Decrease In Average Temperature Research Articles

Simultaneous temperature and particle size measurement of burning iron particles using a single color camera

Iron powder is recognized as a promising clean energy carrier and a recyclable metal fuel due to its high energy density and carbon-free nature. Research focusing on single iron particles is essential for understanding the combustion characteristics and mechanisms of iron powder, as well as for designing reliable iron-fuelled combustors. Temperature and particle size, as key parameters of burning iron particles, are typically measured using optical diagnostic methods. However, low-cost simultaneous measurement methods for the temperature and particle size of burning iron particles are scarce. This study introduces a method employing a single RGB camera to simultaneously measure the temperature and particle size of burning iron particles, validated by a heated thermocouple. Particle size is measured by the intensity of Blue channel based on light attenuation approach, and temperature is measured by the intensity ratio of Red/Green channels based on black-body radiation law. Statistical analyses of the temperature and particle size of iron particles at four different heights above the burner were conducted. Along the heights, the average particle size and temperature of the iron particles generally increase, except at a height of 50 mm, where more iron particles entering the cooling phase lead to a slight decrease in average temperature. The conditional probability density functions of temperature and particle size indicate a statistical dependence between the particle size and temperature of iron particles that larger particle sizes typically correspond to higher temperatures. The results confirm that the simultaneous measurement method is a cost-effective, high-accuracy tool for characterizing the combustion behavior of iron particles.

The Impact of the Radius of the Cutting Blade during the Processing of C 60 ± 2 HRC (DIN) Steel

This study investigates the thermal dynamics of the turning process for C60 steel, focusing on the influence of various machining parameters on temperature rise. Integrating experimental methods and statistical analysis, the research examines the effects of cutting speed (v), feed rate (f), depth of cut (a), and cutting insert tip radius (r) on the average temperature in the cutting zone. Experiments were conducted on heat-treated C60 steel rings, using a custom fixture and a modified Kennametal insert holder to ensure precise temperature measurements, collected via a natural thermocouple method. The findings reveal that cutting speed is the most significant factor influencing temperature rise, followed by feed rate, while depth of cut has a minor impact. Notably, the radius of the cutting insert tip is inversely proportional to the temperature, with an increase in the tip radius resulting in a decrease in average temperature. This inverse relationship underscores the potential for optimizing tool design to enhance heat dissipation and reduce thermal stress on the cutting tool. A fourth-degree polynomial model was developed through regression analysis to correlate thermovoltage (V) with temperature (T), providing a quantitative framework for predicting thermal behavior. The model highlights that cutting speed has the greatest effect on temperature rise, with the highest recorded temperature being 795.09°C. Conversely, larger radius of the cutting insert tip corresponds to lower average temperatures, stabilizing around 757.22°C. These insights offer actionable strategies for optimizing machining processes. By strategically adjusting cutting parameters, particularly cutting speed and feed rate, manufacturers can achieve significant improvements in tool life and product quality. The developed mathematical model serves as a predictive tool for fine-tuning machining conditions, ensuring a balance between productivity and tool longevity. This research contributes substantially to the understanding of thermal dynamics in machining processes. It provides a comprehensive analysis and robust modeling of the effects of cutting parameters on temperature rise, supported by rigorous experimental data and statistical validation. The study underscores the importance of considering thermal effects in machining to optimize efficiency, tool life, and product quality, offering valuable insights for both academic research and practical applications in the field of machining and process optimization.

Aerosol effects during heat waves in summer 2022 and responses to emission change over China

This study explores aerosol direct, indirect, and feedback effects on meteorology and fine particulate matter during heat waves of August 2022 over eastern China by using an online coupled regional climate–chemistry–aerosol model. In this period, aerosols exerted mean direct (DRE) and indirect (IRE) radiative effects of −3.9 Wm−2 and −2.4 Wm−2 at TOA, which totally caused a decrease in average surface air temperature by 0.3 °C over east China, accompanied by decreases in PBLH (planetary boundary layer height) and precipitation and an increase in PM2.5 concentration. With the anthropogenic emission reduction from 2013 to 2022, DRE apparently decreased while IRE changed little, leading to a decrease in total aerosol radiative effect (TRE) by 27% at TOA. The weakened TRE resulted in increases in surface air temperature and precipitation by 0.14 °C and 2.7 mm, respectively, on average over east China, with the maximum warming exceeding 0.5 °C in BTH (Beijing–Tianjin–Hebei province). This study highlights a warming trend due to weakened TRE, which may exacerbate heat wave, and an increasing importance of aerosol IRE relative to DRE due to weak sensitivity of cloud properties to aerosol change during the emission reduction.

