Effects Of Heat Production Research Articles

Effect of heat production on MHD natural convection transport of nanofluid flow via a vertical uniform perforated plate: An unsteady analysis

This article statistically investigates the impact of heat production on the unstable MHD natural convection transport of nanofluid flow via a perforated sheet. The ordinary differential equations (ODEs) are derived from the partial differential equations (PDEs) by using of the similarity transformation. The dimensionless ordinary differential equations (ODEs) may be numerically resolved with the help of the MATLAB ODE45 tool and the finite difference method (FDM) along with the shooting strategy. Four innovative water-based nanofluids such as TiO2, Cu, Al2O3, and Ag are considered nanoparticles. The numerical results have been explained for the role of numerous non-dimensional numbers or parameters such as heat generation or absorption (Q), nanoparticle volume fraction (φ), Dufour number (Df), Prandtl number (Pr), magnetic force parameter (M), Soret number (Sr), and Schmidt number (Sc) on the fluid flow, and heat and mass transfer rates. The fluid temperature drops but velocity is enhanced for higher amounts of Q. Copper nanoparticle volume fraction up to 4 % shows a rise in temperature, concentration, and velocity curves. Heat transfer rate ( − θ′(0)) diminishes by about 124 %, while the values of f′(0) promote by approximately 26 % owing to an increase in the values of Q (heat generation) from 1.0 to 2.0. The value of ( − θ′(0)) increases by 49 %, but f′0 decreases by 15 % due to a rise in Q (heat absorption) from -3.0 to -10.0. The local skin friction coefficient (f′(0)) diminishes by about 65.21 % due to an increase in the values of the magnetic force parameter (M) from 0.5 to 3.5 whereas the rate of heat and mass transfer remain unchanged. As φ increased from 0.01 to 0.04, the local skin friction coefficient (f′(0)) exhibited a 36 % increase, while the heat transport rate (θ′(0)) decreased around by 10 %. In conclusion, a comparison was made between our findings and those of the published research. The comparison indicates a high degree of consistency.

Theoretical estimation of the thermal damages of living tissues caused by laser irradiation in tumor thermal therapy

This article aims to provide theoretical predictions for the thermal reactions of human tissues during tumor thermotherapy when exposed to laser irradiation and an external heat source. For the construction of a theoretical study of bioheat transfer, the selection of a suitable thermal model capable of accurately predicting the required thermal responses is essential. The effect of heat production by heat treatment on a spherical multilayer tumor tissue is evaluated using this approach. Analytical solution for the non-homogenous differential equations is derived in the Laplace domain. The study examines the impact of thermal relaxation time on tissue temperature and the subsequent thermal damage. The numerical findings of thermal damage and temperatures are depicted in a graphical representation. This model explains laser treatment, physical events, metabolic support, and blood perfusion. The numerical outcomes of the recommended model are validated by comparing them to the literatures.

The significance of exponential space-based heat generation and variable thermophysical properties on the dynamics of Casson fluid over a stratified surface with non-uniform thickness

Stratification is characterized as having applications in a variety of energy storage disciplines, including solar thermal energy usage systems. The effect of heat production, magnetic field, and varied fluid characteristics on the flow of Casson fluid across unstratified and stably stratified paraboloid of revolution is investigated in this work. The velocity index is suitable to describe the fluid flow on an upper horizontal surface of a paraboloid of revolution. It is imperative to mention that the upper horizontal surface of a paraboloid of revolution is likened to the pointed surface of an aircraft which is also described as a surface with variable thickness. The governing partial differential equations are transformed into the nonlinear ordinary differential equations using the similarity transformation. The dimensionless nonlinear ordinary differential equations are solved with the help of the Bvp4c numerical algorithm. The effects of relevant parameters are revealed on various profiles and discussed. It is observed that both the temperature and concentration distributions decrease with increase in thermal stratification and solutal stratification parameters when the velocity index parameter

Entropy Generation and Thermal Analysis on MHD Second-Grade Fluid with Variable Thermophysical Properties over a Stratified Permeable Surface of Paraboloid Revolution

Stratification is used in a wide range of energy storage fields, including solar thermal energy systems. This paper investigates entropy optimization and the effects of heat production, magnetic field, and various fluid parameters on the flow of second-grade fluid through unstratified and stably stratified paraboloids of revolution. In the heat transfer equation, stratification, linear thermal radiation, and Joule dissipation have all been explored. The similarity transformation is used to convert the governing PDEs into nonlinear ODEs. The HAM (homotopy analysis method) is used to solve dimensionless nonlinear ODEs. The impact of significant elements on various profiles is exposed and explored. Graphical results are used to examine the influence of the velocity profile, temperature, concentration, and entropy formation rate using tables to indicate the characteristics of skin friction, Nusselt number, and Sherwood number for numerous parameters. It is noticed that the velocity is enhanced by raising the stratification parameter, while the opposite behavior is observed for temperature distribution. The concentration profile declined as the solute stratification parameter was enhanced. For both the unstratified and stratified regions, incremental values of the Brinkman number and magnetic parameter depict augmentation in entropy production, while entropy production drops for a large value of the temperature ratio parameter.

