Papers by Keyword: Temperature Simulation

Abstract: With the COVID 19 pandemic and the rise of polymerase chain reaction (PCR) testing in its wake, affordable large-scale testing became necessary. A thermal cycler for PCR has been developed that is affordable, fast, and accurate. The thermocycler must follow a specific temperature profile consisting of three different temperature levels. To ensure the success of any PCR, the tempering elements must accurately follow the tempering profile and be stable heat sources to maintain any given temperature. A control mechanism is required to approximate this prescribed temperature behavior. The basis for this is a Proportional-Integral-Differential (PID) controller, whose functionality is ensured by a feedback mechanism consisting of a temperature sensor. The PID controller provides precise attainment and maintenance of the temperature levels. A high performance Peltier element is used to heat and cool the PCR system. This is controlled by a programmable power supply and, in combination with a heat dissipation system, achieves heating and cooling powers in excess of 200 W. In addition, different design variants of the thermal cycler were created and their temperature behavior was simulated. These were then implemented, tested and the PID controller tuned accordingly. These tests help to find the best design for the thermal cycler with the optimal heat distribution.

Abstract: This paper presents a new micromachined PCR chip with separable electrodes part and reaction chamber part. The electrodes part, employing Pt film resistor as heaters and sensors, is reusable, and the chamber part is a disposable PDMS-GLASS bonded structure. This PCR chip with reusable electrodes can largely reduce fabrication cost. COMSOL software is used to simulate the temperature distribution of the designed chip and then use infrared thermometer (NEC R300SR) to verify temperature distribution of the fabricated chip. The test results turned out to perfectly fit the simulation of temperature distribution, which provides reliable basis for further PCR amplification experiment.

Abstract: To the problem of Linear motors temperature rise , and according to the basic theory of heat transfer, the heat conduction model of stator slot was established, the thermal conductivity of stator slot and the convection coefficient between the stator and rotor were determined .Based on this , the simulation model of motor transient temperature field operating at the polymorphism was established by using the finite element analysis software such as MagNet and ThemNet. Then the temperature field of the linear motor that work under the long-trem and periodic duty was calculated. Through the contrast and analysis between the simulation results and experimental data, the rationality of the simulation model and the correctness of calculation method were verified, which has effective help to design, manufacture and apply such kinds of special linear motor.

Abstract: Welding parameters have important affect on welding quality. In this paper, temperature field and residual stress field simulation of thin 316L stainless steel plate are performed by finite element method. The welding process is multi-pass butt TIG(Tungsten Inert Gas) welding. Simulation model are established by SYSWELD code with multi-pass bead. A Gaussian heat source representing the arc energy is verified and the temperature distribution in multilayer welding process is simulated. Then the results are compared with test results measured by thermal-couples. Effects of welding speed and interpass cooling time during multi-pass on temperature field and stress field are studied. The results show that the faster the welding speed and the longer the cooling time, the higher the residual stress will be.

Abstract: To the problem of small induction motor that supplied by Variable frequency power temperature rise, according to the basic theory of heat transfer and using finite element analysis software, in the paper, it established a motor of two-dimensional transient temperature field model ,though the equivalent simplify of the structure and thermal conductivity, and the compare between the simulation of finite element software studies and the temperature experimental tests , It confirms the affect that variable frequency power on the motor temperature rise, and finds a simplified simulation of motor temperature field and parameters equivalent approach which do provide effective help to the design and use of the induction motor.

Abstract: Because of lacking a rigid method of setting the initial nodal temperature on the joint face, the accuracy of temperature simulation would be affected in concrete dam. Based on finite element method (FEM) and principle of thermal conversation, we validate and extend a new method of setting the initial nodal temperature on the joint face in this paper. The result of temperature field simulation shows that this method has good accuracy in three-dimension temperature field simulation.

Abstract: The simulation of temperature field during laser direct metal deposition(DMD) were researched. The finite element model of single track cladding, multi-track overlapping and multi-layer deposition were established. The temperature field was simulated by ANSYS software basing on life-and-death element and cycle algorithm. Under different process parameters, the temperature and temperature gradient on the cross-section of sample were simulated during single- track scanning, multi-track overlapping and multi-layer deposition. Temperature cycle curves at different position were analyzed and were consistent with actually value. Both simulation and experiment showed that heat accumulation during continuous forming greatly affected the temperature of molten pool.

Abstract: High current pulsed electron beam is an effective technique for surface sealing of ceramic thermal barrier coatings prepared by electron beam physical vapor deposition. Due to the rapid remelting and solidification, the outer layers of ceramic coatings become smooth and dense, and the protective performance for turbine blades is effectively improved. Because of the complex multi-layered structures in the coatings, a high-current pulsed electron beam treatment requires specific parameter inputs which are related to the temperature field induced by electron energy deposition in the coatings. In this paper, a two-dimensional temperature simulation was performed to demonstrate the melting depth and temperature evolution in ceramic coatings treated by high-current pulsed electron beam. Different energy densities and pulses were studied and discussed for obtaining optimized parameters.

Abstract: Lightweight extrusion profiles with reinforcement elements are promising news in the domain of lightweight construction. The machining of them suffers from several problems: Aside from the question of choosing a suitable tool, feed rate, and milling strategy, an excessive rise in temperature could lead to stress and even a distortion due to the differing thermal expansion of the reinforcement material and the surrounding matrix material. A simulation of the milling process could, in addition to force and collision calculations, recognize this case before manufacturing. For certain milling applications like seal surfaces, a certain roughness of the manufactured surface is necessary. In many other cases, a smooth surface of very high quality is desirable. Available simulation systems usually completely lack the simulation of dynamic effects, which have a great effect on the final surface quality, and therefore are not able to predict the resulting surface quality. In this paper simulation methods are presented that are capable of simulating the dynamic behavior of the tool in the milling process and the resulting flank and ground surface structures. Additionally, a fast temperature simulation for heterogeneous workpieces with reinforcement elements, which is based on the finite difference method and cellular automata, is introduced.