Minimum Temperature Difference Research Articles

Analyses of Vineyard Microclimate in the Eastern Foothills of the Helan Mountains in Ningxia Region, China

Vineyard microclimate is a main determining factor for grape yield and quality. In the Eastern Foothills of the Helan Mountains in the Ningxia region, China, grape is a critical economic crop for wine making. The microclimate of vineyards in 2019 and 2020 was analyzed on the basis of observations from eight vineyards microclimate stations and a national reference station. The vineyard microclimate was compared with the larger-scale local weather conditions, and the vineyard microclimate was compared within and among different climatic zones. In addition, the climate was evaluated at the four study wine grape areas. The results showed that: (1) In the same wine-grape-growing area where the climate was similar, vineyard microclimate was affected by elevation, topography, and soil texture. (2) Excepting average wind velocity, there were no statistically significant (p < 0.05) differences in minimum and maximum air temperatures or relative humidity between the study field microclimate observation stations and the local national reference station. (3) Among the four climate-zone-based wine-grape-growing areas, vineyard microclimate was related to topography, geographical location, and soil type. In particular, the Yinchuan and Qingtongxia areas had an abundant heat resource, and the Hongsipu area had sufficient precipitation and high photosynthetically active radiation (PAR). By contrast, the Shizuishan area had a relatively low-to-moderate amount of heat, precipitation, and radiation resources for grape. (4) According to the climate assessment of agricultural products—wine grape (QX/T 557—2020), the climate was superior in 2019 than in 2020 for wine grapes. In particular, the climate for grape was better in the Yinchuan area than in other study areas. The results of this study are evidence-based and could be used to assist the local wine grape community in making decisions about cultivars, management practices, area expansions, marketing strategies, etc.

Influence of weather conditions on the development and productivity of the bee colonies

The findings showed that weather conditions have a decisive influence on the intensity of bee colonies development and the yield of marketable honey. The study was conducted in the apiary located in the Kaluga region. Ecological conditions in the productive summer zone of bees are assessed as favorable. All bee colonies in the apiary were representatives of the Carpathian breed recommended for breeding in the Kaluga region. The data obtained for two adjacent seasons (2021 and 2022) indicate that the honey harvest conditions of 2022 were much more favorable compared to the previous year in terms of temperature and precipitation. Despite a significant difference in minimum and maximum temperatures during the day, there were no sharp temperature fluctuations during the spring-summer period of 2022, precipitation was frequent, but short-lived. On average, there were only 2 days of precipitation between March and August 2021. During the honey harvest period, there was prolonged dry weather, which had a negative impact on nectar production by plants, the development of bee families, and their productivity. Bee colonies developed more intensively in the spring of 2022; one month after the spring inspection, bee family strength averaged 9.27 beeways, an increase of 0.57 beeways over the previous year. At the end of the season, the total number of the apiary’s bee colonies increased by 11.7 %. The yield of marketable honey for the 2022 season reached 990 kg, which is 2.3 times higher than in 2021. There was 2.2 times more marketable honey received per bee family. The value of marketable products of the apiary increased by 2.35 times.

Constructal optimization of a rectangular non-uniform heat generation area with irregular high thermal conductivity material

Heat conduction models with three non-uniform heat generation conditions in a rectangular heat generation area (RHGA) are set up in this paper. Under given areas of the irregular high thermal conductivity material (HTCM) and RHGA, constructal optimization of the RHGA is conducted by changing the distribution of the HTCM and aspect ratio of the RHGA. The minimum dimensionless average temperature difference (DATD) of the RHGA is gained. It is found that the DATDs of the RHGA with linear heat generation distribution are abated by 82.43% and 82.65% after twice optimizations for boundary and central heat sinks, respectively. For the heat generation in one local area of the RHGA, the two decrements are 36.30% and 52.20%, respectively. For the heat generation in multiple local areas of the RHGA, the two decrements are 35.60% and 71.60%, respectively. The optimal structure of the RHGA with heat generation in multiple local areas and heat sink in the center exhibits the best cooling performance compared with the other models discussed in this paper. Moreover, the best cooling performance of the RHGA is at least augmented by 29.49% than those of the previous studies discussed in this paper.

