4.4 Exergy analysis

Exergy analysis allows to identify the com onents of the ower cycle, whose arameters have greater influence on the maximum ower generation of the

Organic Rankine Cycle. An optimization is done maximizing heat transfer and minimizing pressure drop and overheated and overcooled areas for each of the configurations simulated in CFD. Tables 6 and 7 show the exergy analysis for each heat exchanger, where the last column shows the optimization results. From the results, it is seen that the helical heat exchanger is more efficient than the finned heat exchanger. The overheated area of the helical heat exchanger has similar values than the finned heat exchanger. The overcooled area of the helical heat exchanger is higher than the finned heat exchanger. Pressure drop for the ethylene glycol side for both types of heat exchanger has similar values. The same variable for the gas side is higher in the helical exchanger than in the finned exchanger. Finally, the heat transfer is higher in the helical heat exchanger than in the finned heat exchanger. The heat exchanger has similar dimensions, so it could be a good idea to use a helical heat exchanger to extract as much heat as possible. The pressure drop could be an important factor to consider as well. In that case, the finned heat exchanger could be considered.


#### Table 6.

Exergy balance for the helical-tube geometry.


#### Table 7.

Exergy balance for the finned-tube geometry.

#### Exhaust Gas Heat Recovery for an ORC: A Case Study DOI: http://dx.doi.org/10.5772/intechopen.86075


#### Table 8.

Power output using the helical-tube heat exchanger.


Table 9.

Power output using the finned-tube heat exchanger.