Adapting Harvests: A Comprehensive Study of Farmers’ Perceptions, Adaptation Strategies, and Climatic Trends in Dera Ghazi Khan, Pakistan

Understanding farmers’ perceptions, attitudes, and adaptation strategies toward climate change is important for developing effective policies that support agricultural development and food security in rural communities. This study aimed to understand climatic trends over the past two decades (2003–2022), farmers’ perceptions, and adaptation strategies regarding climate change in Dera Ghazi Khan, Pakistan. The Mann–Kendall trend test identified a significant decrease in average minimum temperature (τ = −0.357, p < 0.05) and an increase in rainfall patterns (τ = 0.337, p < 0.05). A mixed-method approach is employed, utilizing a survey of 180 randomly selected farmers, focus group discussions, and climate data analysis. Ordinal and binary logistic regression models were used to analyze the influence of sociodemographic factors on farmers’ perceptions of climate change and their choice of adaptation strategies. The results indicate that farmers primarily rely on religious beliefs/prayers (65.6%) to cope with climate change, followed by seeking off-farm jobs (50%) and changing fertilizer use (42.2%). The result of the binary logistic regression indicates that among the different demographic characteristics, education, and land size significantly influence farmers’ decisions in taking adaptation measures against climate change. This study emphasizes the need for climate policies that integrate farmer knowledge with meteorological data and sociodemographic analysis to ensure a sustainable agricultural sector in Pakistan. Further research is necessary to explore more effective adaptation methods.

Numerical study on the synergistic effects of ultrasonic transducers and nano-enhanced phase change material in CPU thermal management

This study numerically investigates the effectiveness of concurrently applying nano-enhanced phase change material (NEPCM) and an ultrasonic field for the thermal management of a pin fin heat sink. The role of the NEPCM is to absorb heat from the heat sink wall, while the ultrasonic field generated by ultrasonic transducers facilitates the accelerated melting of the NEPCM. The study investigated how varying the number of ultrasonic transducers positioned near each side wall of the square cross-section heat sink, along with adjusting the concentration of nanoparticles in the NEPCM, impacts the heat sink's performance. The total power consumption of the transducers is assumed to be constant and an increase in their number is associated with a decrease in the power consumption of each transducer. It was observed that raising the number of transducers and lowering the nanoparticle concentration both contributed to a decrease in the CPU's highest temperature. Additionally, it was found that by using the combination of ultrasonic field and NEPCM, the average temperature of CPU can be reduced by 12.33–15.91 °C to the case without the ultrasonic field. Moreover, raising the number of transducers and lowering the nanoparticle concentration both contributed to a decrease in the CPU's average temperature.

The Response of Ross Sea Shelf Water Properties to Enhanced Amundsen Sea Ice Shelf Melting

AbstractIce shelves in the Amundsen Sea have experienced the most rapid melting in the Antarctic and are expected to accelerate throughout this century under climate warming. In this study, a high‐resolution ocean‐sea ice‐ice shelf model is employed to conduct sensitivity experiments to explore the effects of increasing melt rates of the Amundsen Sea ice shelves on hydrography, sea ice and ice shelf in the Ross Sea. The results indicate that the substantial inflow of meltwater significantly freshens the Ross Sea, inhibiting the formation and export of the Dense Shelf Water, the volume of which is reduced by 19%–33% on the shelf. Temperatures in the eastern and western Ross Sea exhibit different responses to the enhanced meltwater input. The freshening of the western Ross Sea weakens the mesoscale eddy activities which are efficient in carrying warm Circumpolar Deep Water onto the shelf, leading to an average temperature decrease of 0.02–0.08°C. Conversely, in the eastern Ross Sea, there is a marked warming outside the shelf under increased meltwater, which results from zonal pressure gradients associated with the meltwater distributions. This consequently causes stronger on‐shelf heat transport and shows warming of 0.12–0.22°C on the eastern Ross Sea shelf. The narrow shelf in the eastern Ross Sea allows the warmer water to reach the Ross Ice Shelf (RIS) front, resulting in an about 6%–9% increase in the RIS melting. These results suggest a possible mechanism for acceleration in the RIS melting in the future that is associated with enhanced meltwater inflow.

