Actual Heat Research Articles

Machine learning-based multi-objective optimization and thermodynamic evaluation of organic Rankine cycle (ORC) system for vehicle engine under road condition

Organic Rankine cycle (ORC) cooperative multi-objective optimization under dynamic driving cycle is the key to obtain the potential of waste heat recovery of internal combustion (IC) engine. The exhaust waste heat energy of IC engine has the characteristics of complex change and strong fluctuation under actual road conditions. The analysis and optimization of the performance of ORC system under single engine operation has some limitations in evaluating the actual waste heat recovery characteristics. Based on Japan10-15 road condition, this paper builds ORC system for vehicle engine model oriented to driving environment. The interaction between operating parameters of ORC system and thermodynamic and thermal economic performance is analyzed. Based on the operating characteristics of the ORC system, the thermal efficiency and power output per unit heat transfer area (POPA) data driven models are established, and the structural parameters of the network are optimized. Based on the multi-objective optimization algorithm, the thermodynamic performance of ORC system under road condition is optimized. The results show that the ORC system has a maximum thermal efficiency of 2.23% and a maximum POPA of 0.55 kW/m2 under Japan10-15 road condition. In this paper, the performance evaluation and multi-objective optimization results of ORC system under road condition can provide a certain reference for the practical application potential of ORC system.

Development and Preliminary Application of Temperature Stress Test Machine for Cast-in-Place Inner Shaft Lining.

Over the past 20 years, as the depth and diameter of shaft lines increased in China, the cracking and water leakage of the inner walls of frozen shafts have become increasingly severe, resulting in significant safety threats and economic losses. Understanding the stress variation patterns of cast-in-place inner walls under the combined effects of temperature and constraint during construction is a prerequisite for evaluating the crack resistance performance of inner walls and preventing water leakage in frozen shafts. The temperature stress testing machine is an important instrument for studying the early-age crack resistance performance of concrete materials under the combined effects of temperature and constraint. However, existing testing machines have shortcomings in terms of applicable specimen cross-sectional shapes, temperature control methods for concrete structures, and axial loading capacity. In this paper, a novel temperature stress testing machine suitable for the inner wall structure shape, capable of simulating the hydration heat of the inner walls, was developed. Then, a reduced-scale model of the inner wall according to similarity criteria was manufactured indoors. Finally, preliminary investigations of the temperature, strain, and stress variations of the inner wall under 100% end constraint conditions were conducted by simulating the actual hydration heating and cooling process of the inner walls. Results show that the hydration heating and cooling process of the inner wall can be accurately simulated. After approximately 69 h of concrete casting, the accumulated relative displacement and strain of the end-constrained inner wall model were -244.2 mm and 187.8 με, respectively. The end constraint force of the model increased to a maximum value of 1.7 MPa and then rapidly unloaded, causing the model concrete to crack in tension. The temperature stress testing method presented in this paper provides a reference for scientifically formulating technical approaches to prevent cracking in cast-in-place concrete inner walls.

Energy and exergy analysis of phase change material based thermoelectric generator with pulsed heat sources

Previous studies focus on the generation capacity of phase change material based thermoelectric generator (PCM-TEG) under a steady-state heat source or single pulsed heat source, which cannot fully reflect the dynamic characteristics of TEG under a diversified actual heat source. Meanwhile, the actual heat sources have unstable characteristics of intermittence and fluctuation, resulting in troubles for TEG to maintain effective thermal management and stable generation. In this work, a three-dimensional transient numerical model of PCM-TEG is proposed to characterize its energy harvesting process under multiple pulsed heat sources, including square, triangular, linear and sinusoidal patterns. The effect principle of heat fluxes and heat source periods on PCM-TEG is sensitively performed, aiming to detect the evolution laws of the temperature field and electric field. The energy and exergy analysis of PCM-TEG is determined to indicate its transmission and conversion process. A comparison analysis of PCM-TEG and TEG is carried out to appreciate the thermal management of PCM from temperature difference and failure-free cycle times. The power generation coupling mechanism of PCM-TEG is further developed concerning the phase transition process and power generation process. The results demonstrate that the temperature difference and output power of PCM-TEG change periodically with the pulsed heat sources. The electrical energy and exergy efficiencies of PCM-TEG under square pulsed heat source are 0.10% and 0.45%, higher than other heat sources. Simultaneously, the maximum output power and the electrical energy efficiency of PCM-TEG can be improved by 173.29% and 80% respectively with the enhanced heat flux. Furthermore, although the transient power generation capacity of TEG is weakened by integrating PCM on the hot side, it can alleviate the thermal fatigue of thermoelectric device and meet its thermal management requirements. This paper is informative to understand the dynamics characteristics and power generation coupling mechanism of PCM-TEG for energy harvesting.

