Hot Plate Temperature Research Articles

Determination of As, Cu, and Pb in different sugar samples by Atomic Absorption Spectrometer with the help of Multivariate Analysis

A simple and rapid method is described for the determination of As, Cu, and Pb in different sugar samples by conventional wet acid digestion [CAD]. A Plackett-Burman experimental design was used as a multivariate strategy for the evaluation of the effects of several variables simultaneously. The variables, hot plate time [HPT], temperature of hot plate (T), Nitric acid [A] and Acid mixture [AM] have been investigated. From these studies, certain variables showed up as significant, and they were optimized by a Plackett-Burman design (PBD) and 23+star central composite design. Optimum values of the variables were selected to determine the contents of As, Cu and Pb in sugar samples, to know whether consumption of sugar is beneficial for human health or not. The accuracy of the optimized procedure was evaluated by analysis of certified reference materials and standard addition technique. The result obtained by optimized method showed a good agreement with the certified values and sufficiently high recovery > 97%

원통형 리튬이온배터리의 화재위험성에 관한 실험연구

Since the use of Li-ion(lithium-ion) battery is so widespread in Korea, it is happen to various fire accidents. The fire characteristics and mechanisms of Li-ion battery are still a major study in battery system. This paper presents fire characteristics and hazards of cylindrical Li-ion battery using fire experiment. The fire experiment is conducted to attain the stage thermal runway of Li-ion battery placed on the hot plate hold on constant temperature. The hot plate temperature is 300 ℃. Also the fire experiment is conducted to analyze SOC(state of charge) and performance of inert gas agent under open space and low oxygen atmosphere injected to inert gas. The results show that cylindrical Li-ion battery occurs thermal runway approximately 150 ℃ and under low oxygen atmosphere. The thermal runway is not occur in low SOC.

Production and characterization of bio-oil and biochar from ablative pyrolysis of lignocellulosic biomass residues

Agricultural residues are one of the large untapped sources of bio-energy in Thailand, with over 30 million tons available per year. They may be utilized to generate renewable liquid and solid fuels. In this work, pyrolysis of lignocellulosic biomass residues (corncobs, coconut shells, and bamboo residue) was carried out in an ablative pyrolysis reactor with rotating blades. Influences of inert carrier gas flows (5–15 L/min) and rotating frequency (4–8 Hz) at a fixed hot plate temperature of 500 °C on generating bio-oil were investigated. Characterization of bio-oil as well as biochar products was performed. Maximum bio-oil yield was found to be about 50% w/w for coconut shell at 5 L/min of flowrate and 8 Hz of the rotating frequency, and 45% w/w for bamboo residues at the same condition. For corncob, the highest bio-oil yield was 72% w/w at 5 L/min of flowrate and 6 Hz of the rotating frequency. Solid char yields were around 23–28% w/w. The heating values of the liquid oil and solid char were about 20–25 and 23–30 MJ/kg, respectively. Rotating blade ablative reactor was able to generate high yields of bio-oil for agricultural residues. The main compounds of the bio-oil obtained were phenolics, including furfuran, organic acids, aldehydes, alcohols, ethers, and ketones.

Modeling the interrelationship between the parameters for improving weld strength in plastic hot plate welding: A DEMATEL approach

Application of plastics is increasing day by day since plastics offer many distinct advantages as compared to metals. Plastics has mainly good thermal and electrical insulation properties, corrosion resistance, chemical inertness, and high strength to weight ratio. Additionally, these are cheaper in cost as compared to conventional materials. Plastics are additionally easy to process. Nowadays, product requirements are getting critical and thus product design is getting more complex in shape. To manufacture intricate complex shape creates complexity in manufacturing process which is sometimes very difficult or almost not feasible to produce with single manufacturing process. To manufacture such critical products, welding is a complimentary process. Type of weld joint and welding process can be selected based on the product design and load application on the product. Hot plate welding is very simple welding process as compared to other plastic welding process and most commonly used. Good quality weld is the prime objective of welding process. Weld strength is dependent on several parameters which may be process parameters as well as product parameters. The objective of this study is to identify the key parameters in hot plate welding process of the plastics using Decision Making Trial and Evaluation Laboratory which is one of the prioritization techniques. Results of the study focus on understanding the key parameters affecting the weld strength. Study shows that hot plate temperature, welding time, and melting time are the key parameters affecting the weld strength.