Thermal Performance and Parametrical Analysis of Topologically-optimized Cross-flow Heat Sinks Integrated with Impact Jet

In this work, two novel cross-flow heat sink structures are firstly designed by means of topological optimization with the objective function which aims to achieve the minimum temperature difference and pressure drop or with the other objective function which aims to get the minimum mean temperature and pressure drop, namely, TOS1 and TOS2. By analyzing the effect of six channel heights Hch of TOS1 and TOS2 with the evaluation criterion j/f, we obtain that TOS2 with the Hch of 5 mm has the best ability of heat dissipation. A impact jet part is then implemented into the TOS2 to form a new integrated heat sink, that is, ITOS. Numerical results show that the ITOS exhibits much better thermal performance than TOS2 and TOS1. The in-depth parametric study on the flow and thermal behaviors of the ITOS shows that the average temperature of the bottom surface of the ITOS increases with the height of the channel of the bottom plate, while the temperature difference peaks at the Hch of 2 mm. The increase of the ratio of cross-flow fluid to total fluid leads to a reduction of the heat dissipation ability, implying that the high thermal performance of the impinging jet plays an important role in the heat transfer process of such ITOS. Finally, the convective heat transfer experiment of the ITOS with the Hch of 5 mm is conducted to testify the optimization and simulation results.

Investigation of thermal effect of floor coverings made of nano metal oxide on wastewater temperature and solar pond performance

In this research, the exit treated wastewater from the gravity filtration unit, mechanical and chemical treatment unit, biological treatment unit and finally UV disinfection treatment unit enters to a solar desalination unit. Wastewater evaporation process is performed in this unit. In this study, in order to increase the UV waves in solar energy, nano-flooring has been used on the floor of the solar pond. The laboratory results show that the average difference between the experimental data and the theoretical results for simple coating, coating made of zinc oxide nanoparticles and coating made of aluminum oxide nanoparticles is equal to 2%, 2.3% and 1.6%, respectively. Laboratory results show that the average temperature difference between theory and laboratory when simple coating, nano zinc oxide coating and nano aluminum oxide coating are used are 0.5%, 2.89% and 0.67%, respectively. The laboratory results show that the minimum and maximum average temperature of different layers of wastewater are related to the months of January and July, respectively. This research shows that the maximum and minimum temperature difference of the first layer and the last layer of wastewater are in April and March, respectively.

Experimental investigation of the thermal performance of high-temperature flat heat pipe with a single heat source and a multi heat source

This study proposed a sodium high-temperature flat heat pipe (HTFHP) and conducted a series experimental research. The experiment compared the impact of different heating power and heat source arrangement on the startup performance and temperature distribution of the HTFHP. The experimental conditions involved varying heating power and different heat source layouts, including the use of either one or two heat sources. Results indicate that the HTFHP could start stably when the input power was 450-600 W. The single heat source started the fastest at an input power of 600W, with a startup time of 893 s. The multiple heat source started the fastest, with a start time of 533 s, when both sides had an input power of 600 W. The startup time shortened as the input power increased. At high input power, the temperature distribution of the HTFHP was more uniform at different positions, and the minimum temperature difference between the evaporating section and the condensing section was 31℃. In multiple heat source condition, the temperature at the evaporating section fluctuated slightly except at the heat source points. The findings indicated that HTFHP has good startup performance, can quickly dissipate heat, and has great potential for application.

Thermal layout optimization for 3D stacked multichip modules

To satisfy the industry’s demand for high storage density in devices of the same size, the multichip stacking packaging technology has emerged. However, 3D stacked multichip modules (MCMs) can lead to higher power and heat flow density, highlighting thermal issues in the packaging structure. This paper utilizes a high-order finite element method (FEM) for efficient simulation of integrated circuits’ thermal problems. Additionally, we propose a particle swarm optimization (PSO) scheme based on dynamic strategies to overcome traditional optimization algorithm limitations, including slow convergence and difficulties in obtaining global optimal solutions. We conducted thermal design optimization on the multichip stacking structure under convection boundary conditions to achieve optimal thermal performance. The proposed multichip stacking collaborative optimization scheme has fast convergence speed, and the optimized multichip layout exhibits minimal temperature differences and balanced heat distribution.

