Types of heat exchanger and flow configurations

One of the simplest designs for a heat exchanger is the double pipe heat exchanger which is schematically illustrated in Fig. 1.19. It consists of two concentric tubes, where fluid 1 flows through the inner pipe and fluid 2 flows in the annular space between the two tubes. Two different flow regimes are possible, either counter-current where the two fluids flow in opposite directions, Fig. 1.19a, or cocurrent as in Fig. 1.19b. 

In practical applications the shell-and-tube heat exchanger, as shown in Fig. 1.20 is the most commonly used design. One of the fluids flows in the many parallel tubes which make up a tube bundle. The tube bundle is surrounded 

Pure crossflow is found in flat plate heat exchangers, as indicated by Fig. 1.22. The temperatures of both fluids also change perpendicular to the flow direction. This is schematically shown in Fig. 1.23. Each fluid element that flows in a crossflow heat exchanger experiences its own temperature change, from the entry temperature which is the same for all particles to its individual exit temperature. Crossflow is often applied in a shell-and-tube heat exchanger when one of the fluids is gaseous. The gas flows around the rows of tubes crosswise to the tube axis. The other fluid, normally a liquid, flows inside the tubes. The addition of 

There are also numerous other special designs for heat exchangers which will not be discussed here. It is possible to combine the three basic flow regimes of countercurrent, cocurrent and crossflow in a number of different ways, which leads to complex calculation procedures. 

The regenerator theory was mainly developed by H. Hausen [1.10]. As it includes a number of complicated calculations of processes that are time dependent no further study of the theory will be made here. The summary by H. Hausen [1.7] and the VDI-Warmeatlas [1.11] are suggested for further study on this topic. 

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