The influence of low-temperature surface induction on evacuation, pump-out hole sealing and thermal performance of composite edge-sealed vacuum insulated glazing

Hermeticity of vacuum edge-sealing materials are one of the paramount requirements, specifically, to the evolution of energy-efficient smart windows and solar thermal evacuated flat plate collectors. This study reports the design, construction and performance of high-vacuum glazing fabrication system and vacuum insulated glazing (VIG). Experimental and theoretical investigations for the development of vacuum edgeseal made of Sn-Pb-Zn-Sb-AlTiSiCu composite in the proportion ratio of 56:39:3:1:1 by % (CS-186) are presented. Experimental investigations of the seven constructed VIG samples, each of size 300 mm·300 mm·4 mm, showed that increasing the hot-plate surface temperatures improved the cavity vacuum pressure whilst expediting the pump-out hole sealing process but also increases temperature induced stresses. Successful pump-out hole sealing process of VIG attained at the hot-plate set point temperature of 50 °C and the approximate cavity pressure of 0.042 Pa was achieved. An experimentally and theoretically validated finite volume model (FVM) was utilised. The centre-of-pane and total thermal transmittance values are calculated to be 0.91 Wm−2K−1 and 1.05 Wm−2K−1, respectively for the VIG. FVM results predicted that by reducing the width of vacuum edge seal and emissivity of coatings the thermal performance of the VIG is improved.

Development of the low-cost hot plate temperature controller using Arduino Uno R3

The low-cost hot plate temperature controller was developed using Arduino Uno R3 microcontroller board. The controller composed of the Arduino microcontroller which was the controller main part, a temperature sensor part and a 7-displays part for monitoring temperature values. The K-type thermocouple connected to MAX31850 IC was established for a temperature sensor. The 4-digit 7 segment display was used for temperature monitoring. The controller program consists of measurement, display and controls the PID parameters was developed in Arduino IDE. The hot plate which has 24-ohm heater wire was applied to this experiment. The result has shown that the temperature in the range of 25-500 degree Celsius was controlled with the resolution of 0.25 degree Celsius. Using the trial and error method for the PID parameter varied the target temperature can be reached with the maximum error was 3 degree Celsius.

Boundary layer instabilities in mixed convection and diffusion flames with an unheated starting length

The following study examines the role of streaklike coherent structures in mixed convection via a horizontal heated boundary layer possessing an unheated starting length. The three-dimensionality of flows in this configuration, which is regularly encountered in practical scenarios, has been experimentally probed using non-invasive detection methods. Experiments were conducted in a wind tunnel at the Missoula Fire Sciences Lab, and the wind speed was varied from 0.70 to 2.47 m/s. The buoyant source was varied significantly by either manipulating the surface temperature of a downstream hot plate or employing a diffusion flame. Streaks were visualized in the flow by means of infrared imaging or high speed video, and a novel detection algorithm was developed to quantify important properties and to spatially track these structures over time. Lognormal distributions of spacing were observed initially, and gradual deviations from this fit indicated a deviation from streaklike behavior. The onset of streaks was determined to be controlled by the pre-existing disturbances populating the incoming boundary layer. Further downstream, buoyant forces dominated the growth and deformation of these structures, whose length scale increased significantly. The width of structures was observed to asymptote to a stable value downstream, and this was determined to be a consequence of the finite distance over which heating was applied.

