It seems like you're discussing the behavior of a system in terms of its thermodynamic properties such as enthalpy (H), viscosity (η), temperature (T), and volume (V). If you're experiencing a discrepancy between theoretical calculations and experimental results, it could be due to various factors:

Assumptions and Simplifications: Theoretical models often make simplifying assumptions that may not perfectly represent real-world conditions. Check if the assumptions used in your calculations match the experimental setup.

Equation of State: The choice of equation of state (EOS) can significantly impact the accuracy of thermodynamic calculations. Ensure that the EOS you're using is appropriate for your system.

Experimental Errors: Experimental data can have errors or uncertainties. Make sure that the experimental measurements are accurate and well-controlled.

Interaction Parameters: Depending on your system, you might need to consider specific interaction parameters between molecules or particles to improve the accuracy of your calculations.

Temperature and Pressure Ranges: Some EOS and models are only valid within specific temperature and pressure ranges. Ensure that you are working within the appropriate range for your system.

Phase Changes: Consider phase transitions that might occur in your system, such as phase equilibrium or phase changes, as these can have a significant impact on properties like enthalpy and pressure.

To address the discrepancy between your theoretical calculations and experimental results, you may need to revisit your model, validate your assumptions, and potentially refine your calculations or experiment. Collaboration with experts in the field or reviewing relevant literature can also be helpful in troubleshooting such issues.

Now scientists have enough thermal property data to test the correctness of the second law of thermodynamics, as long as they are willing.