Decrease In Maximum Temperature Research Articles

Modeling and optimizing perforated twisted tape for heat transfer enhancement

Previous studies on twisted tapes based on empirical design may overlook some structures having exceptional performance. To further develop the design flexibility, we propose a parametric modeling method for perforated twisted tapes (PTTs) in conjunction with multi-objective optimization to achieve heat transfer enhancement within the flow channel. This method considers the influence of structures on hydrothermal performance more thoroughly, and accelerates the development process. The control coefficients in the mathematical descriptions of the geometric characteristics expressed by Bernstein–Bézier functions were specified as the design variables. Two types of PTTs, full-width and half-width, were presented based on the variable ranges of width optimization. In the optimization, the observed objectives were the average temperature, root mean square temperature, and friction factor. A three-dimensional computational fluid dynamics model was employed to analyze the heat transfer and flow behaviors under three friction factor weight coefficients (0.1, 0.3, and 0.5) and was validated against experimental data. The numerical results showed that the maximum decrease in the average temperature and root mean square temperature of the heat source could attain 18.58 K (5.46%) and 2.92 K (72.64%), respectively. The friction factor was reduced by a maximum of 3.59 (57.35%) at the weight coefficient of 0.5 compared to 0.1. Furthermore, according to the performance evaluation criterion (PEC), the half-width PTTs generate less flow resistance and exhibit superior overall performance. The proposed method elaborates on the potential design space and provides a framework for the creation of efficient convective heat transfer devices.

Numerical Study of Stratified Flames Using Reynolds Averaged Navier Stokes Modeling.

Reynolds averaged Navier Stokes technique was used to develop a validated numerical model for stratified flames. The validation was carried out with the experimental data of the non-swirl flames of the Cambridge dual annulus swirl burner. The RNG k–ε turbulence model along with the SG-35 skeletal chemical mechanism was found to give a good prediction of scalar and vector quantities while resulting in the reduction of computational time by 99.75% in comparison with that required for large eddy simulation techniques used in the literature. The effect of stratification at a constant input power, global equivalence ratio, and Reynolds number was examined. At stratification ratios (SRs = ϕin/ϕout) 1 and 2, intense burning, marked by the higher OH concentration, was observed close to the bluff body. Beyond SR = 2, the region of intense burning shifts downstream away from the bluff body. This is a result of the high equivalence ratio in the inner annulus, which is beyond the rich flammability limit of methane–air flames, and as a result, the primary flame region is shifted downstream after the mixtures from inner and outer annulus have mixed properly to produce a mixture with the equivalence ratio in the flammability limit. The maximum temperature was found to increase by 24.1% when the SR is increased from 1 to 2 and the combustion efficiency was found to significantly improve by 267%. The highest maximum temperature of 2249 K is observed for the mildly stratified flame at SR = 2. Beyond SR = 2, the maximum temperature decreases, while the combustion efficiency increases slightly.

Clinical effect of early administration of tocilizumab following the initiation of corticosteroid therapy for patients with COVID-19

IntroductionSevere acute respiratory syndrome coronavirus 2 (SARS-CoV-2) first broke out in Wuhan in December 2019, and has since caused a global pandemic. The efficacy of several drugs has been evaluated, and it is now evident that tocilizumab has a beneficial effect, especially combined with corticosteroids, in patients with Coronavirus Disease 2019 (COVID-19). However, the optimal timing of tocilizumab administration has not yet been established. The goal of the present study was to determine the optimal timing of tocilizumab administration after starting corticosteroid therapy in patients with COVID-19. MethodsWe retrospectively analyzed the clinical characteristics of patients who were hospitalized for COVID-19 and treated with tocilizumab and corticosteroids in our hospital. The patients were divided into concurrent and sequential groups. The concurrent group received tocilizumab ≤24 h after corticosteroids, and the sequential group received tocilizumab >24 h after corticosteroid administration. ResultsThe baseline clinical characteristics of tocilizumab administration were similar between the two groups. White blood cell counts were significantly lower and C-reactive protein levels were significantly higher in the concurrent group than the sequential group. In the concurrent group, tocilizumab administration led to a significant decrease in maximum body temperature. In addition, there were significantly more oxygen-free days in the concurrent group than in the sequential group. However, survival rate was not significantly different between the concurrent and the sequential groups. ConclusionsIn the combination therapy with tocilizumab and corticosteroids, early administration of tocilizumab after starting corticosteroid treatment is effective when treating COVID-19.