Analytical Simulation of Heat and Mass Transmission in Casson Fluid Flow across a Stretching Surface

This research presents a review of an analytical simulation of heat and mass transmission features of steady, non-Newtonian Casson fluid motion across a permeable medium through a stretching surface. The effects of heat production and thermal emission are put into discussion. Mathematically, the governing model is manipulated by a series of nonlinear partial equations, which are then modified into ordinary differential equations with the assistance of appropriate conversion. Analytical results for such equations are then achieved by invoking the notable technique of the homotopy analysis method (HAM), and its solution sounds good while achieving the convergence guaranteed in the convergence table. Some achievements have been made. The consequence of raising the value of the Casson parameter is comprehended to be putting down the velocity field while increasing the temperature field. Also, the concentration field falls with an increase in the Schmidt number, while it rises with an enhancement in the Soret number. The electric parameter due to Lorentz’s force is capable of accelerating the temperature of the fluid but downsizing the velocity.

生物质发酵产热-小型温室棚联用对春冬季烟苗生长温度调控的数值研究

PDF HTML阅读 XML下载 导出引用 引用提醒 生物质发酵产热-小型温室棚联用对春冬季烟苗生长温度调控的数值研究 DOI: 10.5846/stxb202106211652 作者: 作者单位: 作者简介: 通讯作者: 中图分类号: 基金项目: 中国烟草总公司重庆市公司科技项目（NY20190401070012） Numerical study on temperature control of tobacco seedlings in spring and winter using a biomass fermentation heat production-small greenhouse combination Author: Affiliation: Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:小型温室棚作为农业生产的重要设施，可为农作物创造一个温度适宜的、受保护的生长空间，保证作物正常生长、促进作物早熟。以确保重庆地区春冬季烟苗正常发育、维持温室内适宜的土壤温度为导向，对温室棚内温度进行了试验和数值模拟，探究了温室棚内温度分布规律，并在此基础上分析生物质发酵产热对温室棚内土壤温度场的影响。结果表明：试验中埋设稻壳的温室棚内土壤温度平均提高3.5℃且温室棚中平均温度低于10℃的天数明显减少。埋设稻壳的温室棚中烟苗茎高和叶片数增长值最大，平均茎高从移栽时的7.8 cm增长到了12 cm，叶片数从平均5片增长到了11片，均大于未埋设稻壳试验组，这表明土壤中埋设稻壳有助于烟草的生长发育。数值研究表明温室棚内不同深度的土壤层温度变化状况一致，均呈现先降低后升高再降低的趋势。地温随土壤深度的增加而降低，地表下10 cm、20 cm的土壤层区域温度高于10.6℃、8℃，有利于烟苗在低温环境下正常生长。且土壤温度存在一定的昼夜温差，更利于烟苗发育。埋设稻壳的温室土壤层温度变化趋势与未埋设稻壳的温室一致，但其土壤层平均温度、最低温度至最高温度以及昼夜温差分别升高了2.3℃、1.1-5.5℃、4.8℃。试验和数值研究结果表明稻壳发酵产生的热量可以提高和维持温室内土壤温度，对土壤具有保温和热量补给的作用。 Abstract:As an important facility for agricultural production, small greenhouses can create a protected growing space with suitable temperatures for crops to ensure normal growth and promote early crop maturity. In this study, the aim is to ensure the normal development of tobacco seedlings in spring and winter in Chongqing and to maintain a suitable soil temperature in the greenhouse. Experiments and numerical simulations of greenhouse shed temperatures were carried out to investigate the temperature distribution pattern inside the greenhouse. On this basis, the effect of heat production from biomass fermentation on the soil temperature field in the greenhouse was also analyzed. The results showed that the soil temperature in the greenhouses with buried rice hulls increased by an average of 3.5℃ and the number of days when the average temperature in the greenhouses below 10℃ was significantly reduced. The largest increases in stem height and leaf number of tobacco seedlings were observed in the greenhouses with rice hulls. The average stem height increased from 7.8 cm at transplanting to 12 cm and the average number of leaves increased from 5 to 11, both of which were greater than in the experimental group without rice hulls. This indicates that the burial of rice hulls in the soil was beneficial to the growth and development of tobacco seedlings. The numerical study showed that the temperature of the soil layers at different depths in the greenhouse shed varied consistently, all showing a trend of decreasing, then increasing, and finally decreasing. The ground temperature decreased with the increasing soil depth. The temperature of the soil layer 10 cm and 20 cm below the surface was higher than 10.6℃ and 8℃, which was conducive to the growth of tobacco seedlings. And there existed a certain diurnal temperature difference in soil temperature, which was more beneficial to the development of tobacco seedlings in low temperature environment. The trend of soil temperature in the greenhouse with buried rice hulls was same as that in the greenhouse without buried rice hulls, but the average temperature, the minimum to the maximum temperature, and diurnal temperature differences in the soil layer increased by 2.3℃, 1.1-5.5℃, and 4.8℃, respectively. The results of experimental and numerical studies showed that the heat generated by the fermentation of rice hulls could raise and maintain the soil temperature in the greenhouse, providing insulation and heat recharge to the soil. 参考文献 相似文献 引证文献

