This study proposes and investigates a hybrid system that couples an ammonia-fueled protonic ceramic fuel cell (NH3-PCFC) with sweeping gas membrane distillation (SGMD) to co-produce electricity and freshwater. A comprehensive steady-state model is developed, incorporating ammonia decomposition kinetics, NH3-PCFC electrochemistry, and detailed heat- and mass-transfer within the SGMD module. The NH3-PCFC and SGMD submodels are independently validated against published data, providing support for the credibility of the coupled modeling framework. Baseline simulations indicate that the hybrid system achieves a maximum power density of 3,868.26 W m-2 and an overall energy efficiency of 49.2 %, evidencing a clear synergy between electrochemical conversion and waste-heat-driven desalination. Parametric studies indicate that higher operating temperature and thinner electrolyte significantly enhance power output, while hydrogen and air utilization ratios strongly influence system efficiency and exergy destruction. Moreover, increasing SGMD membrane porosity effectively improves freshwater productivity and thermodynamic performance. Resolving the intrinsic trade-off between power density and energy efficiency, a multi-objective NSGA-II optimization delivers a compromise solution with a power density of 6,732.62 W m-2 and an energy efficiency of 51.4 % under balanced operating conditions. The findings indicate the potential feasibility of NH3-PCFC/SGMD cogeneration and provide design guidance for applications in remote, maritime, and resource-limited settings.
Abstract The radially layered composite particle packing structure has garnered considerable research attention due to its demonstrated potential in enhancing heat transfer and suppressing the wall effect. In this work, a combined Discrete Element Method and Computational Fluid Dynamics approach is adopted to systematically investigate the flow and thermal non-equilibrium characteristics in radially layered packed beds. The effects of key parameters, including inlet velocity and temperature, on the non-equilibrium performance are quantitatively evaluated using statistical indicators such as the mean value and root-mean-square. The results indicate that particle diameter and packing structure are key factors determining the radial flow and thermal non-equilibrium. The filling of smaller particles in the annular region effectively reduces the degree of radial flow and thermal non-equilibrium, whereas non-equilibrium fluctuations are intensified at the layered interfaces and within the high-porosity zones of the central region. Along the airflow direction, a significant thermal non-equilibrium is observed, as indicated by a bimodal distribution of the temperature root mean square. As the inlet velocity increases and the flow becomes fully developed, the temperature field becomes more uniform, thereby reducing the thermal non-equilibrium. Furthermore, an increase in inlet velocity exacerbates flow non-equilibrium. High temperature not only amplifies this effect but also extends the spatial extent of the non-equilibrium region.
Long-range interacting systems constitute a paradigmatic framework in which fundamental concepts of thermodynamics and statistical mechanics must be revisited. Characterized by interactions decaying at large distances as a power law r -alpha , these systems are intrinsically non-additive for alpha <= d, where d is the spatial dimension of the system. This leads to the breakdown of standard assumptions such as ensemble equivalence and the concavity of thermodynamic potentials. In this work, we discuss the main properties of long-range systems, using as a concrete case study the Nagle-Kardar model, describing an Ising system with competing nearest-neighbour and possibly next-nearest-neighbour short-range couplings and a long-range all-to-all coupling. This model provides a minimal yet rich framework to investigate the interplay between additivity-breaking effects and short-range correlations, allowing for a detailed analysis of phase diagrams, tricritical behavior, and ensemble inequivalence. The technical tools used to determine its partition function, such as the Hubbard-Stratonovich transformation and the transfer matrix method, are introduced and discussed.
The thermodynamic basis of classical mechanics is presented. In this framework, ideal Newtonian mechanics emerges as the zero-dissipation limit of a more general, dissipative theory. The thermodynamic approach predicts a novel dissipative contribution to the momentum that depends on the applied force, leading to a damping coefficient with a specific, experimentally testable dependence on the inertial mass and the spring constant. A torsion balance experiment with variable moment of inertia has been designed to measure this effect. Several known equations, including a thermodynamic version of the Eliezer-Ford-O'Connell equation of radiation reaction, are recovered as special cases.
