Development of a New Stoichiometric Equilibrium-Based Model for Wood Chips and Mixed Paper Wastes Gasification by ASPEN Plus

Wood and paper residues are usually processed as wastes, but they can also be used to produce electrical and thermal energy through processes of thermochemical conversion of gasification. This study proposes a new steady state simulation model for down draft waste biomass gasification developed using the commercial software Aspen Plus for optimization of the gasifier performance. The model was validated by comparison with experimental data obtained from six different operation conditions. This model is used for analysis of gasification performance of wood chips and mixed paper wastes. The operating parameters of temperature and moisture content (MC) have been varied over wide range and their effect on the high heating value (HHV) of syngas and cold gas efficiency (CGE) were investigated. The results show that increasing the temperature improves the gasifier performance and it increases the production of CO and H2 which leads to higher LHV and CGE. However, an increase in moisture content reduces gasifier performance and results in low CGE.

Stirling Engine Robust Foil Regenerator Efficiency

Combined Heat and Power (CHP) systems are one of the solutions to save energy by utilizing waste heat for addressing global warming and the global energy crisis. In many CHP technologies, the Stirling engine is outstanding since it has the advantage of various energy sources such as solar, geothermal, and industrial heat waste. The regenerator plays a key role in building a high efficiency Stirling Engine. Since it works as an energy storage component in the Stirling engine, its performance directly affects the Stirling engine efficiency. In the previous research, a new regenerator called the robust foil regenerator was designed to improve the performance of the regenerator. The regenerator was manufactured through the method of additive manufacturing techniques since the thickness of each flow channel is 0.3mm. In this research, a test bench was designed and manufactured to reveal the characteristics of the regenerator experimentally. By measuring the pressure drop and the temperature difference through the regenerator, the friction coefficient and the Nusselt number correlations were derived respectively. These correlations were compared to the published friction factor and Nusselt number correlations. In addition, to evaluate the geometrical configuration of the regenerator, the NPH/NTU ratio was calculated using the derived friction coefficient and Nusselt number.

The Design and Analysis of a New Solar-Module Automated Cleaner

In the photovoltaic industry, it is very important that solar modules are kept clean and free of particulates so that the maximum amount of light can get through to the solar cells inside the glass. The development of the new solar-module automated cleaner (S-MAC) is presented in this paper could potentially help keep residential arrays clean and operating at peak efficiency. The design and analysis of the S-MAC is detailed. The S-MAC went through a series of iterative design, but a final design prevailed. In this final design, a cleaning module is deployed via stackable arms and power screws. The stackability of the arms and power screws allows the reach of the cleaning module to vary accounting for arrays that are asymmetric. The arms will also be translated across the array frame via rack and pinion. Thus, the S-MAC product will be adaptable to arrays of any size and even arrays of varying width. Calculations concerning the stresses on the arms during operation as well as calculations concerning how many supports are required to reduce stress on the glass, have been completed and are included in the following sections.

Computational Fluid Dynamics Modeling of a Heat Pipe Evacuated Tube Solar Collector Integrated With Phase Change Material

The increase in greenhouse gas and other global warming emissions makes it necessary to utilize renewable energy sources such as solar energy with high potential for heat production by means of solar thermal collectors. Among various types of solar collectors, evacuated tube solar collector (ETC) has attracted many attentions specially for the application in solar water heater systems (SWHs). However, due to the intermittence in solar intensity during the day, the ETCs may not work at their maximum functionality. There are number of studies investigating the effect of energy storage materials to eliminate the mismatch between supply and demand during peak hours. In the recent work of the authors, application of phase change materials (PCMs) integrated directly within the ETCs is studied experimentally. In this study, the computational fluid dynamics (CFD) modeling of heat pipe evacuated tube solar collector (HPETC) is performed. In order to cross-validate the obtained results to the recent experimental analysis, the boundary conditions are set as the real field-testing data. In the first part of the study, the 3D model of commercially available HPETC is simulated, while in the second part the HPETC integrated with the PCM is developed to analyze the improved thermal distribution. The selected type of PCM is Tritriacontane paraffin (C33H68), with a melting point of 72 °C and latent heat capacity of 256 kJ/kg. The simulation results show a acceptable agreement between the CFD modeling and the experimental data. The results from this study can be the benchmark for efficiency improvement of the ETCs in thermal energy storage systems.

Study of Heating and Cooling Rate of Cobalt Oxide-Based TCES System Using Experimental Redox Kinetics Analysis

Cost-effective solar power generation in CSP plants requires the challenging integration of high energy density and high-temperature thermal energy storage with the solar collection equipment and the power plant. Thermochemical energy storage (TCES) is currently a very good option for thermal energy storage, which can meet the industry requirement of large energy density and high storage temperature. TCES specifically exploits reversible chemical reactions wherein heat is absorbed during the forward endothermic reaction and released during the reverse exothermic reaction. The associated enthalpic storage of energy (i.e., the heat of reaction) offers higher density and enhanced stability compared to sensible and latent heat storage. Metal oxide redox reactions are particularly well-suited for TCES given their characteristically high enthalpy of reaction and high reaction temperature. In addition, the air is suitable as both a heat transfer fluid (HTF) and reactant; thus, simplifying process design and eliminating the need for indirect HTF storage and any intermediate heat exchanger. Among the palette of available metal oxides, cobalt oxide is one of the most promising candidates for TCES given its high enthalpy of reaction with high reaction temperature. One of the critical design parameters for TCES reactors is the optimal heating and cooling rates during respective charging and discharging modes of operation. In order to study the effect of heating/cooling rate on cobalt oxide TCES performance, a constant 10°C/min rate was selected for both storage cycle heating and cooling. Considering the intrinsic redox kinetics of cobalt oxide at considered constant heating/cooling rate, we studied milligram scale quantities of cobalt oxide (99.9% purity, 40 μm average particle size) using a dual-mode thermogravimetric (TGA)/differential scanning calorimetry (DSC) system, which simultaneously measures weight change (TGA) and differential heat flow (DSC) as a function of TCES cycling under continuous air purge. In addition, we investigated the cyclic stability of cobalt oxide in the context of the redox kinetics and particle coarsening behavior, employing scanning electron microscopy (SEM). TGA/DSC tests were conducted for 30 successive cycles using pure cobalt oxide. It was shown that pure cobalt oxide in powder form (38μ particle size) could complete both forward and reverse reaction at the selected heating rate with little degradation between cycles. In parallel, SEM was used to examine morphology and particle size changes before and after heating cycles. SEM results proved grain growth occurs even after only five initial cycles.