Simulation Analysis and Optimization of Temperature Field for Hot In-Place Asphalt Pavement Recycling

The heating temperature field of asphalt pavement is a key factor affecting the quality of pavement heat-in-place recycling (HIR). Using the heat transfer characteristics of HIR, a three-dimensional heat transfer model was simplified into a one-dimensional heat transfer model along the depth direction. A temperature sensor was installed on the site to monitor the temperature change of the asphalt pavement at different depths under different heating powers, and the actual temperature and heat transfer model were highly compatible. Through this model, the influence of heater running speed and heater heat flux density on the temperature field of the asphalt pavement heated by infrared radiation (IR) was calculated by the finite differential method, and an optimal combination of heating is proposed. In accordance with construction continuity and minimum energy consumption principles, at the 3.0–3.5 m/min recommended running speed of the heating machine, the asphalt at a depth of 4 cm satisfied the temperature demand, but the asphalt on the road surface was prone to heat aging. The heating effect of the constant temperature variable power heating (CTVP) is ideal, but the continuous change in heating power increases the difficulty of construction. Constant temperature discrete power heating (CTDP) divides the ideal heat flux density curve into several stages according to the length of the heating plate in the heater, increasing the feasibility of constant temperature heating in engineering and reducing energy consumption.

MENINGKATKAN EFEKTIVITAS KONDENSOR VERTIKAL PIPA HELIKAL KOIL UNTUK DESTILASI MINYAK ATSIRI SEREH

The main focus of this research is to modify the straight pipe of the Citronella essential oil distillation condenser using a helical coil pipe to shorten the distillation time. This study aims to obtain an effective shell-side fluid volumetric rate to shorten the distillation time. The volumetric rate of the shell side fluid varies from 0.72 to 3.66 LPM at a constant pitch ratio of 2.10. Recording of data in the form of temperature, volumetric rate of shell side water, and tube side steam after steady state is reached. The experimental results show that the effectiveness increases with the increase in the volumetric flow rate of the shell side fluid, where the maximum effectiveness at the volumetric flow rate of 3.66 LPM is 69.99%, while the minimum effectiveness at the volumetric flow rate of 0.72 LPM is 44.39%. The results of the validation of the effectiveness of the condenser show a trend curve that is identical to the previous research, with an average deviation of 5.67%. The maximum volumetric flow rate with a minimum distillation time of 120 minutes with a condensate volume of 8 ml or 240 minutes is smaller than the result of straight-pipe condenser distillation by UKM. The maximum effectiveness is due to an increase in the Reynolds number on the shell side, which results in an increase in the actual heat transfer. It can be concluded that the maximum condenser effectiveness at a maximum volumetric rate of 3.66 LPM could be used for refining Citronella essential oil by SMEs.

