Measured Temperature Data Research Articles

Combustion Characteristics of a Hot Water Boiler System Convertibly Fueled by Rice Husk and Heavy Oil - Heavy Oil Combustion Characteristics -

Purpose: With the ever-rising energy prices, thermal energy heavily consuming facilities of the agricultural sector such as commercialized greenhouses and large-scale Rice Processing Complexes (RPCs) need to cut down their energy cost if they must run profitable businesses continually. One possible way to reduce their energy cost is to utilize combustible agricultural by-products or low-price oil instead of light oil as the fuel for their boiler systems. This study aims to analyze the heavy oil combustion characteristics of a newly developed hot water boiler system that can use both rice husk and heavy oil as its fuel convertibly. Methods: Heavy oil combustion experiments were conducted in this study employing four fuel feed rates (7.6, 8.5, 9.5, 11.4 ) at a combustion furnace vacuum pressure of 500 Pa and with four combustion furnace vacuum pressures (375, 500, 625, 750 Pa) at fuel feed rates of 9.5 and 11.4 . Temperatures at five locations inside the combustion furnace and 20 additional locations throughout the whole hot water boiler system were measured to ascertain the combustion characteristics of the heavy oil. From the temperature measurement data, the thermal efficiency of the system was calculated. Flue gas smoke density and concentrations of air-polluting components in the flue gas were also measured by a gas analyzer. Results: As the fuel feed rate or combustion furnace vacuum pressure increased, the average temperature in the combustion furnace decreased but the thermal efficiency of the system showed no distinctive change. On the other hand, the thermal efficiency of the system was inversely proportionally to the vacuum level in the furnace. For all experimental conditions, the thermal efficiency remained in the range of 80.1-89.6%. The CO concentration in the flue gas was negligibly low. The NO and concentration as well as the smoke density met the legal requirements. Conclusions: Considering the combustion temperature characteristics, thermal efficiency, and flue gas composition, the optimal combustion condition of the system seemed to be either the fuel feed rate of 9.5 with a combustion furnace vacuum pressure of 375 Pa or a fuel feed rate of 11.4 with a furnace vacuum pressure between 500 Pa and 625 Pa.

Evaluation of Refractory Lining of the Blast Furnace Hearth and Bottom in Five Years of its Operation on the Basis of the Isotherms Shapes

Based on archival temperature measurement data regarding a blast furnace (capacity of 3200 m3) hearth and bottom refractory lining, empirical isotherms T = 300°C, for various periods of the first five years of the furnace campaign were determined. This resulted in an attempt to assess the hearth and bottom refractory lining in the third month and subsequently, in the next years of the blast furnace operation. The empirical isotherms, determined after the first three months, were compared to the isotherms determined using the method of mathematical modelling. These empirical isotherms were compared to each other, respectively in one-year intervals. The most distinctive changes of the hearth and bottom refractory lining were observed during the first three months of the furnace campaign. In the further period of five years, the changes were insignificant. During the early stage of furnace operation, observed deterioration of the refractory lining was associated with partial damage of the bottom ceramic layer and elephants foot-shaped defects of the refractory lining in the lower, thickened parts of the hearth walls. Early, elephants foot-shaped wear of the refractory lining is related to the mechanism of its wash-out by liquid products of the process during tapping, which results from certain maladjustment of the hearth and bottom inner geometry in modern furnaces to the hydrodynamic conditions of metal and slag flow.

Evaluation of a Simplified Method to Estimate Evaporation Losses From Mosul Dam Reservoir

In this study, the (Linacre) mathematical Pilot model was used to estimate evaporation from free water surface and test the results accuracy of the mathematical evaporation model by comparing it with the values of the measured pan evaporation class (A) at the Mosul dam reservoir. The daily measured temperature data recorded in meteorological station at the Mosul dam reservoir for the period (2003-2006) were used in addition to the calculated dew point temperature from the values of measured temperature and relative humidity to verify the accuracy of the mathematical model in estimating the evaporation from the Mosul dam reservoir northern of Iraq. Statistical tests showed that this model gives a reasonable results. The accuracy of the model is best for the monthly rate evaporation prediction (E1), followed by the rate of ten days and then daily, with coefficient of determination (R2) are (95%) and (93%) and (87%), respectively. The percent errors in the model prediction (E1) are (6.5%) and (6.1%) and (5%) for daily, ten days and monthly prediction respectively. Since the (Linacre) model require very few data (air temperature only), it can be used to overcome the difficulty of lack of the meteorological data. Key word: Linacre model, Mosul dam reservoir, Pan Evaporation.

