N2 - In the paper, a method for determination of the near-critical region boundary is proposed. The boundary is evaluated with respect to variations of specific heat capacity along isobars. It is assumed that the value of specific heat capacity inside the near-critical region exceeds by more than 50% the practically constant value typical for fluids under normal conditions. It appears that large variations of heat capacity are also present for high-pressure subcritical states sufficiently close to the critical point. Therefore, such defined near-critical region is located not only in supercritical fluid domain but also extends into subcritical fluid. As an example, the boundaries of the near-critical region were evaluated for water, carbon dioxide and R143a. L1 - http://journals.pan.pl/Content/94221/PDF/04_paper.pdf L2 - http://journals.pan.pl/Content/94221 PY - 2011 IS - No 2 August EP - 68 DO - 10.2478/v10173-011-0009-1 KW - heat transfer KW - Critical thermodynamic state KW - Near-critical region KW - Specific heat capacity A1 - KwidziƄski, Roman A1 - Trela, Marian A1 - Butrymowicz, Dariusz PB - The Committee of Thermodynamics and Combustion of the Polish Academy of Sciences and The Institute of Fluid-Flow Machinery Polish Academy of Sciences DA - 2011 T1 - A definition of near-critical region based on heat capacity variation in transcritical heat exchangers SP - 55 UR - http://journals.pan.pl/dlibra/publication/edition/94221 T2 - Archives of Thermodynamics