Diffusion characteristic of air pollutant from district heating source driven by urban wind field and layout optimization

District heating is a major contributor to urban air pollution due to the massive emissions from fossil fuel combustion. This paper investigates the diffusion characteristics of air pollutants from district heating sources (DHS) driven by the urban wind field. Firstly, the urban air quality was simulated using the coupled Weather Research and Forecasting model - Community Multiscale Air Quality model (WRF-CMAQ) based on the actual heating emissions in the study region. the results were validated using observed meteorological and environmental data. Next, the study regions were divided into sub-regions based on the prevailing wind direction during the heating season. numerical experiments were designed by planning the heating emission into sub-regions as optimized layouts for DHS. Finally, the air quality was predicted for different layouts using WRF-CMAQ and assess the output of PM2.5 as the indicator. The findings reveal that moving the DHS close to the suburban areas can significantly improve overall air quality, and the best improvement can be obtained by arranging all DHS within the defined windward or leeward sub-regions. It is expected that these findings will provide guiding principles for planning DHS from the perspective of environmental management.

Simulation Analysis of High Radiant Heat Plant Cooling and Endothermic Screen Waste Heat Recovery Performance Based on FLUENT

In this article, we propose the endothermic screen model. The aim is to reduce the problems of the high temperature and low utilization of waste heat in industrial plants with high radiant heat. In this paper, the Rhino software is used to establish the model and import it into the FLUENT software, divide the mesh, set the boundary conditions and analyze the transient temperature field. Finally, the temperature change law in the plant and the waste heat recovery efficiency of the endothermic screen are obtained. The flow of cooling water in the endothermic screen is used to transform and transfer the high-radiation heat inside the plant to the outside. The simulation results show that after adding the endothermic screen, the average indoor temperature drops from 313.33 K to 305.66 K, which has a cooling effect. The waste heat recovery efficiency reaches up to 56%, and the waste heat recovery effect is obvious. The research results can provide a reference for the application of an endothermic screen in actual high radiant heat plants and provide a more comfortable working environment for the plant workers.

ANALISIS PERFORMA HEAT EXCHANGER OIL COOLER UPPER TIPE M10-BFG PADA UNIT 1,2,3,4 PLTA SINGKARAK UNTUK TINDAKAN PEMELIHARAAN

ABSTRACT
 
 Heat Exchanger is equipment used to carry out the process of exchanging heat between two fluids, either liquid (hot or cold) or gas, where these fluids have different temperatures. Singkarak hydropower plant also uses a plate type heat exchanger with the code M10-BFG in operation. Serves to exchange heat in the oil used in the upper oil pot, which functions as a cooler and lubricant for the upper bearing and thrust bearing. Seeing the function of the upper and thrust bearings, which are two important bearings in the unit. A good maintenance process is needed on the plate heat exchanger to maintain the condition of the oil at working temperature, which is at 45-55 0C. Through this research, the authors analyzed the performance of the M10-BFG plate heat exchanger with the parameters of the actual heat transfer coefficient and monthly temperature trends. After doing research with quantitative methods through data collection and data processing, it was found that unit 4 has the highest actual heat transfer coefficient of 875.666-900.574 W, but has the shortest usage time, for 42 days based on the existing trending temperature. This is because in unit 4 the oil flow (870-900 l/minute) is below standard, and the size of the heat exchanger plate (55 cm) has shrunk far from the initial value (63 cm). So it is necessary to carry out corrective maintenance on unit 4. Meanwhile, the lowest actual heat transfer coefficient is found in unit 1 with a value of 706.797-770.027 W and the longest plate heat exchanger usage time is in unit 3, with an estimated 121 days before reaching the 55 0C alarm.

Temperature field model of limited slip clutch based on dynamic heat flux partition characteristics

The interaxle torque distribution of off-road vehicle is interfered with temperature field variation of limited slip clutch during long-time sliding, which is controlled by actual heat flux input. The equivalent heat dissipation model is created based on the suggested calculation method of convective heat transfer equivalent coefficient in various lubrication phases. Further, thermal equilibrium equations of friction pair nodes are solved to produce the temperature field calculation model of dynamic heat flux partition. A clutch sliding bench is set up to verify and analyze the effect of heat flux partition on temperature field by organizing different operating conditions. The results demonstrate that the temperature difference of contact surface calculated by the constant heat flux partition model increases significantly along with sliding time and heat flux. In addition, the deviations of temperature rising rate at stage A and average temperature at stage B of separator plate higher than the experimental result also increases. On the contrary, the decrease value of actual input heat flux of separator plate from initial to steady state gradually increases with the increase of relative speed difference in dynamic heat flux partition model. The calculation deviations of temperature rising rate and average temperature are less than 0.1°C/s and 3°C, respectively. This model offers a novel approach for calculating clutch temperature field.

