Supercritical flow is flow whose velocity is higher than wave velocity. For example , suppose that water is falling on an inclined wall. The speed is so high that. Definition of critical, sub-critical and SuperCritical flow and slope of the channel is also greater than the critical slope is known as supercritical flow. Definition of Research tool | Different forms of research tool 7, views. Type 1 curve: Actual depth is greater than yc and yn, flow is subcritical Supercritical flow transitions to subcritical through a hydraulic jump which represents a.
What’s the difference? Supercritical/subcritical –
Supercritical flow transitions to subcritical through a hydraulic jump which represents a high energy loss with erosive potential. When the actual depth is less than critical depth it is classified as supercritical.
Supercritical flow has a Froude number greater than one. Critical flow is the transition or control flow that possesses the minimum possible energy for that flowrate. Critical flow has a Froude number equal to one. Critical flow is unstable and a small fluctuation in energy will shift the flow into supercritical or subcritical flow. The flow is subcritical and controlled downstream. M1 profiles are common where mild slope streams enter a pool.
M2 profiles can occur upstream of a sudden enlargement in a channel or where the slope becomes steeper. Extraction times can be longer and yields are generally lower due to the fact that there will still be residual waxes and resins that are left behind in the plant material. Supercritical CO 2 can be a much stronger solvent than subcritical CO 2. In addition to extracting lighter oils, supercritical CO 2 can extract the higher molecular weight materials like waxes, paraffins, lipids and resins from the plant, allowing for higher yields and a more complete extraction.
The stronger solvency power also makes the extraction times faster. Supercritical CO 2 extractions at very high temperatures and pressures higher than F and psi can cause thermal degradation of the oils, and when extracting green plant materials can have the potentially negative consequence of extracting chlorophyll. Apeks Supercritical psi and psi Production Series systems all have the ability to run both subcritical and supercritical extractions. This approach is better than fractional separation where extractions are done at high temperature and multiple separators have cascading pressures because the temperature sensitive volatile oils and terpenes are never exposed to high heat.
Heat is the enemy of any botanical oil. Cold separation is critical for maintaining THCA or CBDA of cannabis extraction because cold separation will not decarboxylate extracted oils in the separator. With CO 2 as a solvent for oil extraction, no toxins, heavy metals or hydrocarbon materials come in contact with the extracted oils. Through the use of the three fluid mechanics conservation equations the energy equation, the continuity equation, and the momentum equation , the following equation can be derived relating the conditions before a hydraulic jump to the condition after the jump.
The diagram at the left shows the parameters in the equation. Due to the turbulence in the hydraulic jump, there will be frictional head loss across the jump. The amount of head loss may sometimes be of interest and is given by the following equation:.
Rearranging this equation and substituting the expression for Fr 1 , leads to the following equation for h L in terms of the two depths of flow and the upstream Froude Number:. Consider a hydraulic jump in a 2 ft wide rectangular channel. The flow rate through the channel is 20 cfs and the depth of flow before the jump is 1 ft.
What will be the depth of flow after the hydraulic jump and what will be the head loss across the jump?
Assessing Flow Conditions: Subcritical & Supercritical Flow . What does the difference in the Froude number tell you about the difference in flow conditions. Why should you use subcritical and supercritical CO2 extraction systems? What's the difference between the two? Apeks Supercritical has the answers!. Supercritical: • When the depth lies above the critical curve, the flow is supercritical. • This type of flow often occurs in streams in the plains and broad valley.