.. _real_co2_db_sec: Database for real |CO2| ^^^^^^^^^^^^^^^^^^^^^^^^^ Real pure |CO2| can be characterised by a thermodynamic database to define a Gas or a Solvent by the :ref:`EOS GAS` or :ref:`EOS SOLVENT` data block. The |CO2| database can be included with two different keywords. The first option requires to state explicitly the |CO2| formula weight of 44 g/mol. An example is given below: :: EOS GAS SURFACE_DENSITY 1.87 kg/m^3 FORMULA_WEIGHT 44 g/mol DATABASE co2_db.dat END The alternative option uses the CO2_DATABASE keyword, and does not require to state the |CO2| formula weight, which is assigned to 44.00098, internally, by the simulator. An example is given below: :: EOS GAS SURFACE_DENSITY 1.87 kg/m^3 CO2_DATABASE co2_db.dat END In both cases described above, the external database must have the format of an :ref:`EOS properties database`, and contains all the properties needed do define the |CO2| (density, viscosity, enthalpy, fugacity). A database for pure |CO2| is provided with the software, and it is made available in the database folder found in the installation directory. The data file is called ‘co2_db.dat’ and it is valid in the pressure and temperature ranges reported below: .. math:: \begin{split} &P &= [0.1 – 2500.1] \mbox{ Bar} \\ &T &= [ 0 – 375 ] \mbox{ °C} \end{split} The data is sampled using a discretisation step of dP = 5 Bars for the pressure and dT = 2.5 °C for the temperature. The reference state used for the enthalpy is .. math:: H(P=3.4851\mbox{ MPa}, T=0 °C) = 200 \mbox{ kj/kg}, where :math:`P=3.4851 \mbox{MPa}` and :math:`T = 0 °C` correspond to a state of saturated liquid at :math:`0 °C`. The |CO2| database can be generated using the CO2_SPAN_WAGNER_DB data block. See example below: :: EOS GAS CO2_SPAN_WAGNER_DB PRESSURE_MIN 5 Bar PRESSURE_MAX 100 Bar PRESSURE_DELTA 1 Bar TEMPERATURE_MIN 38 C TEMPERATURE_MAX 150 C TEMPERATURE_DELTA 2 C DATABASE_FILE_NAME co2_db.dat END END Where: PRESSURE_MIN and PRESSURE_MAX are the minimum and maximum pressure values defining the database pressure range. For the validity of the model available, the pressure range must fall within the following limits: :math:`0.1 \mbox{ Bar} < P < 2500 \mbox{ Bar}`. The minimum and maximum pressures are optional, if not entered they are defaulted to 0.1 and 2500 Bar respectively. TEMPERATURE_MIN and TEMPERATURE_MAX are the minimum and maximum temperature values defining the database temperature range. For the validity of the model available, the temperature range must fall within the following limits: :math:`−55°C