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Forecasting Lubricant Demand
Published in R. David Whitby, Lubricant Marketing, Selling, and Key Account Management, 2023
However, the two current problems with hydrogen are the cost of production and the cost of infrastructure. The production cost will fall as the costs of renewable energy, electrolysis (green hydrogen) and carbon capture (blue hydrogen) decrease over time. Hydrogen needs a complete new infrastructure for shipping, delivery and dispensing. The costs and the efficiency losses across this process are significant. Shipping and delivery requires specialty carbon-fibre tanks and compression at 350 bar or 700 bar. Producing liquid hydrogen requires huge amounts of energy. Hydrogen also requires specialty fuelling stations, each costing millions of dollars.
Kinetics of Particles
Published in M Rashad Islam, A K M Monayem H Mazumder, Mahbub Ahmed, Engineering Dynamics, 2022
M Rashad Islam, A K M Monayem H Mazumder, Mahbub Ahmed
When a rocket moves upward while in flight, you will see that a smoke-like white cloud comes out through the end of its nozzles. Can you say why such smoke can be seen? Due to the burning of fuel, gas is formed at very high pressure. We often see this coil of gas from Earth. This gas comes out through the small opening at the rear side of the rocket with tremendous velocity. Due to this, an equally tremendous reaction force is produced, which pushes the rocket upward. Although the mass of the exhaust gas is small, the momentum of the gas is very high due to its velocity. According to the conservation principle of momentum, the rocket also acquires equal but oppositely directed momentum and thus rises upward with a high velocity. Typically, liquid hydrogen is used to fuel a rocket. For ignition, the liquid hydrogen together with oxygen are allowed to enter the combustion chamber. Due to burning of the fuel, high-pressure gas is produced that comes out at a very high speed through the opening at the rear of the rocket.
Alternative Fuel Sources
Published in Michael Frank Hordeski, Hydrogen & Fuel Cells: Advances in Transportation and Power, 2020
Liquid hydrogen as a method for storing and transporting hydrogen can have several advantages over gases. The liquid form has a higher energy density and is easier to transport and handle. At atmospheric pressures, hydrogen is a liquid at −253°C (−423°F), which is only a few degrees above absolute zero. It must be stored in highly insulated tanks. Liquid hydrogen is a cryogenic fuel. Cryogenics is the study of low temperature physics. A beaker of liquid hydrogen at room temperature will boil as if it was on a hot stove. If the beaker of liquid hydrogen is spilled on the floor, it is vaporized and dissipates in a few seconds. If liquid hydrogen is poured on the hand, it would feel cool to the touch as it slides through the fingers. This is due to the thermal barrier that is provided by the skin. But, place a finger in a vessel containing liquid hydrogen and severe injury will occur in seconds because of the extremely cold temperature. In most accidents, the most serious concern would be a fuel fed fire or explosion. In this case, liquid hydrogen is generally considered to be a preferred fuel.
Multidiffusive nanofluid flow over a sphere with time-reliant nonlinear convective regime: Impact of activation energy
Published in Numerical Heat Transfer, Part A: Applications, 2023
Prabhugouda Mallanagouda Patil, Bharath Goudar
We can obtain the triple (multiple) diffusion mechanisms by combining thermal diffusion with two separate species diffusions or by considering three diffusing species. Multiple diffusions are involved in various processes, including the heating of the stratosphere, the movement of water underground, and the preparation of food. There are just a few investigations on triple diffusion in the combined convection regime [13–16]. Because the AE process may be thought of as a binary chemical reaction, it is possible to control the extent of the binary reaction by employing a certain concentration of a species to provide more accurate findings. As a particular species concentration, liquid hydrogen, liquid ammonia, liquid oxygen, and so forth can be used. Liquid hydrogen is utilized in massive quantities in the space programme as the main rocket fuel for combustion with oxygen and to cool the plane’s engine. Further, liquid ammonia finds its applications in the food and beverage industries, internal combustion engines, paper, leather, rubber industries, waste-water management systems, etc. By incorporating nanoparticle diffusions, and specialized species like liquid hydrogen and ammonia, AE applications can be broadened.
Numerical Investigation of Coaxial GCH4/LOx Combustion at Supercritical Pressures
Published in Combustion Science and Technology, 2021
Sindhuja Priyadarshini, Malay K Das, Ashoke De, Rupesh Sinha
In the last few years, there has been an increasing interest in numerical modeling of combustion phenomenon in cryogenic engines due to its complex nature. The combination of liquid hydrogen (fuel) with liquid oxygen (oxidizer) has been widely utilized as rocket fuel and oxidizer for various liquid propulsion systems. Liquid hydrogen (fuel) has multiple advantages like non-toxicity, clean combustion, and the highest specific impulse. But, the low density of H2 (liq.) leads to a large vehicle, a larger tank volume, and higher aerodynamic drag. Moreover, high cost and handling difficulties of H2 (liq.) have prohibited the widespread use of H2 (liq.)-LOx combination in liquid rocket engines (LRE’s) (Sutton 2005). Lately, it has been widely recognized that hydrocarbons are the most effective alternate propellants due to their high-density characteristics resulting in minimization of the propellant tank size and overall operational cost. The lowest hydrocarbon, liquid methane, has inherent properties like higher specific impulse and better cooling capabilities. The various advantages of liquid methane over other higher hydrocarbons have made it the most competitive fuel in combination with the liquid oxygen. Due to its soft cryogenic like characteristics, the GCH4/LOx combination can easily be operated at a cryogenic arrangement.
Stay Cool—Alternatives for Long-Term Storage of Large Quantities of Liquid Hydrogen on a Mars Transfer Vehicle
Published in Nuclear Technology, 2021
Nicholas A. Morris, L. Dale Thomas, D. Keith Hollingsworth
Liquid hydrogen is a cryogenic fluid and therefore must be stored at low absolute temperatures, approximately 14 to 21 K (at 2 atm), to prevent it from changing phase to a gas, an event here forth referred to as boil-off. Boil-off is problematic when storing LH2 for two reasons. First, gaseous hydrogen is very difficult to pump, and second, when LH2 changes to its gaseous form inside a pressure vessel, the pressure rises, which can cause the vessel to exceed its limits and fail. To prevent this from occurring, the gaseous hydrogen must be vented to return the pressure to acceptable limits. As a result, the vented hydrogen is lost, and the overall employable amount of hydrogen propellant is decreased. To account for this loss, more hydrogen must be stored than is required for the mission. This additional hydrogen is a substantial mass penalty, and a 2011 study4 shows that simply improving (reducing the amount of, not eliminating) boil-off is the single largest mass savings step in reaching the DRA’s target mission mass. Completely eliminating boil-off would, of course, further increase mass savings.