Papers by Keyword: Self-Heating

Abstract: Technological advances have offered many conveniences across various aspects of life. Food packaging is also increasingly innovative to meet the dynamic needs of human life. Packaging innovation also extends to practical aspects of use, one of which is the need for self-heating food packaging. Therefore, this research focuses on making heaters for self-heating packaging that work based on non-toxic exothermic reactions using widely available and common materials. The heater is made using a mixture of CaO, NaOH and Mg with a composition of 1:1:0.5. The heat released reaches 70 °C if measured directly within the chemical mixture. In Al-sachet packaging, the heat is measured at less than 50 °C due to poor heat transfer through the aluminum sachet. However, in paper bag packaging, the heat released in water can reach 60 °C for a duration of 15 minutes. A significant drawback of using paper bags is the migration of chemicals from the heating pouch into the water, posing a risk of contaminating the food. Therefore, appropriate heating package design is essential to reduce potential hazards.

Abstract: The construction, operating principles, and Li-ion battery thermal runaway mechanisms were analyzed. The external mechanical damage to a Li-ion battery with the uncontrolled thermal runaway development was investigated. The battery self-heating temperature regime was determined. A possible reactions set leading to intense materials self-heating and decomposition was considered. The battery self-heating stopping by immersing it in a container with a water excess relative to the stoichiometric amount for the lithium metal maximum mass that can accumulate was investigated. The change in resulting aqueous solution pH was measured, and the hydrogen release was also recorded. Reaction completion time dependences was established. The water required amount to absorb the heat that could be released during the reaction was calculated, which correlated with the experimental data. Possible measures to Li-ion batteries prevent and stop the burning were considered.

Abstract: The unique metal to insulator transition (MIT) of vanadium dioxide (VO₂) makes it receiving extensive attention in the application of smart window. As for VO₂-based smart window, the critical transition temperature (T_c) is required to be reduced to near room temperature for practical applications. In this paper, we fabricated VO₂ films on ITO glass by hydrothermal method and applied voltage to ITO, therefore, the joule heat generated by ITO triggered the complete MIT of VO₂ at room temperature in very short time ~3 s with applied voltage of 12 V. The VO₂ film on ITO substrate shows obviously widened hysteresis behavior in the reversible transition process with a thermal hysteresis width of ~33 °C. The widened hysteresis loop makes it possible to stabilize the rutile phase (R) of VO₂ at room temperature via applying a low holding voltage of 6 V. The proposed VO₂/ITO film exhibits promising application in active smart window, and possesses advantages of simple structure, easy-fabricated and low-cost.

Abstract: This paper proposes a new vacuum sensor with CMOS Metal-N-Poly thermoelectric materials which works for both thermoelectric sensing and resistive heating. A new method of vacuum measurement with self-heating is proposed based on the dual phases of heating and sensing for the same element which is realized with CMOS thermoelectric sensor. Using the TSMC 0.35 μm CMOS-MEMS process, the proposed thermoelectric sensor is designed and fabricated with standard CMOS materials of the 4th metal and N-polysilicon to form 64 pairs of central-symmetrical thermocouples. There is an air convection-sensing area at the center of membrane and is filled with array of micro-through-holes to enhance the effect of heat convection. When the air molecules move through the array of hole, the heat exchange will take away the heat to cause a temperature drop of sensing area which gives a weak voltage between the cold and hot end of the thermocouples. The heating of thermopile itself is designed at the first phase and sensing the output voltage at the second phase subsequently. According to a careful investigation of the measurement with a wide range of 10m~10k torr, our proposed sensing scheme based on a thermoelectric type sensor is proved for practical vacuum detection and most of all it is proved as a new approach to use a commercial thermopile without heater, which is easier to include than a special custom design.

