heating unit
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Foods ◽  
2022 ◽  
Vol 11 (2) ◽  
pp. 213
Author(s):  
Lingtao Zhang ◽  
Fan Liu ◽  
Ting Wang ◽  
Shilin Wu ◽  
Yamei Jin ◽  
...  

As an emerging electrotechnology, induced electric field has attracted extensive attention in the development of innovative heat treatment equipment. In this study, a resistance heating unit based on induced electric field was built for inner heating of aqueous electrolyte solutions as well as liquid foods, such as vinegar. NaCl solutions and liquid foods with different conductivity were used to investigate the thermal effect and temperature rise of samples. Saline gel composed of 3% agar powder and 20% NaCl acted as a coil of conductor for inducing high-level output voltage. The utilization of the saline gel coil significantly improved the power conversion efficiency of the heating unit as well as the heating rate. The results revealed that duty cycle and applied frequency had immediate impact on the efficiency of inner heating. Additionally, the rate of temperature rise was proportional to the conductivity of the sample. The temperature of 200 mL NaCl solution (0.6%) increased from 25 °C to 100 °C in 3 min at 40% duty cycle and 60 kHz of applied frequency, and it was a circulating-flow process. The maximum temperature rise of black vinegar was 39.6 °C in 15 s at 60 kHz and 60% duty cycle, while that of white vinegar was 32.2 °C in 30 s under same conditions, whereas it was a continuous-flow process. This novel heating system has realized the inner heating of liquid samples.


Author(s):  
Georgy Serikov ◽  
Irina Serikova

Problem. Possible implementations of thermal stabilization systems for traction batteries of electric vehicles are considered. The analysis of possibilities to increase the efficiency of using lithium-ion rechargeable batteries at the expense of their temperature stabilization is carried out. The influence of the temperature factor on the useful capacity of traction batteries is shown. The microcontroller system of temperature stabilization of double action with function of the timer allowing to establish prematurely a mode of both cooling, and heating of storage batteries is offered. Methodology. The methods of theoretical basic electrical engineering have been developed in the production and calculation of circuits as well as the classical methods of statistics of signals from ADC. Results. The technique of processing information from the current, voltage and temperature sensors using a mathematical apparatus without using harmonic analysis is presented. The hardware implementation of the proposed method allows the use of simplified computing tools. Originality. Complex analysis of the data obtained from the current, voltage and temperature sensors is carried out. During the analysis, the range of velocities with stable operation of the measurement system was determined. Based on the data obtained, it is concluded that the use of a horn antenna as a concentrator substantially eliminates lateral interference and extends the range of possible velocity measurements. It is shown that the level of sampling significantly affects the upper limit of the measurement temperature. Practical value. The following results were obtained: - minimizing the harmful effects of negative temperatures on the battery capacity is possible through the use of preheating; - the system of temperature stabilization should be performed with the possibility of reversing the mode of circulation of thermal energy; - simplification of the process of determining the temperature is possible due to indirect measurements of the internal resistance of the heater; - in the case of pulse-width  control, the service life of the heaters increases, and the heating time is reduced at constant power consumption; - application of the microprocessor system allows to increase functionality and flexibility of adjustment of the heating unit under various traction batteries.


2021 ◽  
Vol 11 (3) ◽  
pp. 157-167
Author(s):  
Aleksandr I. DANILUSHKIN ◽  
Vasilij A. DANILUSHKIN

In the electrical complex “induction heater - deforming equipment”, the limiting performance of the complex is the induction heating unit. In this regard, an important task of increasing the effi ciency of the processing complex is to optimize both the design and operating parameters of the induction heating unit. It is shown that the main design parameter infl uencing the energy characteristics of the complex is the length of the heating system. When optimizing the total length of the heater, an iterative model of the process of induction heating of ferromagnetic billets is used. The power distribution algorithm along the length of a two-section heater is a piecewise continuous function. Optimization of the heater length according to the proposed method made it possible to reduce the heater length from 2.8 m to 2.1 m, i.e. by 25%. To search for eff ective control algorithms for non-stationary modes, a refi ned electrothermal model is proposed in the work. It takes into account the nonlinear dependence of the distribution of the power of the sources of internal heat release on the temperature distribution in the metal of the workpieces along the radial and axial coordinates. The problem of fi nding the optimal control of transient modes of a two-section induction heater of methodical action is formulated and solved. The results obtained provide a minimum of energy consumption for heating billets in transient modes under conditions of technological and energy constraints. Variants of starting the heater at various initial temperature states of the load are considered. The results of a comparative analysis of the eff ectiveness of the obtained control algorithms are presented. The structure of the power supply and control system of the induction heating complex is proposed.


