Command-Line Interface

sandlersteam provides a command-line interface (CLI) for quick thermodynamic calculations without writing Python code.

Overview

The CLI has two main subcommands:

  • state: Calculate properties at a single thermodynamic state

  • delta: Calculate property changes between two states

  • avail: List values of T and P for which explicit steam data is in the tables

Global Options

sandlersteam --help

Shows general help and lists available subcommands. (Note that -h is reserved for enthalpy inputs.)

sandlersteam --version

Displays the installed version of sandlersteam.

state Command

Calculate thermodynamic properties for a pure substance at a specified state.

Syntax

sandlersteam state [OPTIONS]

Required Arguments

You must provide two of the following state variables:

-T, --temperature TEMP

Temperature (C)

-P, --pressure PRESS

Pressure (MPa)

-u, --internal-energy U

Internal energy (kJ/kg)

-v, --specific-volume V

Specific volume (m³/kg)

-h, --enthalpy H

Enthalpy (kJ/kg)

-s, --entropy S

Entropy (kJ/kg-K)

These are optional arguments:

-pu, --pressure-unit PRESSURE_UNIT

Pressure unit for input and output (default: MPa). Options: MPa, bar, atm

-vu, --volume-unit VOLUME_UNIT

Volume unit for output (default: m3). Options: m3, L, cm3

-eu, --energy-unit ENERGY_UNIT

Energy unit for output (default: kJ). Options: J, kJ, MJ

-mu, --mass-unit MASS_UNIT

Mass unit for output (default: kg). Options: kg, g, lbm, mol

Examples

Basic calculation: Methane at 400 K and 0.5 MPa using the Peng-Robinson EOS:

sandlersteam state -T 400 -P 0.5

Output:

T  =   400 C
P  =   0.5 MPa
v  =  0.6173 m3/kg
s  =  7.7938 kJ/kg-K
h  =  3271.9 kJ/kg
u  =  2963.2 kJ/kg
Pv =  308.65 kJ/kg

Saturated steam: At 0.5 MPa:

sandlersteam state -P 0.5 -x 1.0

Output:

T   =  151.86 C
P   =   0.5 MPa
v   =  0.3749 m3/kg
s   =  6.8213 kJ/kg-K
h   =  2748.7 kJ/kg
u   =  2561.2 kJ/kg
Pv  =  187.45 kJ/kg
x   = 1.0 kg vapor/kg total
vL  =  0.001093 m3/kg
sL  =  1.8607 kJ/kg-K
hL  =  640.23 kJ/kg
uL  =  639.68 kJ/kg
PvL =  0.5465 kJ/kg
vV  =  0.3749 m3/kg
sV  =  6.8213 kJ/kg-K
hV  =  2748.7 kJ/kg
uV  =  2561.2 kJ/kg
PvV =  187.45 kJ/kg

delta Command

Calculate changes in thermodynamic properties between two states.

Syntax

sandlersteam delta [OPTIONS]

Options

You are required to provide state variables for both State 1 and State 2. Use the same options as for the state command, but append 1 or 2 to indicate the state. In addition,

--show-states

Display full state information for both states in addition to property differences

Examples

Basic state change calculations:

sandlersteam delta -T1 350 -P1 7.5 -T2 400 -P2 15.5

Output:

State-change calculations for water/steam:
ΔT  =    50 C
ΔP  =     8 MPa
Δv  = -0.0175864 m3/kg
Δs  = -0.33006 kJ/kg-K
Δh  = -40.67 kJ/kg
Δu  = -28.99 kJ/kg
ΔPv = -11.8292 kJ/kg

With state details:

sandlersteam delta -T1 350 -P1 7.5 -T2 400 -P2 15.5 --show-states

Output:

State-change calculations for water/steam:

State 1:                       State 2:
T  =   350 C                   T  =   400 C
P  =   7.5 MPa                 P  =  15.5 MPa
v  =  0.032595 m3/kg           v  =  0.0150086 m3/kg
s  =  6.1792 kJ/kg-K           s  =  5.84914 kJ/kg-K
h  =  3001.65 kJ/kg            h  =  2960.98 kJ/kg
u  =  2758.55 kJ/kg            u  =  2729.56 kJ/kg
Pv =  244.463 kJ/kg            Pv =  232.633 kJ/kg

Property changes:
ΔT  =    50 C
ΔP  =     8 MPa
Δv  = -0.0175864 m3/kg
Δs  = -0.33006 kJ/kg-K
Δh  = -40.67 kJ/kg
Δu  = -28.99 kJ/kg
ΔPv = -11.8292 kJ/kg

Units Reference

The CLI uses units native to the steam tables in Chemical Engineering Thermodynamics by Sandler et al. Default units are as follows:

Property

Unit

Temperature (T)

Celsius (C)

Pressure (P)

Megapascal (MPa)

Specific volume (v)

m³/kg

Enthalpy (H)

kJ/kg

Entropy (S)

kJ/(kg-K)

Internal energy (U)

kJ/kg