Volume 33, Issue 4

Thermal heat efficiency, represented by the heating gain factor, is calculated by using non-equilibrium thermodynamics of discrete systems, thus replacing former estimations and results by finite-time thermodynamics. For performing this calculation, an irreversible Jaynes engine is introduced and compared with conventional heating by heat conduction. Starting out with the second law, represented by Clausius inequalities for the particular parts of the Jaynes engine, the heating gain factor is expressed by their efficiency factors. The entropy productions of the reversible and the totally irreversible limits are considered. The profit of heat supply and the higher stationary temperature of the heated room obtained by using a Jaynes engine are calculated. Comparison with the conventional heating demonstrates that fuel saving is possible by changing the traditional heating technology.

In this paper, we propose using entropy generation theory to interpret and assess a single cell's freezing injury resulting from the irreversible thermodynamic process of heat and mass transfer throughout the cell. Correspondingly, heat and mass transport and entropy generation models at the cellular level were established. Several typical freezing processes of biological cells were investigated by comparing the variation of total cell entropy generation before and after freezing, which could well reflect the cell freezing injury. The simulation accords well with existing experimental results. With the entropy generation theory, it is possible to predetermine the suitable freezing protocol and thus to minimize the freeze injury while assuring the maximum vitality of the cell. Furthermore, an evaluation of cell injury induced by different freezing combinations could be easily performed by taking advantage of the present model. This study helps to better understand the physical-chemical processes during cell freezing. It also suggests a novel way to effectively optimize freezing protocols as well as to evaluate the damage degree involved.

The application of concepts, principles, and methods of thermodynamics of equilibria and processes to bioengineering systems has led to a new and growing field: engineering biothermodynamics. This article, which is meant as the first in a series, gives an outline of basic aspects, changes, and actual examples in this field. After a few introductory remarks, the basic concepts and laws of thermodynamics extended to systems with internal variables, which serve as models for biofluids and other biosystems, are given. The method of thermodynamics is then applied to the problem of thermal stability of aqueous protein solutions, especially to that of myoglobin solutions. After this, the phenomenon of hydration of proteins by adsorption and intrusion of water molecules is considered. Several other phenomena like the adsorption of proteins on solid surfaces or cell membranes and their temperature and pressure-related behavior represented by an equation of state, or the thermodynamics of bacterial solutions including chemical reactions like wine fermentation, etc., will be presented in Parts II and III of this article.