Multiple heating loads participate in the system power regulation control strategy

With the addition of a high proportion of new energy and power electronic equipment, the power system has shown characteristics such as low inertia and significant energy output fluctuation, which has brought great challenges to power/frequency regulation and control of the power system. Therefore, this article uses the inertia characteristics of heat energy on the load side and exerts reasonable start-stop control to play a positive and beneficial role in the power regulation of the power system. Firstly, the room temperature variation process was transformed into a lumped parameter equivalent model. A lumped parameter heat transfer model of a single typical load was built in Simulink, and its dynamic characteristics were analyzed by symbolic calculation. Based on this, a time-domain simulation was carried out to explore the influence of the law of system parameters and external input on the change of system state quantity. Based on time domain simulation, the behavior of the heating load is analyzed. Then, the effects of typical and multiple loads on system power regulation at different outdoor temperatures are studied. It is found that when the average outdoor temperature decreases, the sustainable time of system power upturn will increase, and the sustainable time of downturn will decrease. The power curve of multiple loads simultaneously is more stable, and the adjustment ability is stronger. The reasonable and flexible control method of load switch setting, namely the coherent characteristic load power regulation strategy, realizes the sustainable power optimization of the load to the system in the specified period.

The effects of changes in HITRAN and the water vapor continuum model on infrared radiative transfer calculations and remote sensing applications

This study examines the implications of recent updates to the High Resolution Transmission (HITRAN) database and the MT_CKD water vapor continuum model on infrared radiative transfer calculations and satellite remote sensing applications. Specifically, it assesses the impact of the latest versions of the HITRAN database (i.e. HITRAN2016 and HITRAN2020) and the MT_CKD WV continuum model (i.e. versions 3.2 and 4.1.1) on clear-sky infrared flux calculations and the simulation of satellite infrared channels, specifically those of the Geostationary Operational Environmental Satellite (GOES) Advanced Baseline Imager (ABI). The results indicate that updates to the MT_CKD model tend to reduce atmospheric opacity, while updates to the HITRAN database have the opposite effect. The most significant differences noted are attributed to updates in the MT_CKD, leading to an increase in upward flux of 0.13 Wm−2 for the TRO and a decrease in downward flux of 0.28 Wm−2 for the MLS profile. However, these impacts are not uniform across the spectrum, atmospheric height, or among different atmospheric profiles. Notably, changes in the WV continuum model have significant effects in the far-infrared region. The updates in HITRAN exhibit pronounced differences associated with changes in the spectroscopic parameters of H2O, CO2 and O3. The results of GOES’ ABI channels indicate that changes in HITRAN lead to an average brightness temperature decrease of 0.3 K for channel 12, which exceeds the channel’s sensitivity. This research underscores the importance of continuous updates and evaluations of spectroscopic databases and radiative transfer models to improve the accuracy of atmospheric remote sensing data.

