective of this study is to (a) Analyze land surface temperature in Sukoharjo Regency in 2018 – 2022 (b) Analyze vegetation density index in Sukoharjo Regency in 2018 – 2022 (c) Analyze changes in vegetation density index to land surface temperature in Sukoharjo Regency in 2018 – 2022. The quantitative descriptive analysis method extracting Landsat 8 image data into vegetation density index & land surface temperature, and the SPSS correlation test. The results of the study were obtained in the form of vegetation density index values in 2018, 2020, and 2022 which were dominated by medium vegetation, in 2019 and 2020 low vegetation, and in 2021 dominated by high vegetation. The average land surface temperature in Sukoharjo regency for the period 2018-2022 is in the range of 18.1 – 33.7° C with a fluctuating distribution every year. The correlation of vegetation density index and land surface temperature in 2018-2022 in Sukoharjo Regency obtained negative results with correlation values of -0.536 in 2018, -0.827 in 2019, -0.768 in 2020, -0.516 in 2021, and -0.553 in 2022.

Physiological variables and quality of quail eggs supplemented with magnesium in water under thermal stress

The objective to evaluate the effects of magnesium supplementation in the water of Japanese quails (Coturnix coturnix japonica) on physiological variables and egg quality with the birds kept in a thermoneutral environment and under thermal stress. Three hundred ninety-four (394) quails were used, distributed in a completely randomized 2×4 factorial design (2 temperatures: 24 and 32ºC, and 4 levels of magnesium: 50, 150, 250 and 350 mg L-1), with six replicates and eight birds per experimental unit. The respiratory rate (P<.0001), head temperature (P<.0001), wing temperature (P<.0001), foot temperature (P<.0001), back temperature (P<.0001), body surface temperature (P<.0001) and average body temperature (P<.0001) showed significant differences between the temperatures tested. With the exception of head temperature (P=0.0045), the other variables did not change their values with the increase in the level of magnesium in the water. Egg mass showed a significant difference (P=0.0072) as a function of the level of mannesium in the water. The temperature of the head was higher in birds consuming water with higher levels of magnesium, causing an increase in respiratory rate, and head, wing, foot, back, average surface and body temperatures in birds under thermal stress.

EHD gas pump as a cooling device for electronic components in a horizontal channel

Previous studies have shown that electrohydrodynamic (EHD) gas pumps are a viable alternative for traditional fans. In this study, it further demonstrates that an EHD gas pump is a device particularly ideal for cooling electronic components. To this end, four electronic components which are individually mounted on each wall of a horizontal channel are cooled by a two-stage EHD gas pump. To evaluate the effectiveness of EHD gas pump, two electrode configurations are considered; aligned and offset. Three heat dissipation rates are considered: 100 W/m2, 200 W/m2 and 500 W/m2. The average surface temperature and the maximum temperature (i.e., the hot spot) of each electronic component are carefully examined. The results are compared with those obtained without using an EHD pump. It shows that an EHD pump with offset electrode configuration produces the best cooling effect as it generates more mixing of flow inside the channel. The average surface temperature and the maximum temperature on the electronic components cooled by EHD gas pump with offset configuration are lower than those cooled by EHD pump with aligned electrodes. More importantly, the results show that the performance of EHD pumps in terms of energy efficiency may be further improved when the two stages are operated in uneven voltages.

Rethinking the Susceptibility‐Based Strategy for Marine Cloud Brightening Climate Intervention: Experiment With CESM2 and Its Implications

AbstractPrevious modeling studies indicate that even though marine cloud brightening under a susceptibility‐based strategy is effective in reducing the global average surface temperature, it triggers a La Niña‐like sea‐surface temperature response with cooling mostly confined within lower latitudes. Here we explore a different cloud seeding strategy involving seeding of regions with low susceptibility, primarily over the ocean in midlatitudes during the winter. Simulations with the Community Earth System Model, version 2 reveal that because the regional forcing is weaker and more widespread, cooling is more evenly distributed over the globe. This new strategy also does not result in the La Niña‐like state seen in the other strategies.

Changes in leaf area index by tropical forest transformation to plantations increase below-canopy surface temperatures

Climate change affects life in tropical landscapes by increasing temperatures, among other impacts. In addition, land transformation from forest to other land cover types typically increases temperatures of surfaces exposed to direct solar radiation. In rural areas, however, many organisms including humans live sheltered below canopies, but little is known about below-canopy surface temperatures. We assessed canopy leaf area index (LAI) and below-canopy surface temperatures in a landscape of rural lowland Sumatra, Indonesia. In this region, land-use trajectories in the past decades led from forest to monocultural plantations. We found that LAI varied more than 10-fold, with the highest values observed in forest and low values in rubber and oil palm plantations. Below-canopy surface temperatures increased significantly with decreasing LAI. A decrease in LAI by one unit (m2 leaf area per m2 ground area) increased ground surface temperature by 0.95 °C (confidence interval: 1.07–0.83 °C) around noon. Likewise, the temperatures measured on peoples’ cap or hijab surfaces under the canopy was strongly affected. For a light-brown hijab, the average noon surface temperature increased by 4.0 °C from forest to oil palm. Thus, in addition to climate warming, land transformation and associated declines in canopy LAI significantly increased below-canopy surface temperatures. Strategies for mitigating such potentially adverse temperature effects may include the integration of more and densely foliated trees into landscapes.