Heat Transfer Analysis of the Operation in Delayed Coking Coke Drum

Delayed coking coke drum is the core equipment of delayed coking technology, which experiences almost all the thermal and mechanical loadings during operation. In this study, two coke drum finite element models have been created with four material models and the thermal boundary conditions are determined based on the temperature measurement data. Finite element analysis methods known as function loading and multiple steps analysis are used through the simulation. Temperature distributions and temperature variation curves of different nodes are then obtained by finite element heat transfer analysis. Numerical results show that temperature distribution is complex in the transition section and the water cooling stage has the highest temperature change rate.

Modeling method of heat transfer during Vapour Phase Soldering based on filmwise condensation theory

The paper presents a practical method for calculating the heat transfer during Vapour Phase Soldering (VPS) process. VPS is a reflow soldering method based on condensation heating and used in the electronics manufacturing. The presented explicit model describes solutions for filmwise condensation heat transfer based on the Nusselt theory. Different approaches on describing the filmwise condensation were investigated, compared and modified in order to determine a proper heat transfer coefficient for the VPS process – where the heated assembly can be considered as a horizontal plate. For the verification, measurements were done in an experimental soldering oven. The results of the calculations show a proper approximation with the measured temperature data. Finally the results were compared with a solution obtained from complex multi-physics simulation. The results point out, that the application of filmwise condensation model for VPS can be more practical than a complex multi-physics model, from the aspect of calculation error and computation time.

Machine tool selected point temperature rise identification based on operational thermal modal analysis

A new method to fast identify machine tool selected point temperature rise is presented. Based on operational thermal modal analysis, a temperature rise curve of each machine tool selected point can be obtained, and thermal equilibrium time and steady-state temperature can be calculated based on the measured temperature data during a short time of a warm-up run. The major advantage of this approach is to predict selected point temperature rise of the machine tool in the short test period of time like half an hour instead of 3 to 6-h running test in practice. A spindle system model is analyzed in ANSYS software, and the simulation temperature data of several selected points are treated as the measured temperature. By dealing with the assuming measurement temperature based on the new method, the effectiveness of the method is verified and how to get the minimal time for identification is also illustrated. At last, the temperature rise test in the vertical machining center has been done. The temperature rise of the selected point has been identified in 26.35 min while the time of obtaining the temperature rise curve from the start-up of machine tool to the temperature steady-state machine tool reaching in practice is 320 min. The root mean squared error (RMSE) between the estimated and measured temperature is 0.107 °C, and the error between the estimated and measured steady-state temperature is 0.155 °C. So this method is proven to be effective and quick for identifying the machine tool selected point temperature rise. Furthermore, it has universal applicability due to the validation in the different spindles.

Responses of seasonal and diurnal soil CO2 effluxes to land-use change from paddy fields to Lei bamboo (Phyllostachys praecox) stands

