  We present X-ray spectral analysis of Seyfert 1.5 Active Galactic Nuclei
(AGN) NGC~4151 using \textit{NuSTAR} observation during 2012. This is the first
attempt to fit an AGN data using the physical Two Component Advective flow
(TCAF) solution. We disentangle the continuum emission properties of the source
in the energy range $3.0$ to $70.0$~keV using the spectrum obtained from TCAF
model. This model was used as an additive local model directly in
{\fontfamily{qcr}\selectfont XSPEC}. Additionally, we used a power law (PL)
component, to take care of possible X-ray contribution from the jet, which is
not incorporated in the present version of TCAF. Our primary aim is to obtain
the flow properties and the mass of the central supermassive black hole from
the available archival data.
  Our best estimate of the average mass obtained from spectral fits of three
observations, is $M_{BH}=3.03^{+0.26}_{-0.26}\times 10^7 M_\odot$. This is
consistent with earlier estimations in the literature such as reverberation
mapping, gas kinematics and stellar dynamics around black holes. We also
discuss the accretion dynamics and the flow geometry on the basis of model
fitted physical parameters. Model fitted disk accretion rate is found to be
lower than the low angular momentum halo accretion rate, indicating that the
source was in a hard state during the observation.
