Countercurrent heat exchangers organs

A flow of 1 kg/s of an organic liquid of heat capacity 2.0 kJ/kgK is cooled from 350 to 330 K by a stream of water flowing countercurrently through a double-pipe heat exchanger. Estimate the effectiveness of the unit if the water enters the exchanger at 290 K and leaves at 320 K. 

These traits have received most study in tunas, a group of fishes noted for continuous swimming and for major anatomical differences from other fishes. Of particular importance in the anatomical organization of tunas is the internalization of red muscle, an anatomical feature that appears critical for allowing endothermy to develop. In most fishes, the red muscle is located superficially, where it would be difficult, if not impossible, to prevent loss of metabolically generated heat to the environment. The internalization of the red muscle mass in tunas isolates this tissue from close contact with seawater. There is also an effective isolation from the medium of the circulatory system within red muscle countercurrent exchangers interspersed between red muscle and the arterial circulation supplying the tissue allow much of the heat produced in red muscle to be retained, rather than lost to the environment. 

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