Numerical study on the influence of turbine swirl on exhaust system

This article employed numerical methods to investigate the aerodynamic, thermal, and infrared characteristics of last-stage turbine swirl on a two-dimensional convergent divergent (2D-CD) exhaust system with an afterburner under varying bypass ratios. The research results indicate that the swirl diminishes the thrust coefficient and flow coefficient of the 2D-CD exhaust system with an afterburner. At a bypass ratio of 0.2, the thrust coefficient and flow coefficient decrease by 0.65% and 1.07%, respectively. When the bypass ratio is relatively small, the swirl flow leads to a decrease in the temperature of the afterburner heat shield. Conversely, when the bypass ratio is relatively large, the opposite occurs. The maximum temperature of the heat shield increases by up to 7.2% (bypass ratio = 0.35), while the average temperature decreases by up to 7.1% (bypass ratio = 0.2). The swirl causes an increase in the temperature of the divergent section heat shield, with the most significant deterioration observed at a bypass ratio of 0.25, resulting in a maximum temperature increase in 12.2%. Swirling flow shortens the length of the jet flow, and as the bypass ratio reduces, this attenuation effect becomes more pronounced. When the bypass ratio is 0.2, the length of the core area decreases by 40.3%, and the infrared intensity of the narrow-side jet flow decreases by 12.5%. Overall, on the XOY detection plane, the maximum decrease in infrared intensity is 11.5%, and the maximum increase is 11.7%. On the XOZ detection plane, the maximum decrease in infrared intensity is 15.9%, and the maximum increase is 5.7%.

Last Glacial Maximum climate and atmospheric circulation over the Australian region from climate models

Abstract. The Last Glacial Maximum (LGM; ∼21 kyr ago) was the most recent time that the Earth experienced global maximum ice volume and minimum eustatic sea level. The climate changes over the Australian region at the LGM remain uncertain, including the extent of cooling in the arid interior, changes in the regional atmospheric circulations such as the tropical monsoon and mid-latitude westerlies, and changes in the balance between precipitation and evaporation. In this study, 13 climate model simulations that were included in the Paleoclimate Modelling Intercomparison Project (PMIP) Phases 3 and 4 are used to investigate regional climate (temperature, precipitation, and wind) over Australia at the LGM. The model simulations are compared with existing proxy records and other modelling studies. All models simulate consistent annual and seasonal cooling over the Australian region (defined as 0–45° S, 110–160° E) at the LGM compared to pre-industrial, with a multi-model mean 2.9 °C decrease in annual average surface air temperature over land at the LGM compared to pre-industrial. Models simulate a range of LGM precipitation anomalies over the region. Simulated precipitation changes over tropical Australasia appear to be driven by changes in circulation and moisture transport, which vary greatly between models. Surface moisture balance calculated from precipitation minus evaporation shows little change over much of the Australian land area at the LGM. Changes in the strength and position of the mid-latitude westerlies are uncertain, with wide model disagreement. These results indicate that climate model simulations do not show a robust response in either tropical or mid-latitude circulation to LGM boundary conditions, suggesting that caution is required when interpreting model output in this region. Further analysis based on model evaluation and quantitative model–proxy comparison is required to better understand the drivers of LGM climate and atmospheric circulation changes in this region.

Heating and Evaporation of Sessile Droplets: Simple and Advanced Models.

New advanced and simple two-dimensional (2D) models of sessile droplet heating and cooling and evaporation are suggested. In contrast to the earlier developed one-dimensional (1D) model, based on the assumption that heat supplied from the supporting surface is homogeneously and instantaneously spread throughout the droplet, both new 2D models consider the spatial distribution of this heat. The advanced 2D model is based on the numerical solution to the equations of conservation of mass, momentum, vapor mass fraction, and energy with standard boundary and initial conditions, using COMSOL Multiphysics code. Simple 2D and 1D models assume that droplets retain their truncated spherical shapes during the evaporation process. In the 1D model, the analytical solution to the 1D heat conduction equation inside the droplet is implemented into a numerical code. In the simple 2D model, the 2D version of this equation is solved numerically using COMSOL Multiphysics code. Droplet deformation, temperature gradients along the droplet surface, and the Marangoni effect are not considered in this model. The predictions of all three models are validated using in-house experimental data obtained from studies of sessile droplets of distilled water with initial volumes of 5.2, 3.2, and 2.2 μL, at an ambient temperature of 298.15 K, and at atmospheric pressure. The observed values of normalized droplet radii squared are shown to be close to those predicted by all three models. This allows us to recommend the application of the simplest 1D model for predicting this parameter. The time dependences of the droplet average surface temperature predicted by the advanced 2D model are shown to be close to those observed experimentally. The simple 2D and 1D models can correctly predict the initial rapid decrease in droplet average surface temperature followed by its gradual increase, in agreement with experimental data.

