Crate seuif97

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§SEUIF97

docs.rs Crates.io Version Crates.io Total Downloads Crates.io Downloads (recent)

This is the Rust implementation of the high-speed IAPWS-IF97 package SEUIF97 with C, Python and WASM bindings. It is designed for computation-intensive tasks, such as simulating non-stationary processes, on-line process monitoring, and optimization.

SEUIF97 achieves a 5-20x speedup over naive implementations that use the Rust standard library’s powi() in for loops for the basic equations of Regions 1, 2, and 3.

This package supports 12 distinct input state pairs for calculating 36 thermodynamic, transport, and derived properties (see Properties), and thermodynamic process functions (see Thermodynamic Process Functions).

§What’s New in the Rust Version

The Rust version of SEUIF97 is a major upgrade over the original C implementation, delivering significant improvements in performance, functionality, and ecosystem support.

Feature	C Version	Rust Version
Calculation Speed	Baseline	~2× speedup
Supported Properties	30 properties	36 properties (+6 new)
Package Distribution	PyPI only	Crates.io, PyPI, npm
Direct Property Functions	✗	✓ (new)

For detailed comparison and key improvements, see Rust vs C.

§Acceleration Methods

Profiling-guided loop tiling partitions polynomial summation into cache-friendly tiles with empirically determined boundaries, enabling more effective SIMD vectorization.
Shared-power scaling exploits the mathematical relationship between Gibbs/Helmholtz free energy polynomials and their partial derivatives to compute them simultaneously in a single pass, eliminating redundant power calculations.

For more details on these algorithms, see: code snippets of the acceleration methods.

§Performance Comparison with CoolProp IF97

SEUIF97 achieves 3.4 - 7.6x speedups over CoolProp IF97. See Performance Comparison for detailed benchmark results.

§Property Calculation Functions

The package provides two types of API for property calculation.

§Universal Property Functions

The following 12 input pairs are implemented:

  (p,t), (p,h), (p,s), (p,v)
  (h,s)
  (t,h), (t,s), (t,v)
  (h,x), (t,x), (v,x), (s,x)

Each function accepts an input pair, an output property ID (o_id), and an optional region parameter for faster computation. For example: the input pair (p,t): pt(p,t,o_id), pt(p,t,(o_id,region))

Note:

The region parameter is Rust-only. C, Python and WASM bindings support the o_id form only.
Only linearly related thermodynamic properties are calculable in the wet steam region.

§Direct Property Functions

Function naming convention: {input1}{input2}2{output}.

Input	Outputs	Input	Outputs	Input	Outputs
(p,t)	h,s,v,x	(t,h)	p,s,v,x	(p,x)	t,h,s,v
(p,h)	t,s,v,x	(t,s)	p,h,v,x	(t,x)	p,h,s,v
(p,s)	t,h,v,x	(t,v)	p,h,s,x	(h,x)	p,t,s,v
(p,v)	t,h,s,x	(h,s)	p,t,v,x	(s,x)	p,t,h,v

Total: 48 functions(e.g. pt2h(p,t), ph2t(p,h), hs2p(h,s))

§Thermodynamic Process Functions

The following thermodynamic process functions are implemented:

ishd(pi, ti, pe): isentropic enthalpy drop for steam expansion (kJ/kg)
ief(pi, ti, pe, te): isentropic efficiency for superheated steam expansion (%)

§Install the crate

cargo add seuif97

§Usage

use seuif97::*;
fn main() {    
    let p: f64 = 3.0;
    let t: f64 = 300.0-273.15;
    // universal property functions with o_id parameter only
    let h = pt(p,t,OH);   
    // universal property functions with explicit region for faster calculation
    let s = pt(p,t,(OS,1)); 
    // direct property functions
    let v = pt2v(p,t);

    println!("p={p:.6} t={t:.6} h={h:.6} s={s:.6} v={v:.6}");   

    // thermodynamic process functions
    let pi: f64 = 16.0;
    let ti: f64 = 535.1;
    let pe: f64 = 5.0;
    let delta_h = ishd(pi, ti, pe);
    println!("ishd: pi={pi} ti={ti} pe={pe} delta_h={delta_h:.3}");
}

§C Shared Library

Pre-compiled dynamic link libraries for Windows, Linux and macOS are available in GitHub Releases.