Influence of the cluster formation in a magnetic particle suspension on heat production effect in an alternating magnetic field

In the present study, we concentrate on the results of the unexpected characteristic that the stable particle cluster formation induces a decrease in the degree of heating effect in an alternating magnetic field, by means of Brownian dynamics simulations. If chain-like clusters are stably formed in the system, whether or not a large heating effect is obtained is dependent on the magnitude relationship between the magnetic particle-particle and the magnetic particle-field interaction strengths. As the magnetic particle-particle interaction strength increases and becomes more dominant than the influence of the magnetic field, the magnetic moments of stable chain-like clusters do not have a sufficient tendency to inline in the field direction. This leads to a smaller area of the hysteresis loop, and therefore the stable cluster formation induces a significant decrease in the heating effect.

Preparation and characterization of nano composite bacterialmagnetosomes/pHSP-short hairpin RNA of Polo like protein kinase 1/doxorubicin mediated by magnetosomes

Objective The short hairpin RNA (shRNA) of Polo like protein kinase 1 (shPLK1) and chemotherapy drugs doxorubicin (DOX) were coupled to the carrierbacterialmagnetosomes (BMs). Prepare the novel nano composite bacterialmagnetosomes/pHSP-shPLK1/doxorubicin (BMs/pHSP-shPLK1/DOX) and its characterization were detected. Methods Optimization of culture conditions for the AMB-1 by changing composition of culture medium, Separation and purification of magnetosomes. The morphological characteristics of the magnetosomes were observed under transmission electron microscope (TEM). The recombinant plasmid pHSP-shPLK1 and DOX were coupled to the magnetosomes to construct the complex by using polyethylenimine (PEI). The particle size and the charge of the compositesweredetected. The effect of heat production and the release rate of DOX under the condition of alternating magnetic field were observed, the expression of green fluorescent protein (GFP) in osteosarcoma U2OS cells was detected by immunofluorescence assay after treatment of the complex. Results The optimal culture condition of AMB-1 are 20 μmol/L of ferrous sulfate, 800 mg/L of sodium nitrate, and 200 mg/L of succinic acid. Transmission electron microscopy showed that the magnetosomes were of uniform size and good dispersion. The diameters and the zeta potentials ofof BMs/pHSP-shPLK1/DOX were (129.5±9.7) nm and (-11.7±2.9) mV. Under an alternating magnetic field, the complex can be heated up to 42 ℃ in the 3 min, and the magnetic field strength can be maintained 30 min. Under these conditions, In 24 h and 48 h, the content of DOX in supernatant of 50% fatal bovine serun (FBS) group was significantly higher than that of group PBS (t24 h=6.887, P24 h=0.020; t48 h=17.145, P48 h=0.000), in 48 h the release rate of DOX could reach 54%, and the GFP protein expression was obviously expressed in the cells treated with the complex. Conclusion The compound BMs/pHSP-shPLK1/DOX mediated by the magnetosomes is successfully prepared and is expected to become a new type of nano drug for osteosarcoma treatment. Key words: Magnetosomes; Osteosarcoma; Alternating magnetic field

Heart rate variability during exertional heat stress: effects of heat production and treatment

We assessed the efficacy of different treatments (i.e., treatment with ice water immersion vs. natural recovery) and the effect of exercise intensities (i.e., low vs. high) for restoring heart rate variability (HRV) indices during recovery from exertional heat stress (EHS). Nine healthy adults (26 ± 3 years, 174.2 ± 3.8 cm, 74.6 ± 4.3 kg, 17.9 ± 2.8 % body fat, 57 ± 2 mL·kg·(-1) min(-1) peak oxygen uptake) completed four EHS sessions incorporating either walking (4.0-4.5 km·h(-1), 2 % incline) or jogging (~7.0 km·h(-1), 2 % incline) on a treadmill in a hot-dry environment (40 °C, 20-30 % relative humidity) while wearing a non-permeable rain poncho for a slow or fast rate of rectal temperature (T re) increase, respectively. Upon reaching a T re of 39.5 °C, participants recovered until T re returned to 38 °C either passively or with whole-body immersion in 2 °C water. A comprehensive panel of 93 HRV measures were computed from the time, frequency, time-frequency, scale-invariant, entropy and non-linear domains. Exertional heat stress significantly affected 60/93 HRV measures analysed. Analyses during recovery demonstrated that there were no significant differences between HRV measures that had been influenced by EHS at the end of passive recovery vs. whole-body cooling treatment (p > 0.05). Nevertheless, the cooling treatment required statistically significantly less time to reduce T re (p < 0.001). While EHS has a marked effect on autonomic nervous system modulation and whole-body immersion in 2 °C water results in faster cooling, there were no observed differences in restoration of autonomic heart rate modulation as measured by HRV indices with whole-body cold-water immersion compared to passive recovery in thermoneutral conditions.