Non-invasive accurate time resolved inverse battery calorimetry

Precise knowledge of the battery heat generation rate and the internal temperature rise allows accurate thermal regulation required for enabling fast charging while minimizing side reactions and avoiding thermal runaway. With the necessity of high energy density, the size of batteries is constantly increasing. Because of poor thermal conduction, the thermal lag in large batteries is significant resulting in a considerable temperature gradient within the cell. Existing calorimetry methods only account for the external heat flow measurement and the external temperature rise and therefore cannot account for the thermal lag inside the cell. Additionally, with these methods, the temporal (time-resolved) information of the heat generation rate is compromised, which makes observation and attribution of electrochemical- thermal signatures impossible. As a potential solution, various intrusive techniques such as embedded thermal sensors have been proposed in the literature. However, these techniques are limited in scope. To enable accurate measurement of time-resolved heat flux measurement in commercial batteries, we instead propose a new battery calorimetry approach by combining state-of-the-art commercial calorimetry with an inverse heat transfer algorithm. This inverse calorimetry is completely non-intrusive with no change to commercial calorimeters. The inverse calorimetry reduces the error in heat generation rate to within 10% of the actual heat generation rate compared to 50% from the lumped capacitance method (best existing method). This method enables time resolved observation of electrochemical-thermal signatures such as a negative heat generation rate due to entropy change, which could not be observed from existing calorimetry methods.

Development of a high-resolution top-down model to estimate actual household-level heat pump electricity consumption

Heat pumps can play an important part in decarbonizing the residential sector due to their use of electricity instead of fossil fuels, and their high efficiency, which often exceeds 100%. However, heat pump performance and energy savings vary with climate and individual household energy usage. Recent studies have used geospatial models to estimate potential heat pump energy consumption across the United States. Yet most studies use generic and oversimplified heat pump models. We contribute to this field with a geospatial model based on manufacturer data and measured test data for 16 different R410A, high efficiency, variable speed compressor heat pumps. Using linear regression, we estimate a market average of COP with respect to ambient temperature. From this, we can identify the variation in efficiency with temperature across this technology class. We also use linear regression to estimate demand for heating and cooling as a function of ambient temperature and household characteristics. We compare the performance of both the predicted energy demand and heat pump efficiency against measured data from a heat pump-equipped house in West Lafayette, Indiana, and find that the model predicts daily heat pump electricity consumption with 27.8% relative error, comparable to other building simulation models. By incorporating high-resolution geospatial data inputs, such top-down models can still maintain a large scope across technologies and diverse climates while increasing spatial and temporal resolution.

Investigation of the Enhancement of Boiling Heat Transfer Performance Utilizing a Hybrid Wetting Surface with a Macroscopic Millimeter-Scale Pillar Array