Land-use change often markedly alters soil carbon (C) dynamics such as soil surface CO2 efflux. This study aims to test the hypotheses that converting paddy fields to bamboo stands would markedly reduce soil CO2 efflux and their temperature sensitivity (change of soil CO2 efflux rate by increasing 10 °C of temperature), and change the relationship between soil CO2 efflux and other environmental factors. A 12-month field study was conducted to measure the seasonal and diurnal soil CO2 effluxes in three adjacent paddy field-bamboo forest pairs with the automated soil CO2 flux system (LI-8100). Results showed that soil CO2 effluxes from both of the two land-uses had distinct seasonal patterns, and were reduced from 45.4 to 34.7 t CO2 ha−1 yr−1 in cumulative CO2 emissions when paddy fields were converted to bamboo stands. About 80% of the variation in soil respiration in the bamboo stands was explained by soil temperature; however, a positive relationship between soil CO2 efflux and soil temperature in the paddy field was observed only when the soil was not submerged under water, indicating that soil water saturation in the paddy fields altered the soil CO2 efflux–temperature relationship. A negative relationship (P < 0.01) between soil CO2 efflux and soil moisture was observed in the paddy fields, while no such relationship was observed in the bamboo stands. The apparent temperature sensitivity of soil respiration (Q10) was dependent on the depth of the soil temperature measurement and was increased by converting paddy fields to bamboo stands, rejecting the hypothesis. In Lei bamboo stands, the R2 for the soil respiration-temperature regression was higher using seasonal and diurnal CO2 efflux data together than using the seasonal data alone. We conclude that the conversion of paddy fields to Lei bamboo stands decreased the annual soil CO2 efflux but increased its temperature sensitivity, and altered the relationship between soil respiration and soil moisture. When calculating the Q10, the soil temperature measurement depth and data with diurnal timescale should be taken into account. If such land-use conversion effects are confirmed over the subtropical region in China in future research, this land-use conversion could increase C sequestration in the ecosystem and help mitigate climate change.

Inversion Algorithm Based on the Unscented Kalman Filter for Inverse Heat Conduction Problems

The inverse heat conduction problems (IHCP) analysis method provides a promising approach for acquiring the thermal physical properties of materials, the boundary conditions and the initial conditions from the known temperature measurement data, where the efficiency of the inversion algorithms plays a crucial role in real applications. In this paper, an inversion model that simultaneously utilizes the process evolution information of the objects to be estimated and the measurement information is proposed. The original IHCP is formulated into a state-space problem, and the unscented Kalman filter (UKF) method is developed for solving the proposed inversion model. The implementation of the proposed method does not require the gradient vector, the Jacobian matrix or the Hessian matrix, and thus the computational complexity is decreased. Numerical simulations are implemented to evaluate the feasibility of the proposed algorithm. For the cases simulated in this paper, satisfactory results are obtained, which indicates that the proposed algorithm is successful in solving the IHCP.

Temperature field reconstruction from the partial measurement data using the gappy proper orthogonal decomposition

Fast reconstruction of the temperature field from the partial temperature measurement data is highly desirable in the field of thermal engineering, in which reconstruction algorithms play a crucial role in real applications. Based on the gappy proper orthogonal decomposition technique, a promising approach that integrates the numerical simulation information and the measurement information is proposed in this study for the temperature field reconstruction from the partial measurement data, where the original reconstruction problem is formulated into an optimisation problem. An objective functional, which simultaneously considers the outliers in the measurement data and the model approximation distortions, is presented. Based on the split Bregman iteration technique, an iterative scheme is developed for solving the proposed objective functional. Numerical simulations are implemented to demonstrate the feasibility and effectiveness of the proposed algorithm.

COMSOL Multiphysics validation as simulation software for heat transfer calculation in buildings: Building simulation software validation

The main purpose of this article is a presentation of software validation for a calculation of heat transfer in buildings. The heat transfer calculation in the COMSOL Multiphysics is validated by using the analytical models, by the comparative verification provided by the International Energy Agency in the Task 34, and by the comparison with measured data in real building segment. The last model represents transient heat transfer process in an environment with complicated bindings. The similarity between the COMSOL Multiphysics results and other software tools for building simulations was investigated using the Task 34 results with minor dissimilarities. The comparison of simulation results with measured data is described in the paper with sufficient accuracy. The main deviation between the simulation and measured temperature data was caused by the precise calculation of the convective heat transfer coefficient value.

A novel experimental technique to determine the heat transfer coefficient between the bed and particles in a downer

A novel method for directly measuring the temperature history of mobile hot ferromagnetic particles (steel particles), substituting for reacting particles, in a binary-solid (reacting particles and inert particles) downflow is introduced. The temperature history of the hot steel particles can be obtained by measuring the temperature of the particles at different axial positions using magnetic fields that can separate the steel particles from other bed materials immediately and easily. Employing the magnetic marking method, magnetic sensors were used to detect the change in magnetic flux density in a given magnetic field, and the residence time of the steel particles was also measured. The cross-sectional averaged particle-to-bed heat transfer coefficients were calculated from the experimental results using simple heat balance equations. The measured temperature data have a relatively wide error range; however, the average temperature curves derived from the average particle-to-bed heat transfer coefficients agreed with the temperature plots. Therefore, the experimental method of this study is applicable to the measurement of the particle temperature in a binary-solid downflow. The results showed that there is strong correlation between the particle-to-bed heat transfer coefficients and normalized collision frequency under the laminar gas flow conditions.