Abstract: In this study, a dynamically-controlled column was used to evaluate two ores known to cause heap overheating. This enabled the simulation of heap self-heating under controlled conditions. The lixiviant was inoculated with a consortia of mesophilic and moderately thermophilic microorgaisms, and the impact of rapid temperature increases on biological activity and cell numbers was evaluated. During the leaching of ore sample A, the temperature lagged for 29 days before increasing rapidly from 26 to 88 °C. Cell numbers and solution potential increased concomitantly, before both were reduced as the temperature increased past maximum microbial tolerances. Cell numbers began increasing again within 10 days of reaching temperatures that would facilitate mesophilic growth being restored. During the leaching of ore B, the temperature lagged for 4 days before exhibiting a rapid increase in temperature, increasing from 30 to 76 °C over a six-day period. Cell numbers were reduced with the sudden temperature increase, and did not recover over the remainder of the experiment.

Abstract: A comparable study is made on the energy capability of 190 V LDMOSFETs in Si/SiC, SOI, PSOI and PSOSiC technology, using capacitive and inductive switching circuits established in SILVACO Mixed-mode simulators. The results show that the PSOSiC has a thermal advantage compared with other SOI structures under a 48-μs-power-pulse condition, but the Si/SiC device offers superior cooling and energy handling ability in all switching cases despite having a larger chip area.

Abstract: In this study, a 600 V LDMOSFET using a silicon-on-silicon carbide (Si/SiC) substrate is presented. An SOI counterpart is established with a linear-doped drift region the same as that of the Si/SiC transistor. Simulation results show that they perform similar off-state behaviours, both with a significant tunneling leakage emerging above 450 V at 300 K. In the on-state, the proposed structure has advantages over the SOI, namely lower resistance, higher saturation current and improved self-heating effect. Turn-off performance is also enhanced owing to substantial reduction of the drain-substrate capacitance. These are realised by an “IOS” (Insulator on Silicon) setup embedded in the Si/SiC structure.

Abstract: The packaging of liquid products is conventionally realized by using two production stages, which are the stretch blow molding and the filling. In the stretch blow molding process, hot polyethylene terephthalate (PET) preforms are inflated by pressurized air into a cavity to form plastic bottles. In a follow-up process, these packages are filled by a separate machine with the desired liquid product. In contrast to that, liquid-forming combines the blowing and filling stages by directly using the liquid product to form a plastic bottle. Through this substitution, two main challenges arise. Firstly, there are significant inertia effects through the liquid mass, leading to additional reaction forces and a spatially inhomogeneous pressure distribution inside the preform. Secondly, the heat transfer between preform and fluid is drastically increased. Because of this cooling effect, a specific combination of forming speed as well as initial preform and liquid temperatures is necessary to avoid thermally induced preform rupture. This is based on the fact that the formability of PET rapidly declines below its glass transition temperature (T_g). Consequently, a process control requires the knowledge of how the process parameters influence the preform cooling. In this paper, a numerical simulation of the liquid-forming process (LF) is introduced including the preform cooling during forming. In addition, the strain-dependent self-heating effect of PET is implemented. Process experiments under different parameter combinations are conducted using simplified bottle geometry. Through a comparison of the results from experiments and from simulation, the influence of process parameters on the temperature drop and thus on thermally induced failure is determined. In this way, process understanding and control are increased.

Abstract: The oxidative self-heating process of vegetable oil with high content of unsaturated fatty acids was investigated by the means of sequential scanning calorimetry in safety calorimeter SEDEX. The oil was applied on the cotton, and was put to the standard pressure sample vessel, which was modified for air inlet. The behavior of sample was studied under three rates of air flow. First experiment was carried out in the temperature range between approximately 30 and 350°C at a heating rate of 45°C/h. Second scanning was carried out in the temperature range from 30 to 200°C at heating rate of 10°C/h.

Abstract: In this paper, the thermal conductivity of lateral double diffused metal oxide semiconductor (LDMOS) was studied. In order to optimize their properties, the LDMOS device based on the lower surface of field (RESURF) theory join the second field plate technology. Power device self-heating effect will affect the carrier mobility, making its negative resistance effect in IV characteristic curve under the high-power condition. As the thermal conductivity of SiO2 is low, the self-heating effect of SOI device is more obvious. The simulation using Silvaco -TCAD software for different buried oxide (BOX) with different SOI layer thickness accordingly show that the thicker SOI layer and the thinner buried oxide layer, the smaller the self-heating effect.