Study on the Effect of Bridge Deck Spacing on Characteristics of Smoke Temperature Field in a Bridge Fire

The numerical simulation method is used to simulate the distribution characteristics of the smoke temperature field of a double-deck bridge smoke temperature field during tanker fire under natural ventilation. The influence of the distance between double decks on the truss and ceiling temperature field change in the double-deck bridge is investigated. The results show that the range of high-temperature area gradually decreases with the increase in bridge deck spacing. The maximum excess temperature function of the tunnel ceiling is also applicable to the bridge, but the coefficient is smaller than that of the tunnel experimental formula. An equation is proposed to predict the maximum excess temperature of the truss under different bridge deck spacings. As the bridge deck spacing increases, the maximum excess temperature decreases. The excess temperature of the truss increases along the truss, and the maximum excess temperature appears at the top of the truss. Based on the energy equation, an equation for the excess temperature of the truss is established. As the vertical height increases, the excess temperature of the truss above the fire source exponentially increases. The research results will contribute to the fire hazard evaluation and safety design of bridges.

A novel nanofluid cooling system for modular lithium-ion battery thermal management based on wavy/stair channels

An innovative liquid cooling system that contains stair and wavy channels by alumina nanofluid with copper sheath is numerically analyzed to improve the battery thermal management system's temperature distribution and cooling capacity during discharge/charge processes. The effects of the charge/discharge current rate, alumina nanofluid coolant, inflow velocity, ambient/fluid inflow temperature, stair channel, interfacing regions between adjacent LIBs, and the contact regions between LIBs and wavy channel shell on the thermal efficiency of the battery module was investigated. Based on the outcomes, it is concluded that the addition of coolant alumina nanofluid with a 2% volume fraction notably reduces the highest temperature and temperature non-uniformity across the battery module. Simulation results illustrated that by using a 2% volume fraction of Alumina nanofluid, the peak temperature and temperature difference for the discharge process decreased 1.2 °C and 0.4 °C, compared to DI water, respectively. In addition, increasing the coolant inlet velocity led to a decrease in maximum temperature and temperature difference. Different ambient/fluid inflow temperatures of the battery module are evaluated to simulate different weather climates. An innovative design using the stair channel cooling is finally developed for the LIB thermal management system. Comparing the two stair and straight channels, it is accomplished that the temperature non-uniformity for the stair-type channel is almost reduced by 0.19 °C and 0.22 °C for the discharge and charge processes, respectively.

Surrogate model of liquid cooling system for lithium-ion battery using extreme gradient boosting

Battery thermal management system (BTMS) has been widely regarded as an effective means to mitigate the sensitivities of lithium ion batteries (LIBs) to temperature, as to uphold the safe and high-performance operation of LIBs. On the premise that the volume and cost are limited, optimizing the structure of BTMS becomes relevant. Owing to the complex flow and heat transfer processes, the objective functions of BTMS structural optimization cannot be expressed analytically, but has to be evaluated using finite element method (FEM), which is time-consuming and therefore not scalable. The well-known solution to speed up the evaluation of objective functions is to engage a surrogate model, which offers a fast but slightly inaccurate mapping from the input variable space to the response. In this article, two innovations on surrogate modeling for BTMS structural optimization are proposed. One of them is in terms of input variables of surrogate model, which takes into consideration not only the structural parameters, but also the operating conditions. The other is on the surrogate model itself, in that, extreme gradient boosting (XGBoost) is used to replace the conventional kriging and response-surface methods, which is able to reduce the maximum absolute error of the model by 50%. The errors of maximum temperature and temperature difference decrease 0.179°C and 0.255°C, respectively. Moreover, the computational time of the XGBoost-based model is just 2 ms. The method proposed in this article can be applied on a wide range of structural optimization tasks in real driving cycle of electric vehicles.