A novel flat heat pipe for anti-gravity orientations: Leaf fractal evaporator and bi-directional transport capillary channel

Flat heat pipes (FHPs) could be an innovative solution for thermal management in aerospace applications; without the aid of gravity, FHPs could still transport high density energy fluxes with superior temperature control and almost zero energy consumption. Inspired by the powerful transpiration and liquid transport ability of leaf vein structure of plants, a novel FHP design with bionic grading evaporator structured surface was proposed. In addition, a bi-directional transport capillary structure was built inside this FHP, reducing the vapor–liquid flow path and enhancing condensed liquid return simultaneously, and thereafter promoting phase change intensity of FHPs. In the present research, heat transfer performance of FHP with self-wetting fluid as a coolant has been experimentally investigated under anti-gravity, concerning on heat inputs, filling ratios, diameter ratios, porosities of hybrid capillary wick, and two representative tree-like evaporator plate structures (H type and Y type). Our experimental results indicated that heat transfer capability of FHP showed a minimal temperature difference, which was suitable for multi-gravity working conditions. Interestingly, minimal thermal resistance value of 0.45 ℃/W and average enhancement ratio in heat transfer coefficient of 56.39% were achieved simultaneously at anti-gravity orientations for a novel FHP with the 70 PPI and αMF = 0.2 of hybrid capillary wick. Superior vapor flow and diffusion and permeability capability of FHP were further obtained as filling ratio of 30%. Moreover, due to the Marangoni effect, the addition of SRWFs could reduce the axial and radial thermal resistance of the FHP by 5–7 % under anti-gravity condition. Compared with traditional heat sink, the novelty of this passive heat transfer application was capable for realizing high heat transport performance for aerospace flights and applications.

Body temperature and infection in critically ill patients on continuous kidney replacement therapy

PurposeContinuous kidney replacement therapy (CKRT) is an increasingly common intervention for critically ill patients with kidney failure. Because CKRT affects body temperature, detecting infections in patients on CKRT is challenging. Understanding the relation between CKRT and body temperature may facilitate earlier detection of infection.MethodsWe retrospectively reviewed adult patients (≥ 18 years) admitted to the intensive care unit at Mayo Clinic in Rochester, Minnesota, from December 1, 2006, through November 31, 2015, who required CKRT. We summarized central body temperatures for these patients according to the presence or absence of infection.ResultsWe identified 587 patients who underwent CKRT during the study period, of whom 365 had infections, and 222 did not have infections. We observed no statistically significant differences in minimum (P = .70), maximum (P = .22), or mean (P = .55) central body temperature for patients on CKRT with infection vs. those without infection. While not on CKRT (before CKRT initiation and after cessation), all three body temperature measurements were significantly higher in patients with infection than in those without infection (all P < .02).ConclusionBody temperature is insufficient to indicate an infection in critically ill patients on CKRT. Clinicians should remain watchful for other signs, symptoms, and indications of infection in patients on CKRT because of expected high infection rates.

Can body temperature be a tool to detect ovulation in the mare?

Body temperature variations occur around ovulation in bovine (Suthar et al. 2011; Sakatani et al. 2016) and ovine (Barros de Freitas et al. 2018). Previous studies in the mare were unable to determine such a relationship (Ammons et al. 1989; Hasson and Rahawy 2022). Nevertheless, in another study, a decrease of body temperature within 6 hours after ovulation was highlighted (Bowman et al. 2007). Authors, however, performed a temperature monitoring only at fixed hours. The present work uses identification chips equipped with a temperature sensor (BioThermo™, Antelliq) implanted in the mare neckline to be able to follow temperature variations across 24 hours. Seven mares were monitored around ovulation (2.4±0.9 days before and 3.6±1.7 days after), two of whom were followed across two consecutive ovulations. Phases of the reproductive cycle were determined using daily transrectal ultrasonography. Briefly, three phases were identified: follicular phase (F) when identifying a dominant follicle with a diameter >30mm and uterine edema score at least “+” (scoring from “-“ to “+++”); ovulation day (Ov) being the first day (from 0:00 to 23:59) of corpus luteum appearance; luteal phase (CL) from the day after ovulation with a presence of corpus luteum. Body temperature was measured using a device produced for research-purposes only (Ikalogic, France) able to record temperature automatically every 10 minutes. A total of 4,780 temperature recordings (F n=2,410;Ov n=965; CL n=1,405) were obtained from the 9 studied ovulations and mean body temperature per half an hour was calculated for each mare in order to simplify the statistical analysis. To study temperature variations, paired comparisons between phases were performed (Ov vs F; Ov vs CL; F vs CL) using the temperature differences at each time set. Thus, using a linear mixed model (LMM) temperature differences were compared to zero. Individuals were set as random effect while time set was a fixed effect. Significant higher temperatures in the Ov phase compared to the F phase were identified between 4:30 and 8:00 with a minimum difference of 0.51±0.26°C and a maximum of 0.92±0.26°C. Moreover, temperatures were significantly lower during Ov phase compared to CL phase at specific time sets (from 10:30 to 16:00; 18:30 and from 20:00 to 21:00) with a minimum temperature difference of 0.29±0.17°C and a maximum difference of 0.60±0.16°C. These results are more time specific than in other farm species, probably due to the longer estrus duration in horses. In conclusion, temperature variations do occur around ovulation. A more complete study, however, studying temperature along the whole reproductive cycle is needed to better understand the underlying physiological processes.