Parametric Optimization and Efficiency Assessment of Horizontal Earth Water Pipe Heat Exchanger (EWPHE) in the Context of Bangladesh

This study aimed to evaluate the efficiency of the Earth Water Pipe Heat Exchanger (EWPHE) system in Bangladesh through simulation and experimental work carried out at Joypurhat in Bangladesh during the coldest period of the year, January. Additionally, the study sought to establish the method for selecting optimal installation parameters of EWPHE to increase performance and efficiency. A simulation model was made in the TRNSYS (v16.0) platform to determine the optimum values of design parameters. The simulation was run by altering its operating parameters, such as the rate of water flow, length of the pipe, built materials of the pipe, and the diameter of the underground pipeline. According to the findings, pipe burial can be done to a depth of 3.5 meters to achieve optimal output. The results of comparing four distinct materials, namely GI, Steel, PVC, and HDPE, show that these materials' characteristics do not significantly affect how well the systems perform. Additionally, as the water flow rate is increased, it is shown that the EWPHE performance is declining. According to the simulation results, it is concluded that a pipe with a length of 50 meters would be sufficient in the proposed EWPHE system to reach an average temperature decrease from 35 °C to 27 °C. Subsequently, in the field experiment, the EWPHE system had an average efficacy of 55% throughout January, which is quite promising. Journal of Engineering Science 14(2), 2023, 79-88

Local variation in brain temperature explains gender-specificity of working memory performance.

Exploring gender differences in cognitive abilities offers vital insights into human brain functioning. Our study utilized advanced techniques like magnetic resonance thermometry, standard working memory n-back tasks, and functional MRI to investigate if gender-based variations in brain temperature correlate with distinct neuronal responses and working memory capabilities. We observed a significant decrease in average brain temperature in males during working memory tasks, a phenomenon not seen in females. Although changes in female brain temperature were significantly lower than in males, we found an inverse relationship between the absolute temperature change (ATC) and cognitive performance, alongside a correlation with blood oxygen level dependent (BOLD) signal change induced by neural activity. This suggests that in females, ATC is a crucial determinant for the link between cognitive performance and BOLD responses, a linkage not evident in males. However, we also observed additional female specific BOLD responses aligned with comparable task performance to that of males. Our results suggest that females compensate for their brain's heightened temperature sensitivity by activating additional neuronal networks to support working memory. This study not only underscores the complexity of gender differences in cognitive processing but also opens new avenues for understanding how temperature fluctuations influence brain functionality.

Standard metabolic rate variation among New Zealand Orthoptera

Standard metabolic rates (SMR) of ectotherms reflect the energetic cost of self-maintenance and thus provide important information about life-history strategies of organisms. We examined variation in SMR among fifteen species of New Zealand orthopteran. These species represent a heterogeneous group with a wide geographic distribution, differing morphologies and life histories. Gathering original data on morphological and physiological traits of individual species is a first step towards understanding existing variability. Individual metabolic rates of ectotherms are one of the first traits to respond to climate change. Baseline SMR datasets are valuable for modeling current species distributions and their responses to a changing climate. At higher latitudes, the average environmental temperature decreases. The pattern that cold-adapted ectotherms display higher SMR at colder temperatures and greater thermal sensitivity to compensate for lower temperatures and the shorter growing and reproductive seasons is predicted from the metabolic cold adaptation (MCA) hypothesis. We predict higher SMR for the orthopteran species found at higher latitudes. We further compared the index of thermal sensitivity Q10 per species. We used closed-system respirometry to measure SMR, at two test temperatures (4 °C and 14 °C), for the fifteen species acclimated to the same conditions. As expected, we found significant differences in SMR among species. The rate of oxygen consumption was positively correlated with body mass. Our findings do not support the MCA hypothesis. In fact, we found evidence of co-gradient variation in SMR, whereby insects from higher elevations and latitudes presented lower SMR. We discuss our findings in relation to life histories and ecology of each species. The novel physiological data presented will aid in understanding potential responses of these unusual species to changing climatic conditions in Aotearoa/New Zealand.

