Infrared Radiation Heating Method Research Articles

Evaluation of Quality Characteristics of Potato Slices during Drying by Infrared Radiation Heating Method under Vacuum

The effect of drying behaviour on the drying rate and quality characteristics of potato slices in a vacuum- infrared drying system was studied. In this work, the effect of the infrared radiation powers (100, 150, and 200 W) and vacuum levels (20, 80, 140 mmHg and atmosphere pressure) at different slice thickness (1, 2 and 3 mm) on drying rate and shrinkage percentage and rehydration capacity were investigated. From the study, it was concluded that IR power level has a significant effect on processing time and drying rate. With increasing radiation power, time drying is reduced and consequently drying rate is increased. The drying rate curve of potato slices at initial drying time is in the ascending phase because of surface moisture evaporation and after this phase due to the start of influence of water from within of material to surface descending phase occurs. Also, shrinkage percentage increased with increase of sample thickness. In other words, shrinkage was decreased at different thickness with an increase of infrared radiation power and vacuum level. It was discovered that the long period of drying and increase of sample thickness may have contributed to a decrease in rehydration capacity. Because of porous texture of potato, as soon put in boiling water for 3 minutes, the water absorption process quickly started and before the insert damage to product tissues, to maximum amount of water absorption will reach. The results also showed that with increasing shrinkage, rehydration capacity was decreased.

Evaluation of Thermal Shock Resistance of Ti(C,N)-Mo2C-Ni Cermet by Infrared Radiation Heating Method

Evaluation of Thermal Shock Resistance of Ti(C,N)-Mo2C-Ni Cermet by Infrared Radiation Heating Method

Estimation of thermal shock resistance of fine porous alumina by infrared radiation heating method

The thermal shock resistance of α-alumina porous capillary, the support material for hydrogen-permselective microporous ceramic membrane was studied. To study the effect of porosity on the thermal shock resistance systematically, porous alumina with different porosities was fabricated, and the thermal shock resistance of the fabricated samples as well as the porous capillary was estimated by the infrared radiation heating method. The mechanical and thermal properties concerned to the thermal shock resistance were also measured and the effect of the porosity on the properties was carefully examined. The fracture strength was not changed with temperature, but decreased with the porosity. The fracture toughness, Young's modulus and thermal conductivity were also decreased with porosity. Thermal shock resistance of porous alumina was estimated quantitively by the experimental thermal shock parameters, thermal shock strength, R1c and thermal shock fracture toughness, R2c. The thermal shock parameters of porous alumina were much lower than dense alumina, and decreased with porosity due to the decreasing of fracture strength and thermal conductivity. The experimental thermal shock strength was good accordance with that calculated from the material properties in this study. Thermal shock strength of porous alumina capillary at service temperature could be estimated by the comparison experimental and calculated thermal shock strength.

Technical Note: Development of Infrared Radiation Heating Method for Sustainable Tomato Peeling

Although lye peeling is the widely industrialized method for producing high quality peeled fruit and vegetable products, the peeling method has resulted in negative impacts by significantly exerting both environmental and economic pressure on the tomato processing industry due to its associated salinity issues and wastewater disposal problems. The objective of this research was to develop alternative peeling methods with reduced or no caustic usage to produce high quality peeled tomatoes. The feasibility of using infrared radiation (IR) peeling and lye-IR peeling as alternative technologies was evaluated against control treatment which used regular lye peeling alone. Peeling performance and peeled tomato quality of three tomato cultivars were determined. The metrics for peeling performance were peelability, peeling easiness, and peeling weight loss. The color and texture of peeled tomatoes were measured as quality indicators. The study showed that IR peeling resulted in a similar peeling easiness but yielded lower peeling loss and firmer peeled product for the same or slightly longer peeling time when compared to regular lye peeling method. Pretreatment with low concentration of lye solution prior to IR treatment did not show any advantages over IR peeling alone. Because IR dry-peeling produced high quality product without using water and salts, it is concluded that it has a good potential as an alternative peeling method to the regular lye peeling method.