Recycling Li-Ion Batteries: Robotic Disassembly of Electric Vehicle Battery Systems

This paper presents the application of robotics for the disassembly of electric vehicle lithium-ion battery (LIB) packs for the purpose of recycling. Electric vehicle battery systems can be expensive and dangerous to disassemble, therefore making it cost inefficient to recycle them currently. Dangers associated with high voltage and thermal runaway make a robotic system suitable for this task, as the danger to technicians or workers is significantly reduced, and the cost to operate a robotic system would be potentially less expensive over the robots lifetime. The proposed method allows for the automated or semi-automated disassembly of electric vehicle LIB packs for the purpose of recycling. In order to understand the process, technicians were studied during the disassembly process, and the modes and operations were recorded. Various modes of interacting with the battery module were chosen and broken down into gripping and cutting operations. Operations involving cutting and gripping were chosen for experimentation, and custom end of arm tooling was designed for use in the disassembly process. Path planning was performed offline in both MATLAB/Simulink and ROBOGUIDE, and the simulation results were used to program the robot for experimental validation.

Modelling and Experimental Validation of a Controllable Energy Harvester for Pressure Regulation

A pico-scale Francis turbine (or energy harvester) was designed, fabricated and tested for pressure regulation and power generation application. The prototype energy harvester contains pivotable guide vanes and a controllable load to change the runner speed. This allows the simultaneous variation of the pressure drop and the output power. A computational fluid dynamics (CFD) model of the turbine was developed in ANSYS CFX 18.1 to evaluate the turbine’s sensitivity to geometric parameters such as the clearance gap size of the guide vane and its modularity. In conjunction to the CFD model, the electric generator’s characteristics were used to predict the turbine performance at varying guide vane angles. The turbine was prototyped and tested using a custom-built experimental set-up. The pico-scale turbine, with a runner diameter of 1.42 inches, was able to output up to 100 W of electrical power at its rated flowrate of 29 GPM. By varying the guide vane angles, the pressure drop and the hydraulic efficiency varied between 3–22 psi and up to 60% respectively. When validated against the experimental results, the CFD model showed a good agreement despite its low computational cost. The energy harvester’s initial characteristics demonstrate its potential as a game changer in the control valve market.

Measured Performance of a Variable Transmission Glazing System

Variable Transmission Glazing (VTG) windows are an energy efficiency measures that have relatively high first cost. This paper describes the in-situ performance of VTG installed in an atrium space at the University of Portland. An experiment was conducted using thermocouples and photosensors to examine temperature gradients and solar gains across electrochromic glazing windows to quantify the performance of the installed system in terms of energy and cost saving. The system performance was measured with an average efficiency of 98.73% when the VTG was operating. The annual savings of the glazing system installed was estimated to be $7,683.

Sensitivity of Thermal Transport in Uranium Dioxide to Fission Gas

Understanding the effect of fission gas generation on thermal resistance in various nuclear fuels is critical for managing fuel performance. Fission gas in the fuels degrades its thermal properties by altering the lattice vibrations. It results in thermal expansion that increases the thermal resistance and decreases the structural stability of the fuels. In this research, thermal transport in uranium dioxide is studied at a microscopic level when Xe and Kr gasses interact with uranium and oxygen atoms. Reverse non-equilibrium molecular dynamics (RNEMD) is used to calculate the thermal resistances and provide an understanding about the effect of the fission gas release on phonon transport. The results show that the thermal conductivity of uranium dioxide is decreased nearly by 78% by the presence of only one fission gas bubble. The thermal transport in uranium dioxide is shown to become highly diffusive by a single fission gas bubble and a large temperature drop in temperature profiles are observed in all simulation structures with fission gas bubbles. The average interfacial thermal resistance across a fission gas bubble is estimated to be 2.1 × 10−9 Km2/W.

Plasma Decomposition of Carbon Dioxide: Simulations and Experiments

Simulations and experiments are conducted to model, simulate, test and demonstrate the effect of plasma discharges on decomposition of carbon dioxide (CO2). A pin-to-plane discharge is employed in gas samples containing CO2. A high voltage plasma system is used which was previously shown to be able to decrease CO2 concentration in gas samples. The discharge is modeled and described, including monitoring electrical parameters such as current and voltage. The present study investigated plasma decomposition of carbon dioxide experimentally, and through simulation. A plasma micro-discharge was utilized to better understand plasma-CO2 interactions. Enhancements are suggested to help increase the efficiency and yield of the plasma-CO2 decomposition process. Gas samples are analyzed over time using a CO2 meter.