共查询到20条相似文献,搜索用时 15 毫秒
1.
SHI Junye JIANG Cailing QIAO Junsheng CHEN Jiangpin LI Xiaoping ZHANG Xiaojun 《Frontiers in Energy》2008,2(2):174
Thermal performance is the most important issue to be considered when a thermal module is designed for a notebook personal computer (PC). Because the fan causes air-borne noise and affects the user’s comfort, the acoustic characteristics of the module attract more attention. Experiments were conducted to study the noise sources, the noise characteristic and the main factors influencing the noise level. The difference between the air-borne noise of the thermal module and the whole computer system was analyzed and its propagating characteristics were derived. The influence of I/O ports on the air-borne noise was also studied experimentally. 相似文献
2.
Anbang Chen Song Li Dongtao Huang 《Frontiers of Energy and Power Engineering in China》2008,2(4):443-447
The flow field in a cross flow fan was simulated by solving the 2-D unsteady Reynolds-averaged Navier-Stokes equations. The
calculated pressure fluctuations of the blades, the vortex wall, and the rear wall were then used as noise sources to calculate
the sound field. The Ffowcs Williams-Hawkings (FW-H) equation was employed to predict the noise field caused by these sources.
The predictions show that the rear wall and the vortex wall sources contribute significantly to the total noise and that both
the predicted aerodynamic performance and noise agree well with the experimental results.
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Translated from J Tsinghua Univ (Sci & Tech), 2007, 47(2): 236–239 [译自: 清华大学学报(自然科学版)] 相似文献
3.
Yufeng Zhang Shufeng Sun Rongyi Zhao 《Frontiers of Energy and Power Engineering in China》2008,2(2):129-133
Different assessment indices for thermal environments were compared and selected for proper assessment of indoor thermal environments.
30 subjects reported their overall thermal sensation, thermal comfort, and thermal acceptability in uniform and non-uniform
conditions. The results show that these three assessment indices provide equivalent evaluations in uniform environments. However,
overall thermal sensation differs from the other two indices and cannot be used as a proper index for the evaluation of non-uniform
environments. The relationship between the percentage and the mean vote for each index is established.
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Translated from J Tsinghua Univ (Sci & Tech), 2006, 46(12): 1949–1952 [译自: 清华大学学报(自然科学版)] 相似文献
4.
Junjie Gu Jin Tian Xuezhi Peng 《Frontiers of Energy and Power Engineering in China》2008,2(2):164-168
Correlation dimension as a tool to describe machinery condition is introduced. Vibration signals of the fan under different
working conditions are analyzed using a threshold filtering algorithm based on the region relativity of the wavelet coefficients
for reducing noise. The result shows that the characteristics of the signal could be preserved completely. The correlation
dimension is able to identify conditions of the fan with faults compared with the normal condition, thereby providing an effective
technology for condition monitoring and fault diagnosis of mechanical equipment.
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Translated from Journal of North China Electric Power University, 2007, 34(1): 59–62 [译自: 华北电力大学学报] 相似文献
5.
Junqi DONG Jiangping CHEN Zhijiu CHEN 《Frontiers of Energy and Power Engineering in China》2008,2(1):99-106
Experimental studies were conducted to investigate the air-side heat transfer and pressure drop characteristics of a novel
louvered fins and flat tube heat exchangers. A series of tests were conducted for 9 heat exchangers with different fin space
and fin length, at a constant tube-side water flow rate of 2.8 m3/h. The air side thermal performance data were analyzed using the effectiveness-NTU method. Results were presented as plot
of Colburn j factor and friction factor f against the Reynolds number in the range of 500–6500. The characteristics of the heat transfer and pressure drop of different
fin space and fin length were analyzed and compared. In addition, the curves of the heat transfer coefficients vs. pumping
power per unit heat transfer area were plotted. Finally, the area optimization factor was used to evaluate the thermal hydraulic
performance of the louvered fins with differential geometries. The results showed that the j and f factors increase with the decrease of the fin space and fin length, and the fin space has more obvious effect on the thermal
hydraulic characteristics of the novel louvered fins.
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Translated from Journal of Shanghai Jiaotong University, 2007, 41(3): 380–383 [译自: 上海交通大学学报] 相似文献
6.