Influence of fin size and distribution on solid-liquid phase change in a rectangular enclosure

This paper details a numerical study of solid-liquid phase change heat transfer in a rectangular enclosure with the aim of optimizing the number, dimension, and positioning of fins in the enclosure. The enclosure is exposed on one side to a constant heat flux of 1000 W/m2 for 3 h and both the total fin mass and the PCM mass are kept constant in all simulated cases. The heat diffusion equation in the PCM uses the equivalent heat capacity method while natural convection driven PCM motion in the enclosure is modeled through the buoyancy force, using a modified viscosity and an additional volume force term in the Navier-Stokes momentum conservation equation. Three efficiency assessment parameters are used: (i) the height-averaged temperature of the front hot plate which should remain as low as possible for the longer possible time, (ii) the energy stored inside the PCM as a function of time, and (iii) the heat transfer rate and heat flux between the front plate and the PCM. For each simulated case, complementary data such as the standard deviation of temperature along the heated plate and the ratio of sensible heat to latent accumulation are also calculated. Results show that increasing the number of fins diminishes both the stabilization temperature and the stabilization time of the front plate during phase change, and accelerates the sensible and latent storage of energy in the PCM. Using thinner but longer fins provides the same impact except that the stabilization time also increases as the fin length is increased. Besides, at constant fin mass, varying fin spacing have marginal impact on the latent heat storage performance and on the hot plate temperature stabilization. The study also shows that the surface area plays the largest role in the increase of the heat transfer rate between the front plate and the PCM, while configurations which can promote stronger natural convection lead to higher heat flux. Finally, it was observed that systems allowing easier heat transfer to the back plate during melting provide a higher ratio of sensible heat to latent accumulation, while the standard deviation of the front plate temperature decreases as the number of fins or the spacing between fins increases.

Production and characterization of the mechanical and thermal properties of expanded polystyrene with recycled material

<p>Three materials were made with mixtures of virgin expanded polystyrene (EPS) grade S3 and recycled material from multipurpose EPS packaging. The latter was subjected to washing and grinding in a blade mill, with percentages by weight of recycled material 10, 15, and 20%. The mechanical properties of these materials were evaluated by testing compressive strength and flexural, impact, and thermal properties using the techniques of differential scanning calorimetry and thermogravimetry. Hot plate and steady state temperature profiles in a non-steady state were simulated with Octave 3.6.4. The results obtained for the three mixtures showed little variation in the properties of compression, impact, glass transition, and thermal diffusivity with respect to the reference material. The regularity of the decline in mass loss as a function of temperature evidences homogeneity in the samples. The flexural strength decreased the maximum failure load compared to the virgin material, and the thermal conductivity exceeded 0.06W/mK, reducing their insulating capacity. These materials can be industrially manufactured in order to produce packaging, caissons, and spheres, among other things.</p>

Haze particles removal and thermally induced membrane dehumidification system

Abstract Air conditioning systems consume a large portion of energy to remove the latent heat of moisture to reach the indoor comfort level in Southeast Asia due to the high relative humidity. The worsening air pollution causes significant health concerns in recent years. Therefore, an efficient strategy to simultaneously remove both haze particles and excess humidity is very important, particularly for large buildings. In this study, a thermally induced membrane dehumidification system was established by using waste energy to create a partial pressure difference of water vapor across the membrane to reduce the excess humidity. A pilot scale system test showed that the removal of water vapor was a function of hot plate temperature and up to 12.4% of water vapor could be effectively removed by using a merely 0.55 m2 polytetrafluoroethylene - polydimethylsiloxane (PTFE-PDMS) flat membrane with the aid of an air blower at a pressure of 8.54 mbar. As a result, the inlet air with a water vapor concentration of 24.3 ± 0.5 g/m3 dropped to 21.3 ± 0.5 g/m3 after the dehumidification. The calculated energy saving in this dehumidification process was about 10.8% with ΔE = 93.0 kJ/h. In addition, the newly developed stacked polypropylene - polydimethylsiloxane (PP-PDMS) filter showed the particle removal efficiency up to 98.2% with a very minimal pressure loss of 0.18 mbar.