Design &amp; Thermal Analysis of Heat Pipes

Abstract: Heat pipes are a unique type of heat transfer device that can transport large amounts of heat through a small crosssectional area, with minimal temperature differences. They offer high thermal conductance and low thermal impedance. In this study, we analyzed the impact of operating parameters on heat pipe performance and predicted optimal values for parameters such as temperature input, thermal expansion coefficient, and thermal conductivity. Our results demonstrate that these parameters have a significant impact on the performance of heat pipes. The material used here for the analysis is Copper alloy. The parameters were calculated and have done its Thermal analysis using ANSYS software

Thermal and hydrodynamic characteristics of single-phase flow in manifold microchannels with countercurrent regions

Manifold microchannel heat sink is promising to dissipate high heat fluxes for electronic devices due to its high surface to volume ratio. Traditional Z-type manifold encounters fluid flow maldistribution and a high temperature difference. In this work, two inlets and countercurrent flows are introduced into the manifold arrangement to alleviate these problems in the Z-type manifold microchannels. Six cases with different manifold arrangements are numerically investigated using single-phase HFE-7100 at mass flow rates ranging from 56.8 to 117.78 mg/s. The results show that the maximum temperature, average temperature, and temperature difference of the revised arrangements are all lower than these of the traditional Z-type manifold arrangement. The minimum temperature difference for an ideal multi inlet manifold arrangement can be less than 0.2 K, while the value is about 5.3 K for the traditional Z-type manifold arrangement. The revised arrangement can also improve the uniformity of mass flux distributions. The ratio of the maximum to the minimum mass flux within microchannels is 12.83 for the traditional Z-type manifold, while this value is about 5.82 for cases with two inlets and countercurrent zones. A longer flow path and a higher local pressure drop in the revised arrangements results in higher pressure drops than the traditional Z-type manifold microchannels. Compared with the traditional Z-type arrangement, heat transfer coefficients and performance evaluation criterion are higher for the improved cases. The presence of a countercurrent zone can improve the comprehensive performance of the manifold microchannel. New criterion based on the thermal resistance calculated at the maximum temperature is proposed to evaluate the cooling performance of electronics.

Multiscale Deblurred Feature Extraction Network for Automatic Four-Rod Target Detection in MRTD Measuring Process of Thermal Imagers.

The minimum resolvable temperature difference (MRTD) at which a four-rod target can be resolved is a critical parameter used to assess the comprehensive performance of thermal imaging systems, which is important for technological innovation in military and other fields. Recently, there have been some attempts to use an automatic objective approach based on deep learning to take the place of the classical manual subjective MRTD measurement approach, which is strongly affected by the psychological subjective factors of the experimenter and is limited in accuracy and speed. However, the scale variability of four-rod targets and the low pixels of infrared thermal cameras have turned out to be a challenging problem for automatic MRTD measurement. We propose a multiscale deblurred feature extraction network (MDF-Net), a backbone based on a yolov5 neural network, in an attempt to solve the aforementioned problem. We first present a global attention mechanism (GAM) attention module to represent strong images of the four-rod targets. Next, a Rep VGG module is introduced to decrease the blur. Our experiments show that the proposed method achieves the desired effect and state-of-the-art detection results, which innovatively improve the accuracy of four-rod target detection to 82.3% and thus make it possible for the thermal imagers to see further and to respond faster and more accurately.

