AixLib.Media.Refrigerants.UsersGuide.Naming

# .AixLib.Media.Refrigerants.UsersGuide.Naming

Naming and abbreviations

## Information

In general, both the naming and the abbreviations follow the guidelines presented in the media package of the Modelica standard library. However, adaptions are made for functions and variables related to the Helmholtz equation of state. These adaptions are presented below.

#### Naming of refrigerant models

The naming of the models follows the guideline presented below:

Refrigerant _ Reference Point _ Range of validity for pressure _ Range of validity for temperature _ Approach of calculating fitted formulas

1. Refrigerant: Name of the refrigerant, e.g. R134a or R410a.
2. Reference Point: Reference point chosen for the model, e.g. IIR (h = 200 kJ/kg and s = 1 kJ/kg/K at 273.15 K at saturated liquid line).
3. Validity pressure: Range of validity for pressure given in bar. Caution: 0.5 bar is written as 05 or 39.5 bar is written as 395.
4. Validity temperature: Range of validity for temperature in K. Caution: No digits are presented.
5. Approach: Approach of calculating fitted formulas. Currently, three different calculating rules are implemented.

- Record: The fitting coefficients used for the fitted formulas are stored in records.
- Formula: Fitted formulas are hard-coded in the refrigerant model due to simulation speed and, therefore, all fitting coefficients are directly stored in the models.
- Horner: Fitted formulas are hard-coded in the refrigerant model using the Horner pattern due to simulation speed and, therefore, all fitting coefficients are directly stored in the models.

#### Abbreviations of parameters, constants, variables and functions

Some special abbreviations are introduced for functions and variables related to the Helmholtz energy equation of state. Some examples are given below:

"Abbreviations for EoS" cellpadding="2" border="1" width="80%" style="border-collapse:collapse;">

Expression | Abbreviation | Comment
alpha_0 | f_Idg | Helmholtz energy of ideal gas
alpha_r | f_Res | Helmholtz energy of residual gas
tau * d(alpha_0)/(dtau)_delta=const. | t_fIdg_t | Partial derivative of f_Idg with respect to tau
tau*tau * dd(alpha_0)/(dtau*dtau)_delta=const. | tt_fIdg_tt | Partial derivative of f_Idg with respect to tau*tau
tau*delta * dd(alpha_r)/(dtau*ddelta) | td_fRes_td | Partial derivative of f_Res with respect to tau*delta

Some special abbreviations are introduced for partial derivatives. Some examples are given below:

"Abbreviations for partial derivatives" cellspacing="0" cellpadding="2" border="1" width="80%" style= "border-collapse:collapse;">

Expression | Abbreviation | Comment
d(d)/(dp)_h=const. | ddph | Partial derivative of density with respect to pressure at constant specific enthalpy
d(T)/(ds)_p=const. | dTsp | Partial derivative of temperature with respect to specific entropy and constant pressure
d(Tsat)/(dp) | dTp | Partial derivative of saturation temperature with respect to pressure
d(dl)/(dp) | ddldp | Partial derivative of bubble density with respect to pressure
d(dv)/(dp) | ddvdp | Partial derivative of dew density with respect to pressure

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