Industrial Oven Research Articles

Modelling of temperature distribution along PCB thickness in different substrates during reflow

Purpose In this paper, analytical modelling of heat distribution along the thickness of different printed circuit board (PCB) substrates is presented according to the 1 D heat transient conduction problem. This paper aims to reveal differences between the substrates and the geometry configurations and elaborate on further application of explicit modelling. Design/methodology/approach Different substrates were considered: classic FR4 and polyimide, ceramics (BeO, Al2O3) and novel biodegradables (polylactic-acid [PLA] and cellulose acetate [CA]). The board thicknesses were given in 0.25 mm steps. Results are calculated for heat transfer coefficients of convection and vapour phase (condensation) soldering. Even heat transfer is assumed on both PCB sides. Findings It was found that temperature distributions along PCB thicknesses are mostly negligible from solder joint formation aspects, and most of the materials can be used in explicit reflow profile modelling. However PLA shows significant temperature differences, pointing to possible modelling imprecisions. It was also shown, that while the difference between midplane and surface temperatures mainly depend on thermal diffusivity, the time to reach solder alloy melting point on the surface depends on volumetric heat capacity. Originality/value Results validate the applicability of explicit heat transfer modelling of PCBs during reflow for different heat transfer methods. The results can be incorporated into more complex simulations and profile predicting algorithms for industrial ovens controlled in the wake of Industry 4.0 directives for better temperature control and ultimately higher soldering quality.

Development of the physical and mathematical model of the baking process of the dough pieces in bakery ovens

The object of research is the physical and mathematical models designed to describe the heat and mass transfer inside the porous material during baking. In order to improve the quality and at the same time reduce energy consumption in production, as well as improve the technical and economic indicators of the operation of furnaces, the duration and safety of their operation, the designs of furnace units are being improved, new ones are being developed and their thermal conditions are being optimized. One of the biggest problems is the task of replacing obsolete oven designs with new ones, with automatic regulation of the thermal regime of baking, which will ensure high quality bread while reducing fuel, steam, electricity and human resources. Since the quality of products, in particular, taste, aroma, porosity, gloss, appearance and other indicators of bakery products, largely depends on the design of the furnace unit, the thermal and hygrothermal conditions of the working chamber, as well as its proper operation. These factors affect the loss during baking, which can vary from 6 to 12 %, which affects the yield of bread. This paper presents a physical and mathematical model of the process of baking dough pieces in baking ovens using the example of the industrial oven K-BOM-25 (Ukraine) developed by the author.A mathematical model of the process of baking bread in the gas channels of the baking chamber is given taking into account radiation-convective heat transfer, mass transfer taking into account the introduction of water vapor to moisten the dough pieces and turbulence of the multiphase flow. The dependence of the multiphase flow turbulence is formulated on the basis of the Euler equations averaged over Reynolds. This model allows with sufficient accuracy and detail to take into account the technological conditions and design features of modern conveyor baking ovens. And it also allows for extensive parametric studies of conjugate heat transfer in them with access to the final indicator – the quality of finished products.

Optimization of electrostatic powder coat cure oven process: A capstone senior design research project

Abstract This paper describes one successful example of a capstone senior design research project that deals with optimization of the electrostatic powder coat cure process. Optimizing any manufacturing process provides a company with extensive benefits obtained through increased productivity, reduced manufacturing costs, and quicker time to market. Along with the explicit production cost benefits, a company will also reap the benefits of a decreased environmental impact and increased market competitiveness accruing from increased productivity. Therefore, companies are incentivized to continually improve, and optimize their production processes. One such process that many products, throughout numerous industries, go through is the painting process. While painting a product can aid in easily identifying certain brands (e.g. John Deere green, Caterpillar yellow, New Holland blue, International Harvester red, etc.), the main purpose of providing a painted surface is to protect the product from environmental corrosion, and wear in addition to providing a drastically longer life cycle to the product. One of the most important steps of the painting process is the curing of the paint on the surface of the product. This is normally done through an industrial oven set at appropriate temperatures and times depending on the paints used and the products to be painted. Using DOE, ANOVA, and other statistical analysis tools for data collection and analysis, a cure oven set at 450 °F for 40 minutes was optimized to 450 °F for 38 minutes. This provides a 5% decrease in both process time and natural gas usage while continuing to maintain the same level of quality. This demonstrates the effectiveness of DOE tools and statistical analysis of collected data coupled with the principles of process optimization in increasing productivity and reducing overall production costs.

