Multi-pass and Mixed Flow Recuperators

To increase the necessary surface area with a simple tube and annulus arrangement, the length of the tube may be too large for practical purposes. In order to make the heat exchanger more compact, which is desirable from space considerations, and also to reduce the heat loss from the outside surface, it is necessary to have several tubes and perhaps several passes or bundles of tubes. The flow can be either cross flow, or a mixture of parallel flow, counter flow, and cross flow as shown in Figure 7.13. The latter case is called mixed flow.

Figure 7.13 Multi-pass Recuperator