Investigasi Pengaruh Flow terhadap Pembacaan Suhu Air Sensor DS18B20 pada Shower Therapy

The shifting lifestyle trends towards prolonged periods of sitting have led to an increase in health issues such as stress, depression, and even hypertension. In the pursuit of maintaining health, therapy, particularly shower therapy, has become a popular choice for its perceived ability to provide warmth, relaxation, and alleviate fatigue. However, questions arise regarding whether the water temperature in shower therapy changes as water flows at specific rates and how this might influence the therapy's effectiveness. This research aims to observe whether the water temperature in shower therapy is affected by the flow rate using the DS18B20 temperature sensor. The method involves measuring the water temperature at rest and while it flows at various flow rates. Water flow is controlled using a dimmer on the booster pump, while temperature measurements are taken using the DS18B20 temperature sensor and water flow meter sensor. The test results indicate that water at temperatures of 38-43°C flowing through pipes experiences an average temperature decrease of approximately 1.53°C. However, the temperature decrease does not exhibit a linear relationship with the flow rate. These findings suggest the possibility of other factors, such as the surface area of the conduit (pipes), influencing the temperature reduction in shower therapy. Hence, further research to examine the impact of the surface area of the conduit on the temperature reduction in shower therapy is warranted to obtain a more comprehensive understanding.

CFD modeling of flow, combustion and NOx emission in a wall-fired boiler at different low-load operating conditions

In the context of achieving carbon peaking and carbon neutrality, the implementation of flexible peak shaving techniques is of significant importance to coal-fired units. Operating coal-fired units under different low loads can result in decreased combustion efficiency, unstable combustion, and increased emissions of nitrogen oxides (NOx) during the combustion of pulverized coal. However, few studies have been carried out wall-fired boiler under low-load operation in most papers. This paper employs numerical simulation to investigate the flow, temperature, composition concentration fields, as well as combustion stability and NOx emission characteristics of a 600 MWe wall-fired under various low-load (specifically, 400, 300, 240 and 200 MWe) conditions. The simulations demonstrate that reducing the boiler load leads to decreases in the amount of filling gas and the average temperature of the furnace. Despite the overall decrease in average furnace temperature with load reduction, the central part of the furnace can reach 1400 K at low load (200 MWe), due to the strong flame stability of centrally fuel-rich burner. The NOx concentrations for 400, 300, 240, and 200 MWe were 475.9, 498.4, 361.9 and 259.7 mg/Nm3, respectively. The NOx concentration initially increases with the load reduction, and decreases as the load is further reduced. Considering the broad industrial application prospect of flexible peak shaving of coal-fired boilers, these research results provide guidance and suggestions for different load operation of wall-fired boilers, and provide theoretical support for low load stable combustion operation of wall-fired boilers.

Analyzing the effect of normally distributed cooling channels on a photovoltaic thermal solar unit

Photovoltaic thermal (PVT) systems convert solar radiation into electrical and thermal energy while keeping the PV's temperature within a permissible range. This paper presents a numerical analysis of a novel normal cooling technique for the PV module and a new AI prediction model. It considers a cooling direction normal to the PV panel using rectangular cascade channels with two different orientations. This cascading of the flow inlet channels helps keep the inflow temperature as cold as possible along the PV panel. The numerical simulations are performed based on a flow rate range of 0.00024: 0.0012 LPM, insolation of 400: 1200 W/m2, convection coefficients of 5.48 and 20.7 W/m2.K, and ambient temperatures of 298 and 308 K. The proposed PVT system achieves a decrease in the cell's average temperature by 27K while improving the electrical, thermal, and overall efficiencies by 4.8%,59.5%, and 73.33%, respectively. The numerical database is used for building an ANN prediction model based on a radial base function neural network with Gorilla troops optimizer (RBFNN-GTO). The proposed RBFNN-GTO model is developed to predict the main performance parameters of the PVT which are thermal efficiency, electrical efficiency, overall efficiency, average temperature of the PV panel, and the model temperature un-uniformity. It achieves an overall correlation coefficient of 0.9997 concerning the numerical database and showed an average MSE of 5.4313E-4.

