  It has been proposed that particles bouncing between magnetized flows
converging in a reconnection region can be accelerated by the first order Fermi
mechanism. Analytical considerations of this mechanism have shown that the
spectral index of accelerated particles is related to the total plasma
compression within the reconnection region similarly to the case of diffusive
shock acceleration mechanism. As a first step to investigate the efficiency of
Fermi acceleration in reconnection regions in producing hard energy spectra of
particles in the solar corona, we explore the degree of plasma compression that
can be achieved at reconnection sites. In particular, we aim to determine the
conditions for the strong compressions to form. Using a two-dimensional
resistive MHD numerical model we consider a set of magnetic field
configurations where magnetic reconnection can occur including a Harris current
sheet, a force-free current sheet, and two merging flux ropes. Plasma
parameters are taken to be characteristic of the solar corona. Numerical
simulations show that strong plasma compressions ($\geq 4$) in the reconnection
regions can form when the plasma heating due to reconnection is efficiently
removed by fast thermal conduction or radiative cooling process. The radiative
cooling process which is negligible in the typical 1 MK corona can play an
important role in the low corona/transition region. It is found that plasma
compression is expected to be strongest in low-beta plasma $\beta \sim
0.01-0.07$ at reconnection magnetic nulls.
