A Model of the Enhancement of Combustion of Coal-Water Slurry Fuels Using High-Intensity Acoustic Fields

1991 ◽  
Vol 113 (4) ◽  
pp. 268-276 ◽  
Author(s):  
S. Yavuzkurt ◽  
M. Y. Ha
Keyword(s):  
Mass Transfer ◽  
High Intensity ◽  
Slip Velocity ◽  
Sound Pressure ◽  
Pressure Level ◽  
Water Evaporation ◽  
Acoustic Fields ◽  
Water Slurry ◽  
Burn Out ◽  
Coal Water Slurry

Combustion of coal-water slurry fuels is simulated in the presence of high-intensity acoustic fields which increases heat and mass transfer from the droplets and particles, and thereby enhances the combustion. The steady-slip velocity and acoustically induced slip velocity are calculated along particle trajectories, giving the augmented Nusselt and Sherwood numbers in the presence of high-intensity acoustic fields compared with no-sound conditions. The paper also presents the water evaporation and char burn-out history for particles with diameters between 90–110 μm exposed to sound pressure levels of 160–170 dB and compares the results to similar cases under no acoustic field. A decrease in the char burn-out length of about 12.1 percent at 160 dB, 18 percent at 165 dB, and 24 percent at 170 dB sound pressure level is obtained compared to the case with no sound for 100-μm particles introduced at centerline.

A Model of the Enhancement of Coal Combustion Using High-Intensity Acoustic Fields

1991 ◽  
Vol 113 (4) ◽  
pp. 277-285 ◽  
Author(s):  
S. Yavuzkurt ◽  
M. Y. Ha ◽  
G. Koopmann ◽  
A. W. Scaroni
Keyword(s):  
Mass Transfer ◽  
Heat And Mass Transfer ◽  
Acoustic Field ◽  
High Intensity ◽  
Coal Combustion ◽  
Sound Pressure ◽  
Pulverized Coal ◽  
Acoustic Fields ◽  
Coal Particles ◽  
Sound Pressure Levels

A model for the enhancement of coal combustion in the presence of high-intensity acoustic fields has been developed. A high-intensity acoustic field induces an oscillating velocity over pulverized coal particles otherwise entrained in the main gas stream, resulting in increased heat and mass transfer. The augmented heat and mass transfer coefficients, expressed as space and time-averaged Nusselt and Sherwood numbers for the oscillating flow, were implemented in an existing computer code (PCGC-2) capable of predicting various aspects of pulverized coal combustion and gasification. Increases in the Nusselt and Sherwood numbers about 45, 60 and 82.5 percent at sound pressure levels of 160, 165 and 170 dB for 100-μm coal particles were obtained due to increase in the acoustic slip velocity associated with the increased sound pressure levels. The main effect of the acoustic field was observed during the char combustion phase in a diffusionally controlled situation. A decrease in the char burn-out length (time) of 15.7 percent at 160 dB and 30.2 percent at 170 dB was obtained compared to the case with no sound for the 100-μm coal particles.

Study on Desulfurization Characteristic of Desulphurizing Coal Water Slurry

2013 ◽  
Vol 807-809 ◽  
pp. 1459-1463
Author(s):  
Chang Xing Shi ◽  
Hai Xiang Tang
Keyword(s):  
Calcium Carbonate ◽  
Barium Carbonate ◽  
Pulverized Coal ◽  
Water Evaporation ◽  
Desulfurization Rate ◽  
Water Slurry ◽  
Coal Water Slurry ◽  
Desulfurization Efficiency ◽  
Reaction Atmosphere

With calcium carbonate and barium carbonate as desulfurizers, combustion desulphurization experiments of coal water slurry and pulverized coal were respectively done in the ZCL. The results show that desulfurization efficiency in coal water slurry is prior to the same pulverized coal. The desulfurization characteristic of desulphurizing coal water slurry was analyzed by comparing the desulfurization efficiency of coal water slurry and pulverized coal. The reaction atmosphere in the boiler is different from the pulverized coal because of water evaporation ,and the CO content was lower ,so the decomposing rate for desulphurization products was reduced,after water evaporated ,it formed microstructures which was considered as favorable to the desulfurization rate .

Development of piezoceramic electroacoustic transducers for acoustic devices with a sound pressure of 125 dB or more

2019 ◽  
pp. 11-16
Author(s):  
A. F. Geyer ◽  
V. A. Ponomarev
Keyword(s):  
Sound Pressure Level ◽  
High Intensity ◽  
Sound Pressure ◽  
Pressure Level ◽  
Electroacoustic Transducer ◽  
Acoustic Device ◽  
Exciting Voltage

The increased sound pressure level of piezoceramic electroacoustic transducers is important for acoustic devices designed to create high-intensity sound, 125 decibels or more. This is especially true of acoustic devices that use a group of transducers. An electroacoustic transducer that develops a higher sound pressure can greatly reduce the number of radiating elements in an acoustic device. In the performed work electroacoustic transducers are created that capable to develop sound pressure level up to 125 dB. The article presents the results of the development of electroacoustic transducers for three frequency versions. The scheme of the generator of the exciting voltage for electroacoustic converters with the raised sound pressure is offered and investigated. The result is particularly relevant when used in multi-element sound-emitting devices, as repeatedly reduces the required number of converters to achieve the same result.

