Increasing awareness for the effective utilization of energy resources, minimizing operating cost and maintenance-free operation have led to the development of efficient heat exchangers such as compact heat exchangers. London and Shah in their elaborate discussion of the classification of heat exchangers have defined the “compact heat exchanger” as one having a surface area density of more than 700 m² per m³. Such compactness is achieved by providing the extended surfaces, that is, fins on the flow passages that work as the secondary heat transfer area.