Experimental investigation on a solar parabolic collector using water-based multi-walled carbon-nanotube with low volume concentrations

A limited experimental work was on multi-walled carbon nanotube (MWCNT)—water nanofluid with surfactant in the solar parabolic collector at low volume concentrations. At high-volume concentrated nanofluid, the pressure drop was more due to an increase in the viscosity of the working fluid and an increase in the nanoparticle cost; hence it is not economical. This report attempted to use Sodium Dodecyl Benzene Sulfonate (SDBS) surfactant in the low-volume concentrated MWCNT-water nanofluid to establish effective heat transfer in solar parabolic collector applications. The stable MWCNT-water nanofluid was prepared at 0.0158, 0.0238, and 0.0317 volume concentrations. The experiments were conducted from 10:00 to 16:00 at 6, 6.5 and 7 L/min flow rates concerning ASHRAE Standards. At the 7 L/min flow rate of the working fluid, having a minimum temperature difference between the working fluid and absorber tube leads to better heat transfer. The increased volume concentration of MWCNT in the water enhances the surface area interaction between water and MWCNT nanoparticles. This results in maximum solar parabolic collector efficiency at 0.0317 vol% with a 7 L/min flow rate and 10–11% higher than the distilled water.

Optimization of LFP Pouch Cell Tab Design for Uniform Temperature Distribution

An increase in the size of large-format Li-ion batteries (LIBs) may lead to nonuniform temperature distribution, which degrades the performance and lifespan of the LIBs. To address this issue, we performed design optimization using a 3D electrochemical-thermal coupled model for 55 Ah LFP/graphite large-format pouch cells. To minimize temperature differences in Normal Tab (NT), Lateral Tab (LT), and Counter Tab (CT) types of LIBs, design optimization was performed on the width, height, and attachment position of each positive and negative Table The upper and lower limits of each design variable were set as constraints without exceeding the sum of the total area of the tabs of the initial NT type. Owing to the optimization of the NT, LT, and CT types, the temperature difference in the optimized CT type was 79.2% less than in the initial NT type. Additionally, the potential difference decreased by 37.1%, minimizing ohmic heat. Aging analysis of 2500 cycles was performed to analyze the improvement in the lifespan due to the uniform temperature distribution. Consequently, the capacity retention rate of the optimized CT type was 6.5% higher than that of the initial NT type. Thus, the temperature distribution and lifespan of LIBs were improved by design optimization.

Color‐Tunable Organic Light‐Emitting Displays for Interactive Multi‐Signal Visualization

AbstractOptoelectronic devices integrated with multiple functions for interactive signal visualization have become increasingly important in the intelligent era. Here, a color‐tunable organic light‐emitting diode (CTOLED) is developed to achieve a user‐interaction intelligent device that enables multicolor visualization of infrared light and temperature distribution via the modulation with a multi‐stimuli responsive silicon (Si) sensor for the first time. The key to the color‐tunable functionality of the CTOLED is an ultrathin exciton‐blocking layer between different emitting layers, which leads to the quantitative correlation of driving current and emitted visible color. As a result, the user can manipulate the silicon/color‐tunable organic light‐emitting diode (Si/CTOLED) device through the infrared pen, and the “writing” spatial information and the infrared intensity can influence the display patterns and colors. Besides, the temperature is sensed by the flexible Si/CTOLED device and is displayed in corresponding different colors, which is promising as a wearable temperature visualization monitor and directly interact with a user. The temperature monitor exhibits ultrasensitivity with a low minimum distinguishable temperature difference of only 65 mK. The Si/CTOLED devices open new possibilities for the development of intelligent devices and have promising multi‐disciplinary applications.

Simulation and redesigning the methanol production cycle using coil-wound liquefied natural gas heat exchangers

The current research uses Aspen Software to find the best way to run the petrochemical methanol complex. This was done by using pinch technology and arranging the heat exchanger network. First, a process flow diagram of the Kaveh industrial plant was used to simulate different plant parts. Then retrofit the plant’s heat exchanger network to minimize capital costs and improve energy efficiency. Plotting the composite curve of the streams, the type, and the quantity of hot and cold utilities came next., and the most economical minimum temperature difference, etc. The best capital cost decreased by around 70%, while the utilities increased by about 50%, and the payback money lasted for 6 months. The methanol cycle was redesigned using coil-wound heat exchangers to improve operational flexibility because of high-temperature streams.The capital costs decreased by around 10%, and utility costs were saved with the liquefied natural gas heat exchangers.