The thermal environment and thermal comfort of disaster relief tents in high-temperature composite environment

To ensure the safety and comfort of personnel inside disaster relief tents, this study investigated the distribution of the thermal environment within the tents under composite conditions of high temperature and solar radiation. Furthermore, the interior environmental comfort was evaluated. An experimental platform for tent testing was developed, utilizing a wind tunnel coupled with multiple disaster scenarios and a thermal manikin system. The experiments were conducted under various conditions, including high temperatures and radiation levels of 300 W/m2, 600 W/m2, and 900 W/m2, as well as a wind speed of 1.2 m/s. Two scenarios were considered: doors and windows open or closed. The thermal environmental parameters inside the tent were measured, and the Comfort Prediction Model for Vehicles (CPMV) was employed to assess the thermal comfort of the interior environment. The results indicated a significant temperature rise inside the tent due to the radiation environment, with the maximum top surface temperature reaching 62 °C at 600 W/m2. Notably, a clear temperature stratification was observed among the three horizontal levels inside the tent. Opening the doors and windows resulted in a reduction of temperature below the 1.8 m level. However, when the external radiation intensity exceeded 600 W/m2, the cooling effect was minimal. The temperature stratification phenomenon inside the tent disappeared in the presence of wind, leading to an average temperature decrease of approximately 10 °C. The humidity inside the tent remained lower than the outside humidity. Owing to external irradiation, the black globe temperature inside the tent consistently exceeded the air temperature. The maximum heat flux occurred on the inner side of the tent near the top when the doors and windows were closed, reaching 250 W/m2, while the central heat flux remained relatively stable. When the external radiation during summer was around 300 W/m2, living inside the tent was within an acceptable range. As the radiation exceeded 600 W/m2, the overall thermal sensation became hot, and at 900 W/m2, the interior of the tent became excessively hot and intolerable. In such circumstances, it is recommended to regulate the duration of stay or implement cooling measures to prevent heat stress.

Aircraft engine nozzle guide vane surface temperature optimization

An optimization method based on the sensitivity of global and local geometric parameters is proposed to improve the cooling efficiency of E3 engine nozzle guide vane. For 29 geometric parameters that affect the vane maximum temperature in the cooling design, the sensitivity ranking of them is firstly obtained by the DOE method. Then the most influential parameters including the diameter or location of the film cooling hole are selected as the optimization variables to decrease the maximum surface temperature of the nozzle guide vane. On this basis, to further reduce the local temperature downstream the pressure side, a new duck-paw type film cooling hole is applied. The duck-paw type film cooling hole was produced with the adjoint method through identifying the sensitivity of the geometric boundary parameters of the film cooling holes. Compared to the cylindrical holes, the duck-paw shaped film cooling hole can greatly improve the cooling efficiency under the same conditions. The duck-paw type film cooling holes are applied to the last two rows of film cooling holes located on the pressure side of nozzle guide vane. Three-dimensional conjugate flow and heat transfer analysis results show that the maximum temperature of the optimized cooling structure vane is reduced by 39K, and the average temperature decreases by nearly 20K.

Influence of using nanofluid and phase change material on the performance of a solar thermal panel to provide the required energy of an office building in a mine

This paper examines the effect of using fins installed on tubes placed under a solar panel (SOP) numerically. The SOP is employed to generate electricity and hot water in a mine. The helical fins are mounted around the tubes under the SOP. By changing the cross-section of the fins, unsteady simulations are performed. Besides, OM37 phase change material (PCM) is utilized under the SOP and the tubes are placed inside the PCM. Alumina water nanofluid (NFD) flows inside the tubes, which are analyzed in two phases. The results show that for models M1 and M2 in 1500s, the use of tubes with a DIT of 5 mm under the SOP leads to a decrease in the SOP's average temperature of 8.58 and 8.24° respectively. The use of model M2 results in a lower outlet temperature (T-O) of the NFD when the tube DIT is 3 mm. Model M1 leads to a lower NFD T-O most of the time. Using the designed solar system can provide 56% of the hot water needed in the hot seasons and 18% of the hot water needed in the cold seasons for the building placed inside the mine.