A Thermogravimetric Study of the Behaviour of Biomass Blends During Combustion

The ignition and combustion behavior of biomass and biomass blends under typical heating conditions were investigated. Thermogravimetric analyses were performed on stalk and woody biomass, alone and blended with various additive weight ratios. The combustion process was enhanced by adding oxygen to the primary air. This led to shorter devolatilization/pyrolysis and char burnout stages, which both took place at lower temperatures than in air alone. The results of the ignition study of stalk biomass show a decrease in ignition temperature as the particle size decreases. This indicates homogeneous ignition, where the volatiles burn in the gas phase, preventing oxygen from reaching the particle surface.The behavior of biomass fuels in the burning process was analyzed, and the effects of heat production and additive type were investigated. Mixing with additives is a method for modifying biofuel and obtaining a more continuous heat release process. Differential scanning calorimetric-thermogravimetric (DSC-TGA) analysis revealed that when the additive is added to biomass, the volatilization rate is modified, the heat release is affected, and the combustion residue is reduced at the same final combustion temperature.

Poster Board Number: 13: Examination of the Effects of Heat Production in Bone Caused by Dental Implant Drills With Different Surface Characteristics

Poster Board Number: 13: Examination of the Effects of Heat Production in Bone Caused by Dental Implant Drills With Different Surface Characteristics

SE—Structures and Environment: An Advanced Experimental Composting Reactor for Systematic Simulation Studies

An advanced experimental composting reactor was constructed for systematic simulation studies of the effects of oxygen levels and temperature on carbon and nitrogen turnover in the composting process. The reactor was thermally insulated and equipped with a fan to mix the compost gases in order to eliminate possible gradients in temperature and gas composition. It was also equipped for independent control of oxygen level and temperature in the compost matrix. The control of oxygen content in the compost gas was such that 95% of the readings of the oxygen level were in the interval 16·01±0·26% during an initial experiment. In the same experiment, 95% of the temperature readings were in the interval 54·6±0·5°C. The volume of the reactor was approximately 200 l to allow for taking samples for analysis during prolonged experiments. The system was equipped for continuous monitoring of gas flow and emissions of the gases CO2, NH3and N2O from the reactor. The water content in the compost matrix was controlled by adding water and mixing the material once a day to compensate for moisture losses due to drying as an effect of heat production and aeration. The regulation of water content was less precise than regulation of temperature and oxygen content and the average water content in the reactor varied within the interval 57·5–70·5%. It was concluded that the performance of the reactor was satisfactory for future systematic experiments.

Effects of heat production on the temperature pattern and stresses on frictional hardening of cylindrical components

Effects of heat production on the temperature pattern and stresses on frictional hardening of cylindrical components

Thermogenic, thermolytic and body temperature effects of fenfluramine, a 5-hydroxytryptamine agonist, in the domestic fowl ( Gallus domesticus)

1. 1. Intramuscular injection of the 5-HT agonist dl-fenfluramine increased the metabolic rate of mature cockerels by about 25% over the following 22 hr. The acute effect, over the 3 hr following injection, attained 40% at 10°C, 35% at 20°C and 25% at 32°C. 2. 2. Heat loss mechanisms (peripheral vasodilatation, postural change and panting) were also stimulated, to an extent which varied with ambient temperature. 3. 3. Food intake, respiratory quotient and locomotor activity were significantly reduced by fenfluramine injection. 4. 4. The opposing effects on heat production and heat loss had an influence on deep-body temperature which varied from a reduction of 0.5°C at 10°C ambient to an increase of about 0.5°C at 32°C. 5. 5. The 5-HT blocker, methysergide, prevented the effects of fenfluramine on both heat production and heat loss for about 5 hr after injection. 6. 6. The autonomic ganglion blocker, hexamethonium chloride, reduced the thermogenic but not the heat-loss effects of fenfluramine. 7. 7. The results suggest that dl-fenfluramine has centrally-occurring but independent effects on heat production and a number of heat loss effectors, and that the heat production effect is mediated by the autonomic nervous system. The effect of fenfluramine on deep-body temperature appears to result from an altered equilibrium between heat production and heat loss.