Note: GitHub Releases builds produce library names with platform-specific suffixes. Example: seuif97-windows-x86_64-cdecl.dll. Linux and macOS follow the same naming pattern. Rename them to seuif97.dll / libseuif97.so / libseuif97.dylib before use to match the local build naming convention.

Interfaces and examples are provided in the ./demo_using_lib/ directory, supporting a wide range of languages and environments.

C/C++, Python, C#, Java, Excel VBA, Rust, Fortran, Golang, JavaScript/TypeScript

#include <stdlib.h>
#include <stdio.h>

#define OH 4

extern double pt(double p,double t,short o_id);
extern double pt2s(double p,double t);

int main(void)
{
    double p = 16.0;
    double t = 530.0;
    // universal property functions with o_id parameter only
    double h = pt(p, t, OH);
    // direct property functions
    double s = pt2s(p, t);
    printf("p,t %f,%f h= %f s= %f\n", p, t, h, s);
    return EXIT_SUCCESS;
}

Comprehensive Cross-language Examples

The Rankine Cycle Steady-state Simulator in Python, C++, Rust and Modelica

§Python binding

Install from PyPI

https://pypi.org/project/seuif97/

pip install seuif97

from seuif97 import *

OH=4

p=16.0
t=535.1
# universal property functions with o_id parameter only
h=pt(p,t,OH)
# direct property functions
s=pt2s(p,t)
print(f"p={p}, t={t} h={h:.3f} s={s:.3f}")

Comprehensive Examples in Python

T-S Diagram

§WASM binding

Install from npm:

npm install seuif97

Detailed documentation: README_WASM.md
NPM package: seuif97

import init, { pt, pt2s } from 'seuif97';

await init();

const p = 16.0;  // MPa
const t = 535.1; // °C
// universal property functions (with o_id parameter only)
const h = pt(p, t, 4);     // kJ/kg
// direct property functions
const s = pt2s(p, t);      // kJ/(kg·K)

console.log('Properties at p = 16.0 MPa, t = 535.1 °C:');
console.log(`H: ${h.toFixed(3)} kJ/kg`);
console.log(`S: ${s.toFixed(5)} kJ/(kg·K)`);

§Properties

Property	Unit	Symbol	o_id	o_id(i32)
Pressure	MPa	p	OP	0
Temperature	°C	t	OT	1
Density	kg/m³	ρ	OD	2
Specific Volume	m³/kg	v	OV	3
Specific enthalpy	kJ/kg	h	OH	4
Specific entropy	kJ/(kg·K)	s	OS	5
Specific exergy	kJ/kg	e	OE	6
Specific internal energy	kJ/kg	u	OU	7
Specific isobaric heat capacity	kJ/(kg·K)	cp	OCP	8
Specific isochoric heat capacity	kJ/(kg·K)	cv	OCV	9
Speed of sound	m/s	w	OW	10
Isentropic exponent	—	k	OKS	11
Specific Helmholtz free energy	kJ/kg	f	OF	12
Specific Gibbs free energy	kJ/kg	g	OG	13
Compressibility factor	—	z	OZ	14
Steam quality	—	x	OX	15
Region	—	r	OR	16
Isobaric cubic expansion coefficient	1/K	ɑv	OEC	17
Isothermal compressibility	1/MPa	kT	OKT	18
Partial derivative (∂v/∂T)p	m³/(kg·K)	(∂v/∂T)p	ODVDT	19
Partial derivative (∂v/∂p)T	m³/(kg·MPa)	(∂v/∂p)T	ODVDP	20
Partial derivative (∂p/∂T)v	MPa/K	(∂p/∂T)v	ODPDT	21
Isothermal throttling coefficient	kJ/(kg·MPa)	δt	OIJTC	22
Joule-Thomson coefficient	K/MPa	μ	OJTC	23
Dynamic viscosity	Pa·s	η	ODV	24
Kinematic viscosity	m²/s	ν	OKV	25
Thermal conductivity	W/(m.K)	λ	OTC	26
Thermal diffusivity	m²/s	a	OTD	27
Prandtl number	—	Pr	OPR	28
Surface tension	N/m	σ	OST	29
Static Dielectric Constant	—	ε	OSDC	30
Isochoric pressure coefficient	1/K	β	OPC	31
Isothermal stress coefficient	kg/m³	βp	OBETAP	32
Fugacity coefficient	—	φ	OFI	33
Fugacity	MPa	f	OFU	34
Relative pressure coefficient	1/K	αp	OAFLAP	35