Molecular dynamics simulation of obstacle number effect on heat and mass transfer of argon flow inside the platinum nanochabnnels

Nanochannels (NCs) are structures for mass transfer (MT) and heat transfer (HT) procedures in actual usages. Prior reports display the atomic behavior of various fluids inside perfect NCs. This study uses the molecular dynamics simulation (MDS) to examine the impact of number of obstacles (N.Os) on argon flow inside Platinum NCs. Simulation outputs are presented by calculating the physical quantities such as temperature (T), potential energy (PE), density (D)/temperature (T)/velocity (V) profiles, and interaction energy (IE). MDS results show that as the N.O increases, the maximum density increases from 0.093 to 0.099 atom/Å3. The maximum velocity decreases from 0.0031 to 0.0025 Å/ps by increasing the N.Os. The maximum temperature decreases from 329.46 to 318.43 K. By increasing the N.Os, the fluid particles' oscillations (FP) and their temperature also decrease. This mechanism can reduce the temperature in the HT process. In addition, with increasing the N.Oss from 1 to 4, the IE increases from −60.52 to -70.86 eV. This increase in IE can reduce the atomic stability of NCs. This behavior reduces the lifetime of NCs in heat/mass transfer processes. Therefore, it is expected that with the outcomes of the current examination and the control of the N.Os, we can optimize the various processes like MT and HT for industrial purposes.

Integration of Computational Fluid Dynamics and Artificial Neural Network for Optimization Design of Battery Thermal Management System

The increasing popularity of lithium-ion battery systems, particularly in electric vehicles and energy storage systems, has gained broad research interest regarding performance optimization, thermal stability, and fire safety. To enhance the battery thermal management system, a comprehensive investigation of the thermal behaviour and heat exchange process of battery systems is paramount. In this paper, a three-dimensional electro-thermal model coupled with fluid dynamics module was developed to comprehensively analyze the temperature distribution of battery packs and the heat carried away. The computational fluid dynamics (CFD) simulation results of the lumped battery model were validated and verified by considering natural ventilation speed and ambient temperature. In the artificial neural networks (ANN) model, the multilayer perceptron was applied to train the numerical outputs and optimal design of the battery setup, achieving a 1.9% decrease in maximum temperature and a 4.5% drop in temperature difference. The simulation results provide a practical compromise in optimizing the battery configuration and cooling efficiency, balancing the layout of the battery system, and safety performance. The present modelling framework demonstrates an innovative approach to utilizing high-fidelity electro-thermal/CFD numerical inputs for ANN optimization, potentially enhancing the state-of-art thermal management and reducing the risks of thermal runaway and fire outbreaks.

High temperature generated by sliding metal friction and its effectiveness as an ignition source for hydrogen

Frictional processes caused by faults can lead to hot surfaces and mechanical sparks. On this basis, two ignition modes with mechanical spark and hot surface as ignition source are determined to ignite hydrogen. Temperature development tests as well as ignition tests are carried out in friction equipment according to the applied friction strength and different materials. The temperature of the hot surface is detected by thermocouples and an infrared camera. Results show that as the wear rate increases, the maximum temperature decreases. At a friction pressure of 22.24 N and friction speed of 10.47 m/s, the peak temperatures of cast iron, 304 stainless steel, and 316 stainless steel are 750 ± 7.5 °C, 773 ± 7.7 °C and 781 ± 7.8 °C, respectively. The lower the thermal conductivity of the metallic material, the higher the maximum temperature reached by the hot surface. The ignition delay time mainly depends on the friction strength and the thermal conductivity of the metal. The lowest friction-ignitable concentrations (LFCs) of hydrogen are determined under different friction conditions. As the friction strength increases, the LFCs of hydrogen decrease. The LFCs of 304 and 316 stainless steel to ignite hydrogen are lower than those of cast iron.

