Transfer coefficients of sensible heat on a snowmelt surface

1994 ◽  
Vol 53 (3-4) ◽  
pp. 233-240 ◽  
Author(s):  
N. Ishikawa ◽  
Y. Kodama
Keyword(s):  
Sensible Heat ◽  
Transfer Coefficients

Diffusion Layer Theory for Turbulent Vapor Condensation With Noncondensable Gases

1993 ◽  
Vol 115 (4) ◽  
pp. 998-1003 ◽  
Author(s):  
P. F. Peterson ◽  
V. E. Schrock ◽  
T. Kageyama
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Mass Transfer ◽  
Vapor Condensation ◽  
Sensible Heat ◽  
Transfer Coefficients ◽  
Heat Transfer Coefficients ◽  
Noncondensable Gas ◽  
Noncondensable Gases ◽  
Vertical Tubes

In turbulent condensation with noncondensable gas, a thin noncondensable layer accumulates and generates a diffusional resistance to condensation and sensible heat transfer. By expressing the driving potential for mass transfer as a difference in saturation temperatures and using appropriate thermodynamic relationships, here an effective “condensation” thermal conductivity is derived. With this formulation, experimental results for vertical tubes and plates demonstrate that condensation obeys the heat and mass transfer analogy, when condensation and sensible heat transfer are considered simultaneously. The sum of the condensation and sensible heat transfer coefficients becomes infinite at small gas concentrations, and approaches the sensible heat transfer coefficient at large concentrations. The “condensation” thermal conductivity is easily applied to engineering analysis, and the theory further demonstrates that condensation on large vertical surfaces is independent of the surface height.

Latent and Sensible Heat-Transfer Rates in the Boiling of Binary Mixtures

1982 ◽  
Vol 104 (3) ◽  
pp. 474-478 ◽  
Author(s):  
J. R. Thome
Keyword(s):  
Heat Transfer ◽  
Heat Transport ◽  
Binary Mixtures ◽  
Boiling Heat Transfer ◽  
Constant Heat Flux ◽  
Absolute Pressure ◽  
Sensible Heat ◽  
Transfer Coefficients ◽  
Heat Transfer Coefficients ◽  
Boiling Heat Transfer Coefficient

Nucleate pool boiling bubble departure data were obtained for the liquid nitrogen-argon cryogenic binary mixture system at 1.3 atmospheres absolute pressure. The latent and sensible heat transport rates at individual boiling sites were calculated from the data to deduce their effect on the degradation in the boiling heat-transfer coefficient in binary mixtures. The latent heat-transfer rate is a result of the bubble evaporation mechanism and the sensible heat-transport rate is due to cyclic thermal boundary layer stripping by departing bubbles. The latent and sensible heat-transport rates at individual boiling sites were found to decrease to a minimum at the maximum vapor-liquid mole fraction difference for both constant heat flux and wall superheating conditions. The large decrease in binary boiling heat-transfer coefficients was thus partially explained by the retardation of these two mechanisms and should be included in any model for predicting boiling heat-transfer coefficients in binary and multicomponent mixtures.

The use of heat transfer coefficients in estimating sensible heat loss from the pig

1977 ◽  
Vol 25 (3) ◽  
pp. 271-279 ◽  
Author(s):  
L. E. Mount
Keyword(s):  
Heat Transfer ◽  
Body Weight ◽  
Heat Loss ◽  
Radiant Heat ◽  
Heat Losses ◽  
Sensible Heat ◽  
Transfer Coefficients ◽  
Wind Speeds ◽  
Heat Transfer Coefficients ◽  
Environmental Temperatures

SUMMARYHeat transfer coefficients are used to calculate convective and radiant heat losses from pigs of 4, 20 and 60 kg body weight at 20 and 30 °C environmental temperatures for different wind speeds. Comparisons with heat losses estimated from whole-animal calorimetry suggest that calculations with heat transfer coefficients can lead to useful approximate estimates of heat loss from the pig.

scholarly journals Bulk transfer coefficients of momentum and sensible heat over semiarid grassland surface and their parameterization scheme

2013 ◽  
Vol 62 (9) ◽  
pp. 099202
Author(s):  
Yue Ping ◽  
Zhang Qiang ◽  
Li Yao-Hui ◽  
Wang Run-Yuan ◽  
Wang Sheng ◽  
...  
Keyword(s):  
Parameterization Scheme ◽  
Sensible Heat ◽  
Transfer Coefficients ◽  
Semiarid Grassland ◽  
Bulk Transfer Coefficients

scholarly journals Calculation of sensible-heat flux over a melting ice surface using simple climate data and daily measurements of ablation