The characteristics of three-dimension flow dynamics inside the volute of a G4-73No.8D centrifugal fan was simulated numerically
using a computational fluid dynamics(CFD) technique. The generation, evolution, and noise of the vortex were investigated
when cylinder-shaped and cone-cylinder-shaped anti-vortex rings were added separately. Numerical results showed that large-scale
vortices were broken effectively and the flow fields inside the fan were more uniform with the two anti-vortex rings installed.
Experimental results indicated A-sound level and spectrum noise of the refitted fan decreased and the two anti-vortex rings
were effective in decreasing vortex noise. The cone-cylinder-shaped anti-vortex ring was more effective than the cylinder-shaped
one in breaking large-scale vortexes and decreasing vortex noise.
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Translated from Proceedings of the CSEE, 2006, 26(17): 117–121 [译自: 中国电机工程学报] 相似文献
7.
Huang Yongcheng Zhou Longbao Pan Keyu 《Frontiers of Energy and Power Engineering in China》2007,1(2):239-244
Fischer-Tropsch (F-T) diesel fuel is characterized by a high cetane number, a near-zero sulphur content and a very low aromatic
level. On the basis of the recorded incylinder pressures and injector needle lifts, the combustion characteristics of an unmodified
single-cylinder direct-injection diesel engine operating on F-T diesel fuel are analyzed and compared with those of conventional
diesel fuel operation. The results show that F-T diesel fuel exhibits a slightly longer injection delay and injection duration,
an average of 18.7% shorter ignition delay, and a comparable total combustion duration when compared to those of conventional
diesel fuel. Meanwhile, F-T diesel fuel displays an average of 26.8% lower peak value of premixed burning rate and a higher
peak value of diffusive burning rate. In addition, the F-T diesel engine has a slightly lower peak combustion pressure, a
far lower rate of pressure rise, and a lower mechanical load and combustion noise than the conventional diesel engine. The
brake specific fuel consumption is lower and the effective thermal efficiency is higher for F-T diesel fuel operation.
Translated from Journal of Xi’an Jiaotong University, 2006, 40(1): 5–9 [译自: 西安交通大学学报] 相似文献
8.
Gang Chen Bing Li Fei Chen Shuhong Huang 《Frontiers of Energy and Power Engineering in China》2008,2(2):211-215
Reducing the enormous maintenance cost is essential to enhance the competitiveness for power plants. An overall design scheme
for condition-based maintenance of induced fans is proposed for large thermal power plants. The interface of the above framework
is simple and convenient; the optimum maintenance strategy is given by condition monitoring and risk evaluating. The decisionsupported
system was used in Guangdong Shajiao C Power Plant. The results show that it is a feasible maintenance optimization scheme
for power plants.
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Translated from J Huazhong Univ of Sci & Tech (Natural Science Edition), 2007, 35(1): 63–66 [译自: 华中科技大学学报(自然科学版)] 相似文献
9.
Junqi DONG Jiangping CHEN Zhijiu CHEN 《Frontiers of Energy and Power Engineering in China》2008,2(3):291-297
Experimental studies of air-side heat transfer and pressure drop characteristics of offset strip fins and flat tube heat exchangers
were performed. A series of tests were conducted for 9 heat exchangers with different fin space, fin height, fin strip length
and flow length, at a constant tube-side water flow rate of 2.5 m3/h. The characteristics of the heat transfer and pressure drop of different fin space, fin height and fin length were analyzed
and compared. The curves of the heat transfer coefficients vs. the pumping power per unit frontal area were then plotted.
Moreover, the enhanced heat transfer mechanism of offset strip fins was analyzed using field synergy theory. The results showed
that fin length and flow length have more obviously effect on the thermal hydraulic characteristics of offset strip fins.
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Translated from Journal of Shanghai Jiaotong University, 2007, 41(3): 366–369, 375 [译自: 上海交通大学学报] 相似文献
10.
A simulation was performed, which concerned the feasibility of seasonal underground thermal energy storage (UTES) in Tianjin,
China. The investigated system consisted of 8 boreholes. In summer, residual solar thermal energy was emitted into the soil
surrounding the borehole heat exchangers through which the stored energy was extracted in winter with a ground coupled heat
pump (GCHP) to provide a proper heating temperature. A simulation study was performed to study the influence of system operation
modes on thermal recovery based on the experimental data of a GCHP system, local meteorological conditions and soil properties
in Tianjin. The results indicate a thermal recovery ratio of less than 67% and different temperature distributions under three
modes. Finally, an operation mode was suggested based on both lower loss and better thermal recovery in the UTES.