Temperature Control and Stabilization of an Industrial Oven Using Thermoelectric Devices as the Stabilize Actuator

Temperature Control and Stabilization of an Industrial Oven Using Thermoelectric Devices as the Stabilize Actuator

The effects of an internal isolated plate on natural convective heat transfer inside an industrial oven

This paper concerns with the problem of natural convection heat transfer inside an industrial oven with an internal plate. The model is simulated numerically as a square cavity with an isolated plate laid horizontally or vertically inside it. Different ranges of Rayleigh number from laminar to turbulent flow regimes were investigated numerically and inherent flow structures and the amount of transferred heat were obtained. The governing Reynolds-averaged Navier-Stokes and energy equations are discretized and solved applying finite-volume method. Moreover, a two-layer zonal model is applied for near-wall turbulent properties. Comparing the present results with similar previous studies and experimental data shows that the employed zonal model is more accurate than other existing turbulent models. Our results also demonstrate that the total rate of heat transferred by a cavity with internal isolated plate is always lower than that of a bare cavity. As the distance of internal plate from the cavity wall decreases, its effect on the reduction of overall heat transfer increases accordingly. We also determined a distance between the plate and the cavity wall with less than 2% change in relative Nusselt number and deduced that the maximum distance of vertical plate is always greater than that of the horizontal plate at each Rayleigh number. Furthermore, a dead zone is created between the hot wall and the plate with low velocities, the temperatures close to the hot wall temperature, and very weak circulation, which can significantly reduce the overall heat transfer in the cavity. The results of this work can be used in glass industries and reduction of heat loss in industrial ovens by placing the glass sheets inside them in appropriate position.

Evaluation of microwave toasting of corn flakes

During flake production, corn undergoes processes of cooking, drying, tempering, laminating, and toasting. The toasting dictates the attributes of the finished product for the consumer acceptability. Traditionally corn flakes are toasted in high efficiency forced convection systems such as rotary or fluidized-bed ovens. The aim of the present work was to study microwave thin layer toasting of cooked flakes using a household oven. Flakes toasted in a fluidized-bed industrial oven were adopted as control. The effect of microwave power level and process time on the kinetics of dehydration and quality parameters such as bulk density, thickness, and sensorial attributes of flakes were investigated. Kinetics data were satisfactorily simulated by Peleg's equation as function of drying time. A relationship between moisture ratio, output energy, and microwave power was also derived from experimental tests. A significant reduction of processing time in comparison with the traditional method was observed by selecting a suitable level of microwave power. Practical applications This paper describes an innovative and novel method to obtain organoleptically acceptable corn flakes. The results demonstrated that microwave heating can be used to substitute the traditional drying systems used for flakes toasting, with the possibility of reaching a reduction of process time, depending on the accurate selection of process parameters.

CARACTERIZAÇÃO DE BIOMASSA RESIDUAL DE FÁBRICA DE PAPEL-CARTÃO PARA APROVEITAMENTO ENERGÉTICO

Um dos problemas da indústria de papel e celulose é a disposição de resíduos sólidos em aterros industriais, pela escassez de áreas disponíveis para esta finalidade e ao impacto ambiental gerado. Uma das formas de avaliar o potencial energético de materiais celulósicos residuais é pela determinação do seu poder calorífico. Esta pesquisa teve como objetivo caracterizar os resíduos celulósicos de uma fábrica de papel-cartão por análise imediata e análise elementar, para estimar o poder calorífico e avaliar o potencial de aproveitamento energético na combustão misturada com cavacos na fornalha de caldeira. Foram analisados os combustíveis normalmente queimados na caldeira de biomassa para geração de vapor: cavacos de madeira de pinus, cascas de madeira de pinus e os resíduos gerados na fabricação de papel-cartão: fibras e fiapos de madeira da fabricação de pasta mecânica de madeira, fibras da estação de tratamento de efluentes - ETE e cinzas da caldeira. Os resíduos celulósicos fibras da ETE, fibras e fiapos de madeira apresentaram potencial para utilização energética, desde que submetidos a processo de secagem para redução da umidade e aumentar o poder calorífico. As cinzas da caldeira tem poder calorífico residual podendo ser reaproveitadas na combustão com cavacos de madeira.

