Wiktionary
n. (context astronomy English) The velocity of a star relative to the Sun
Wikipedia
Space velocity may be about,
- Space velocity (astronomy), the velocity of a star in the Galactic coordinate system.
- Space velocity (chemistry), the relation between volumetric flow and reactor volume in a chemical reactor.
In chemical engineering and reactor engineering, space velocity refers to the quotient of the entering volumetric flow rate of the reactants divided by the reactor volume (or the catalyst bed volume) which indicates how many reactor volumes of feed can be treated in a unit time (for instance, a reactor with a space velocity of 7 h is able to process feed equivalent to seven times the reactor volume each hour). It is commonly regarded as the reciprocal of the reactor space time. In industry, space velocity can be further defined by the phase of the reactants at given conditions. Special values for this measurement exist for liquids and gases, and for systems that use solid catalysts.
By definition, space velocity can be expressed mathematically as SV ≡ υ0 / V. In this expression, υ0 represents the volumetric flow rate of the reactants entering the reactor and V represents the volume of the reactor itself. This expression is the reciprocal of the definition for the reactor space time, τ (i.e. SV = 1/τ). However, the space time is measured at the conditions of the reactor entrance while the space velocity is often measured at a set of standard conditions, so the reported space velocity may be different from the reciprocal of the measured space time.
Calculations are straightforward when the reactor volume is known and the incoming reactant flow rate is known. For example, if 70 feet/hour of a reactant enter a reactor with an internal volume of 250 feet, the calculated space velocity is approximately 0.28 hour. This can be viewed as the number of reactor changes the system is undergoing in one hour.
Liquid hourly space velocity (LHSV = Reactant Liquid Flow Rate/Reactor Volume)
It is a method for relating the reactant liquid flow rate to the reactor volume at a standard temperature. Usually, this temperature ranges from 60° Fahrenheit to 75° Fahrenheit (15.6° Celsius to 23.9° Celsius). The volumetric flow rate is treated as a liquid at these conditions, even though the actual material may be a gas under normal operating conditions.
Gas hourly space velocity (GHSV = Reactant Gas Flow Rate/Reactor Volume)
It is a similar method for relating the reactant gas flow rate to the reactor volume. GHSV is usually measured at standard temperature and pressure. Different industries may have their own definitions for standard temperature and pressure and these conditions may be closer to ambient conditions than to the International Union of Pure and Applied Chemistry values of 32 °F (0 °C) and 1 bar (100 kPa). It is always important for an engineer to check the basis of calculation.
Weight hourly space velocity (WHSV = Mass Flow/Catalyst Mass)
It differs from LHSV and GHSV, because volume is not utilized. Mass, rather than volume, provides the basis for WHSV (weight basis). This measurement typically is used to describe catalytic reactors, and denotes the quotient of the mass flow rate of the reactants divided by the mass of the catalyst in the reactor.
Usage examples of "space velocity".
And by hitting the wall at roughly a hundred and eighty thousand kilometers per second, he would carry an n-space velocity of a bit more than fourteen thousand KPS across it with him.
That translated to an effective normal-space velocity of many hundreds of times light-speed, but all that mattered were relative speeds, and their better particle and radiation shielding let Reichman's ships attain a velocity twenty percent greater than that.
That is, a ship may translate from hyper-space to normal-space at any hyper-space velocity without risking destruction.
As a consequence, merchantmen were limited to a maximum n-space velocity of about .
On the other hand, the velocity bleed effect applied equally regardless of the direction of the translation (that is, one lost 92% of one's velocity whether one was entering hyper-space from normal-space or normal-space from hyper-space), which meant that leaving hyper automatically decelerated one's vessel to a normal-space velocity only 08% of whatever its velocity had been in hyper-space.
With the inevitable velocity bleed-off, that gave them an n-space velocity of almost exactly 5,000 KPS .
With the inevitable velocity bleed-off, that gave them an n-space velocity of almost exactly 5,000 KPS.
If a hostile task force emerged within energy weapon range of the defenses, those defenses would be destroyed before they could reply, but ships transiting a wormhole junction arrived with a normal-space velocity of barely a few dozen kilometers per second, far too little for a high-speed attack run.
Even with the acceleration rates the compensator permitted, no manned vessel could maintain a normal space velocity above eighty percent of lightspeed, for the particle and radiation shielding to survive such velocities simply did not exist.