Changes in the means of temperatures and rainfall of the period 1981-2010 with respect to mean values of 1951-80 over the Indian stations

In this paper, the changes in monthly and annual means of maximum temperature, minimum temperature and rainfall at well distributed 178 stations of India for the period 1981-2010 as compared to the respective means of 1951-80, are determined and analysed. To test the significant differences at the station, Student’s t test has been applied.
 Increasing trend in monthly and annual mean maximum temperature is found at most places of southern and western regions of India. There is a decrease in maximum temperature in Indo-Gangetic Plains (IGP) region in January to June months. Significant rise in maximum temperature in all months except August is found at more places in southern part (south of 20° N) of India than northern part(north of 20° N). Significant fall in the temperature is found at a few places of the country. The same trend is found in annual maximum temperature. Minimum temperature has increased at most places of the country in all months except April to June where in it decreased over northern, central and eastern regions. During November to March months, minimum temperature increased more at most places of northern part of the country. Annual minimum temperature has increased at most places of the country except over UK, Significant fall in minimum temperature is observed at some places of the country.
 There is a less change in monthly rainfall all over the country. Annual rainfall slightly decreased at most places of the country except Meghalaya, WB and Kerala where it increased. There is a significant fall in annual rainfall at some places of the country.

Co-pyrolysis of cashew nut, coconut shells, and rice husk waste: kinetic and thermodynamic investigations

ABSTRACT Co-pyrolysis of low ash content of coconut shell (CNS) and cashew nuts shells (CCS), and high ash content rice husk (RH) blends was performed using thermal gravimetric analysis (TGA). RH was blended with both CCS and CNS at 0, 30, 60, and 100% RH by mass. Results showed that CCS and CNS have low ash contents of 2.7 and 1.5%, respectively, while RH has high ash content of 26.7% on dry basis. TGA under nitrogen gas study was carried out at three heating rates of 10, 15, and 20 K/min. It was observed that the increase of CCS/CNS increased decomposition rates of blends. For example, RH increased from 6 to 7.7%/min when CNS was added. Furthermore, addition of low ash content leads to high decrease of maximum decomposition rates compared to high-high or low-low ash blends. Synergistic analysis has found out that a positive effect is observed when CNS/CCS is added to RH. The decrease of maximum decomposition temperature of 60–63°C compared to other studies of 10°C for all low and 40° for all high ashes is of great advantage. Flynn-Wall-Ozawa (FWO), Kissinger-Akahra-Sunose (KAS), and DAEM kinetic model analysis for 0.1 ≤ α ≤ 0.75 were used between 315 and 840°C. FWO model gave activation energy of 85, 70, and 75 kJ/mol, for RH, CNS, and CCS, respectively. Addition of low ash content biomass reduced activation energy of RH, activation energy of RH was reduced from 85 to 72 kJ/mol when CNS was added. RH requires high energy than the rest, example, RH needed 66.29 kJ/mol of energy compared to 51% of CNS and 56 kJ/mol for CCS. The entropy results were negative which implies a different orientation of molecules from origin samples properties. The Gibbs-free energies were positive and thus non-spontaneous process. Empirical models generated using SB model indicated that kinetics depends on reaction order and acceleration mechanism rather than diffusion and nuclei growth. Kinetically, the blending of high and low ash content biomass leads to high decrease of operating temperature and activation energy compared to low-low or high-high ash content blends. It has been recommended to further study on quality and quantity of product from such blends and the possibility of pre-treatment methods such as microwaves to improve pyrolysis of such blend.

A copper nanoparticle enhanced phase change material with high thermal conductivity and latent heat for battery thermal management

In order to maintain the safety temperature of power battery pack within electric vehicle, an anti-leakage composite phase change materials (CPCM) of paraffin (PA)/expanded graphite (EG)/copper nanoparticle (CN) with enhanced thermal conductivity was proposed. Its thermal properties and heat dissipation were verified by thermal property test and discharge experiment respectively. The results show that PA/EG/CN can well control the temperature of the battery pack within a safe range. The CPCM-based battery module shows excellent heat dissipation, the maximum temperature (Tmax) decrease 2.6 °C and 7.2 °C during 1 C and 2 C discharge tests. The temperature difference is 1.0 °C and 0.8 °C. The cooling effect is better under high-rate discharge. During multiple discharge-charge cycle, we find that although the latent heat of the CPCM is limited, the latent heat of the CPCM can be effectively recovered for the abeyance time, which proposes a guiding strategy for the design of CPCM battery thermal management system.