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Translated from Journal of North China Electric Power University, 2007, 34(2): 74–77 [译自: 华北电力大学学报] 相似文献
11.
A combustion instability detection method that uses the wavelet detail of combustion pressure fluctuations is put forward.
To confirm this method, combustion pressure fluctuations in a stoker boiler are recorded at stable and unstable combustion
with a pressure transducer. Daubechies one-order wavelet is chosen to obtain the wavelet details for comparison. It shows
that the wavelet approximation indicates the general pressure change in the furnace, and the wavelet detail magnitude is consistent
with the intensity of turbulence and combustion noise. The magnitude of the wavelet detail is nearly constant when the combustion
is stable, however, it will fluctuate much when the combustion is unstable.
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Translated from Journal of Shanghai Jiaotong University, 2007, 41(3): 342–346 [译自: 上海交通大学学报] 相似文献
12.
Plume concentration prediction is one of the main contents of radioactive consequence assessment for early emergency response
to nuclear accidents. Random characteristics of atmospheric diffusion itself was described, a random walk model of atmospheric
diffusion (Random Walk) was introduced and compared with the Lagrangian puff model (RIMPUFF) in the nuclear emergency decision
support system (RODOS) developed by the European Community for verification. The results show the concentrations calculated
by the two models are quite close except that the plume area calculated by Random Walk is a little smaller than that by RIMPUFF.
The random walk model for atmospheric diffusion can simulate the atmospheric diffusion in case of nuclear accidents, and provide
more actual information for early emergency and consequence assessment as one of the atmospheric diffusion module of the nuclear
emergency decision support system.
Translated from Chinese Journal of Nuclear Science and Engineering, 2006, 26(1): 39–45 [译自: 核科学与工程] 相似文献
13.
Liu Bin Su Wanhua Wang Hui Huang Haozhong 《Frontiers of Energy and Power Engineering in China》2007,1(4):420-427
Cycle fuel energy distribution and combustion characteristics of early in-cylinder diesel homogenous charge compression ignition
(HCCI) combustion organized by modulated multi-pulse injection modes are studied by the engine test. It is found that heat
loss due to unburned fuel droplets and CO emission can be decreased effectively by injection mode regulation, and thermal
efficiency can be potentially increased by 4%–12%. From the analyses of combustion process, it is also found that diesel HCCI
combustion is a process with a finite reaction rate and is very sensitive to injection timing and injection mode. At injection
timing of −90°CA ATDC, extra low NOx emissions can be obtained along with high thermal efficiency.
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Translated from Transactions of CSICE, 2006, 24(6): 385–393 [译自: 内燃机学报] 相似文献
14.
Youjie LI Peiqing LUO Zhibin ZHOU Rongqiang CUI Jianhua HUANG Jingxiao WANG 《Frontiers of Energy and Power Engineering in China》2008,2(4):519-523
Rapid thermal processing (RTP) of SiN
x
thin films from PECVD with low temperature was investigated. A special processing condition of this technique which could
greatly increase the minority lifetime was found in the experiments. The processing mechanism and the application of the technique
to silicon solar cells fabrication were discussed. A main achievement is an increase of the minority lifetime in silicon wafer
with SiN
x
thin film by about 200% after the RTP was reached. PC-1Dsimulation results exhibit an enhancement of the efficiency of the
solar cell by 0.42% coming from the minority lifetime improvement. The same experiment was also conducted with P-diffusion
silicon wafers, but the increment of minority lifetime is just about 55%. It could be expected to improve the solar cell efficiency
if it would be used in silicon solar cells fabrication with the combination of laser firing contact technique.
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Translated from Journal of Shanghai Jiaotong University, 2008, 42(1): 152–155 [译自: 上海交通大学学报] 相似文献
15.
