Volume 40, Issue 1

We revisit the classic thermodynamic problem of maximum work extraction from arbitrary-sized source of heat and sink, modelled as perfect gases. For a given initial state of the process, we assume ignorance of the final temperatures. We quantify the prior information about the process and assign a prior distribution to the unknown temperature(s). This requires that we also take into account the temperature values which are not regarded in standard analysis. In the present formulation, however, such values appear to be consistent with the given prior information and hence are included here in the inference. We derive estimates of the efficiency at optimal work from the expected values of the final temperatures, and show that these match with the exact expressions in the limit when any one of the systems is very large compared to the other. For other relative sizes of the source and the sink, a weighted mean is defined over the estimates from two valid inference procedures, that generalizes the procedure suggested earlier in [J. Phys. A: Math. Theor. 46 (2013), 365002]. The mean estimate for efficiency obtained in this way agrees with the results of the optimal performance quite accurately.

Measurements on hydrodynamic and electro-osmotic permeability of water and aqueous solutions of KNO 3 and Pb(NO 3 ) 2 in the concentration ( C ) range of 10-4$10^{-4}$ M to 10-3$10^{-3}$ M are made across the Nylon-66 membrane. The data obtained are used to ascertain the form of transport equation using the theory of non-equilibrium thermodynamics. Conductance of membrane equilibrated with water and aqueous solutions are measured and the data are used to estimate phenomenological coefficients. These phenomenological coefficients are used to determine the average pore radius, the average number of pores and the membrane constant. Zeta potentials are evaluated using electro-osmotic permeability and membrane-permeant conductance data to understand the electrical nature of the membrane-permeant interface. It is observed that hydrodynamic permeability and electro-osmotic permeability depend linearly on the applied pressure difference and the potential difference, respectively.

In classical thermodynamics, the maximum power obtained from a system is defined as exergy (availability). However, the term exergy is used for reversible cycles only; in reality, reversible cycles do not exist, and all systems are irreversible. Reversible cycles do not have such restrictions as time and dimension, and are assumed to work in an equilibrium state. The objective of this study is to obtain maximum available work for SI, CI and Brayton cycles while considering the aforementioned restrictions and assumptions. We assume that the specific heat of the working fluid varies with temperature, we define optimum compression ratios and pressure ratio in order to obtain maximum available work, and we discuss the results obtained. The design parameter most appropriate for the results obtained is presented.

Adenosine triphosphate (ATP) production in living cells is very important. Different researches have shown that in terms of mathematical modeling, the domain of these investigations is essentially restricted. Recently the thermodynamic models have been suggested for calculation of the efficiency of oxidative phosphorylation process and rate of energy loss in animal cells using chemiosmotic theory and non-equilibrium thermodynamics equations. In our previous work, we developed a mathematical model for mitochondria of animal cells. In this research, according to similarities between oxidative phosphorylation process in microorganisms and animal cells, Golfar's model was developed to predict the non-equilibrium thermodynamic behavior of the oxidative phosphorylation process for bacteria in aerobic condition. With this model the rate of energy loss, P / O ratio, and efficiency of oxidative phosphorylation were calculated for Escherichia coli in aerobic condition. The results then were compared with experimental data given by other authors. The thermodynamic model had an acceptable agreement with the experimental data.

This study undertakes the experimental and theoretical investigation of heat losses from a cylindrical cavity receiver employed in a solar parabolic dish collector. Simultaneous energy and exergy equations are used for a thermal performance analysis of the system. The effects of wind speed and its direction on convection loss has also been investigated. The effects of operational parameters, such as heat transfer fluid mass flow rate and wind speed, and structural parameters, such as receiver geometry and inclination, are investigated. The portion of radiative heat loss is less than 10%. An empirical and simplified correlation for estimating the dimensionless convective heat transfer coefficient in terms of the Re $\mathrm {Re}$ number and the average receiver wall temperature is proposed. This correlation is applicable for a wind speed range of 0.1$0.1$ to 10 m/s. Moreover, the proposed correlation for Nu $\mathrm {Nu}$ number is validated using experimental data obtained through the experiments carried out with a conical receiver with two aperture diameters. The coefficient of determination R 2 and the normalized root mean square error (NRMSE) parameters were calculated, and the results show that there is a good agreement between predicted results and experimental data. R 2 is greater than 0.95$0.95$ and the NRMSE parameters is less than 0.06$0.06$ in this analysis.