Simulation study on cooling effect of two-phase liquid-immersion cabinet in data center

• When the inlet velocity is greater than 0.6 m/s, the two-phase immersion cabinet using Novec 649 can ensure the normal operation of the chip. • After using Novec 7000, a maximum decrease in the chip average temperature is 17.32 °C. • The horizontal baffle between the upper and lower chips can significantly reduce the maximum temperature difference of upper chip, with a maximum decrease of 31.37%. Two phase immersion liquid cooling cabinet can meet the cooling needs of high-density data center. However, the cabinet has the problem of poor heat dissipation effect caused by evaporation pressure fluctuation. The two-phase liquid-immersion cabinet with external condenser can discharge the generated vapor in time to maintain its pressure stability. But its cabinet-scale thermal management performance has not been investigated in detail yet. In this paper, the cabinet simulation model is established to evaluate the effects of inlet velocity, coolant type and cabinet internal structure on chip cooling effect from two aspects of thermal safety and temperature uniformity. The results show that the inlet velocity and the coolant type have great influence on the chip safety. When the inlet subcooling degree is constant, the drop range of chip temperature decreases gradually with the increase of coolant flow rate. The decline range is almost unchanged when the inlet velocity is greater than 0.6 m/s. At the same inlet subcooling degree and velocity, compared with Novec 649, the chip temperature decreased significantly after using Novec 7000 with lower boiling point. And the latent heat of vaporization also affected the temperature drop range, the average chip temperature decreased by 17.32 °C at most. The horizontal baffle between the upper and lower chips can significantly improve the overall temperature uniformity of the cabinet. Under the design conditions, the temperature uniformity coefficient of chip can be decreased by 55.64%, which is conducive to its safe and stable operation.

Experimental Study on the Performance of a Dew-Point Evaporative Cooling System with a Nanoporous Membrane

In this paper, a plate counter-flow dew-point evaporative cooling system was designed with a nanoporous membrane covered on the surface of the wet channel for enhancement of heat and mass transfer. First, the operating principle of this device and theoretical analysis of nanoporous membrane evaporation were discussed in detail. Then, the impacts of several operating parameters on cooling performance, mainly including inlet air temperature, humidity, velocity, and the effect of utilizing the membrane, were investigated in trials. It was found that the cooling performance can be improved by using membrane significantly. In the dry channel, the maximum temperature decrease can reach 12.5 °C. At a high inlet air temperature, the product air can be dropped to a lower temperature, contributing to a more significant heat transfer process. Lower humidity, on the other hand, resulted in a reduced product air temperature and a lower cooling efficiency. Under the condition of 50% humidity, the wet-bulb efficiency and dew-point efficiency were 1.09 and 0.79, respectively. With the inlet air velocity increasing from 1.5 m/s to 2 m/s, the outlet air temperature would rise, and the wet-bulb efficiency and dew-point efficiency would decrease. To achieve better cooling performance, inlet air velocity ought to be limited to a low speed.

A Decrease in the Daily Maximum Temperature during Global Warming Hiatus Causes a Delay in Spring Phenology in the China–DPRK–Russia Cross-Border Area

Spring phenology is the most sensitive indicator of climate change and exploring its response to climate change has important implications for ecosystem processes in the study area. The temperature changes before and after the global warming hiatus may affect the spatiotemporal pattern of land surface phenology. In this paper, taking the China–DPRK (Democratic People’s Republic of Korea)–Russia cross-border region as an example, based on GIMMS NDVI data, the Polyfit-Maximum method was used to extract the start date of the vegetation growing season (SOS). The variation trend of SOS and its response to climate change were analyzed in the early (1982–1998) and late (1998–2015) periods of the warming hiatus. At the regional scale, the spatial distribution of the SOS in the China–DPRK–Russia (CDR) cross-border area presents an elevation gradient, which is earlier in high-elevation areas and later in low-elevation areas. The temporal and spatial trend of SOS is mainly correlated by daytime maximum temperature (Tmax). The significant increase in Tmax in the early period promoted the advance of SOS (0.47 days/year), and the decrease in Tmax in the later period caused the delay of SOS (0.51 days/year). While the main influencing factor of the SOS changes in the region in the early and late periods was Tmax, the response of the SOS changes in China, DPRK and Russia to climate change also changed with the dramatic temperature changes during the warming hiatus. The Chinese side is increasingly responding to Tmax, while the North Korean side is becoming less responsive to climatic factors, and precipitation and radiation on the Russian side are driving the advance of the SOS.

