Biogas Upgrading and Ammonia Recovery from Livestock Manure Digestates in a Combined Electromethanogenic Biocathode—Hydrophobic Membrane System

Anaerobic digestion process can be improved in combination with bioelectrochemical systems in order to recover energy and resources from digestates. An electromethanogenic microbial electrolysis cell (MEC) coupled to an ammonia recovery system based on hydrophobic membranes (ARS-HM) has been developed in order to recover ammonia, reduce organic matter content and upgrade biogas from digested pig slurry. A lab-scale dual-chamber MEC was equipped with a cation exchange membrane (CEM) and ARS with a hydrophobic membrane in the catholyte recirculation loop, to promote ammonia migration and absorption in an acidic solution. On the other hand, an electromethanogenic biofilm was developed in the biocathode to promote the transformation of CO2 into methane. The average nitrogen transference through the CEM was of 0.36 gN m−2 h−1 with a removal efficiency of 31%, with the ARS-HM in the catholyte recirculation loop. The removal of ammonia from the cathode compartment helped to maintain a lower pH value for the electromethanogenic biomass (7.69 with the ARS-HM, against 8.88 without ARS-HM) and boosted methane production from 50 L m−3 d−1 to 73 L m−3 d−1. Results have shown that the integration of an electromethanogenic MEC with an ARS-HM allows for the concomitant recovery of energy and ammonia from high strength wastewater digestates.

Hydrogen and oxygen recirculation control system for an electric power plant based on an electrochemical generator

Развитие водородной энергетики ведет к увеличению использования электрохимических генераторов (ЭХГ) в морских транспортных средствах в качестве вспомогательных и основных энергоустановок. Топливом для таких энергетических установок являются водород и кислород. Важной для таких энергетических установок является экологическая составляющая При прямом преобразовании химической энергии топлива в электрическую в топливных элементах, побочным продуктом реакции является только вода. В статье рассматривается система управления рециркуляцией рабочих газов - водорода и кислорода в электрохимическом генераторе. Система управления состоит из двух независимых субблоков - контура рециркуляции водорода и контура рециркуляции кислорода. Каждый субблок, работающий по своему алгоритму, построен на программируемом логическом контроллере и управляемой арматуре. В статье также приведены режимы работы системы управления рециркуляцией газов. The development of hydrogen energy increases electrochemical generators (ECG) using in marine vehicles as an auxiliary and main power plants. The fuel for such power plants are hydrogen and oxygen. The environmental component is important for such power plants. When the chemical energy of a fuel is directly converted into electrical energy in fuel cells, there are only water is a by-product of the reaction. The article discusses the control system of the working gases recirculation - hydrogen and oxygen in an electrochemical generator. The control system consists of two independent subunits - a hydrogen recirculation loop and an oxygen recirculation loop. Each subunit is built on a programmable logic controller and controlled armature, working according to its own algorithm. The article also describes the operating modes of the gas recirculation control system.

Lyapunov-Based Nonlinear Feedback Control Design for Exhaust Gas Recirculation Loop of Gasoline Engines

For gasoline engine with an exhaust gas recirculation loop, a challenging issue is how to achieve maximum brake efficiency while providing the desired torque. This paper presents a solution to this challenging issue via dynamical control approach which consists of two phases: optimal equilibrium point generation and feedback regulation of the optimized operating mode. First, a mean-value model is developed to represent the dynamical behavior of the intake manifold and exhaust manifold focused on gas mass flows. Then, the control scheme is constructed based on the control-oriented model. Mainly, the optimal set-points are designed by solving the optimal programming problem of maximizing the brake efficiency under demand torque constraint which is the first control design stage, and the dynamical model to the feedback stabilization regulation control for improving transient performance is at the second stage. Lyapunov-based design is used for the derivation of the state feedback law. Furthermore, the proposed exhaust manifold pressure estimator is also coupled into the controller to replace the cost prohibitive exhaust pressure sensor. Finally, experimental validations on the test bench are provided to evaluate the proposed controller.