Structs§

o_id_region_args: the parameters:
o_id: the property of id;
region: the region in the IAPWS-IF97,optional

Constants§

OALFAP: αp - Relative pressure coefficient 1/K
OBETAP: βp - Isothermal stress coefficient, kg/m³
OCP: cp - Specific isobaric heat capacity kJ/(kg·K)
OCV: cv - Specific isochoric heat capacity kJ/(kg·K)
OD: ρ - Density kg/m³
ODPDT: (∂p/∂t)v - Partial derivative MPa/K
ODV: η - Dynamic viscosity Pa.s dv
ODVDP: (∂V/∂P)T - Partial derivative m³/(kg·MPa)
ODVDT: (∂V/∂T)p - Partial derivative m³/(kg·K)
OE: e - Specific exergy kJ/kg
OEC: δt - Isobaric cubic expansion coefficient 1/K
OF: f - Specific Helmholtz free energy kJ/kg
OFI: fi- Fugacity coefficient
OFU: f* - Fugacity MPa
OG: g - Specific Gibbs free energy kJ/kg
OH: h - Specific enthalpy kJ/kg
OIJTC: δt - Isothermal throttling coefficient kJ/(kg·MPa)
OJTC: μ - Joule-Thomson coefficient K/MPa joule
OKS: k - Isentropic exponent
OKT: kT - Isothermal compressibility 1/MPa
OKV: ν - Kinematic viscosity m²/s
OP: p - Pressure MPa
OPC: β - Isochoric pressure coefficient 1/K
OPR: Pr - Prandtl number
OR: r - Region
OS: s - Specific entropy kJ/(kg·K) )
OSDC: ε - Static Dielectric Constant
OST: σ - Surface tension N/m
OT: t - Temperature °C
OTC: λ - Thermal conductivity W/(m.K) tc
OTD: a - Thermal diffusivity m²/s
OU: u - Specific internal energy kJ/kg
OV: v - Specific Volume m³/kg
OW: w - Speed of sound m/s
OX: x - Steam quality
OZ: z - Compressibility factor