The heat transfer process is an important part of energy utilization and conversion, and boiling heat transfer is one of the most significant and effective heat transfer modes in use. Enhancing boiling heat transfer can directly improve energy use efficiency and promote the sustainable development of the energy industry. Surfaces with mixed wetting topologies have been proven to possess the potential to enhance boiling heat transfer. However, the heat transfer promoting mechanism of these types of surfaces requires further clarification on actual heat exchanger surfaces with macroscale heat transfer enhancement structures, such as millimeter-scale pillars. In this study, the boiling heat transfer enhancement mechanism and the performance of the hybrid wetting surfaces with an array of macropillars were explored using both experimentation and numerical simulation. In the experiment, the single bubble growth dynamics at the onset sites of nucleation of these hybrid wetting surfaces in the initial boiling stage were recorded using a CCD camera with a top view. The boiling heat transfer coefficient was also measured at the stable boiling stage. Within the entire tested range of heat flux (3.75–18 W/cm2), the hybrid wetting surfaces significantly enhanced the boiling heat transfer, and the HPo(bottom)–HPi(top) surface (surf-2) exhibited the best heat transfer performance. At the representative heat flux 12.5 W/cm2, the boiling heat transfer coefficient of the HPo (bottom)–HPi (top) surface (surf-2) and the HPi (bottom)–HPo (top) surface (surf-3) were more than 33% and 18% higher than the pure copper flat surface, and more than 16% and 3% higher than the uniform HPi surface (surf-4), respectively. On the one hand, due to the view field of camera being blocked by the fiercely growing bubbles in the stable boiling stage, it was difficult to record bubble numbers and gather statistics at the onset sites of nucleation in order to correlate the bubble dynamics with the mechanism of boiling heat transfer enhancement. On the other hand, the single bubble growth dynamics recorded during the initial boiling stage lacked information about the hybrid wetting surfaces in the vertical cross-sectional plane. Therefore, a two-dimensional VOF-based numerical simulation was adopted to supplement the contribution of hybrid wetting surfaces in the vertical plane. The simulation results indicated that the hybrid wetting surfaces with macropillars can inhibit bubble overgrowth and accelerate bubble departure compared with spatially uniform hydrophobic surface. The bubble radius and departure time on surf-2 were smaller than those on surf-3. These are believed to be the reasons why the surf-2 surface exhibited the best heat transfer performance in the experiment. Both the experiment and numerical analysis proved that the hybrid wetting surfaces with macroscale pillars can promote the boiling heat transfer, thus demonstrating potential applications in actual horizontal or vertical tube boiling heat exchangers.

Determination of fire protection distances during a tesla model s fire in a closed parking lot

This study modelled an electric vehicle fire on the example of a Tesla Model S (USA) in a closed car park. Such fires pose an increased danger due to their rapid spread, the presence of a large number of vehicles, the release of toxic combustion products and heavy smoke. In fact, the rapid spread of a fire in a closed car park is caused by unreasonably small distances between vehicles. Thus, the purpose of the study was to determine the minimum fire protection distances due to an electric vehicle fire in a closed car park using the example of Tesla Model 3. For this purpose, the objects and their physical characteristics were described, input and environmental parameters were set, and a mathematical model of the dynamics of fire development was formed. This made it possible to establish the minimum fire protection distance during the free development time of 610 s for an electric vehicle fire in a closed car park, which is 10 m along the flank and 6 m along the front. The difference in fire protection distances on the flank and front is explained by the design features of the electric vehicle. That is, the flank area of the flame will be larger than the front of the burning electric vehicle, and therefore the heat radiation power will also be greater. The actual heat radiation power is the key factor affecting fire protection distances. The results of the study can be used in the design of various types of car parks and the safe placement of vehicles in them. Fire protection distances between cars in enclosed car parks can be taken into account by insurance companies when assessing the risk of damage to cars due to fires. And also by fire and rescue units involved in extinguishing such fires, to ensure the safety of rescuers