Energy-Saving Analysis of Epichlorohydrin Plant Based on Entransy

To improve energy efficiency and to recover energy, various mathematical models, such as pinch analysis, entropy analysis, exergy analysis, and entransy analysis, have been established to analyze heat transfer networks. In this study, these methods were applied to analyze the energy-saving effect of the epichlorohydrin unit in a certain enterprise. The results showed that when the minimum heat transfer temperature difference (ΔTmin) was 10K, 15K, and 20K, the efficiencies of the second law of thermodynamics calculated by entropy analysis were 88.02%, 93.52%, and 99.49%, respectively. The analytical method calculated an efficiency of 61.01%, 59.28%, and 57.27%, respectively, with public works’ savings of 16.59%, 14.86%, and 12.02%. The pinch analysis method achieved public works’ savings of 22.80%, 21.50%, and 19.35%. The entransy analysis method calculated an entransy transfer efficiency of 42.81%, 42.13%, and 41.00%, respectively, with public works’ savings of 19.41%, 18.01%, and 15.70%. Based on the results, entropy analysis was found to be contrary to the principle of minimum entropy production. Exergy analysis was not able to establish a heat transfer network. The pinch analysis method was not suitable for determining the thermal efficiency of a heat transfer network as the criterion for evaluating energy saving. On the other hand, the entransy analysis method was able to establish a heat transfer network and evaluate the heat utilization of the network by entransy transfer efficiency. Overall, the data analysis was reasonable.

Thermal performance analysis and experimental verification of lithium-ion batteries for electric vehicle applications through optimized inclined mini-channels

Power units (i.e., batteries) of electric vehicles (EVs) generate heat while being charged or discharged, which deteriorates their performance and reliability over time. This paper investigates a comprehensive spectrum of geometric and thermo-fluidic parameters of a liquid coolant flowing through mini-channels. These are embedded in the surface of an EV battery to curtail overheating. Design parameters such as aspect ratio and angular orientation of the mini-channels were varied randomly to investigate several geometric configurations that are scarcely intuitive. The coolant mass flow rate and the fluid inlet temperature were also varied through a large dataset of randomly distributed values. A real-time EV driving cycle was implemented alongside an experimentally validated model to evaluate the battery operation, which evidenced the complex dependence of the battery’s thermal state with different levels of cooling retrofitting. The study also analyzed the parasitic power consumption arising from the pumping and cooling energy demands to drive the coolant system to achieve an optimally designed retrofit for a reliable battery performance. It was found that the mini-channel parameters considerably affect the thermal performance of the battery. However, the optimized case was found to have a minimum temperature difference in the battery and a minimum power requirement. The case with a fluid inlet velocity of 0.13 m/s, a fluid inlet temperature of 312.9 K, an aspect ratio of 1.7, and an inclination angle of 4.9° was found to be the most suitable, leading to a refrigeration power requirement of 0.85 W only. The battery temperature after the end of the driving cycle was maintained at 313 K.

Optimization of Chenzhuang Combined Station through Pinch Analysis

The energy flow relation in the heating and heat exchanging process in a combined station is complicated. The heat exchanging network of Chenzhuang combined station has unreasonable energy utilization. First, pinch analysis for Chenzhuang combined station is performed by selecting pinch temperature differences within a reasonable temperature range. The pinch situation and minimum heating and cooling load are determined through the problem table. Then the energy-saving potential of the heat-exchanging network, which is optimized and retrofitted, is calculated. Finally, according to the results of energy costs and heat exchanger costs, the relationship between minimum pinch temperature difference and costs is plotted, with obtaining the optimal pinch temperature difference. Hereafter, pinch analysis is performed again, and the pinch temperature and energy-saving potential are calculated under the optimal pinch temperature difference. The results show that when the temperature difference of the pinch point is 20°C, the total cost of the corresponding combined station is the lowest, and the energy-saving potential reaches 14.3%.