Investigating coherent streaks in wildfires via heated plates in crosswind

Streaklike coherent structures are consistently observed in boundary layer flames, but their role in modifying heat and mass transfer remains unknown. In the following experiment, a non-reactive thermal plume was employed to study analogous streaks in an environment where the local source of buoyancy could be directly modified. A horizontal hot plate was exposed to crossflow, and infrared thermography was successfully employed to capture thermal traces of streaks on the surface. Post-processing of surface temperature data enabled the quantification of important properties of streaks, such as location, spacing, width, and strength. The distribution of streak spacing was found to have a lognormal distribution. Mean streak spacing and width increased with downstream distance, indicating the amplification and aggregation of coherent structures. Streak spacing decreased when either the hot plate temperature increased from 150°C to 300°C or the wind speed increased from 0.5 to 1.2m/s. Streaks were seen to modify the spanwise distribution of heat transfer to the surface, most notably when the hot plate temperature was increased from 150°C to 300°C.

Highly Sensitive Sensors Based on Metal-Oxide Nanocolumns for Fire Detection.

A fire detector is the most important component in a fire alarm system. Herein, we present the feasibility of a highly sensitive and rapid response gas sensor based on metal oxides as a high performance fire detector. The glancing angle deposition (GLAD) technique is used to make the highly porous structure such as nanocolumns (NCs) of various metal oxides for enhancing the gas-sensing performance. To measure the fire detection, the interface circuitry for our sensors (NiO, SnO2, WO3 and In2O3 NCs) is designed. When all the sensors with various metal-oxide NCs are exposed to fire environment, they entirely react with the target gases emitted from Poly(vinyl chlorides) (PVC) decomposed at high temperature. Before the emission of smoke from the PVC (a hot-plate temperature of 200 °C), the resistances of the metal-oxide NCs are abruptly changed and SnO2 NCs show the highest response of 2.1. However, a commercial smoke detector did not inform any warning. Interestingly, although the NiO NCs are a p-type semiconductor, they show the highest response of 577.1 after the emission of smoke from the PVC (a hot-plate temperature of 350 °C). The response time of SnO2 NCs is much faster than that of a commercial smoke detector at the hot-plate temperature of 350 °C. In addition, we investigated the selectivity of our sensors by analyzing the responses of all sensors. Our results show the high potential of a gas sensor based on metal-oxide NCs for early fire detection.

Power Response of a Planar Thermoelectric Microgenerator Based on Silicon Nanowires at Different Convection Regimes

Abstract A thermoelectric microgenerator based on multiple silicon nanowire arrays is fabricated and its performance evaluated for different convection regimes. Mature silicon microfabrication technology is used to fabricate the device structure. As a post-process, a bottom-up approach is used to grow silicon nanowires by a VLS-CVD mechanism. The thermal design of the microgenerator features a thermally isolated silicon platform which is connected to the bulk silicon rim through several arrays of silicon nanowires. Simulations are carried out to evaluate the need of an external heat sink to improve the thermal gradient seen by the nanowires and the power output of the microgenerator. Results show a significant improvement with a heat sink raising the thermal gradient from 3 K to approximately 100 K when the external temperature gradient is 300 K. Experimental measurements with different convection regimes also show a radical improvement on the power output comparing natural convection and two different forced convection regimes. The first forced convection regime is a broad airflow from a commercial CPU fan placed on top of the device, while the second (air jet forced convection) uses a syringe to focus the airflow from the compressed air line to the platform. The maximum output power for a natural convection regime is 2.2 nW for a hotplate temperature of 200 °C, while the air jet forced convection regime generates up to 700 nW, which correspond to 35 µW/cm2 considering a device footprint of 2 mm2.

