Liquid Organic Hydrogen Carriers Applied on Methane–Hydrogen-Fueled Internal Combustion Engines: A Preliminary Analysis of Process Heat Balance

Abstract

One of the main issues that has limited the use of hydrogen as an energy vector for a long time is its low energy density per unit of volume. Alternative chemical storage methods have been developed in recent years to overcome the limitations associated with compressed or liquified hydrogen storage. One of these is the Liquid Organic Hydrogen Carrier (LOHC), which utilizes organic hydrocarbons that can capture hydrogen (through an exothermic hydrogenation reaction) and release hydrogen (through an endothermic dehydrogenation reaction). In this paper, a 0D model of an internal combustion engine fueled with a mixture of hydrogen and methane was used to investigate whether the enthalpy of the exhaust gases can balance the heat rate required to self-sustain the dehydrogenation stage. Two LOHC+ compounds were considered, namely, Perhydro-dibenzyltoluene and Perhydro-N-Ethylcarbazole. Four different hydrogen-to-methane ratios were considered, assuming an engine maximum brake power ranging from 500 to 6000 RPM. An energy balance was performed, balancing the dehydrogenation heat rate and the exhaust gas cooling heat rate, in order to establish the minimum temperatures of the exhaust gases required to self-sustain the LOHC+ dehydrogenation. We demonstrated that the minimum exhaust temperatures required to self-sustain the process in different running regimes and at different hydrogen-to-methane ratios are lower than literature and experimental exhaust temperatures.

Strategic Model for Charging a Fleet of Electric Vehicles with Energy from Renewable Energy Sources

“…The authors recommend the use of stationary energy storage facilities in such situations. Energy from RES will soon also be used to produce hydrogen for storage and to power hydrogen fuel cell vehicles [21]. In this individual case, they propose using an energy storage with an energy capacity of 100 kWh.…”

“…The scope of operation and service activities for electric cars is much smaller, which translates into lower costs of warranty and post-warranty inspections at vehicle service stations. Electric vehicles are also ecological at the point of use because they do not emit any harmful substances into the atmosphere [19][20][21]. The most ecological form of propulsion for all types of vehicles is electric drive, using electricity generated from RES to charge the battery.…”

Control Strategies for Piston Trajectory in Ionic Compressors for Hydrogen Storage

“…The pump speed n and pump displacement V d determine the flow of hydraulic fluid into the hydraulic system. The pump displacement V d is obtained using Equation (10).…”

“…Due to the low energy density of hydrogen at atmospheric pressure [8], its direct application in fuel-cell vehicles may require the vehicle to be refueled frequently or have a larger storage space, ultimately increasing costs [9]. Expanding the storage pressure of hydrogen by compressing it is an effective solution for increasing its volumetric energy density [10]. Commonly utilized technologies for compressing hydrogen consist of reciprocating piston compressors [11], diaphragm compressors, linear compressors, metal hydride compressors [12], and ionic liquid compressors [13].…”