Exchangers, one pass

When the outlet temperatures of both fluids are identical, the MTD correction fac tor for a 1 2 shell-and-tube exchanger (one pass shell... 

Mean-temperature-difference (MTD) correction factor. When the outlet temperatures of both fluids are identical, the MTD correction factor for a 1 2 shell-and-tube exchanger (one pass shell side, two or more passes tube side) is approximate 0.8. For a single-pass aircooled heat exchanger the factor is 0.91. A two-pass exchanger has a factor of 0.96, while a three-pass exchanger has a factor of 0.99 when passes are arranged for counterflow. 

FIG. 11-2 Diagram of a 1-2 exchanger (one well-baffled shell pass and two tube passes with an equal number of tubes in each pass). 

Berg, W. E. and J. L. Berg, Elow Patterns for Isothermal Condensation in One-Pass Air-Cooled Heat Exchangers, Heat Trans-fierEng.,. 4, April-June (1980) p. 21. 

Table 11.3 One pass (read left to right) through the step.s of a basic genetic algorithm scheme to maximize the fitness function f x) = using a population of six 6-bit chromosomes. The crossover notation aina2) means that chromosomes Ca, and Ca2 exchange bits beyond the bit. The underlined bits in the Mutation Operation column are the only ones that have undergone random mutation. See text for other details.

In many of the applications of heat transfer in process plants, one or more of the mechanisms of heat transfer may be involved. In the majority of heat exchangers heat passes through a series of different intervening layers before reaching the second fluid (Figure 9.1). These layers may be of different thicknesses and of different thermal conductivities. The problem of transferring heat to crude oil in the primary furnace before it enters the first distillation column may be considered as an example. The heat from the flames passes by radiation and convection to the pipes in the furnace, by conduction through the... 

In these designs there is one pass for the fluid on the shell-side and a number of passes on the tube-side. It is often an advantage to have two or more shell-side passes, although this considerably increases the difficulty of construction and, very often therefore, several smaller exchangers are connected together to obtain the same effect. 

High-purity water for special applications is obtained by distillation or by ion exchange, the exchange of one type of ion in a solution by another. In ion exchange, water passes through a column packed with a material such as zeolite, an aluminosilicate with a very open structure that can capture ions such as Mg2+ and Ca2+ and exchange them for H+ ions (see Box 13.4). 

Figure 16 Schematic of a shell-and-tube heat exchanger (one-shell pass and one-tube pass)...

If the total number of tubes is n, there are n/2 tubes in one pass on the oil side, that is the oil passes through 2 tubes in traversing the exchanger. 

Figure B.l shows the American TEMA (Tubular Exchanger Manufacture Association) standards that are largely accepted. The codification makes use of three letters that indicate the type of stationary head, shell and rear head, respectively. One of the most common types is AES or AEL that designate removable channel and cover (A), one-pass shell (E) and fixed tube sheet (L) or floating-rear (S). A similar...

Please submit this information as a complete formal report. Include a short section outlining what further calculations would have been necessary if the specification of 100 tubes in a one-pass exchanger had not been given. 

Step 3. The exothermic heat of reaction must be removed, and the reactor feed must be heated to a high enough temperature to initiate the reaction. Since the heat of reaction is not large and complete one-pass conversion is not achieved, the reactor exit temperature is only 32°F higher than the reactor inlet temperature. Since heat transfer coefficients in gas-to-gas systems are typically quite low, this small temperature differential would require a very large heat exchanger if only the reactor effluent is used to heat the reactor feed and no furnace... 

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