  We studied the specific heat and thermal conductivity of the spin-triplet
superconductor Sr2RuO4 at low temperatures and under oriented magnetic fields
H. We resolved a double peak structure of the superconducting transition under
magnetic field for the first time, which provides thermodynamic evidence for
the existence of multiple superconducting phases. We also found a clear
limiting of the upper critical field Hc2 for the field direction parallel to
the RuO2 plane only within 2 degrees. The limiting of Hc2 occurs in the same
H-T domain of the second superconducting phase; we suggest that the two
phenomena have the same physical origin.
