IF97

IF97 is the high-speed package of IAPWS-IF97 in Rust with C and Python binding. It is suitable for computation-intensive calculations，such as heat cycle calculations, simulations of non-stationary processes, real-time process monitoring and optimizations.

Through the high-speed package, the results of the IAPWS-IF97 are accurately produced at about 5-20x speed-up compared to using the powi() of the Rust standard library in the forloop directly when computing the basic equations of Region 1,2,3.

The Fast Methods

1. The multi-step method unleashes the full power of the compiler optimizations while using powi() with the for loop
2. The recursive method computes the polynomial values of the base variable and its derivatives

In IF97, 36 thermodynamic, transport and further properties can be calculated.

The following 12 input pairs are implemented:

```txt (p,t) (p,h) (p,s) (p,v)

(t,h) (t,s) (t,v)

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

(h,s)
```

Usage

Install the crate

bash cargo add if97

The type of functions are provided in the if97 package:

```txt struct oidregionargs { oid: i32, region: i32, }

fn(f64,f64,R) -> f64 where R: Into, ``````

• the first,second input parameters(f64) : the input propertry pairs
• the third and fourth input parametes:
  • the third : the property ID of the calculated property - o_id
  • the fourth option parameter: the region of IAPWS-IF97
• the return(f64): the calculated property value of o_id

```txt pt(p:f64,t:f64,oidregion:R)->f64 ph(p:f64,h:f64,oidregion:R)->f64 ps(p:f64,s:f64,oidregion:R)->f64 pv(p:f64,v:f64,oidregion:R)->f64

th(t:f64,h:f64,oidregion:R)->f64 ts(t:f64,s:f64,oidregion:R)->f64 tv(t:f64,v:f64,oidregion:R)->f64

hs(h:f64,s:f64,oidregion:R)->f64

px(p:f64,x:f64,oid:i32)->f64 tx(p:f64,x:f64,oid:i32)->f64 hx(h:f64,x:f64,oid:i32)->f64 sx(s:f64,x:f64,oid:i32)->f64

``` Example

```rust use if97::*; fn main() {

let p:f64 = 3.0;
let t:f64= 300.0-273.15;

let h=pt(p,t,OH);
let s=pt(p,t,OS);
// set the region
let v=pt(p,t,(OV,1));
println!("p={p:.6} t={t:.6} h={t:.6} s={s:.6} v={v:.6}");

} ```

The C binding

Building the dynamic link library

• cdecl

bash cargo build -r --features cdecl * stdcall: Win32 API functions

bash cargo build -r --features stdcall

The convenient compiled dynamic link libraries are provided in the ./dynamic_lib/

• if97.dll: Windows64 and Windows32

• libif97.so: Linux64

The functions in C ```c double pt(double p,double t,short oid); double ph(double p,double h,short oid); double ps(double p,double s,short oid); double pv(double p,double v,short oid);

double tv(double t,double v,short oid); double th(double t,double h,short oid); double ts(double t,double s,short o_id);

double hs(double h,double s,short o_id);

double px(double p,double x,short oid); double tx(double t,double x,short oid); double hx(double h,double x,short oid); double sx(double s,double x,short oid); ```

Examples

• ./demousinglib/: C, Python, C#, Excel VBA, Java, Fortran

```c

include

include

include

define OH 4

define OS 5

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

int main(void) { double p = 16.0; double t = 530.0; double h = pt(p, t, OH); double s = pt(p, t, OS); printf("p,t %f,%f h= %f s= %f\n", p, t, h, s); return EXIT_SUCCESS; } ```

The Python binding

Install

bash pip install if97

Examples

```python from if97 import *

OH=4 OS=5

p=16.0 t=535.1 h=pt(p,t,OH) s=pt(p,t,OS) print(f"p={p}, t={t} h={h:.3f} s={s:.3f}") ``` T-S Diagram

Properties

| Propertry | Unit | Symbol | oid | oid(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 | | Isobari 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 | | fi | OFI | 33 | | Fugacity | MPa | f* | OFU | 34 | | Relative pressure coefficient | 1/K | αp | OAFLAP| 35|