A Three-Dimensional Numerical and Multi-Objective Optimal Design of Wavy Plate-Fins Heat Exchangers

This paper presents a method for optimizing wavy plate-fin heat exchangers accurately and efficiently. It combines CFD simulation, Radical Basis Functions (RBF) with multi-objective optimization to improve the performance. The optimization of the Colburn factor j and the friction coefficient f is regarded as a multi-objective optimization problem, due to the existence of two contradictory goals. The approximation model was obtained by Radical Basis Functions, and the shape of the heat exchanger was optimized by multi-objective genetic algorithm (MOGA). The optimization results showed that j increased by 17.62% and f decreased by 20.76%, indicating that the heat exchange efficiency was significantly enhanced and the fluid structure resistance reduced. Then, from the aspects of field synergy and tubulence energy, the performance advantage of the optimized structure was further confirmed

The research about radiometric technology of two-dimensional rotary table based on image gray level

Abstract It is difficult to measure infrared radiation quantitatively for fast dynamic targets such as aircraft and missile. At present, there are many problems such as low measurement accuracy, feedback delay, and complex measurement system. In this paper, a radiation measurement scheme based on image grayscale is proposed. The scheme adopts a two-dimensional turntable structure, which can measure the radiation quantity rapidly and accurately. Based on the image method, this method is used to calibrate the gray value of the target point and compare it with that of the absolute standard radiator, so as to obtain the radiation value of the target indirectly. The key of this method is to establish an accurate radiation measurement model. The proposed model based on dynamic calibration is about 50% more accurate than the traditional model. The final measurement accuracy of this model is 75%. Through the infrared radiation measurement of specific dynamic objects in two-dimensional space, it is found that the dynamic calibration model based on this measurement method has higher measurement precision

Analysis of Water-Cooled Intercooler Thermal Characteristics

With the incremental power of construction machinery diesel engines, the power performance of diesel engines and the pollutant emissions from the exhaust gas have imposed increasingly stringent requirements on the intake cooling system of diesel engines. This paper compared the j/f evaluation factors for fin unit bodies of water-cooled intercooler (including straight fins and rectangular misaligned fins) by means of CFD simulation, and found that the rectangular misaligned fins had an 8% advantage in comprehensive performance. With the rectangular staggered fin intercooler, it was found that under the same conditions, the cooling efficiency of the dual-pass water-cooled intercooler is higher than that of the single-pass water-cooled intercooler, and the uniformity factor of the temperature difference field of the dual-pass water-cooled intercooler is 1.5% higher than that of the latter. The accuracy of the overall simulation of the intercooler is verified by the field test. The dual-pass and single-pass water-cooled intercooler both can maintain heat balance under working conditions, and its average air inlet temperature is 10 °C lower than that of the original air-cooled intercooler, which provides support for further reducing the engine air inlet temperature. The results provide a theoretical basis for the performance improvement of water-cooled intercoolers

Analysis of Water-Cooled Intercooler Thermal Characteristics

With the incremental power of construction machinery diesel engines, the power performance of diesel engines and the pollutant emissions from the exhaust gas have imposed increasingly stringent requirements on the intake cooling system of diesel engines. This paper compared the j/f evaluation factors for fin unit bodies of water-cooled intercooler (including straight fins and rectangular misaligned fins) by means of CFD simulation, and found that the rectangular misaligned fins had an 8% advantage in comprehensive performance. With the rectangular staggered fin intercooler, it was found that under the same conditions, the cooling efficiency of the dual-pass water-cooled intercooler is higher than that of the single-pass water-cooled intercooler, and the uniformity factor of the temperature difference field of the dual-pass water-cooled intercooler is 1.5% higher than that of the latter. The accuracy of the overall simulation of the intercooler is verified by the field test. The dual-pass and single-pass water-cooled intercooler both can maintain heat balance under working conditions, and its average air inlet temperature is 10 °C lower than that of the original air-cooled intercooler, which provides support for further reducing the engine air inlet temperature. The results provide a theoretical basis for the performance improvement of water-cooled intercoolers