Fuel reformation by piston compression of rich air-fuel mixture

The purpose of this paper is to investigate and describe the fuel reformation by diesel piston compression to change the ignitability of commercial fuels for marine engines. The engine operational conditions were first investigated by CHEMKIN Pro with n-heptane as a fuel, an HCCI engine with port fuel injection was operated by n-heptane based on simulation results, and the production of reformed gases (hydrogen, carbon monoxide, methane, and ethylene) were measured by emission analyzers. The fuel reformation becomes active above a 2.0 equivalence ratio and higher intake air temperature conditions, and the molar fractions of the reformed gases can be varied by the maximum in-cylinder average temperature during the reforming processes. An indirect injection diesel engine was newly introduced and the diesel fuel reformation characteristics were evaluated. Further, the fuel decomposition processes were investigated by CHEMKIN Pro. The results suggest that the hydrogen and carbon monoxide are produced via a number of production paths in the fuel decomposition into small hydrocarbons and chemical production controls of hydrogen and carbon monoxide will be difficult. However, the production paths of methane and ethylene formation are limited by the decomposition of hydrocarbons and this suggests the possibility of chemical production control of methane and ethylene.

Energetics of water in the Solar System

Water is vital for space exploration, from drinking to fuel reformation, and is naturally abundant in the Solar System [1–16]. While in-situ resource utilization (ISRU) requires vastly less energy than transporting resources, the energetics has scarcely been explored besides on Earth and limited analysis on Mars’ vapor. Here, we develop a thermodynamic framework to quantify the energy requirements for resource extraction from 18 water sources on 11 planetary bodies. We find that desalinating saline liquid brines, where available, could be the most energetically favorable option and the energy required to access water vapor can be four to ten times higher than accessing ice deposits. While desalination energetics are highly sensitive to salt concentration, we show that desalination energetics only vary by a factor of 2 with respect to the type of salt present. Additionally, unlike chemical mixtures, the minimum energetics are insensitive to composition in physical mixtures (e.g., ice-regolith and inert vapor mixtures). Additionally, by deriving and computing the equation-of-state for pure water, we extend the least work estimates of atmospheric water harvesting by 94°C lower than previous studies that depend on predetermined databases. The presented approach and data may inform decisions regarding water harvesting, habitation, and resource reformation.

Experimental Investigation of a Novel Combined Rapid Compression-Ignition Combustion and Solid Oxide Fuel Cell System Format Operating on Diesel

Climate change concerns have forced the automotive industry to develop more efficient powertrain technologies, including the potential for fuel cell systems. Solid oxide fuel cells (SOFCs) demonstrate exceptional fuel flexibility and can operate on conventional, widely available hydrocarbon fuels with limited requirements for fuel reformation. Current hybrid powertrains combining fuel cell systems with internal combustion engines (ICEs) fail to mitigate the disadvantages of requiring fuel reformation by placing the engine downstream of the fuel cell system. This work, thus investigates the upstream placement of the engine, eliminating the need for fuel processing catalysts and the heating of complex fuel reformers. The ICE burns a fuel-rich mixture through rapid compression ignition, performing partial oxidation fuel reformation. To test the feasibility of a fuel cell system operating on such ICE exhaust, chemical kinetic model simulations were performed, creating model exhaust containing ∼43.0% syngas. A micro-tubular SOFC (μT-SOFC) was tested for power output with this exhaust, and generated ∼730 mW/cm2 (∼86% of its maximum output obtained with pure hydrogen fuel). Combustion testing was subsequently performed in a test chamber, and despite insufficient equipment limiting the maximum pressure of the combustion chamber, began to validate the model. The exhaust from these tests contained all of the predicted chemical species and, on average, ∼21.8% syngas, but would have resembled the model more closely given higher pressures. This work examines the viability of a novel combined ICE and fuel cell hybrid system, displaying potential for a more cost-effective/efficient solution than current fuel cell systems.

The Effects of Initial Conditions on the Composition of the On-Board Fuel Reformation Chamber in an HCCI Engine

Based on the CHEMKIN software, a model of the reforming chamber was built to simulate the on-board fuel reforming process in a Homogeneous Charge Compression Ignition (HCCI) engine. The effects of the initial pressure and temperature of the chamber on the reformed gas were studied. The results show that the main species in the reformed gas are H2 and CO. This paper investigated the effect of initial temperature on the reformed gas, in order to get the optimum initial temperature. Under the optimum initial temperature (1300 K), some important conclusions have been drawn by changing initial pressures of the chamber. Initial pressure may have great effect on other species, but has a small effect on mole fractions of H2 and CO. By comparing the concentrations of H2 and CO between low and high initial pressures under the optimum initial temperature, it can be concluded that H2 and CO are still the main species in the reformed gas.