Performance Characteristics of PTC Elements for an Electric Vehicle Heating System
A high-voltage positive temperature coefficient (PTC) heater has a simple structure and a swift response. Therefore, for cabin heating in electric vehicles (EVs), such heaters are used either on their own or with a heat pump system. In this study, the sintering process in the manufacturing of PTC elements for an EV heating system was improved to enhance surface uniformity. The electrode production process entailing thin-film sputtering deposition was applied to ensure the high heating performance of PTC elements and reduce the electrode thickness. The allowable voltage and surface heat temperature of the high-voltage PTC elements with thin-film electrodes were 800 V and 172 °C, respectively. The electrode layer thickness was uniform at approximately 3.8 μm or less, approximately 69% less electrode materials were required compared to that before process improvement. Furthermore, a heater for the EV heating system was manufactured using the developed high-voltage PTC elements to verify performance and reliability.
The Metallization of PTC Ceramic by Magnetron Sputtering
Abstract DC magnetron sputtering was applied in the deposition of the electrodes of the BaTiO 3 -based PTC ceramics. Multi-layered films of Ti/Ni-Cu/Ag and Al/Ni-Cu/Ag were prepared as the electrodes of PTCR ceramics. Experimental results indicated that there could form good ohmic contacts between BaTiO 3 -based PTC ceramics and the electrode materials. Also, the electrodes had good adhesion to the substrates and high-temperature welding characteristics. The proposed method has such advantages as economic consumption of production cost and controllable process, thus is suitable for large-scale industrial production.
Modeling of chemical reactors—XXIX mixing-cell model for packed bed reactors. Steady state considerations. Problems of multiplicity
Abstract The axial heat and mass transfer in tubular catalytic reactors may be described by mixing-cell model and diffusion model as well. The diffusion description yields for a strong exothermic reaction and adiabatic conditions three steady state profiles, on the other hand the mixing-cell model gives rise to more than three steady states. A simple numerical and graphical analysis for mixing-cell model is presented.