New characteristics of Meiyu precipitation changes in the middle and lower reaches of the Yangtze River since 2000

This study comprehensively analyzed the long-term changes of Meiyu in the middle and lower reaches of the Yangtze River with regard to precipitation, precipitation threshold, and interdecadal changes in atmospheric circulation. Results revealed obvious new features of Meiyu precipitation since 2000. (1) Meiyu precipitation shows a significant linear increase trend, with an average increment of 73.5 mm every 10 years. The increase in torrential rain is the most significant, accounting for 61% of the total precipitation increase, and its proportion has been increasing, while the proportions of light, moderate, and heavy rain in the total precipitation have been decreasing. (2) At the interdecadal scale, Meiyu precipitation and the local surface average temperature show opposite changes. Meiyu precipitation decreases by approximately 150 mm for every 1°C increase in the average temperature. This inverse correlation was not evident before 2000. (3) The saturated specific humidity in this area shows a significant increasing trend, indicating that precipitation in this area is caused by a higher threshold of atmospheric saturation and condensation, which may be a reason for the low Meiyu precipitation during high-temperature years. (4) The main atmospheric circulation in East Asia associated with Meiyu shows clear interdecadal changes, including the Western North Pacific Subtropical High and South Asian High having become significantly stronger and having extended westward and eastward, respectively, thereby facilitating the occurrence and persistence of Meiyu precipitation. The atmospheric circulation patterns associated with Meiyu, such as the Western North Pacific Subtropical High and South Asian High, have more significant impacts on Meiyu precipitation.

Asymmetry of hemispheric climate during MIS 16 versus MIS 12

Marine isotope stage (MIS) 16 (676-621 ka) and MIS 12 (478-424 ka) stand out as two significant glacial periods during the late Quaternary, demonstrating consistent continental ice volume or sea level, as discerned from benthic δ18O records. Intriguingly, the average sea surface temperature (SST) during MIS 16 surpasses that of MIS 12 by approximately 0.54–0.79 °C, while the atmospheric CO2 concentration during MIS 16 is approximately 16 ppmv lower than that of MIS 12. The underlying mechanism driving these discrepancies remains enigmatic. In this study, we present new high-resolution X-ray fluorescence (XRF) and grain size records covering the interval from 700 to 400 ka from Ocean Drilling Program (ODP) Site 1090 in the South Atlantic Ocean. We also integrated benthic δ13C, ice-rafted debris (IRD) and carbonate ion concentration ([CO32−]) records globally, to elucidate the distinct climate evolution during the MIS 16 versus MIS 12. Our findings suggest that MIS 12 is distinguished by a more substantial Antarctic ice-sheet, coupled with a weakened and/or equatorward displacement of southern westerly winds, and expansion of southern source water (SSW) alongside contractive northern source water (NSW). Conversely, the opposite climate state can be observed in MIS 16. The elevated atmospheric CO2 in MIS 12 and diminished atmospheric CO2 in MIS 16 may be attributed to reconfigurations in the ocean carbon reservoir regulated by the reorganization of deep-water masses and meridional ocean circulation, as a result of the divergent evolution of bipolar ice-sheets. Our study underscores the critical role of the interplay between the two polar regions in modulating deep-sea carbon storage on the orbital timescale and atmospheric CO2. This interplay is essential for a comprehensive understanding of past and future carbon cycle adjustments in response to climate change.

Thermographic evaluation and sensible heat emission of quails (Coturnix coturnix japonica) kept at different temperatures

The aim of this research was to evaluate the surface temperature and sensible heat emission of Japanese quails kept in a climate chamber at different temperatures: 24.0, 27.0, 30.0 and 33.0°C. The surface temperature was obtained using thermographic images collected in five regions (head, wings, back, legs and crest), calculating the average surface temperature (ST), the gradient between ST and air temperature (AT) and heat emissions by convection and radiation. The experimental design used was entirely randomised, with four treatments and six replications. Surface temperature in all regions of the birds' bodies and ST rose as air temperature rose, and the gradient between ST and AT decreased as AT rose, a fact which can make it difficult for the animals to exchange sensible heat with the environment. The crest and feet had the highest and lowest ST values, respectively. The heat emitted by the birds through convection and radiation decreases as the ambient temperature rises, and of the total heat emitted, there was a predominance of convection.

Deleterious Effects of Heat Stress on the Tomato, Its Innate Responses, and Potential Preventive Strategies in the Realm of Emerging Technologies.

