Pressure Drop and Heat Transfer

Palen, J. W. and Taborek, J., Solution of Shell-Side Flow Pressure Drop and Heat Transfer by Stream Analysis Method (Heat Transfer Research, Inc., Alhambra, CA), AICHE Chemical Engineering Progress Symposium Series No. 92, Vol. 65 (1969), pp. 53-63. 

Refer to the earlier section in this chapter, because tubeside pressure drop and heat transfer are subject to the same conditions as other tubular exchangers. 

The minimum number of the tube rows recommended to establish a proper air flow pattern is 4, although 3 rows can be used. The typical unit has 4-6 rows of tubes, but more can be used. Although more heat can be transferred by increasing the number of tubes, the required fan horsepower will be increased however, this balance must be optimized for an effective economical design. Tubes are laid out on transverse or longitudinal patterns however, the transverse is usually used due to the improved performance related to pressure drop and heat transfer. The tube pitch is quite important for best air-side performance. A typical representative tube arrangement for design optimization is for hare-tube O.D., tinned-tube O.D., and tube pitch ... 

Palen, J.W. and TABORAK, J. Chem. Eng. Prog. Sym. Ser. No. 92, 65 (1969) 53. Solution of shell side flow pressure drop and heat transfer by stream analysis method. 

ESDU Engineering Sciences Data Unit Report 83038 Baffled shell and tube heat exchangers flow distribution, pressure drop and heat transfer on the shell side. (ESDU International, London 1983)... 

We attempt here to describe the fundamental equations of fluid mechanics and heat transfer. The main emphasis, however, is on understanding the physical principles and on application of the theory to realistic problems. The state of the art in high-heat flux management schemes, pressure and temperature measurement, pressure drop and heat transfer in single-phase and two-phase micro-channels, design and fabrication of micro-channel heat sinks are discussed. 

Pressure Drop and Heat Transfer in a Single-Phase Flow 33... 

Experimental and numerical study of the pressure drop and heat transfer in a single-phase micro-channel heat sink by Qu and Mudawar (2002a,b) demonstrated that the conventional Navier-Stokes and energy equations can adequately predict the fluid flow and heat transfer characteristics. 

Pressure drop and heat transfer in a single-phase incompressible flow. According to conventional theory, continuum-based models for channels should apply as long as the Knudsen number is lower than 0.01. For air at atmospheric pressure, Kn is typically lower than 0.01 for channels with hydraulic diameters greater than 7 pm. From descriptions of much research, it is clear that there is a great amount of variation in the results that have been obtained. It was not clear whether the differences between measured and predicted values were due to determined phenomenon or due to errors and uncertainties in the reported data. The reasons why some experimental investigations of micro-channel flow and heat transfer have discrepancies between standard models and measurements will be discussed in the next chapters. 

Qu W, Mudawar 1 (2002a) Experimental and numerical study of pressure drop and heat transfer in a single-phase micro-channel heat sink. Int J Heat Mass Transfer 45 2549-2565 Qu W, Mudawar 1 (2004) Measurement and correlation of critical heat flux in two-phase micro-channel heat sinks. Int J Heat Mass Transfer 47 2045-2059 Qu W, Mudawar 1 (2002b) Prediction and measurement of incipient boiUng heat flux in micro-channel heat sinks. Int J Heat Mass Transfer 45 3933-3945... 

In Chap. 5 the available data related to flow and heat transfer of a gas-liquid mixture in single and parallel channels of different size and shape are presented. These data concern flow regimes, void fraction, pressure drop and heat transfer. The effects of different parameters on flow patterns and hydrodynamic and thermal characteristics of gas-liquid flow are discussed. 

The subject of Chap. 6 is boiling in micro-channels. Several aspects of boiling are also considered for conventional size channels and comparison with micro-channels was carried out. Significant differences of ONB in micro-channels have been discussed compared to conventional channels. Effect of dissolved gases on boiling in water and surfactant solution was revealed. Attention was paid on pressure drop and heat transfer, critical heat flux and instabilities during flow boiling in microchannels. 

Brutin B, Tadrist L (2004) Pressure drop and heat transfer analysis of flow boUing in micro-channel influence of the inlet condition on two-phase flow stability. Int J Heat Mass Transfer 47 2367-2377... 

Landau LD, Lifshitz EM (1959) Fluid mechanics, 2nd edn. Pergamon, London Landerman CS (1994) Micro-channel flow boiling mechanisms leading to Burnout. J Heat Transfer Electron Syst ASME HTD-292 124-136 Levich VG (1962) Physicochemical hydrodynamics. Prentice HaU, London Morijama K, Inoue A (1992) The thermohydraulic characteristics of two-phase flow in extremely narrow channels (the frictional pressure drop and heat transfer of boiling two-phase flow, analytical model). Heat Transfer Jpn Res 21 838-856... 

The pressure-drop and heat-transfer coefficients in empty tube reactors can be calculated using the methods for flow in pipes given in Volume 1. 

It is the full wetted perimeter that determines the flow regime and the velocity gradients in a channel. So, in this book, de determined using the full wetted perimeter will be used for both pressure drop and heat transfer calculations. The actual area through which the heat is transferred should, of course, be used to determine the rate of heat transfer equation 12.1. 

The Engineering Sciences Data Unit has also published a method for estimating shell-side the pressure drop and heat transfer coefficient, EDSU Design Guide 83038 (1984). The method is based on a simplification of Tinker s work. It can be used for hand calculations, but as iterative procedures are involved it is best programmed for use with personal computers. 

More accurate, but more complex, methods could be used to predict the two-phase pressure drop and heat transfer coefficients. 

ESDU 84023 (1985) Shell-and-tube exchangers pressure drop and heat transfer in shellside downflow condensation. 

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