Contributions of Voice and Nonverbal Communication to Perceived Masculinity–Femininity for Cisgender and Transgender Communicators

2020 ◽  
Vol 63 (4) ◽  
pp. 931-947
Author(s):  
Teresa L. D. Hardy ◽  
Carol A. Boliek ◽  
Daniel Aalto ◽  
Justin Lewicke ◽  
Kristopher Wells ◽  
...  
Keyword(s):  
Fundamental Frequency ◽  
Sound Pressure Level ◽  
Sound Pressure ◽  
Vocal Tract ◽  
Presentation Mode ◽  
Pressure Level ◽  
Presentation Modes ◽  
Audiovisual Stimuli ◽  
Vocal Tract Resonance ◽  
Point Light

Purpose The purpose of this study was twofold: (a) to identify a set of communication-based predictors (including both acoustic and gestural variables) of masculinity–femininity ratings and (b) to explore differences in ratings between audio and audiovisual presentation modes for transgender and cisgender communicators. Method The voices and gestures of a group of cisgender men and women ( n = 10 of each) and transgender women ( n = 20) communicators were recorded while they recounted the story of a cartoon using acoustic and motion capture recording systems. A total of 17 acoustic and gestural variables were measured from these recordings. A group of observers ( n = 20) rated each communicator's masculinity–femininity based on 30- to 45-s samples of the cartoon description presented in three modes: audio, visual, and audio visual. Visual and audiovisual stimuli contained point light displays standardized for size. Ratings were made using a direct magnitude estimation scale without modulus. Communication-based predictors of masculinity–femininity ratings were identified using multiple regression, and analysis of variance was used to determine the effect of presentation mode on perceptual ratings. Results Fundamental frequency, average vowel formant, and sound pressure level were identified as significant predictors of masculinity–femininity ratings for these communicators. Communicators were rated significantly more feminine in the audio than the audiovisual mode and unreliably in the visual-only mode. Conclusions Both study purposes were met. Results support continued emphasis on fundamental frequency and vocal tract resonance in voice and communication modification training with transgender individuals and provide evidence for the potential benefit of modifying sound pressure level, especially when a masculine presentation is desired.

Influence of the Acoustic Reflex on Vowel Recognition

1986 ◽  
Vol 29 (3) ◽  
pp. 420-424 ◽  
Author(s):  
Michael Dorman ◽  
Ingrid Cedar ◽  
Maureen Hannley ◽  
Marjorie Leek ◽  
Julie Mapes Lindholm
Keyword(s):  
Auditory System ◽  
Sound Pressure ◽  
Dynamic Range ◽  
Recognition Accuracy ◽  
Pressure Level ◽  
Acoustic Reflex ◽  
The Poor ◽  
Stapedial Reflex ◽  
Vowel Recognition ◽  
High Sound

Computer synthesized vowels of 50- and 300-ms duration were presented to normal-hearing listeners at a moderate and high sound pressure level (SPL). Presentation at the high SPL resulted in poor recognition accuracy for vowels of a duration (50 ms) shorter than the latency of the acoustic stapedial reflex. Presentation level had no effect on recognition accuracy for vowels of sufficient duration (300 ms) to elicit the reflex. The poor recognition accuracy for the brief, high intensity vowels was significantly improved when the reflex was preactivated. These results demonstrate the importance of the acoustic reflex in extending the dynamic range of the auditory system for speech recognition.

Case study: Theoretical calculation model and variable condition analysis research on the water-splashing noise for natural draft wet cooling towers

2020 ◽  
Vol 68 (2) ◽  
pp. 137-145
Author(s):  
Yang Zhouo ◽  
Ming Gao ◽  
Suoying He ◽  
Yuetao Shi ◽  
Fengzhong Sun
Keyword(s):  
Theoretical Model ◽  
Sound Pressure Level ◽  
Water Droplet ◽  
Water Distribution ◽  
Sound Pressure ◽  
Cooling Tower ◽  
Distribution Patterns ◽  
Calculation Model ◽  
Pressure Level ◽  
Cooling Towers

Based on the basic theory of water droplets impact noise, the generation mechanism and calculation model of the water-splashing noise for natural draft wet cooling towers were established in this study, and then by means of the custom software, the water-splashing noise was studied under different water droplet diameters and water-spraying densities as well as partition water distribution patterns conditions. Comparedwith the water-splashing noise of the field test, the average difference of the theoretical and the measured value is 0.82 dB, which validates the accuracy of the established theoretical model. The results based on theoretical model showed that, when the water droplet diameters are smaller in cooling tower, the attenuation of total sound pressure level of the water-splashing noise is greater. From 0 m to 8 m away from the cooling tower, the sound pressure level of the watersplashing noise of 3 mm and 6 mm water droplets decreases by 8.20 dB and 4.36 dB, respectively. Additionally, when the water-spraying density becomes twice of the designed value, the sound pressure level of water-splashing noise all increases by 3.01 dB for the cooling towers of 300 MW, 600 MW and 1000 MW units. Finally, under the partition water distribution patterns, the change of the sound pressure level is small. For the R s/2 and Rs/3 partition radius (Rs is the radius of water-spraying area), when the water-spraying density ratio between the outer and inner zone increases from 1 to 3, the sound pressure level of water-splashing noise increases by 0.7 dB and 0.3 dB, respectively.

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