Evolution of weather parameters and trend analysis over Junagadh, Gujarat

Climate change is one of the most important worldwide issues talked among the scientists and researchers. The temperature and rainfall trends are analyzed for meteorological data of Junagadh station in Gujarat. India over approximately last three decades stretching between years 1971 to 2013. The long–term change in temperature and rainfall has been assessed by linear trend analysis. The increasing trend in mean monthly maximum temperature (MMAX) and total mean rainfall (TMRF) is confirmed by Mann-Kendall trend test. It is evident from that monthly mean temperature have increased significantly for all the months except the months of April and October for which a very weak decrease in mean maximum temperature is observed. This implies that at Junagadh, the highest increase in temperature occurred in November (0.0210C) during 1980-2011 period. The annual mean of monthly maximum temperatures (MMAX) observed an increasing trend having an annual decreasing of 0.0040C year during 1980-2011. It is evident TMRF have increased for the months April, May August and September whereas it shows decreasing trend in January, Feb, March, June, July, October, November and December. This implies that at Junagadh, the highest increase in TMRF occurs in August and increased by (0.029 mm) during the last 1980-2011. The highest decrease in TMRF occurs in June and decreased by (2.153mm) during the same period. The annual mean of total monthly rainfall observed a decreasing trend having an decrease of 0.249 mm/year during the last 31 years.

The antipyretic effectiveness of dipyrone in the intensive care unit: A retrospective cohort study.

IntroductionDipyrone (metamizol) is regularly used in critical care for pain and fever treatment, especially in Germany and Spain. However, indication for antipyretic therapy in critically ill patients is currently unclear and data for both the risk and benefit of dipyrone treatment in the intensive care environment are scarce. We hypothesized that antipyretic efficiency of dipyrone would not exceed antipyretic efficiency of acetaminophen. We therefore aimed to compare temperature courses in critically ill patients receiving either intravenous dipyrone, acetaminophen or no antipyretic medication.Material and methodsWe included 937 intensive care unit (ICU) patients with body temperature recordings of at least 37.5°C. We investigated temperature decrease associated with dipyrone or acetaminophen and additionally compared it to an untreated control group.ResultsWithin the eight-hour study interval, maximum body temperature decrease in patients without antipyretic medication was -0.6°C (IQR: -1.0 to -0.4°C; n = 315). Maximal decrease in body temperature was higher both with dipyrone (-0.8°C (IQR: -1.2 to -0.4°C); p = 0.016; n = 341) and acetaminophen (-0.9°C (IQR: -1.6 to -0.6°C); p<0.001; n = 71), but did not differ between dipyrone and acetaminophen (p = 0.066). As compared to untreated patients, dipyrone only led to a marginal additional decrease in body temperature of only -0.1°C. Maximum of antipyretic effectiveness was reached four hours after administration.ConclusionAntipyretic effectiveness of dipyrone in ICU patients may be overestimated. Given the lack of prospective data, clinical evidence for antipyretic dipyrone therapy in the ICU is insufficient and warrants further critical evaluation.