The tomato is a fruit vegetable rich in nutritional and medicinal value grown in greenhouses and fields worldwide. It is severely sensitive to heat stress, which frequently occurs with rising global warming. Predictions indicate a 0.2 °C increase in average surface temperatures per decade for the next three decades, which underlines the threat of austere heat stress in the future. Previous studies have reported that heat stress adversely affects tomato growth, limits nutrient availability, hammers photosynthesis, disrupts reproduction, denatures proteins, upsets signaling pathways, and damages cell membranes. The overproduction of reactive oxygen species in response to heat stress is toxic to tomato plants. The negative consequences of heat stress on the tomato have been the focus of much investigation, resulting in the emergence of several therapeutic interventions. However, a considerable distance remains to be covered to develop tomato varieties that are tolerant to current heat stress and durable in the perspective of increasing global warming. This current review provides a critical analysis of the heat stress consequences on the tomato in the context of global warming, its innate response to heat stress, and the elucidation of domains characterized by a scarcity of knowledge, along with potential avenues for enhancing sustainable tolerance against heat stress through the involvement of diverse advanced technologies. The particular mechanism underlying thermotolerance remains indeterminate and requires further elucidatory investigation. The precise roles and interplay of signaling pathways in response to heat stress remain unresolved. The etiology of tomato plants' physiological and molecular responses against heat stress remains unexplained. Utilizing modern functional genomics techniques, including transcriptomics, proteomics, and metabolomics, can assist in identifying potential candidate proteins, metabolites, genes, gene networks, and signaling pathways contributing to tomato stress tolerance. Improving tomato tolerance against heat stress urges a comprehensive and combined strategy including modern techniques, the latest apparatuses, speedy breeding, physiology, and molecular markers to regulate their physiological, molecular, and biochemical reactions.

Land use inspection technique affects land surface temperature from satellite data

This research aims to present a land use inspection technique that affects land surface temperature from satellite data by using Maha Sarakham province, Thailand as a case study. Procedures: 1) Analyze land use from Sentinel-2 Satellite data that can be divided into 4 categories such as water, agriculture, forest, and urban, 2) Analyze land surface temperature from Sentinel-3 Satellite data. The study results found that urban area has the highest average surface temperature followed by forest area, water area, and agricultural area respectively. The analyzed data from the satellite found the highest average surface temperature is 32.20°C. The result shows that this inspection technique can analyze land surface temperature in other areas of the countryThis research aims to present a land use inspection technique that affects land surface temperature from satellite data by using Maha Sarakham province, Thailand as a case study. Procedures: 1) Analyze land use from Sentinel-2 Satellite data that can be divided into 4 categories such as water, agriculture, forest, and urban, 2) Analyze land surface temperature from Sentinel-3 Satellite data. The study results found that urban area has the highest average surface temperature followed by forest area, water area, and agricultural area respectively. The analyzed data from the satellite found the highest average surface temperature is 32.20°C. The result shows that this inspection technique can analyze land surface temperature in other areas of the country.

Fabrication of carbon fiber/cement composites with controllable precise patterned structures via facile computerized embroidery

Carbon fibers exhibit good electrothermal performance; however, they break easily during the weaving process. This study used a facile computerized embroidery process to design and fabricate carbon fibers with controllable and precise patterned structures. The obtained carbon fiber/cement composites (CFCs) exhibited excellent electrothermal performance (100 ℃ under 30 V), low energy consumption (400 mW/℃), and homogeneous heat distribution with a unique heating element (carbon fibers) structure. The difference between the maximum and average surface temperatures improved, and the surface heat distributions of the CFCs under different structures were determined using a finite element simulation. CFCs with different complex heat element structures were successfully fabricated, and the mechanism regulating the heat distribution of the CFCs was revealed. Embroidery technology provides a novel strategy for the fabrication of carbon fiber/cement composite materials with a controllable carbon fiber structure, thereby significantly broadening the application of cement composites for electrothermal applications.

Effect of temperature sampling methods on sphere packed tube heat transfer coefficient determination

This paper investigates the heat transfer characteristics and the pressure drop of a sphere packed tube using Computational Fluid Dynamics (CFD) simulation. The turbulent kinetic energy of the fluid exhibits significant variation based on the differing accumulation structures of the particles, which is deemed to greatly influence the heat transfer characteristics. Consequently, the temperature distribution at the outer wall becomes inhomogeneous. Previous studies have overlooked the relative positioning between the thermocouples and the particles, potentially leading to inaccurate estimations of the heat transfer coefficient and discrepancies between CFD simulations and real-world experiments. To address this, two temperature sampling methods are employed in this paper to estimate the heat transfer coefficients: one method involves measuring the temperatures at various sampling positions, while the other uses the surface average temperature of the packed area as the sample temperature. Interestingly, it is found that different temperature sampling methods significantly impact the heat transfer coefficients. This study serves as a reminder for future research on sphere packed tubes to prioritize temperature sampling positions.