Understanding Thermal Overdrive in Industrial Ovens

Abstract A temperature management system is essential to accurately monitor and control the heat treating process for maximum productivity and product quality.

Studying heat transfer on inclined printed circuit boards during vapour phase soldering

PurposeThe paper aims to present an investigation of heating during vapour phase soldering (VPS) on inclined printed circuit board (PCB) substrates. The PCB is a horizontal rectangular plate from the aspect of filmwise condensation with a given inclination setting.Design/methodology/approachThe paper focuses on the measurement of temperature distribution on the PCBs with a novel setup immersed in the saturated vapour space. The measuring instrumentation is optimized to avoid and minimize vapour perturbing effects.FindingsThe inhomogeneity of the heating is presented according to the lateral dimensions of the PCB. The inclination improves temperature uniformity, improves heat transfer efficiency; however, a minor misalignment may affect the flow and result in uneven heating.Practical implicationsThe results can be implemented for practical improvements in industrial ovens with the use of intended inclination. The improvements may consequently point to more efficient production and better joint quality.Originality/valueThe novel method can be used for deeper investigation of inclination during and can be complemented with numerical calculations. The results highlight the importance of precise PCB holding instrumentation in VPS ovens.

Sustainability indicators for industrial ovens and assessment using Fuzzy set theory and Monte Carlo simulation

Industrial ovens play a significant role in many manufacturing and process industries. Despite the desire to enhance sustainability throughout this sector, research looking to improve the sustainability of industrial ovens is in its infancy. This paper presents seven sustainability indicators to assess potential oven investment; these include system air flow, production efficiency, operating costs, quality, capital investment, toxicity and employment opportunity. The indicators are straightforward, can be scored with readily available data and have been weighted by industrial experts. A hybrid multi-criteria approach using Fuzzy set theory and Monte Carlo simulation has been developed to help evaluate the sustainability of alternative improvement options. The approach is required as previous methodologies only present desirability as a singular figure; and therefore decision makers are not provided with sufficient information on associated risk. The presented approach incorporates uncertainty throughout, and gives option desirability in terms of mean, standard deviation and variance. The risks using this method are better understood and can significantly aid industrial decision makers. The sustainability indicators and hybrid approach have been demonstrated using a case study in the manufacturing industry; to identify the most sustainable way to increase cure conversion within an oven. Amongst the three options: increasing oven size, increasing oven temperature and new product formulation, increasing oven temperature shows the highest desirability, while new product formulation though has a lower desirability has the highest certainty. Furthermore, a cumulative desirability distribution plot gives a basis to select option that is aligned with the business's risk strategy.

Industrial oven improvement for energy reduction and enhanced process performance

Industrial ovens consume a considerable amount of energy and have a significant impact on product quality; therefore, improving ovens should be an important objective for manufacturers. This paper presents a novel and practical approach to oven improvement that emphasises both energy reduction and enhanced process performance. The three-phased approach incorporates product understanding, process improvement and process parameter optimisation. Cure understanding is developed using Dynamic Mechanical Analysis (DMA) and CIE-Lch colour tests, which together highlight the impact of temperature variation on cure conversion and resulting product quality. Process improvement encompasses thermodynamic modelling of the oven air to evaluate the impact of insulation on temperature uniformity and system responsiveness. Finally, process parameters, such as temperature, pressure negativity and air flow, are optimised to reduce energy consumption. The methodology has been effectively demonstrated for a 1 MW festoon oven, resulting in an 87.5 % reduction in cooling time, saving 202 h of annual downtime and a reduction in gas consumption by 20–30 %.

