Volume 38, Issue 3

Abstract. Shear-induced viscosity and thermal conductivity measurements were performed for viscoelastic fluids. This research was also designed to investigate the extent to which the thermal conductivity of viscoelastic fluids is affected by fluid motion under conditions in which it is known that the viscous properties undergo significant changes, and then the effect of the shear-induced thermal conductivity measured on the convective heat transfer enhancement for a heat exchanger system. It was also found experimentally that the thermal conductivity increased with shear rate for two polyacrylamide solutions of 1000 and 2000 wppm with order of 23%–43% and 17%–21%, respectively, depending on temperature (20–50 °C). The increase in the thermal conductivity with a shear rate was greater for lower concentration polyacrylamide solutions than for higher concentration ones, with a difference of 8%–22% depending on temperature range (20–50 °C). The convective heat transfer enhancement with the shear-induced thermal conductivity in the infinite rectangular duct was of the order of 41%–74% and 41%–52% over the entire temperature range (20–50 °C) of the two polyacrylamide solutions of 1000 and 2000 wppm, respectively.

Abstract. This article is an adapted version of the introductory chapter of a book whose publication is imminent. It bears the title “Biothermodynamics – The role of thermodynamics in biochemical engineering.” The aim of the paper is to give a very short overview of the state of biothermodynamics in an engineering context as reflected in this book. Seen from this perspective, biothermodynamics may be subdivided according to the scale used to formalize the description of the biological system into three large areas: (i) biomolecular thermodynamics (most fundamental scale), (ii) thermodynamics of metabolism (intermediary scale), and (iii) whole-cell thermodynamics (“black-box” description of living entities). In each of these subareas, the main available theoretical approaches and the current and the potential applications are discussed. Biomolecular thermodynamics (i) is especially well developed and is obviously highly pertinent for the development of downstream processing. Its use ought to be encouraged as much as possible. The subarea of thermodynamics of live cells (iii), although scarcely applied in practice, is also expected to enhance bioprocess research and development, particularly in predicting culture performances, for understanding the driving forces for cellular growth, and in developing, monitoring, and controlling cellular cultures. Finally, there is no question that thermodynamic analysis of cellular metabolism (ii) is a promising tool for systems biology and for many other applications, but quite a large research effort is still needed before it may be put to practical use.

Abstract. This paper considers non-equilibrium energy transport in the solid due to short-pulse heating and presents an analytical solution for electron and lattice site temperature distributions inside the solid. The study is extended to include the solution of the governing energy equation for the volumetric and the surface heat sources. It is found that the electron temperature obtained from the volumetric heat source differs considerably from that corresponding to the surface heat source model; in which case, the electron temperature is higher for the surface heat source than for the volumetric heat source at the surface, despite the fact that the same value of peak intensity is used in both cases.

Abstract. Entransy is a function recently introduced in thermodynamics. This function is analyzed critically in relation to the classical thermodynamic approach in order to understand its physical fundamentals. The crucial problem is that thermodynamic analysis shows that entransy does not contain any new information in comparison with a classical thermodynamic analysis of systems. Furthermore, entransy dissipation analysis is a duplicate of entropy generation analysis.

Abstract. In this study, gas hydrate formation kinetics of methane and ethane binary mixtures has been studied and data of mixed methane–ethane hydrate formation at 0.1, 0.2, 0.3, 0.5, 0.68, 0.8, and 0.9 mole fractions of methane and at a temperature of 277.15 K and an initial pressure of approximately 3.6 MPa were collected. The thermodynamic natural path was used for modeling the hydrate formation rate in a constant volume process. The results show that there is good agreement between model prediction and experimental data, with an average error of 0.9%. It was observed that the values of these parameters are dependent on the concentration of components in the mixtures. The results indicate that this model can predict constant volume experimental data of binary mixture hydrate.