On-Board Fuel Processing for a Fuel Cell−Heat Engine Hybrid System

Abstract

Fuel cells operated with hydrogen are more efficient than internal combustion engines, because the combustion in the internal combustion engine is less reversible than the electro-oxidation of hydrogen in the fuel cell. Hydrogen can be produced out of hydrocarbons, such as natural gas, or renewable resources at stationary facilities, but fuel cells operated with pressurized hydrogen stored on board require advanced hydrogen infrastructure for commercialization. An alternative to on-board storage of hydrogen is on-board processing of a liquid hydrocarbon to hydrogen via steam reforming. However, on-board reforming of hydrogen is less energy-efficient than centralized production of hydrogen. Moreover, on-board reforming, purification, and subsequent oxidation of the reformate in a fuel cell is not more efficient than a hybrid electric vehicle technology assisted internal combustion engine. We propose a fuel cell-heat engine hybrid system, which consists of a membrane reformer, a fuel cell, and a reciprocating internal combustion engine, and estimate the efficiency of the proposed hybrid system. Steam reforming of a hydrocarbon requires additional heat input, which can be recovered from the waste heat of an internal combustion engine. On the other hand, the retentate of the membrane reformer can be used in the internal combustion engine to further increase the system efficiency. Methanol is proposed as the fuel for the membrane reformer because the temperature level required is low enough to recover waste heat of reciprocating internal combustion engines for steam reforming of methanol. The hybrid system proposed is more flexible than a fuel cell with an on-board reformer, because additional fuel can be directly combusted in the internal combustion engine at cold start or rapid load increase. Because fuel cell efficiency decreases with load and internal combustion engine efficiency increases with load, the overall system efficiency is less load-dependent compared to the efficiencies of each of these technologies. The power of an automobile engine is considered as a benchmark for the system proposed.

Modeling and experimental verification of a 25W fabricated PEM fuel cell by parametric and GMDH-type neural network

“…PEM fuel cells considerable features such as low operating temperature, high power density, rapid load change compatibility and easy assembling, have made them a reliable choice for the next generation power sources for transportation, stationary, and portable applications [3][4][5][6][7][8][9][10][11][12].…”

Determination of Syngas Premixed Gasoline and Methanol Combustion Products at Chemical Equilibrium via Lagrange Multipliers Method

“…Given the same exhaust gas amount and temperature, the lower energy requirement of a reformer increases the output of a reactor in contact with an exhaust gas heat exchanger. 6 Besides steam reforming, methanol can also be decomposed to syngas for use as a motor fuel in order to reduce automobile emissions. 7 The endothermic decomposition of methanol (eq 1) has been demonstrated to produce H 2 -rich syngas as an engine fuel.…”

“…When the temperature difference between the SI engine exhaust gas temperature and the ethanol reforming temperature is considered, the reaction enthalpy for complete ethanol steam reforming to H 2 and CO 2 (ΔH r = 173.46 kJ/mol) is too high to be recovered out of exhaust gas. 6 Low-temperature steam reforming of an equimolar ethanol solution to a mixture of H 2 , CH 4 , and CO 2 is a promising reaction pathway for ethanol steam reforming via exhaust gas recovery. A copper-plated Raney nickel catalyst is stable and active enough to reform ethanol below 300°C.…”

Model of A Direct Methanol Fuel Cell-Internal Combustion Engine Hybrid System for Automotive Propulsion

“…The reaction enthalpy can be recovered from the exhaust gas of a spark ignition engine via a heat exchanger (1), whereas a membrane integrated into the catalytic reformer purifies reformed hydrogen for a fuel cell (2). The bleed gas of the membrane reformer can be combusted in a spark ignition engine and further liquid fuel can be added for a fast load response (3). Consequently, the efficiency and CO 2 emissions per kWh mechanical energy produced is decreased due to heat recovery, although load flexibility is maintained by retaining the combustion engine.…”