Development of correlations and artificial neural network models to predict second-degree burn time for thermal-protective fabrics

Firefighters and operators working near industrial furnaces or ovens usually encounter extreme environmental conditions. Heat transfer through fabrics exposed to such high heat flux exposures causes skin burn. There are various parameters which govern heat transfer and second degree burn time in such situations. In this work, six dimensionless parameters associated with heat transfer through fabrics exposed to various flame and radiant heat flux exposures are obtained. Correlations for dimensionless second degree burn time are obtained in terms of other non-dimensional parameters. These separate correlations for each type of exposure can be used to obtain thermal protective performance (TPP) of any fabric exposed to different type of heat conditions, provided that fabric material, fabric geometric parameters, air gap between fabric and skin, and intensity of heat exposure are known. Artificial neural network (ANN) approach is also used to predict TPP of clothing. Multi-layer feed-forward back-propagation networks are developed for different type of exposures. Results shows that both correlations and ANN approach used in the study are promising. ANN model predictions are found to agree better with experimental observations as compared to the outcome of developed correlations. Importance of various dimensionless parameters obtained using dimensional analysis are also emphasized.

Environmental impact of polymer-waste disposal

The laboratory carbonization of well-known polymers to 850°C is studied, in order to determine the benzo[a]pyrene emissions. In carbonization, the exhaust gases from all the polymers contain benzo[a]pyrene in levels far exceeding workplace air standards. The levels are higher for carbon-chain polymers than for heterochain polymers. The utilization of polymer wastes with the coal batch in coke ovens is investigated. It is found that the yield of gas and its content of benzo[a]pyrene are several times higher than for industrial coke ovens. This means that, in the industrial coking of coal batch with added carbon-chain polymers, elevated expansion pressure should be expected in the coke oven, along with increased atmospheric emissions of benzo[a]pyrene.

Bioactive maca (Lepidium meyenii) alkamides are a result of traditional Andean postharvest drying practices

Maca, Lepidium meyenii Walpers (Brassicaceae), is an annual herbaceous plant native to the high plateaus of the Peruvian central Andes. Its underground storage hypocotyls have been a traditional medicinal agent and dietary staple since pre-Columbian times. Reported properties include energizing and fertility-enhancing effects. Published reports have focused on the benzylalkamides (macamides) present in dry hypocotyls as one of the main bioactive components. Macamides are secondary amides formed by benzylamine and a fatty acid moiety, with varying hydrocarbon chain lengths and degree of unsaturation. Although it has been assumed that they are usually present in fresh undamaged tissues, analyses show them to be essentially absent from them. However, hypocotyls dried by traditional Andean postharvest practices or industrial oven drying contain up to 800μgg−1 dry wt (2.3μmolg−1 dry wt) of macamides. In this study, the generation of macamides and their putative precursors were studied during nine-week traditional drying trials at 4200m altitude and in ovens under laboratory conditions. Freeze–thaw cycles in the open field during drying result in tissue maceration and release of free fatty acids from storage and membrane lipids up to levels of 1200μgg−1 dry wt (4.3μmolg−1 dry wt). Endogenous metabolism of the isothiocyanates generated from glucosinolate hydrolysis during drying results in maximal benzylamine values of 4300μgg−1 dry wt (40.2μmolg−1 dry wt). Pearson correlation coefficients of the accumulation profiles of benzylamine and free fatty acid to that of macamides showed good values of 0.898 and 0.934, respectively, suggesting that both provide sufficient substrate for amide synthesis during the drying process.

Definition of rational modes of operation of baking ovens

The flue gas temperature is one of the main variables that are most sensitive to changes in load in industrial ovens. This temperature in turn is associated with the loss of heat from the flue gases. The last value determines the change in fuel consumption, not directly related to the load. Therefore, the problem of determining a rational oven load is reduced mainly to establish the exact or approximate relation tf1=f(G).The authors is studied the work at alternating mode of ovens with recirculation of combustion products - the most common type of baking ovens. In these furnaces load increase leads to an increase of tf1, and decrease - to decrease of tf1.Increasing the temperature of the flue gas with increasing of oven productivity is explained by the fact that productivity causes a corresponding change in the heat flow to the working chamber of the oven. This change is due to increased fuel consumption and increasing the initial temperature of the heating gases. The growth in the total enthalpy heat transfer ΔQ gas determines the increase of them, which leads to increase of tf1.Thus, the change in heat flow into the working chamber is caused by a change in the temperature difference of the heating gases. The calculations show that the change in different modes of temperature difference, calculated as the difference between the average temperature of the heating gas and the walls of the working chamber by the law of convective heat transfer, well reflects the change under the same conditions.The obtained research can be applied to bakeries, at installation and after repair of baking ovens in order to obtain high-quality products with minimal cost of fuel-energy resources.