2009 ◽  
Vol 50 (50) ◽  
pp. 9-15 ◽  
Author(s):  
Roger J. Braithwaite
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Heat Transfer Coefficient ◽  
Wind Speed ◽  
Transfer Coefficient ◽  
Sensible Heat Flux ◽  
Sensible Heat ◽  
Climate Data ◽  
Transfer Coefficients ◽  
Monthly Basis

AbstractSensible-heat flux is obviously important for glacier ablation but is difficult to measure routinely. Sensible-heat flux can be estimated from wind-speed and temperature data using a dimensionless heat-transfer coefficient. Values of the heat-transfer coefficient are evaluated for six sites by correlating measured melt energy with a wind–temperature variable (product of daily mean wind speed, temperature and mean atmospheric pressure for the altitude in question). Data are available for short periods from two sites in Arctic Canada and two sites in North Greenland, and for hundreds of days of record at Nordbogletscher and Qamanârssûp sermia in South and West Greenland, respectively. Average transfer coefficients for four out of the six sites are close to 0.003, which is in reasonable agreement with values reported elsewhere, while larger values of 0.0047 and 0.0057 are found at the other two sites. Heat-transfer coefficients are also estimated on a monthly basis for the two long records, and substantial variations are found, suggesting that the method should not be used for <20–30 days of data. The present study is based on manually observed ablation and climate data, but the approach could be updated to use data from automatic recording stations using modern sensors.

scholarly journals An improved non-iterative surface layer flux scheme for atmospheric stable stratification condition

2013 ◽  
Vol 6 (4) ◽  
pp. 6459-6492
Author(s):  
Y. Li ◽  
Z. Gao ◽  
D. Li ◽  
L. Wang ◽  
H. Wang
Keyword(s):  
Full Range ◽  
Stable Stratification ◽  
Iteration Scheme ◽  
Surface Fluxes ◽  
Turbulent Transfer ◽  
Sensible Heat ◽  
Transfer Coefficients ◽  
Iterative Computation ◽  
Stable Conditions ◽  
Relative Errors

Abstract. Parameterization of turbulent fluxes under stably stratified conditions has always been a challenge. Current surface fluxes calculation schemes either need iterations or suffer low accuracy. In this paper, a non-iteration scheme is proposed to approach the classic iterative computation results using multiple regressions. It can be applied to the full range of roughness status 10 ≤ z/z0 ≤ 105 and −0.5 ≤ log(z0/z0h) ≤ 30 under stable conditions 0< RiB ≤ 2.5. The maximum (average) relative errors for the turbulent transfer coefficients for momentum and sensible heat are 12% (1%) and 9% (1%), respectively.

Evaporation of sweat from sedentary man in humid environments

1977 ◽  
Vol 42 (5) ◽  
pp. 767-772 ◽  
Author(s):  
L. G. Berglund ◽  
R. R. Gonzalez
Keyword(s):  
Thermal Sensation ◽  
Water Vapor Pressure ◽  
Heat Rate ◽  
Sensible Heat ◽  
Ambient Water ◽  
Transfer Coefficients ◽  
Chamber Temperature ◽  
Temperature Sensations ◽  
Sensory Responses ◽  
Male Subjects

Physiological and sensory responses were observed in four male subjects while they were seated on a balance. The chamber temperature always equaled mean skin (Tsk)(34–36 degrees C), thus eliminating all sensible heat transfer. Ambient water vapor pressure (Pa) was increased in steps from 10 to 40 Torr. Tests at air velocities from 0.1 to 2.4 m/s were conducted with subjects nude and clothed. Esophageal temperature (Tes) and Tsk, heat rate (HR) and weight loss (M) were measured throughout the 2.5-h tests. After each 25-min humidity step subjects recorded their warm discomfort, sensation of sweating, and thermal sensation. Results: Tsk, HR, and M were unaffected by humidity until critical Pa (P a crit) was reached above which M decreased and Tsk and HR increased rapidly. P a crit decreased with clothing and decreasing velocity. Tes remainded relatively constant throughout the tests. Sweating, discomfort and temperature sensations increased gradually with increasing Pa. Above P a crit sweating and discomfort sensations accelerated markedly. Mass transfer coefficients and clothing vapor conductance factors were evaluated. Skin wettedness at Pa crit decreased from 74% at 0.1 m/s to 35% at 2.4 m/s.

Sign in / Sign up

Export Citation Format

Share Document