Description
Return tmp = (feedPressure+retentatePressure)/2-permeatePressure and netDrivingPressure = tmp-osmoticDifference.
Membrane calculations distinguish feed, permeate and reject streams, gross recovery and recycle, and hydraulic from osmotic pressure. A local mass balance or pressure difference is only one part of membrane transport and operating performance.
Return tmp = (feedPressure+retentatePressure)/2-permeatePressure and netDrivingPressure = tmp-osmoticDifference.
When to use this tool
Use Membrane Transmembrane Pressure One Module when checking a supplied membrane stream balance or driving-pressure term.
How to use the tool and how it works
- Enter feedPressure, retentatePressure, permeatePressure, osmoticDifference. Use the units and conventions below.
- Run the tool. Correct any format, range, or cross-field input error before interpreting the output.
- Read tmp, netDrivingPressure. Use the output convention below.
Return tmp = (feedPressure+retentatePressure)/2-permeatePressure and netDrivingPressure = tmp-osmoticDifference. Enter every pressure in the same unit and on a consistent absolute or gauge basis; osmoticDifference is the feed-side minus permeate-side osmotic pressure under this convention.1
| Input field | Meaning and units | Accepted input |
|---|---|---|
| feedPressure | Feed Pressure | Required. Finite number. |
| retentatePressure | Retentate Pressure | Required. Finite number. |
| permeatePressure | Permeate Pressure | Required. Finite number. |
| osmoticDifference | Feed-side minus permeate-side osmotic pressure on the common pressure unit basis. | Required. Finite number. |
| Output field | Interpretation | Returned shape |
|---|---|---|
| tmp | Tmp | Required. Finite number. |
| netDrivingPressure | Net Driving Pressure | Required. Finite number. |
{
"input": {
"feedPressure": 6,
"retentatePressure": 4,
"permeatePressure": 1,
"osmoticDifference": 2
},
"output": {
"tmp": 4,
"netDrivingPressure": 2
}
}Limitations and assumptions
- Negative pressures or driving pressures are accepted arithmetic inputs. The mean pressure approximation does not model axial pressure profiles, fouling, permeability, membrane integrity or safe operating limits.
- Inputs must satisfy both the field types and the cross-field conditions above. Invalid input causes an error; a successful false flag or documented placeholder is a different result.
- Numeric calculations use binary floating point unless exact decimal-integer arithmetic is explicitly stated. No hidden measurement tolerance or decimal rounding is added; nonfinite or out-of-contract results are rejected. Numeric signed-zero results are exported as zero.
Alternative or Complementary methods
Use a complete process and membrane model for recirculation, concentration polarization, fouling, energy use and operating constraints.
References
Similar or alternative tools
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Return permeateFlow = feedFlow*recovery, concentrateFlow = feedFlow*(1-recovery), permeateConcentration = feedConcentration*(1-rejection) and concentrateConcentration = feedConcentration*(1-recovery*(1-rejection))/(1-recovery).
- Biofilter One Layer Pressure Drop
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