Synthesis of Co(OH)F@Al nanobelt array on various substrates for pyro-MEMS

Metastable intermolecular composites (MICs) composed by solid fuel and oxidizer can undergo violent redox reaction with release of huge amount of energy. Integration of MIC with microelectromechanical-system (MEMS) is of particular interest to meet the demand of miniaturization in modern pyrotechnic devices. Meanwhile, fluorine-containing oxidizers are favored in MIC owing to their potential to fluorinate the oxide passivation layer in common elemental fuels. Herein, Co(OH)F was employed for the first time as a novel fluorine-containing oxidizer in Al-based MIC. Vertically aligned Co(OH)F@Al nanobelt arrays (NAs) with tunable morphology were successfully fabricated on a variety of substrates (Si, glass, Ni, Cu, Ti) via a facile hydrothermal synthesis followed by electron beam evaporation. The whole fabrication process is highly compatible with modern MEMS technology. The thermal behavior of pure Co(OH)F and Co(OH)F@Al composites was comprehensively investigated by TG-DSC and a series of ex-situ and in-situ characterization. It was found that, Co(OH)F@Al composites achieved main exothermal reaction before melting of Al regardless of morphology and equivalence ratio. This feature is attributed to the etching of Al2O3 shell by HF released from Co(OH)F which is termed as pre-ignition reaction. To elucidate the effect of micro-structure on the actual specific heat release, we proposed a phenomenological model which can be a reference for future micro-structure design of MIC.

Dynamic shock response of high-entropy alloy with elemental anomaly distribution

Elemental inhomogeneities formed during the actual preparation or heat treatment of high entropy alloys (HEAs) have a profound effect on the mechanical properties of HEAs. In this work, molecular dynamics (MD) was used to simulate the plastic response of CoCrFeNiMn HEAs with Mn element as the concentration fluctuation variable under shock loading. The results show that the unique physical shock properties, including shock wave propagation, dislocation evolution, defect collapse, and energy dissipation, are related to the anomaly arrangement of Mn elements. Compared to the uniform distribution of Mn elements, the gradient distribution of Mn leads to lattice mismatch between heterogeneous tissues, increasing the energy barriers of the dislocation mediated slip and reducing the probability of generating disordered atoms (from 27.9 to 11.5%), which results in anomalous shock strength in the Hugoniot elastic limit (HEL) (from 69.1 Gpa to about 72.9 Gpa). As the main product of shock energy conversion, energy dissipation is subjected to the complex interaction between the shock compression and the reflection unloading, and the gradient distribution of Mn element can significantly reduce the efficiency of shock energy conversion due to dislocation activity and crystal phase changes caused by lattice mismatch. Finally, when defective structures are introduced, the gradient dislocation nucleation and energy conversion fluctuations of the microstructure were observed during shock loading. This work can provide a new perspective for further understanding the influence of solid solutions with non-uniform element distribution on the plastic deformation mechanism of high entropy alloys subjected to extreme dynamic shock.

High-Temperature Behaviour of Zn-Based Galvannealed Coatings on Steel.

The potential of using a Zn-based, hot-dip coating to limit steel scale formation was investigated. The phase evolution within a pure Zn and a Zn0.1Al coating on a medium-carbon (0.5 wt.% C, 0.25 wt.% Si) steel sheet during a series of heat treatment steps was investigated. Such Zn-based coatings react with the steel substrate depending on the actual heat treatment condition. A series of expected intermetallic phases was observed via SEM/EDX and XRD techniques, such as ζ, δ and Γ phases along the η(Zn) phase. The η(Zn) phase was transformed to mainly δ and Γ phases during galvannealing (500 °C). The rapid quenching from 850 °C enabled the formation of the supersaturated α-(Fe) solid solution with increased Zn content. A continuous, intact, ~20 µm thick coating was observed after the final step of the heat treatment procedure, while signs of liquid metal embrittlement (LME) were not observed near the coating/steel interface. This will ensure reliable protection against heavy scale formation on heat-treated steel parts.

Identification of climate change impact and thermal comfort zones in semi-arid regions of AP, India using LST and NDBI techniques

