ISENTROPIC_EFF

Overview

Convert between isentropic and polytropic efficiency for compression.

Excel Usage

=ISENTROPIC_EFF(p_inlet, p_outlet, k_isentropic, eta_poly)

• p_inlet (float, required): Initial pressure of gas [Pa]
• p_outlet (float, required): Final pressure of gas [Pa]
• k_isentropic (float, required): Isentropic exponent of the gas (Cp/Cv) [-]
• eta_poly (float, required): Polytropic efficiency of the process [-]

Returns (float): Isentropic efficiency calculated from polytropic efficiency [-]

Examples

Example 1: 10x compression with 78% polytropic efficiency

Inputs:

p_inlet	p_outlet	k_isentropic	eta_poly
100000	1000000	1.4	0.78

Excel formula:

=ISENTROPIC_EFF(100000, 1000000, 1.4, 0.78)

Expected output:

0.7027614191263858

Example 2: 5x compression with 85% polytropic efficiency

Inputs:

p_inlet	p_outlet	k_isentropic	eta_poly
100000	500000	1.4	0.85

Excel formula:

=ISENTROPIC_EFF(100000, 500000, 1.4, 0.85)

Expected output:

0.8134564953798419

Example 3: High efficiency compressor

Inputs:

p_inlet	p_outlet	k_isentropic	eta_poly
100000	300000	1.3	0.92

Excel formula:

=ISENTROPIC_EFF(100000, 300000, 1.3, 0.92)

Expected output:

0.9094730418849563

Example 4: Different gas (lower k)

Inputs:

p_inlet	p_outlet	k_isentropic	eta_poly
100000	400000	1.2	0.8

Excel formula:

=ISENTROPIC_EFF(100000, 400000, 1.2, 0.8)

Expected output:

0.7762548175131004

Python Code

import micropip
await micropip.install(["fluids"])
from fluids.compressible import isentropic_efficiency as fluids_isen_eff

def isentropic_eff(p_inlet, p_outlet, k_isentropic, eta_poly):
    """
    Convert between isentropic and polytropic efficiency for compression.

    See: https://fluids.readthedocs.io/fluids.compressible.html#fluids.compressible.isentropic_efficiency

    This example function is provided as-is without any representation of accuracy.

    Args:
        p_inlet (float): Initial pressure of gas [Pa]
        p_outlet (float): Final pressure of gas [Pa]
        k_isentropic (float): Isentropic exponent of the gas (Cp/Cv) [-]
        eta_poly (float): Polytropic efficiency of the process [-]

    Returns:
        float: Isentropic efficiency calculated from polytropic efficiency [-]
    """
    # Validate and convert inputs
    try:
        p_inlet = float(p_inlet)
    except (ValueError, TypeError):
        return "Invalid input: p_inlet must be a number."

    try:
        p_outlet = float(p_outlet)
    except (ValueError, TypeError):
        return "Invalid input: p_outlet must be a number."

    try:
        k_isentropic = float(k_isentropic)
    except (ValueError, TypeError):
        return "Invalid input: k_isentropic must be a number."

    try:
        eta_poly = float(eta_poly)
    except (ValueError, TypeError):
        return "Invalid input: eta_poly must be a number."

    # Validation
    if p_inlet <= 0:
        return "Invalid input: p_inlet must be positive."
    if p_outlet <= 0:
        return "Invalid input: p_outlet must be positive."
    if k_isentropic <= 1:
        return "Invalid input: k_isentropic must be greater than 1."
    if eta_poly <= 0 or eta_poly > 1:
        return "Invalid input: eta_poly must be between 0 and 1."

    try:
        result = fluids_isen_eff(P1=p_inlet, P2=p_outlet, k=k_isentropic, eta_p=eta_poly)
        return float(result)
    except Exception as e:
        return f"Error: Failed to compute isentropic efficiency: {str(e)}"

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