Entropy Generation in Human Respiration System: a Review Paper
Abhijit Hazra ; Sujay Biswas ; Sujit Kumar Garai ; Anupam Barik ;
The irreversible processes involve heat and result in entropy generation, which tends to accumulate within the system. For example, friction heats up and slows down moving parts. The analysis of a number of natural processes can be facilitated by assuming that they are in fact reversible. These processes are called quasi-reversible. The respiratory system consists of two lungs, right and left, situated in the thorax and connected via their primary bronchi to the trachea and upper airway of the nose and mouth, The bronchi, or more generally the airways, then form a branching network which, for the most part, is a sequence of bifurcations. Each level of branching is called a generation, starting with the trachea as generation n=0, the primary bronchi, generation n=1, and so on. For a perfectly bifurcating system, there will be 2n airway tubes at generation n. For 0≤ n≤ 16, the airways only conduct the gas flow in and out, they do not have any specializes apparatus for exchange of oxygen and carbon dioxide between air and blood. It is the conducting zone. For 17 ≤ n≤19, there start to appear small air sacs, alveoli, on the airway walls. Alveoli are thin-walled and compliant with a rich capillary blood supply and are designed for gas exchange. These special airways are the respiratory bronchioles.