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Your search keyword '"Zhu, Hengxuan"' showing total 12 results
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12 results on '"Zhu, Hengxuan"'

5. Vests with Radiative Cooling Materials to Improve Thermal Comfort of Outdoor Workers: An Experimental Study.

Author

Wang, Yao, Zhao, Bohao, Zhu, Hengxuan, Yang, Wei, Li, Tianpeng, Cao, Zhen, and Wang, Jin

Subjects
THERMAL comfort, VESTS, COOLING, HUMAN comfort
Abstract

This study focuses on improving human thermal comfort in a high-temperature outdoor environment using vests with a radiative cooling coating. The effects of coating thickness on the radiative cooling performance were first evaluated, and an optimal thickness of 160 μm was achieved. Then, six subjects were recruited to evaluate the thermal comfort in two scenarios: wearing the vest with radiative cooling coatings, and wearing the standard vest. Compared with the standard vest, the coated vest decreases the maximum temperature at the vest inner surface and the outer surface by 5.54 °C and 4.37 °C, respectively. The results show that thermal comfort is improved by wearing radiative cooling vests. With an increase of wet bulb globe temperature (WBGT), the improving effects tend to decline. A significant improvement in human thermal comfort is observed at a WBGT of 26 °C. Specifically, the percentage of thermal sensation vote (TSV) wearing the cooling vest in the range of 0 to 1 increases from 29.2% to 66.7% compared with that of the untreated vest. At the same time, the average value of thermal comfort vote (TCV) increases from −0.5 to 0.2. [ABSTRACT FROM AUTHOR]

Published
2024
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6. Comparison and analyses of two thermal performance evaluation models for a public building

Author

Sun Xuemei, Zhu Saihong, Zhu Hengxuan, Duan Runze, and Wang Jin

Subjects
thermal response, thermal mass model, thermal reserve coefficient, thermal inertia, 81.70.pg, 47.55.pb, 07.20.-n, 91.60.ki, Physics, QC1-999
Abstract

Recently, investigations on building thermal inertia are mainly involved with the materials of the building envelope. Usually, other influencing factors are ignored, such as room ventilation, indoor heat storage, indoor cold source, indoor heat source and human behavior. In this paper, two models based on thermodynamics are given to evaluate building thermal performance. One is thermal mass model, and the other one is thermal reserve coefficient model. Based on thermal response testing data in a non-heating season, the thermal mass model was adopted to classify the envelope type, and the delay rules between the indoor temperature and the outdoor meteorological parameters are analyzed. In a heating season, the delay rules among the outdoor temperature, indoor temperature and supply water temperature are obtained by changing the supply water temperature. Thermal performance of the targeted building is evaluated with the thermal reserve coefficient model. For the same public building, two evaluation models tend to be consistent. These two evaluation models presented in this paper can be applied for the optimal design of buildings envelope.

Published
2019
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7. A Novel Evaluation Method For Particle Deposition Measurement

Author

Song Tao, Liu Chao, Zhu Hengxuan, Zeng Min, and Wang Jin

Subjects
gas turbine, deposition, microstrip antenna, return loss, vivaldi antenna, 81.15.fg, 84.40.ba, Physics, QC1-999
Abstract

Normal operation of gas turbines will be affected by deposition on turbine blades from particles mixed in fuels. This research shows that it is difficult to monitor the mass of the particles deposition on the wall surface in real time. With development of electronic technology, the antenna made of printed circuit board (PCB) has been widely used in many industrial fields. Microstrip antenna is first proposed for monitoring particles deposition to analyse the deposition law of the particles accumulated on the wall. The simulation software Computer Simulation Technology Microwave Studio (CST MWS) 2015 is used to conduct the optimization design of the PCB substrate antenna. It is found that the S11 of vivaldi antenna with arc gradient groove exhibits a monotonous increase with the increase of dielectric layer thickness, and this antenna is highly sensitive to the dielectric layer thickness. Moreover, a cold-state test is carried out by using atomized wax to simulate the deposition of pollutants. A relationship as a four number of times function is found between the capacitance and the deposited mass. These results provide an important reference for the mass detection of the particle deposition on the wall, and this method is suitable for other related engineering fields.