Numerical simulation and emission analysis of ammonia/oxygen premixed combustion process in micro-combustor with baffle

Ammonia has attracted extensive attention, and its popularization and application in various power equipment has become one of the current hotspots. However, in the combustion-based micro power system, the combustion and emission characteristics of ammonia at micro scale are still unclear. In this paper, the combustion and emission characteristics of ammonia/oxygen in micro burner with baffle were studied by numerical simulation. By changing the length, width, position of the baffle and inlet velocity, the effects of various factors on temperature field, NO emission and radiation efficiency were obtained. The results show that compared with micro conventional burner, the addition of baffle reduces the channel temperature, radiation efficiency and NO emission. As the baffle length increases, the channel maximum temperature and NO emission decrease first and then increase. The mass fraction of NO in the exhaust gas increases as the baffle width increases under constant flow rate. As the baffle moves downstream, NO emission presents a parabolic distribution. When the baffle with length of 5 mm and width of 0.5 mm is placed 3 mm away from the inlet, the radiation and emission performance are the best. The mass fraction of NO decreases by 24.71% compared with micro planar combustor.

Natural Convection of Reacting Chemical in Square Enclosure with Circular Cylinder

Natural convection characteristics of a reacting chemical are presented considering a circular cylinder at different locations in a square cavity. The problem is formulated providing a detailed description of the transformations. To end, the physical domain is changed to the computational domain using a suitable coordinate transformation. We then solve the equations employing the finite difference method. The magnitude of stream function and maximum temperature are in general substantially augmented owing to the increase of horizontal, vertical, or diagonal distance between the centers of the circular cylinder and the square enclosure. But in the case of changing the vertical or diagonal locations the above quantities for a cylinder down from the horizontal centerline are found to be higher than those for a cylinder up from it. For higher values of the Lewis number (), Rayleigh number (), and buoyancy force parameter (), magnitude of stream function increases, whereas maximum temperature decreases. Contrary to this, the Frank-Kamenetskii number () strongly enhances the strength of stream function and the maximum temperature. From this investigation, one can achieve knowledge to formulate a problem for more complex geometry. In addition, the results might be used to improve the shortcomings of present technologies or to invent a new state-of-the-art technology.

Попередження інтраопераційної ненавмисної гіпотермії у пацієнтів із політравмою

Актуальність. Ненавмисна гіпотермія розвивається спонтанно як наслідок травми, хірургічного втручання та наркозу в результаті порушення відповідності теплопродукції тепловтрат і пригнічення компенсаторної терморегуляційної відповіді. Мета: вивчити ефективність способу корекції інтраопераційної ненавмисної гіпотермії з використанням системи конвекційного обігріву в пацієнтів із політравмою. Матеріали та методи. Обстежено 20 пацієнтів із політравмою, яким проводились ургентні оперативні втручання. Пацієнти були розділені на 2 групи: I — основна група (n = 10), в якій інтраопераційно проводилося активне зігрівання системою конвекційного обігріву WarmAir 135 (CSZ) з використанням ковдр для зігрівання в умовах операційної; II — контрольна група (n = 10) без використання конвекційного зігрівання. Вивчалася температура ядра тіла (Тсо): початково, через 30, 60 хвилин і наприкінці операції. Розраховувалися наступні показники: мінімальна (Тмін.) і максимальна (Тмакс.) температура, середня температура (Тср.), температурний діапазон (Тдіап. = Tмакс. – Тмін.). Результати. У всіх пацієнтів із політравмою та проведенням ургентних хірургічних втручань відзначається розвиток клінічно значущої ненавмисної гіпотермії. На етапі 60 хвилин інтраопераційного періоду Тсо була вірогідно вище в I групі (35,38 ± 0,28 °С) порівняно з пацієнтами II групи (34,70 ± 0,39 °С) (p &lt; 0,05). Виявлено вірогідно вищий рівень середньої Тсо в I групі (35,53 ± 0,66 °С) порівняно з II групою (34,67 ± 1,74 °С) пацієнтів (p &lt; 0,05). Діапазон температур, який являє собою різницю максимальної та мінімальної Тсо, був вірогідно нижче в I групі пацієнтів (1,36 ± 0,74 °С) порівняно з II групою (4,55 ± 1,11 °С) (p &lt; 0,05). Висновки. Використання в комплексі інтенсивної терапії конвекційної системи зігрівання хоча й не дозволяє досягти вихідних значень Тсо, але попереджає прогресування поглиблення гіпотермії, ефективно забезпечуючи підтримку температурного гомеостазу у критичних пацієнтів із політравмою.