IAPWS92_DPSAT_DT
This function computes the first derivative of saturation pressure with respect to temperature from the IAPWS-92 equation, and also returns the associated saturation pressure.
The evaluated quantities are:
\left(\frac{dP_{sat}}{dT}, P_{sat}\right) = f(T)
where T is saturation temperature.
Excel Usage
=IAPWS92_DPSAT_DT(T)T(float, required): Water saturation temperature for derivative evaluation (K).
Returns (dict): Excel data type with saturation pressure derivative as primary value and saturation pressure as an additional property.
Example 1: Derivative and saturation pressure at moderate temperature
Inputs:
| T |
|---|
| 400 |
Excel formula:
=IAPWS92_DPSAT_DT(400)Expected output:
{"type":"Double","basicValue":7483.47,"properties":{"dPsat dT":{"type":"Double","basicValue":7483.47},"Psat":{"type":"Double","basicValue":245765}}}
Example 2: Derivative and saturation pressure near room temperature
Inputs:
| T |
|---|
| 300 |
Excel formula:
=IAPWS92_DPSAT_DT(300)Expected output:
{"type":"Double","basicValue":207.913,"properties":{"dPsat dT":{"type":"Double","basicValue":207.913},"Psat":{"type":"Double","basicValue":3536.72}}}
Example 3: Derivative and saturation pressure at elevated temperature
Inputs:
| T |
|---|
| 500 |
Excel formula:
=IAPWS92_DPSAT_DT(500)Expected output:
{"type":"Double","basicValue":49008.6,"properties":{"dPsat dT":{"type":"Double","basicValue":49008.6},"Psat":{"type":"Double","basicValue":2639220}}}
Example 4: Derivative and saturation pressure near critical temperature
Inputs:
| T |
|---|
| 640 |
Excel formula:
=IAPWS92_DPSAT_DT(640)Expected output:
{"type":"Double","basicValue":242499,"properties":{"dPsat dT":{"type":"Double","basicValue":242499},"Psat":{"type":"Double","basicValue":20265800}}}
Python Code
Show Code
from chemicals.iapws import iapws92_dPsat_dT as chemicals_iapws92_dpsat_dt
def iapws92_dpsat_dt(T):
"""
Compute saturation pressure derivative with respect to temperature using IAPWS-92.
See: https://chemicals.readthedocs.io/chemicals.iapws.html#chemicals.iapws.iapws92_dPsat_dT
This example function is provided as-is without any representation of accuracy.
Args:
T (float): Water saturation temperature for derivative evaluation (K).
Returns:
dict: Excel data type with saturation pressure derivative as primary value and saturation pressure as an additional property.
"""
try:
dPsat_dT, Psat = chemicals_iapws92_dpsat_dt(T)
return {
"type": "Double",
"basicValue": dPsat_dT,
"properties": {
"dPsat dT": {"type": "Double", "basicValue": dPsat_dT},
"Psat": {"type": "Double", "basicValue": Psat}
}
}
except Exception as e:
return f"Error: {str(e)}"