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Superficial deposits
Published in A.C. McLean, C. D. Gribble, Geology for Civil Engineers, 2017
A glacier deposits its remaining load of moraine at the ice front. If this is static, the coarse gravel and boulders form an irregular ridge called a terminal moraine. A series of recessional moraines, of similar character, may be formed at successive halting stages as the ice front retreats. Finer fractions of the moraine are transported by melt waters issuing from tunnels in the glacier and from wasting ice at the front of the glacier. The position of such a tunnel mouth may be marked as the ice front retreats by an elongated hummock of cross-bedded sand and gravel. The rate of flow of the meltwater stream decreases as it spreads, free from the confinement of the tunnel walls, and much of its load is dropped. A sinuous ridge called an esker may form as the tunnel mouth changes position while the ice retreats, if there is a steady supply of sand. A more complicated retreat, with large masses of stagnant ice present, may produce lines of hummocks called kames. When a large block of ice melts, it leaves a depression in the drift (commonly a few metres across and one or two metres deep) called a kettle hole. Sand and fine gravel may be carried for kilometres from the ice front, and be deposited as a flat spread of well bedded, well sorted sediments. Other terms, such as kame terrace and fluvioglacial fan, are used to describe landforms produced by spreads of gravel and sand.
Vertical Gradients In Peatlands
Published in George Mulamoottil, Barry G. Warner, Edward A. McBean, Wetlands, 2017
The co-occurrence of peatland species with indicators associated with the European period show that deforestation by early European settlers caused the floating peat mats to form on the surface of what was either a lake or shallow open water wetland in the pre-European period (Warner et al., 1989; Warner, 1993). Deforestation and agricultural fields likely reduced the regulating effects of forest cover on snowmelt during the spring thaw. This would have resulted in either increased surface runoff and spring floods in the undrained kettle holes or a rise in the local ground water table, or both. The peatland shrubs and mosses were favored by the rise in water levels in the kettle holes and established floating carpets of vegetation over the open water bodies.
Groundwater Targeting Using Remote Sensing
Published in Prasad S. Thenkabail, Remote Sensing Handbook, 2015
“Kettle holes” are formed by the collapse of till and ice-contact sediments as isolated masses of residual ice melt. Kettle holes may be found on kame terraces, wide parts of eskers, till plains, and terminal moraines.
Coupled two-fluid flow and wall heat conduction modeling of nucleate pool boiling
Published in Numerical Heat Transfer, Part A: Applications, 2021
Milan M. Petrovic, Vladimir D. Stevanovic
The interfacial drag force per unit volume is calculated as where denotes the interfacial drag coefficient and is the bubble mean diameter. The drag coefficient depends on the vapor volume fraction (void) in the two-phase mixture. For lower values of void the interfacial drag coefficient is calculated with the modified Ishii-Zuber correlation [40] (the original correlation is modified by the multiplication with 0.4 [37]) where the function of void is given as For higher values of void the interfacial drag coefficient is determined with the correlation derived by Stosic and Stevanovic [37] in the same algebraic form as applied in the CATHARE correlation [41] The accuracy of void and liquid and vapor velocities prediction depends on proper modeling of interfacial drag force in two-phase systems. Here presented closure law for the interfacial drag force prediction was tested and validated for steam-water two-phase flows in nuclear steam generators [37], for water-air flows around tubes in a bundle [42] and for kettle reboiler two-phase flows [43].
Case study on energy audit in HPCL, Mazgaon Dock Ltd, Mumbai
Published in International Journal of Ambient Energy, 2020
Santosh D. Dalvi, Chandrababu Divakaran, Pranav Kumar Pandey, Ajay Tiwari
Steam and cooling tower water used for the chemical reaction in the Kettle/Settling Tank in the coils (indirect heating/cooling) and same coils are used for both the cases. Therefore, a separate steam header and cooling water header installed in the plant; if heating/cooling is not required for the process then it returned back to the cooling tower or boiler through the respective headers. Figure 4 represents the cooling tower pump which is installed in the HPCL plant. However, steam and cooling water normally circulate in the respective headers but these are not required all the time as its requirement depends upon the product/process requirements. Therefore, steam and cooling water circulates in the respective headers is redundant, causes steam and electricity losses. It is observed that a pump motor running for the cooling tower and it supplied water to the header. Therefore, it is recommended to replace this pump motor with the appropriate size of new IE3 motor (3.7 kW) which will be useful to save the energy in the cooling tower pump.