Prediction of coke oven wall pressure

Internal gas pressure (IGP) developed by coking coals upon carbonisation accounts for oven wall pressure (OWP). If not controlled, this OWP may be potentially dangerous as it can easily exceed the 10kPa acceptable limit. In this work, a simple, physically based, expression of IGP in a slot-type coke oven is presented, validated on data available in literature and modified into a ready-to-use expression of OWP fitted on measurements from the movable wall pilot oven of the Centre de Pyrolyse de Marienau (CPM) over a wide range of single coals. Expressed as a function of coal characteristics and carbonisation conditions, this OWP prediction is accurate enough to serve as a process tuning tool. However, probably because additivity rule does not apply easily to inert content, the model fails to predict OWP in case of blends. Extrapolation from the pilot oven to the industrial oven has been proved.

Systematic approach to industrial oven optimisation for energy saving

Industrial ovens consume a sizable proportion of energy within the manufacturing sector. Although there has been considerable research into energy reduction of industrial processes throughout literature, there is not yet a generalised tool to reduce energy within industrial ovens. The systematic approach presented aims to guide an engineer through five stages of oven optimisation. These involve defining the scope of the optimisation project, measuring and analysing process variables in order to develop fundamental understanding of the system so that an optimisation plan can be established and then implemented. The paper gives an application example of the methodology to a curing oven within a masking tape manufacturing facility. This approach showed an estimated annual saving of 1,658,000 kWh (29% reduction of the oven's energy consumption and a 4.7% reduction of the whole plant's energy consumption) with very little capital expenditure. As the methodology can be tailored to accommodate individual optimisation options for each oven scenario, while still providing a clear pathway, it has potential applications within the wider manufacturing industry.

Effect of Heating Rate on Coke Quality and Productivity in Nonrecovery Coke Making

The productivity and coke quality of a nonrecovery oven depends on coal blend, operating parameters, and heating rate. A numerical methodology has been proposed for predicting temperatures of the intermediate points with the help of measured temperature in the coke oven. The model was validated with an actual temperature profile of five industrial ovens. The developed model can predict the temperature profile of the oven for a given set of operating conditions. The heating rate under normal operation was found to be in the range of 0.64–1.17°C/min. The effect of temperature variation inside the oven was also correlated with the coke quality and productivity.

A method for calculating the absorption properties of triatomic gases

Formulas are proposed for the steam and carbon dioxide absorption coefficients, which are widely used in calculations of radiant heat transfer in industrial ovens and furnaces and containing empirical correction multipliers approximated over the beam length by logarithmic polynomials the coefficients of which are interpolated with respect to gas temperature. Generally, the error in the steam and carbon dioxide absorption capacities calculated using these formulas does not exceed 3%, which is quite acceptable in engineering calculations of radiant heat transfer. It is shown that the absorption capacity of a mixture of steam and carbon dioxide calculated using the exponential function of the total absorption coefficient does need correction for mutual absorption of beam energy by the components of medium.

Study on Heating Behaviour of Coal during Carbonization in Non-Recovery Oven

The coking process is based on the transformation of coal into coke at high temperature. In non-recovery coke oven, heating is usually asymmetric, this may be due to the fact that heating is provided by controlled combustion of volatile matter of charged cake at oven crown and sole flue.In the present investigation, a simp lified temperature profiles were simu lated to typical temperature pro files of the non-recovery coke oven. The selection criterions of ovens were based on the oven temperature and coking time. Based on measurement of heating pattern, a numerical methodology was proposed for predicting temperature of the intermed iate point by using Lagrange interpolation method. Further, a MATLA B-based algorith m was used to predict the same heating pattern based on actual temperature profile in a non-recovery oven. The model was tested and validated with actual temperature profile of six industrial ovens. The model also reproduces the main feature of the measured temperature profile and shown good agreement with experimental data of industrial oven. The pred icted temperature pro file can discriminate d ifferent operating conditions and works well even at low level of temperature deviation. These variations will affect the heating rate and coking cycle, superimposed on the oven crown and sole temperature pattern. However, the operating temperatures were the most important factor fo r normal operation and found that the heating rate of normal operation was varied in the range of 1.06 -0.62℃/ min at a height of 200mm fro m top & bottom and centre of the charged cake.