Wang Dechang Wu Jingyi Wang Ruzhu Dou Weidong 《Frontiers of Energy and Power Engineering in China》2007,1(3):347-351
A novel silica gel-water adsorption chiller consisting of two adsorption/desorption chambers and an evaporator with one heat-pipe
working chamber is experimentally studied. The dynamic operating characteristics of the chiller and the thermodynamic characteristics
of the adsorber are obtained. The experimental results show that the dynamic operating characteristics of the chiller and
the thermodynamic characteristics of the adsorber are satisfactory and that the cycle is a novel and effective adsorption
cycle. A mass recovery process increases the cyclic adsorption capacity of the system and improves adaptability of the chiller
to a low-grade heat source. In addition, the experiment indicates that this novel chiller is highly suitable for an air conditioning
system with a low dehumidification requirement or a system with a large cycle flowrate and an industrial cooling water system.
Translated from Journal of Shanghai Jiaotong University, 2006, 40(2): 306–310 [译自: 上海交通大学学报] 相似文献
16.
The flow and heat transfer characteristics of porous heat-storage wall in greenhouse are studied by using the one-dimensional
steady energy two-equation model for saturated porous medium. The results show that the heat exchange between the air and
the solid matrix of the porous heat-storage wall depends upon the inlet air velocity, the porosity and the permeability of
porous medium, and the thermal conductivity of the solid matrix. Because the incidence of solar radiation on the porous heat-storage
wall is not uniform, the new composite porous solar wall with different porosity is proposed to reduce the disadvantageous
effect.
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Translated from Journal of Engineering Thermophysics, 2008, 29(2): 284–286 [译自: 工程热物理学报] 相似文献
17.
The slotted fin concept was employed to improve the air cooling performance of plate-fin in heat sinks. Numerical simulations
of laminar heat transfer and flow pressure drop were conducted for the integral plate fin, discrete plate fin and discrete
slotted fin heat sinks. It is found that the performance of the discrete plate fin is better than that of the integral continuum
plate fin and the performance of slotted fin is better than that of the discrete plate fin at the same pumping power of the
fan. A new type of heat sink characterized by discrete and slotted fin surfaces with thinner fins and smaller spaces between
fins is then proposed. Preliminary computation shows that this type of heat sink may be useful for the next generation of
higher thermal load CPUs. The limit of cooling capacity for air-cooling techniques was also addressed.
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Translated from Journal of Xi’an Jiaotong University, 2006, 40(11): 1241–1245 [译自: 西安交通大学学报] 相似文献
18.
Tianwen FANG Meng DING Jin ZHOU 《Frontiers of Energy and Power Engineering in China》2008,2(4):528-533
The characteristics of supersonic cold flows over cavities were investigated experimentally and numerically, and the effects
of cavities of different sizes on supersonic flow field were analyzed. The results indicate that the ratio of length to depth
L/D within the range of 5–9 has little relevance to integral structures of cavity flow. The bevel angle of the rear wall does
not alter the overall structure of the cavity flow within the range of 30°–60°, but it can exert obvious effect on the evolvement
of shear layer and vortexes in cavities.
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Translated from Journal of National University of Defense Technology, 2007, 29(3): 1–5 [译自: 国防科技大学学报] 相似文献
19.
A Venturi flow meter was designed to accurately measure the mass flow rate of pulverized coal in power plant pipelines. Numerical
simulations of the dilute turbulent gas-solid two-phase flow in a horizontal Venturi tube were used to study the effects of
Venturi tube geometry on the pressure distribution in the mixture. The results show that Venturi tube geometry strongly influences
the metering of the dilute gas-particle two-phase flow. The geometry can be optimized to improve the precision of the measurement
and ensure stable measurements. Furthermore, the geometries of three types of Venturi tubes were optimized for an experimental
study of pulverized coal mass flow rate measurements.
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Translated from Journal of Tsinghua University (Sci & Tech), 2007, 47(5): 666–669 [译自: 清华大学学报( 自然科学版)] 相似文献
20.
Jie YIN Jianxing REN Dunsong WEI 《Frontiers of Energy and Power Engineering in China》2008,2(4):461-465
Superfine pulverized coal technology can effectively reduce NO
x
emission in coal-fired power plant boilers. It can also economize the cost of the power plant and improve the use of the
ash in the flue gas. Superfine pulverized coal technology, which will be widely used in China, includes common superfine pulverized
coal technology and superfine pulverized coal reburning technology. The use of superfine pulverized coal instead of common
coal in large-scale power plants will not only reduce more than 30% of NO
x
emission but also improve the thermal efficiency of the boiler.
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Translated from Journal of Shanghai University of Electric Power, 2006, 22(4): 333–337 [译自: 上海电力学院学报] 相似文献