Heat Generation in Ferrous Metal Piles

1993 ◽  
Vol 115 (3) ◽  
pp. 168-174
Author(s):  
S. R. Gollahalli ◽  
J. E. Francis ◽  
D. Varshney
Keyword(s):  
Experimental Study ◽  
Bulk Density ◽  
Surface Area ◽  
Heat Generation ◽  
Temperature Rise ◽  
Ferrous Metal ◽  
Laboratory Scale ◽  
Spontaneous Heating ◽  
Marine Transport ◽  
Ferrous Material

A laboratory-scale experimental study of the basic processes and controlling parameters involved in the spontaneous heating of a pile of ferrous metal turnings during their marine transport is presented. The results indicate that the salinity of seawater, the amount of moisture coming in contact with the turnings, the surface area of turnings, the volume of container, and the bulk density of the pile affect the temperature rise in the ferrous material.

Differential Bone-Refuse Accumulation in Food-Preparation and Traffic Areas on an Early Ecuadorian House Floor

1990 ◽  
Vol 1 (2) ◽  
pp. 150-169 ◽  
Author(s):  
Peter W. Stahl ◽  
James A. Zeidler
Keyword(s):  
Bulk Density ◽  
Surface Area ◽  
Fish Bone ◽  
Horizontal Distribution ◽  
Total Weight ◽  
Food Preparation ◽  
Large Size ◽  
Traffic Area ◽  
High Concentrations ◽  
House Floor

Ethnographic observations of floor formation in an occupied and an abandoned Achuar jea dwelling structure are combined with contemporary taphonomic studies of swept and trampled surfaces. These studies suggest that refuse accumulation and incorporation are markedly different in food-preparation areas with ash deposits around fixed hearth features when compared to regularly trampled traffic areas of domestic earthen house floors. These points are examined in the horizontal and vertical analysis of highly fragmented bone remains in an Early Formative domestic house floor at the site of Real Alto, in the coastal lowlands of southwestern Ecuador. The food-preparation area of the Structure 1 house floor contained high concentrations of bone specimens characterized by their large size (over 25 mm), broad surface area, low bulk density, and greater total weight, vertically distributed throughout the ash matrix. The traffic area contained bone specimens characterized by their small size (under 25 mm), narrow surface area, high bulk density, and lower total weight, distributed unevenly in vertical profile. The horizontal distribution of fish bone only partially followed the observed pattern, as a proportionately greater amount of large fish bone was located in the traffic area. This analysis demonstrates the potential utility of bone refuse as a sensitive and reliable taphonomic indicator for inferential arguments regarding house-floor deposition.

An improved model on forecasting temperature rise of high-speed angular contact ball bearings considering structural constraints

2018 ◽  
Vol 70 (1) ◽  
pp. 15-22 ◽  
Author(s):  
De-xing Zheng ◽  
Weifang Chen ◽  
Miaomiao Li
Keyword(s):  
Heat Generation ◽  
Temperature Rise ◽  
High Speed ◽  
Structural Constraints ◽  
Ball Bearings ◽  
Content Type ◽  
Grid Model ◽  
Simulation Results ◽  
Operation Parameters ◽  
Improved Model

Purpose Thermal performances are key factors impacting the operation of angular contact ball bearings. Heat generation and transfer about angular contact ball bearings, however, have not been addressed thoroughly. So far, most researchers only considered the convection effect between bearing housings and air, whereas the cooling/lubrication operation parameters and configuration effect were not taken into account when analyzing the thermal behaviors of bearings. This paper aims to analyze the structural constraints of high-speed spindle, structural features of bearing, heat conduction and convection to study the heat generation and transfer of high-speed angular contact ball bearings. Design/methodology/approach Based on the generalized Ohm’s law, the thermal grid model of angular contact ball bearing of high-speed spindle was first established. Next Gauss–Seidel method was used to solve the equations group by Matlab, and the nodes temperature was calculated. Finally, the bearing temperature rise was tested, and the comparative analysis was made with the simulation results. Findings The results indicate that the simulation results of bearing temperature rise for the proposed model are in better agreement with the test values. So, the thermal grid model established is verified. Originality/value This paper shows an improved model on forecasting temperature rise of high-speed angular contact ball bearings. In modeling, the cooling/lubrication operation parameters and structural constraints are integrated. As a result, the bearing temperature variation can be forecasted more accurately, which may be beneficial to improve bearing operating accuracy and bearing service life.