Inverse Estimation of the Front Surface Temperature of a 3-D Finite Slab Based on the Back Surface Temperature Measured at Coarse Grids

The accuracy of the solution of the inverse heat conduction problem (IHCP) can be improved by using fine grids, but measured temperature data on fine grids are usually not available due to limits imposed by the size and spacing of the temperature sensors. A new method is proposed to recover the front surface temperature of a finite slab using fine grids based on the back surface temperature measured with coarse grids. Effects of heat conduction in the sensor substrate and contact thermal rsesistance are also taken into account. The proposed method is applied to solve a three-dimensional IHCP with stainless steel and aluminum target slabs. The results show that the front surface temperature can be recovered with satisfactory accuracy. Both the distortion of the temperature distribution and the discrepancy from the exact solutions are reduced by using the new method.

Characteristic Analysis of DS18B20 Temperature Sensor in the High-voltage Transmission Lines’ Dynamic Capacity Increase

Dynamic capacity increase in high voltage electric power transmission line is currently the most economical method for solving electric power transmission bottleneck nowadays. DS18B20 temperature sensor is applied to the dynamic capacity increase of high voltage transmission lines to measure the conductor temperature and ambient temperature. The paper is focused on the experiment of DS18B20 both in the laboratory and outside. From the result of the lab temperature measurement data analysis, using 4 DS18B20’s is the most suitable plan, considering both accuracy and economical efficiency. In the experiment outside, we get four groups of conductor (uncharged) temperature and four groups of ambient temperature. The data proved that DS18B20 has good stability, and small measurement error. It is suitable for measuring the temperature of conductor and ambient in dynamic capacity increase, and helpful to improve the accuracy of the calculation of capacity increasing.

Simulation and Test for the Thermal Behaviour of a Prototype Synchronous Generator with HTS Armature Windings

Abstract A synchronous generator prototype with HTS armature windings and a permanent magnet rotor (HTS-PM) was developed. The temperature evolution during cooling and operation processes of the HTS coils was analyzed by finite element method (FEM). The simulated results coincided well with the temperature measurement data acquired by PT-100 sensors. Cooling time, terminal temperature, contact thermal conductivity, during cooling, as well as the proportion between real and calculated iron loss, contact thermal conductivity, at various rotating speeds during operation, were worked out using the FEM model.

Thermal transient test and strength evaluation of a thick cylinder model made of Mod.9Cr-1Mo steel

Mod.9Cr-1Mo steel is a candidate material for the primary and secondary heat transport system components of the Japan sodium-cooled fast reactor. However, there is little evidence to support the structural integrity of components made of Mod.9Cr-1Mo steel in a practical environment. To verify the failure mode and assess creep–fatigue damage, a thick cylinder test model made of Mod.9Cr-1Mo steel was subjected to 1873 cycles of accelerated thermal transient loading using a large-scale sodium loop through which liquid sodium at 600°C and 250°C flowed repeatedly, with the period of each transient being 2h and 1h, respectively. After completion of the test, the test model was inspected using liquid penetrant testing. Observations using a scanning electron microscope and hardness testing were then performed to characterize creep–fatigue damage in the structural model subjected to cyclic thermal transient loading in a sodium environment. Heat transfer analysis based on the measured temperature data and elastic and inelastic thermal stress analyses using finite element analysis were performed to evaluate the relationship between creep–fatigue damage and the observed crack conditions. Finally, the characteristics of creep–fatigue damage under cyclic thermal loading in a sodium environment and the evaluation methods were considered.