2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Soyoung Kim ◽  
Kyunghi Hong ◽  
Heeran Lee

Purpose This study aims to provide information on how to monitor the temperature setting of a heating device in order to implement a heating unit successfully in the smart clothing by observing voluntary heating behavior of wearers.Design/methodology/approach Subjects wearing base layers and additional clothing were asked to turn on and off the switch when wanted in the cold environmental chamber. Tolerable range of skin temperature (TST) depending on the location of body was obtained by observing the temperature at the time when the heating device was turned on and off during a rest–running–rest protocol.Findings The TST was 32.8–49.4 °C and decreased to 31.3–37.6 °C around abdomen and back waist, respectively. Changes in the wearers' voluntary control behavior were observed depending on the individual's level of cold-sensitivity and activity level of rest and running. TST was 35.8–49.4 °C (Rest 1: rest before exercise), 40.0–42.0 °C (Running) and 35.3–43.2 °C (Rest 2: rest after exercise) for cold-sensitive group, whereas it was 32.8–36.2 °C (Running) and 34.4–45.7 °C (Rest 2: rest after exercise) for cold-insensitive group.Originality/value In this study, results with detailed body locations and wearer's thermal sensitivity provide practical references for the implementation of a heating device to the comfortable multilayered smart clothing.


2021 ◽  
Vol 11 (2) ◽  
pp. 71
Author(s):  
Liming Zhai ◽  
Yaosen Chen ◽  
Zhiwei Li ◽  
Xiaochen Chen ◽  
Jiongming Wang ◽  
...  

In view of the insufficient heating capacity of a supercritical 600 WM unit, it is necessary to determine whether the equipment of the extraction and return heat pipe system can operate normally after the transformation, so as to check the adaptability of the extraction and return heat pipe system equipment of the heating unit. Based on the actual situation and heat balance before and after the transformation of the heating system, this study selects the extracting steam and heat return pipe system of the heating units at all levels, and makes adaptive accounting from the design parameters of the pipeline, and the calculations of steam flow rates or pipe diameters of the pipeline, which provide scientific basis and evaluation for the feasibility of the retrofit scheme.


2021 ◽  
Vol 13 (19) ◽  
pp. 10651
Author(s):  
Miae Seong ◽  
Cheolsoo Lim ◽  
Jaehyun Lim ◽  
Jaewan Park

In this study, a basic study was performed to analyze the seasonal temperature status of a research room in the Global Environment Research Building, where ceiling-embedded indoor units are installed to study the room temperature status of the building, as well as to improve its thermal environment. In addition, a direction for improvement of the indoor thermal environment in the winter was proposed through a CFD (computational fluid dynamics) simulation and was proven by an additional experiment. Through the results of this study, it appeared that if the ceiling-embedded indoor unit was installed in the small indoor space without considering the thermal vulnerability of its perimeter boundary, the air temperature of the upper part was greatly different from that of the bottom part in the winter. Based on the PMV measurement result, the case that used both FCUs and convectors showed 1.33, the biggest maximum and minimum difference, and the case that used all FCUs, convectors and circulating fans showed 0.68, the smallest maximum and minimum difference. Therefore, it was considered that the operating method suggested in the room used in this study would improve not only the temperature stratification but also the thermal comfort. Hence, in this study, as a means to improve the stratification, convectors were installed to minimize the effect of the external thermal environment, and angle-controllable air flowing fans were installed to mitigate the stratification distribution. With such a result, it was intended to present essential data for the improvement of the thermal environment, as well as the conservation of heating energy in the winter, by reviewing the use of the ceiling-embedded indoor units in the future.


Sensors ◽  
2021 ◽  
Vol 21 (18) ◽  
pp. 6252
Author(s):  
Mariacarla Arduini ◽  
Jochen Manara ◽  
Thomas Stark ◽  
Hans-Peter Ebert ◽  
Jürgen Hartmann

An improved apparatus for measuring the spectral directional emissivity in the wavelength range between 1 µm and 20 µm at temperatures up to 2400 K is presented in this paper. As a heating unit an inductor is used to warm up the specimen, as well as the blackbody reference to the specified temperatures. The heating unit is placed in a double-walled vacuum vessel. A defined temperature, as well as a homogenous temperature distribution of the whole surrounding is ensured by a heat transfer fluid flowing through the gap of the double-walled vessel. Additionally, the surrounding is coated with a high-emitting paint and serves as blackbody-like surrounding to ensure defined boundary conditions. For measuring the spectral directional emissivity at different emission angles, a movable mirror is installed in front of the specimen, which can be adjusted by a rotatable arrangement guiding the emitted radiation into the attached FTIR-spectrometer. The setup of the emissivity measurement apparatus (EMMA) and the measurement procedure are introduced, and the derived measurement results are presented. For evaluating the apparatus, measurements were performed on different materials. The determined emissivities agree well with values published in literature within the derived relative uncertainties below 4% for most wavelengths.