Evaluation of Thermal Shock Resistance of Ceramics by Up-Shock Method and Water-Quench Method.

An up-shock method was proposed as a new technique for estimating the thermal shock resistance of ceramics. The method uses a disk-shaped specimen which is heated by infrared ray and by a constant heat flux at the central area. This technique enables an evaluation of thermal shock strength, Rc, directly from the power charge, despite the fact that Rc consists of some of the properties of the tested material. In this paper, the thermal shock resistance of Al2O3 and Si3N4 are estimated by both the up-shock method and the improved water-quench method which was presented earlier. The results of the infrared radiation heating method show that the thermal shock strength of Si3N4 was 7 times as high as Al2O3's one. In the water quench method the heat transfer coefficient of water was indispensable for the quantitative estimation. In this study we show that the up-shock method is more suitable for the evaluation of the thermal shock resistance for ceramics.

Estimation of Thermal Shock Fracture Toughness of Si<sub>3</sub>N<sub>4</sub>

An infrared radiation heating method was proposed previously as a new technique for estimating thermal shock strength and thermal shock fracture toughness of ceramics using a thin-circular disk with or without an edge crack, heated by infrared rays at the center with a constant heat flux. In this paper, thermal shock fracture toughness was measured by the above method in four kinds of silicon nitride. Temperature distributions, thermal stresses and stress intensity factors for the specimens were also analyzed considering the temperature dependent thermal conductivity, thermal diffusivity and thermal expansion of the materials. The experimental results show that the highest value of thermal shock fracture toughness was observed in the material having the higher thermal conductivity, which was developed by growing the grains and decreasing the amount of the grain boundary phase.

サーメットの耐熱衝撃性評価ヘの赤外線放射加熱法の適用

Thermal shock resistance of cermets was tried to evaluate by the infrared radiation heating method that a thin circular disk is heated and fractured by infrared ray concentrated on the central area with a constant heat flux. Thermal shock fracture toughness R2c could be measured for specimens with an edge notch, while thermal shock strength R1c could not for the specimens without the notch. It was thought, however, that R2c might depend on radius of curvature of the edge notch. Using the data of R2c, thermal shock strength R1c was calculated from the consideration of stress concentration. As a result, it was considered that thermal shock strength R1c could be applied to evaluation of thermal shock resistance of cermet and thermal shock resistance of Ti(C, N)-Mo2C-Ni cermets increased with an increase in the content of nitrogen and Ni.

物性値の温度依存性を考慮した熱応力／応力拡大係数解析 円板に一定熱流束を与える場合

An infrared radiation heating method was proposed previously as a new technique for estimating thermal shock parameters directly from electrical power charge. The method uses a thin-circular disk heated by infrared rays at the central area with a constant heat flux. In this report, temperature and stress distributions in the disk are analyzed numerically considering the temperature-dependent material properties of alumina and float glass, namely, temperature-dependent thermal conductivity and thermal diffusivity for the temperature distribution and temperature-dependent thermal expansion for the stress distribution. Furthermore, stress intensity factors are analyzed for a disk with an edge crack subjected to a constant heat flux. These results show that the temperature dependence of material properties has siginificant effects on the temperature and stress distributions.

Thermal Shock Fracture Testing for Float Glass by Infrared Radiation Technique

An infrared radiation heating method was proposed previously as a new technique for estimating thermal shock resistance of ceramics, and a concept of thermal shock fracture toughness and stress intensity factors for a disk-shaped specimen with an edge crack was expressed. The method uses a thin circular disk which is heated by infrared ray at the central area with a constant heat flux. The technique makes it possible to evaluate the thermal shock strength, R1c, and thermal shock fracture toughness, R2c, directly from the electric power charged and the time to fracture, despite the fact that R1c and R2c consist of the thermal properties of the material tested. In this report, the thermal shock strength and the thermal shock fracture toughness for float glass at room and high temperature are evaluated by the infrared radiation heating technique, and shown as a function of temperature when the specimen failures. The thermal shock parameters obtained experimentally are also compared with the estimated values which are calculated by combining the temperature-dependent mechanical properties of float glass.