Spray impingement

Direct water spray cooling must be carried out with care. The spray chamber must be designed to ensure complete evaporation of all Hquid droplets before the gas enters the baghouse. Spray impinging on the chamber walls can result ia a dust mud iaside the chamber and any increase ia gas dewpoint may result in baghouse problems or atmospheric plume condensation. Spray nozzle wear can result in coarse or distorted spray and wetted bags, and water pressure failure can cause high temperature bag deterioration. 

Directly cools the vessel metal wall by spray impingement and rundown and, in sufficient quantity, can prevent vessel failure by reducing excessively high metal wall temperatures even in an empty, or nearly empty, vessel. 

As noted above, any direct dryer, in principle, can be converted to superheated steam operation (e.g., flash, fluid bed, spray, impinging jet, conveyor dryers, etc.). Thermal efficiencies can be improved and the unit size reduced by supplying a part of the heat indirectly (e.g., by conduction or radiation). Note that the inversion temperature is lowered in the presence of indirect heat supply, which is a further benefit. For example, in the presence of appropriate radiant heating, the inversion temperatnre dropped from 250 C to ITO C for a specific case reported in the literature. 

C. Mundo, C. Tropea, M. Sommerfeld On the modelling of liquid sprays impinging on surfaces. Atom. Sprays, 8, 625-652 (1998). 

R.O. Grover, D.N. Assanis, A.M. Lippert, S.H. El Tahry, M.C. Drake, T.D. Pansier, D.L. Harrington, A critical analysis of splash criteria for GDI spray impingement, ILASS Americas, 15th Annual Conference on Liquid Atomization and Spray Systems, Madison, May 2002. 

Bai CX, Rusche H, Gosman AD (2002) Modeling of gasoline spray impingement Atomization and Sprays 12 1-27. 

Panao MRO, Moreira ALN (2005a) Flow characteristics of spray impingement in PFI injection systems. Experiments in Fluids 39 364—374. 

Panao MRO, Moreira ALN (2009a) Heat transfer correlation for intermittent spray impingement a dynamic approach. International Journal Thermal Science 48(10) 1853-1862. 

Pautsch A, Shedd T (2005). Spray impingement cooling with single- and multiple-nozzle arrays. Part II visualization and empirical models. International Journal of Heat and Mass Transfer 48 3176-3184. 

Another important dimensionless variable is the ratio of chamber-to-pintle diameters, djdp. Typical values for this quantity range from 3 to 5 [2]. Finally, the skip distance is defined as the length that the annular flow must travel before impacting the radial holes divided by the pintle diameter, LJd. A typical value for this parameter is around 1 larger skip distances are subject to substantial deceleration of the liquid due to friction against the pintle post whUe very short skip distances may lead to spray impingement on the head-end of the combustion chamber. 

Arai, M. and Saito, M., Atomization Characteristics of Jet-to-Jet and Spray-to-Spray Impingement Systems, Atom. Sprays, Vol. 9, pp. 399-417, 1999. 

Based on the spray impingement mechanism, a new double-layers diffluent combustion system for DI diesel engine is proposed which has a collision platform with circular oriented-surface in order to improve the characteristics of air-fuel mixture and combustion process of diesel engine. 

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