Hypertension ◽  
2021 ◽  
Vol 78 (Suppl_1) ◽  
Author(s):  
Jordan C Patik ◽  
Joseph M Stock ◽  
Nathan T Romberger ◽  
Shannon L Lennon ◽  
William B Farquhar ◽  
...  

Impaired vascular function likely contributes to the association between dietary sodium intake and the development of cardiovascular disease. Using the cutaneous microvasculature as a model, we have previously shown that a high sodium (HS) diet blunts local heating-induced vasodilation in normotensive individuals with salt resistant (SR) blood pressure (BP). However, the effect of a HS diet on the cutaneous microvasculature in normotensive salt sensitive (SS) individuals remains unclear. Therefore, we tested the hypothesis that cutaneous microvascular function is reduced by a HS diet to a greater degree in SS compared to SR individuals. After each 7-day controlled feeding diet (low sodium (LS) = 20 mmol/day; HS = 300 mmol/day), an intradermal microdialysis fiber was inserted in the ventral forearm and perfused with Ringer’s solution. Skin blood flow (SkBF) was continuously monitored via laser Doppler flowmetry and a local heating unit was placed over the fiber and heated to 42°C until SkBF reached a stable plateau. Site-specific maximal SkBF was determined by perfusing 28mM sodium nitroprusside and heating to 43°C. Mean arterial pressure (MAP) was assessed at regular intervals on the contralateral arm and was used to calculate cutaneous vascular conductance (CVC = SkBF / MAP). Subjects wore a 24-hr ambulatory BP monitor and collected their urine on the final day of each diet. Fourteen subjects (9W / 5M, 42 ± 14 yr) whose MAP increased >5 mmHg (Δ8 ± 1 mmHg) on the HS diet were defined as SS and were compared to 14 age- (43± 14 yr) and sex-matched SR subjects (Δ1 ± 3 mmHg). SS and SR had similar MAP at baseline (88 ± 9 vs. 90 ± 8 mmHg, P = 0.88) and urinary sodium excretion was increased similarly across groups by the HS diet (Δ239 ± 104 vs. Δ220 ± 66 mmol / 24 hr, P = 0.20). Cutaneous vasodilation in response to local heating was decreased on the HS diet relative to the LS diet in both SS (Δ-9 ± 9 %CVCmax, P = 0.005) and SR (Δ-9 ± 9 %CVCmax, P=0.005); however, there was not a group x diet interaction (P = 0.99). In contrast to our hypothesis, these results suggest that the deleterious effects of high sodium diets on cutaneous microvascular function are similar in normotensive salt sensitive and salt resistant individuals.


Author(s):  
Steven Hill ◽  
Richard P.Turner

AbstractA series of ring compression tests using BS970:708M40 alloy steel samples were studied. These tests were conducted using a 2-factor soak-temperature variable, namely 1030 °C and 1300 °C, and a 4-factor lubricant variable consisting of unlubricated samples, synthetic water-based, graphite water-based, and graphite and molybdenum disulphide viscous grease. The lubricant agents were all applied to the tool/billet interface. Process variables such as blow force and heating were controlled with the use of a gravitationally operated drop hammer and an automated programmable induction-heating unit. This matrix of the experimental parameters offered a sound base for exploring dominant factors impacting upon bulk deformation. This deformation was measured using fully calibrated equipment and then systematically recorded. A finite element modelling framework was developed to further improve the thermo-mechanical deformation process understanding, with finite element (FE) predictions validated through experimental measurement. Through the combined experimental and FE work, it was shown that temperature variation in the experimental parameter matrix played a larger role in determining deformation than the lubrication agent. Additionally, the use of synthetic and graphite water-based lubricants does not necessarily produce greater deformation when used in high-temperature forgings due to the lubricants breaking down, evaporating, or inducing rapid billet cooling as a result of the carrier used (water). Graphite-molybdenum disulphate grease far outperforms the other lubricants used in this trial in reducing friction and allowing deformation to occur across a die-face.


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