A general model for estimation of daily global solar radiation using air temperatures and site geographic parameters in Southwest China

Estimation of daily global solar radiation (Rs) from routinely measured temperature data has been widely developed and used in many different areas of the world. However, many of them are site specific. It is assumed that a general model for estimating daily Rs using temperature variables and geographical parameters could be achieved within a climatic region. This paper made an attempt to develop a general model to estimate daily Rs using routinely measured temperature data (maximum (Tmax, °C) and minimum (Tmin, °C) temperatures) and site geographical parameters (latitude (La, °N), longitude (Ld, °E) and altitude (Alt, m)) for Guizhou and Sichuan basin of southwest China, which was classified into the hot summer and cold winter climate zone. Comparison analysis was carried out through statistics indicators such as root mean squared error of percentage (RMSE%), modeling efficiency (ME), coefficient of residual mass (CRM) and mean bias error (MBE). Site-dependent daily Rs estimating models were calibrated and validated using long-term observed weather data. A general formula was then obtained from site geographical parameters and the better fit site-dependent models with mean RMSE% of 38.68%, mean MBE of 0.381MJm−2d−1, mean CRM of 0.04 and mean ME value of 0.713.

국내 식품냉장창고 온도분포 분석 및 적정 확률분포모델 설정

ABSTRACT - This study was to present the proper probability distribution models that based on the data for sur-veys of food cold storage temperatures as the input variables to the further MRA (Microbial risk assessment). Thetemperature was measured by directly visiting 7 food plants. The overall mean temperature for food cold storages inthe survey was 2.55 ± 3.55 o C, with 2.5% of above 10 o C, −3.2 o C and 14.9 o C as a minimum and maximum. Tempera-ture distributions by space-locations was 0.80 ± 1.69 o C, 0.59 ± 1.68 o C, and 0.65 ± 1.46 o C as an upper (2.4~4 m), mid-dle (1.5~2.4 m), and lower (0.7~1.5 m), respectively. Probability distributions were also created using @RISKprogram based on the measured temperature data. Statistical ranking was determined by the goodness of fit (GOF) todetermine the proper probability distribution model. This result showed that the LogLogistic ( −4.189, 5.9098, 3.2565)distribution models was found to be the most appropriate for relative MRA conduction. Key words: cold food storage, temperature distribution, MRA (microbial risk assessment), probability distribution model

An improved three-dimensional inverse heat conduction procedure to determine the tool-chip interface temperature in dry turning

An improved three-dimensional inverse heat conduction procedure is proposed to quantitatively solve the steady-state tool-chip interface temperature in dry turning. The infrared method is utilized to measure the temperature on the rake face of the insert in transient cooling process after the feed motion is halted. With the experimentally measured temperature data, the 3-D heat conduction model of the cutter and an optimization scheme are used to solve the effective heat flux on tool-chip interface and the interface temperature during turning. This inverse procedure facilitates the determination of the temperature at tool-chip interface in dry turning process, which is still a challenge for existing experimental and numerical methods.

A robust and fast algorithm for three-dimensional transient inverse heat conduction problems

Despite numerous studies of inverse heat conduction problems (IHCP) over the last several decades, their solutions still suffer from the mathematical difficulties and the bottleneck of currently available numerical methods for large-scale problems. In this paper, we present a robust and efficient algorithm for the solution of a specific type of three-dimensional (3D) IHCP commonly involved in various engineering applications. The solution method incorporates the Tikhonov regularization for tackling the severe ill-posedness and the conjugate gradient (CG) method for solving the resulting minimization problems. A model function approach is used to significantly reduce the effort needed to find the optimal Tikhonov regularization parameter. The proposed solution method requires no a priori knowledge of the measurement noise and is much more computationally efficient than the traditional Tikhonov regularization-based inversion approaches. Thus, it can be used for the efficient solution of large-scale practical problems. Two simulation case studies of practical significance are presented to validate and assess the performance of the proposed method. Finally, the solution method is successfully applied to the reconstruction of instantaneous heat fluxes from experimentally measured temperature data.

Thermal interaction between near-water atmospheric layer and surface water layer on the northeastern shelf of the Black Sea

Thermal interaction between near-water atmospheric layer and surface water layer is considered within long-term, seasonal, synoptic, and mesoscale variability ranges from long-term air and water temperature measurement data. It is established that long-term mean monthly values of water temperature within annual cycle are greater than corresponding values of air temperature. Equations of relationships are obtained for long-term mean annual, mean seasonal, and mean monthly air and water temperature values.