Andhra Pradesh, in southern India, frequently experiences warm summers and winters. However, the year-round greater relative humidity and the positioning of the summer hot spots are linked to actual weather heat exhaustion during the warmest months. Climate change is a significant—and frequently disregarded—factor in the relationship between climate and mortality. With the use of the Land Surface Temperature (LST) and Normalized Difference Built-up Index (NDBI), we sought to identify the climatic change in this research. Additionally, we attempted to identify the Thermal Comfort Zones (TCZs) in Andhra Pradesh, South India's semi-arid regions. Arc GIS and ERDAS Imagine were used to process the satellite data of Landsat 4–5 (TM & MSS), Landsat 7 ETM+, and Landsat 8 OLI for the development of LST and NDBI. The research was conducted for the past thirty years from 1990 to 2020. The resultant thermal comfort zones map was classified into four zones, Zone - I (Safe zone), Zone – II (Moderately safe zone), Zone – III (Risk Zone), and Zone -IV (Highly Risk Zone). The relation between the LST and NDBI is also revealed using correlation regression analysis in the study region. It has been noted that urban centre and high-density regions had greater LST than rural locations. The study finds that although this differs from one ecological zone to another and the distribution of LST intensity in the urban area depends on its changing LULC, various types of land cover within an urban region might impact the spatial pattern of urban LST. The main conclusions of this study might help policymakers understand the need of enabling more sustainable urban development in cities.

Simulation Investigation on Thermal Characteristics of Thermal Battery Activation Process Based on COMSOL

Current thermal simulation methods are not suitable for small-size fast-activation thermal batteries, so this paper provides an improved simulation method to calculate thermal cell temperature changes using the COMSOL platform. A two-dimensional axisymmetric model of thermal batteries has been established, considering the actual heat release situation and the mobile heat source of thermal batteries. Based on it, the temperature change and electrolyte melting of thermal batteries under high-temperature conditions (50 °C) have been simulated, in which the temperature change law, thermal characteristics, and electrolyte melting characteristics have been analyzed in depth. The results show that the additional heating flakes and insulation design above and below the stack can effectively reduce heat loss. Most of the melting heat of the electrolyte flows in from the negative side. In addition, the thermal battery activation time has been calculated to be 91.2 ms at the moment when all the thermal battery electrolyte sheets begin to melt, and the absolute error was within 10% compared with the experimental results, indicating that the simulation model has high accuracy and can effectively broaden the simulation area of thermal batteries.

Analysis of Cylinder Drying Intensity of Cut Tobacco Based on Enthalpy Method

Cylinder drying of cut tobacco is one of the key processing technologies in cigarette manufacturing. And complex mass transfer and heat transfer phenomena were involved. In this paper, a thermodynamic model have been built for cut tobacco during cylinder drying process. The relationship of different process parameters and thermodynamic data were analyzed by canonical correlation method, including amount of heat Qv produced in moisture evaporation of cut tobacco, amount of heat Qs produced in temperature increase of cut tobacco, total amount of heat Q and thermal efficiency coefficient η. The results showed that the thermodynamic model explained the actual cut tobacco heating and heat distribution well in the cylinder drying process. The variation coefficients of the four thermodynamic parameters of cut tobacco under the same processing conditions were all less than 5.0%. It is proved that the thermodynamic model established during cylinder drying process of cut tobacco is feasible.

Improved Bayesian Optimization Framework for Inverse Thermal Conductivity Based on Transient Plane Source Method

In order to reduce the errors caused by the idealization of the conventional analytical model in the transient planar source (TPS) method, a finite element model that more closely represents the actual heat transfer process was constructed. The average error of the established model was controlled at below 1%, which was a significantly better result than for the analytical model, which had an average error of about 5%. Based on probabilistic optimization and heuristic optimization algorithms, an optimization model of the inverse heat transfer problem with partial thermal conductivity differential equation constraints was constructed. A Bayesian optimization algorithm with an adaptive initial population (BOAAIP) was proposed by analyzing the influencing factors of the Bayesian optimization algorithm upon inversion. The improved Bayesian optimization algorithm is not affected by the range and individuals of the initial population, and thus has better adaptability and stability. To further verify its superiority, the Bayesian optimization algorithm was compared with the genetic algorithm. The results show that the inversion accuracy of the two algorithms is around 3% when the thermal conductivity of the material is below 100 Wm-1K-1, and the calculation speed of the improved Bayesian optimization algorithm is three to four times faster than that of the genetic algorithm.