In the present study we analyze the factors which can lower hyperpolarization of fluids produced in a continuous flow regime by the parahydrogen-induced polarization technique. We use the findings of this analysis to examine the flow rate dependence of propane hyperpolarization produced in the heterogeneous propylene hydrogenation by parahydrogen over Rh/TiO2 catalyst. We have estimated the maximum attainable propane H-1 hyperpolarization yield and the corrected percentage of pairwise hydrogen addition in heterogeneous hydrogenation, which was found to be similar to 7%. The approach developed for polarization analysis is useful for the optimization of experimental setup and reaction conditions to obtain maximum hyperpolarization for parahydrogen-based catalyst-free continuously generated fluids applicable in biomedical magnetic resonance imaging.