Published
2019
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10. Heat Transfer characteristics and Friction Factor of Various Nanofluids in a Double-pipe Heat Exchanger

Author

Wang, Jin, Pang, Yu, Li, Tan, Zhu, Hengxuan, Baleta , Jakov, Sundén, Bengt, and Ban, Marko et al.

Subjects
Nanofluid, nanoparticle, convective heat transfer, heat exchanger, friction factor
Abstract

An experimental research was conducted to investigate effects of nanofluids on heat transfer characteristics in a double-tube counter-flow heat exchanger. With nanoparticle mass fraction of 0.5%-2% and Reynolds number of 4500-14500, friction factor was analyzed by using four nanofluids, i.e., CuO- water, Al2O3-water, ZnO-water, and SiC-water nanofluids. Results show that SiC-water nanofluid with a mass concentration of 1.5% has the best improvement of heat transfer performance, and 1% CuO- water nanofluid has the lowest friction factor when Reynolds number varies from 4500 to 14500. Based on testing results of Nusselt number and friction factor, the 1% CuO-water nanofluid as a working medium inside a double-tube exchanger, shows a great advantage due to a relatively high heat transfer performance and a low friction factor.

Published
2019

11. Effect of various hole configurations on wall film cooling performance

Author

Wang, Jin, Liu, Chao, Zhu, Hengxuan, Baleta, Jakov, Sundén, Bengt, and Ban, Marko et al.

Subjects
Physics::Fluid Dynamics, Film cooling, computational fluid dynamics, injection angle, backward injection, gas turbine
Abstract

Increasing temperature at the gas turbine inlet has far exceeded the melting point of the metal materials. In recent years, the film cooling technology has protected gas turbine blades from the erosion of high-temperature gases. As is well-known, an optimal injection angle of film cooling holes can provide a full coverage to the cooling protection for blade walls. Previous studies mainly focuses on the traditional (forward) injection angle, i.e., the jet flow is consistent with flow direction of the mainstream, but research about a backward injection of the jet flow is insufficient. In this paper, all numerical simulations are used to analyze flow characteristics and film cooling performance of the backward injection hole in a simplified channel, and physical mechanism of improved cooling performance from the backward injection hole is revealed by a comparison with simulated results based on a forward injection hole. The results show that the backward injection hole can weaken the strength of the kidney vortices, and the spanwise cooling distribution of the jet flow on wall surface is wider than the forward injection. Moreover, at low blowing ratios, film cooling performance for the backward hole is worse than the forward hole, whereas the backward hole at high blowing ratios has better film cooling performance than the forward one. At the blowing ratio of 1.5, the overall average film cooling effectiveness for the backward hole increases by 619% compared to for the forward hole.

Published
2019

12. Numerical simulation of the effect of backward hole configuration on improving film cooling performance

Author

Wang, Jin, Liu, Chao, Zhu, Hengxuan, Baleta, Jakov, Sundén, Bengt, and Ban, Marko et al.

Subjects
Physics::Fluid Dynamics, Film cooling, computational fluid dynamics, injection angle, backward injection, gas turbine
Abstract

Increasing temperature at the gas turbine inlet has far exceeded the melting point of the metal materials. In recent years, the film cooling technology has protected gas turbine blades from the erosion of high-temperature gases. As is well- known, an optimal injection angle of film cooling holes can provide a full coverage to the cooling protection for blade walls. Previous studies mainly focuses on the traditional (forward) injection angle, i.e., the jet flow is consistent with flow direction of the mainstream, but research about a backward injection of the jet flow is insufficient. In this paper, all numerical simulations are used to analyze flow characteristics and film cooling performance of the backward injection hole in a simplified channel, and physical mechanism of improved cooling performance from the backward injection hole is revealed by a comparison with simulated results based on a forward injection hole. The results show that the backward injection hole can weaken the strength of the kidney vortices, and the spanwise cooling distribution of the jet flow on wall surface is wider than the forward injection. Moreover, at low blowing ratios, film cooling performance for the backward hole is worse than the forward hole, whereas the backward hole at high blowing ratios has better film cooling performance than the forward one. At the blowing ratio of 1.5, the overall average film cooling effectiveness for the backward hole increases by 619% compared to for the forward hole.

Published
2019

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