Numerical study on the ignition behavior of coal dust layers in air and O2/CO2 atmospheres

Understanding the fundamental basis of coal dust layers ignition behavior is of interest for the mitigation of industrial fires and explosions. This paper develops a 2D numerical method to investigate the self-ignition of coal dust layers with an emphasis on the roles of the oxygen mole fraction and diluent gas. A global one-step 2nd-order reaction kinetic model considering both coal density and oxygen density is used to estimate the reaction rate of self-heating process until ignition. In addition, the overall heat transfer coefficient is evaluated based on a steady state method and the kinetic parameters are estimated by fitting experimental and numerical temperature evolution figures. This model has been found to be valid to predict the transient temperature and concentration profiles until ignition. The numerical results of the minimum ignition temperature of dust layers (MITL) are in close agreement with experimental observations. The ignition delay time and the most sensitive ignition position (MSIP) of dust layer are found to vary with varying ambient gas conditions, hot plate temperatures and ambient temperatures using the verified model. The model provides a satisfactory explanation for the dependence of ignition characteristics of coal dust layer in oxygen-enriched oxy-fuel atmospheres.

적외선 램프 가열방식을 이용한 태양전지 셀의 솔더링 공정 및 열처리 조건 별 특성 평가

A key point of a soldering process for photovoltaic (PV) modules is to increase an adhesive strength leading a low resistivity between ribbon and cell. In this study, we intended to optimize a heating condition for the soldering process and characterize the soldered joint via physical and chemical analysis methods. For the purpose, the heating conditions were adjusted by IR lamp power, heating time and hot plate temperature for preheating a cell. Since then the peel test for the ribbon and cell was conducted, consequently the peel strength data shows that there is some optimum soldering condition. In here, we observed that the peel strength was modified by increasing the heating condition. Such a soldering property is affected by a various factors of which the soldered joint, flux and bus bar of the cell are changed on the heating condition. Therefore, we tried to reveal causes determining the soldering property through analyzing the soldered interface.

Sedimentation in nanofluids during a natural convection experiment

This study presents an experimental investigation of the thermophysical behavior of γ-Al2O3–deionized (DI) H2O nanofluid under natural convection in the classical Rayleigh–Benard configuration, which consists of a cubic cell with conductive bottom and top plates, insulated sidewalls and optical access. The presence of nanoparticles either in stationary liquids or in flows affects the physical properties of the host fluids as well as the mechanisms and rate of heat and mass transfer. In the present work, measurements of heat transfer performance and thermophysical properties of Al2O3–H2O nanofluids, with nanoparticle concentration within the range of 0.01–0.12vol.%, are compared to those for pure DI water that serves as a benchmark. The natural convective chamber induces thermal instability in the vertical direction in the test medium by heating the medium from below and cooling it from above. Fixed heat flux at the bottom hot plate and constant temperature at the top cold plate are the imposed boundary conditions. The Al2O3–H2O nanofluid is tested under different boundary conditions and various nanoparticle concentrations until steady state conditions are reached. It is found that while the Rayleigh number, Ra, increases with increasing nanoparticle concentration, the convective heat transfer coefficient and Nusselt number, Nu, decrease. This finding implies that the addition of Al2O3 nanoparticles deteriorates the heat transfer performance due to natural convection of the base fluid, mainly due to poor nanofluid stability. Also, as the nanoparticle concentration increases the temperature at the heating plate increases, suggesting fouling at the bottom surface; a stationary thin layer structure of nanoparticles and liquid seems to be formed close to the heating plate that is qualitatively observed to increase in thickness as the nanoparticle concentration increases. This layer structure imposes additional thermal insulation in the system and thus appears to be responsible in a big extend for the reported heat transfer degradation. Also, for relatively high nanoparticle concentrations of 0.06 and 0.12vol.%, as the heating flux increases the rate of heat transfer deterioration increases. Specifically in the case of maximum nanoparticle concentration, 0.12vol.%, when the turbulence intensity increases, by increasing the applied heat flux, the Nusselt number remains constant in comparison with lower nanoparticle concentrations. This behavior can be attributed mainly to the physical properties of the Al2O3 nanopowder used in this study and the resulting interactions between the heating plate and the nanoparticles.