Functions§

hs: hs(h,s,o_id) - the property of o_id (thermodynamic,transport,etc)
hs(h,s,(o_id,reg)) - the property of o_id in the region of reg(thermodynamic,transport,etc)
hs2p: hs2p(h,s) - Calculate pressure from enthalpy and entropy
hs2t: hs2t(h,s) - Calculate temperature from enthalpy and entropy
hs2v: hs2v(h,s) - Calculate specific volume from enthalpy and entropy
hs2x: hs2x(h,s) - Calculate steam quality from enthalpy and entropy
hx: hx(h,x,o_id) - the property of o_id(thermodynamic)
hx2p: hx2p(h,x) - Calculate pressure from enthalpy and steam quality
hx2s: hx2s(h,x) - Calculate specific entropy from enthalpy and steam quality
hx2t: hx2t(h,x) - Calculate temperature from enthalpy and steam quality
hx2v: hx2v(h,x) - Calculate specific volume from enthalpy and steam quality
ief: ief(pi,ti,pe,te) - Isentropic efficiency (%) for superheated steam expansion
ishd: ishd(pi,ti,pe) - Isentropic enthalpy drop
ph: ph(p,h,o_id) - the property of o_id (thermodynamic,transport,etc)
ph(p,h,(o_id,reg)) - the property of o_id in the region of reg(thermodynamic,transport,etc)
ph2s: ph2s(p,h) - Calculate specific entropy from pressure and enthalpy
ph2t: ph2t(p,h) - Calculate temperature from pressure and enthalpy
ph2v: ph2v(p,h) - Calculate specific volume from pressure and enthalpy
ph2x: ph2x(p,h) - Calculate steam quality from pressure and enthalpy
ps: ps(p,s,o_id) - the property of o_id (thermodynamic,transport,etc)
ps(p,s,(o_id,reg)) - the property of o_id in the region of reg(thermodynamic,transport,etc)
ps2h: ps2h(p,s) - Calculate specific enthalpy from pressure and entropy
ps2t: ps2t(p,s) - Calculate temperature from pressure and entropy
ps2v: ps2v(p,s) - Calculate specific volume from pressure and entropy
ps2x: ps2x(p,s) - Calculate steam quality from pressure and entropy
pt: pt(p,t,o_id) - the property of o_id (thermodynamic,transport,etc)
pt(p,t,(o_id,reg)) - the property of o_id in the region of reg(thermodynamic,transport,etc)
pt2h: pt2h(p,t) - Calculate specific enthalpy from pressure and temperature
pt2s: pt2s(p,t) - Calculate specific entropy from pressure and temperature
pt2v: pt2v(p,t) - Calculate specific volume from pressure and temperature
pt2x: pt2x(p,t) - Calculate steam quality from pressure and temperature
pv: pv(p,v,o_id) - the property of o_id(thermodynamic,transport,etc)
pv(p,v,(o_id,reg)) - the property of o_id in the region of reg(thermodynamic,transport,etc)
pv2h: pv2h(p,v) - Calculate specific enthalpy from pressure and specific volume
pv2s: pv2s(p,v) - Calculate specific entropy from pressure and specific volume
pv2t: pv2t(p,v) - Calculate temperature from pressure and specific volume
pv2x: pv2x(p,v) - Calculate steam quality from pressure and specific volume
px: px(p,x,o_id) - the property of o_id (thermodynamic)
px2h: px2h(p,x) - Calculate specific enthalpy from pressure and steam quality
px2s: px2s(p,x) - Calculate specific entropy from pressure and steam quality
px2t: px2t(p,x) - Calculate temperature from pressure and steam quality
px2v: px2v(p,x) - Calculate specific volume from pressure and steam quality
sx: sx(s,x,o_id) - the property of o_id(thermodynamic)
sx2h: sx2h(s,x) - Calculate specific enthalpy from entropy and steam quality
sx2p: sx2p(s,x) - Calculate pressure from entropy and steam quality
sx2t: sx2t(s,x) - Calculate temperature from entropy and steam quality
sx2v: sx2v(s,x) - Calculate specific volume from entropy and steam quality
th: th(t,h,o_id) - the property of o_id(thermodynamic,transport,etc)
th(t,h,(o_id,reg)) - the property of o_id in the region of reg(thermodynamic,transport,etc)
th2p: th2p(t,h) - Calculate pressure from temperature and enthalpy
th2s: th2s(t,h) - Calculate specific entropy from temperature and enthalpy
th2v: th2v(t,h) - Calculate specific volume from temperature and enthalpy
th2x: th2x(t,h) - Calculate steam quality from temperature and enthalpy
ts: ts(t,s,o_id) - the property of o_id(thermodynamic,transport,etc)
ts(t,s,(o_id,reg)) - the property of o_id in the region of reg(thermodynamic,transport,etc)
ts2h: ts2h(t,s) - Calculate specific enthalpy from temperature and entropy
ts2p: ts2p(t,s) - Calculate pressure from temperature and entropy
ts2v: ts2v(t,s) - Calculate specific volume from temperature and entropy
ts2x: ts2x(t,s) - Calculate steam quality from temperature and entropy
tv: tv(t,v,o_id) - the property of o_id(thermodynamic,transport,etc)
tv(t,v,(o_id,reg)) - the property of o_id in the region of reg(thermodynamic,transport,etc)
tv2h: tv2h(t,v) - Calculate specific enthalpy from temperature and specific volume
tv2p: tv2p(t,v) - Calculate pressure from temperature and specific volume
tv2s: tv2s(t,v) - Calculate specific entropy from temperature and specific volume
tv2x: tv2x(t,v) - Calculate steam quality from temperature and specific volume
tx: tx(t,x,o_id) - the property of o_id (thermodynamic)
tx2h: tx2h(t,x) - Calculate specific enthalpy from temperature and steam quality
tx2p: tx2p(t,x) - Calculate pressure from temperature and steam quality
tx2s: tx2s(t,x) - Calculate specific entropy from temperature and steam quality
tx2v: tx2v(t,x) - Calculate specific volume from temperature and steam quality

Crate seuif97

Crate seuif97 Copy item path

§SEUIF97

§What’s New in the Rust Version

§Acceleration Methods

§Performance Comparison with CoolProp IF97

§Property Calculation Functions

§Universal Property Functions

§Direct Property Functions

§Thermodynamic Process Functions

§Install the crate

§Usage

§C Shared Library

§Python binding

§WASM binding

§Properties

Structs§

Constants§

Functions§

Crate seuif97