Physical Properties Variability of Zinc Powders Obtained by Electrochemical Method

2021 ◽  
Vol 316 ◽  
pp. 689-693
Author(s):  
K.D. Naumov ◽  
V.G. Lobanov
Keyword(s):  
Particle Size ◽  
Specific Surface ◽  
Bulk Density ◽  
Surface Area ◽  
Specific Surface Area ◽  
Current Density ◽  
Zinc Concentration ◽  
Regulatory Change ◽  
Average Particle ◽  
Zinc Powders

The aim of this paper is to establish a regulatory change of zinc powders key physicochemical properties with varying electroextraction conditions. It was studied influence zinc concentration, alkali concentration and current density. Quantitative dependencies of zinc powders particle size and specific surface area from mentioned electroextraction parameters are shown. At increasing of zinc concentration, decreasing of NaOH concentration and decreasing of current density of powders particle size growth, correspondingly specific surface area is declined. It is indicated, that electrolytic zinc powders bulk density varies from 0.61 g/cm3 to 0.75 g/cm3 with a decrease of average particle size from 121 μm to 68 μm. In comparison, spherical powders bulk density used in various industries is currently 2.45-2.6 g/cm3. In all experiments, metal zinc content varied in the range of 91.1-92.5%, the rest - ZnO. To a greater extent, this indicator depends on powder washing quality from alkali and storage conditions.

A Convective-Heat Transfer Model for Underground Combustion

1968 ◽  
Vol 8 (04) ◽  
pp. 323-324
Author(s):  
C.H. Kuo
Keyword(s):  
Temperature Distribution ◽  
Convective Heat ◽  
Heat Generation ◽  
Temperature Rise ◽  
Combustion Front ◽  
Combustion Process ◽  
Front Velocity ◽  
Paradoxical Result ◽  
Heat Recuperation ◽  
Heat Front

In the underground combustion process, part of the heat generated at the combustion front is carried downstream by convection. Temperature distribution in the combustion process can be obtained by including a delta function for heat generation at the combustion surface. This is similar to the hot-fluid injection model of Lauwerier. The dimensionless temperature in the reservoir, phi T1(x, t), and the overburden, phi T2(x, y, t), are as follows: ..........................................(1) ..........................................(2) The ratio R of the heat-front velocity, u, h, to the combustion front velocity, uc, is one of the most important factors governing the temperature distribution in the pay zone. For cases of ub less than uc, no heat is carried ahead of the combustion front and the temperature at the combustion front remains constant for all times. The fraction of the heat stored between the heat front and the combustion front decreases as the time increases. This is because more of the heat is consumed in heating the formation behind the heat front and in heating the cap and bass rock. A more advantageous condition obtains for uh is greater than uc. For this case, the formation ahead of the combustion front is preheated and the amount of heat in this region increases with time. Therefore, due to heat generation and preheating, the total temperature rise at the combustion front also increases with time. Eq. 1 also shows that the temperature at the combustion front is higher at a given time for a thinner reservoir. This seemingly paradoxical result takes place because the amount paradoxical result takes place because the amount of heat recovered from the overburden and subrock upstream of the combustion front is almost independent of the pay zone thickness. On the other hand, this heat is distributed in the pay zone, which has a heat content directly proportional to the formation thickness b. For thin reservoirs, therefore, the temperature rise in the pay zone due to heat recuperation is higher than that in thick reservoirs. For very thick pay zones (h-oo) there would be no heat recuperation, and consequently the combustion- front temperatures would be lowest. For many cases encountered, uh is smaller than uc. Convective-heat transport. ahead of the combustion front can be achieved by increasing uh to obtain the condition uh, >uc. The wet and partially quenched combustion processes have a similar objective. The temperature at the combustion front, however, decreases as the uh/uc ratio increases. If this temperature should fall below the ignition point, the fire would die out. Consequently, at any point, the fire would die out. Consequently, at any time there exists a maximum ratio of uh/uc for which the formation ahead of the combustion front can be heated to increase oil mobility while combustion is maintained. For the case where the heat front moves faster than the combustion front (uh is greater than uc), the downstream heat efficiency E can be derived by applying the integration method given in Ref. 3. P. 323

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