Experimental investigation of U value of double-glazed window with inter-pane blinds using Taguchi techniques

In this research article, Taguchi L18 orthogonal array has been employed on guarded heat plate apparatus to determine ‘unit heat loss rate’ (U value) of a double-glazed window with inter-pane venetian blinds by varying processes and glazing system’s parameters, i.e. temperature difference between hot and cold plates, low-emissivity (low-e) coating and its location, slat angle of blinds, pane spacing and hot plate temperature (selected as per composite climate in India). The analyses of the raw data and signal-to-noise (S/N) ratio of the response parameters have been performed using analysis of variance (ANOVA). The insignificance of temperature of hot plate has been reiterated. The optimum parameters predicted on the basis of analyses of S/N ratio (pooled ANOVA) are (a) temperature difference of 10 °C, (b) presence of low-e coating on inner surface of outside pane, (c) slat angle of 90° and (d) pane spacing of 32 mm. The quantification of the influence of various parameters on U value has been done through prediction of percentage contribution. The significant parameters in order of their decreasing percentage contribution are presence of low-e coating (49.2 %), slat angle (32.52 %), temperature difference between hot and cold plates (8.76 %) and pane spacing (4.33 %), respectively.

급속 열처리 시스템을 위한 물/공기 액적류 충돌 제트의 냉각 특성에 관한 연구

ABSTRACT In the present work, a series of numerical calculations have been conducted on the cooling of a hot surface using an air/water mist jet. In some cooling processes, such as in the glass-tempering process, direct contact between the cold water drops and the hot surface should be avoided, because this may cause surface cracks due to the sharp temperature gradients. Thus, the main focus of this study is finding the appropriate operating conditions for maximum cooling without direct contact between the drops and the surface. A series of numerical experiments have been performed, and, at the same time, those results were compared with those of the previous experiments for verification purposes. The effects of droplet impinging velocity, hot plate temperature, and liquid loading ratio for mono-dispersed drops of various sizes were studied in detail.KeyWords : Mist Flow( ), Jet Impinging( ), Hot Plate( ), Mist-jet Cooling Map액적류 충돌 제트 고온 평판 (액적충돌기준선도) # Corresponding Author : jklee99@kyungnam.ac.kr Tel: +82-55-249-2613, Fax: +82-55-249-2617

Comparative study of simulation and experimentation for the U-value of double-glazed windows with inter-pane blinds

This article applies the Taguchi design on a simulation as well as on an experimentation technique to determine the thermal transmittance (U-value) of a double-glazed window with inter-panes blinds so as to explore its performance potential for a particular Indian climate. Environmental parameters are selected per the composite climate in India. Simulated results show a maximum of 20% variation when compared with experimental ones. Analysis of results shows that Taguchi methods are effective in ranking the effect of various parameters on the U-value of identified glazing units. The low-emissivity glazing system ranks first, followed by slat angle, temperature difference, pane spacing, and temperature of hotplate (representing climatic conditions). The analysis of means is also carried out to identify the best combination of levels of various parameters.

Towards MEMS Pellistor Spectrometers

We report on an innovative use of high-temperature MEMS heater platforms as micro pellistor spectrometers. MEMS heater elements, initially designed for use as thermal infrared emitters, were fitted with thin-film noble metal layers to enable catalytic combustion processes on the hotplate surface. The modified heater platforms were operated in a range of combustible gas ambients while applying saw-tooth-like heater waveforms. Measurements of this kind revealed the heat of reaction vs. hotplate temperature profiles for each individual gas. We find that different families of gases yield distinctly different heat of reaction vs. temperature profiles and that these profiles allow the different families, and members inside some of these families, to be distinguished.