Twisted magnetic fields should be ubiquitous in the solar corona. Emerging twisted flux ropes as well as complex photospheric motions provide continuous influx of the magnetic helicity. It has been shown recently, that kink-instability in twisted coronal loops results in magnetic reconnection and particle acceleration distributed within large volume, including the lower corona and, possibly, chromosphere. Hence, a solar flare scenario involving energy release within a flux ropes can be a viable alternative to the standard flare model, where the energy release is confined to a small volume located in the upper corona.

We discuss our recent results on the energy release and particle acceleration during magnetic reconnection in twisted coronal loops. The evolution is modelled using resistive MHD, including heat conduction and radiation. We consider the effects of field topology and atmospheric stratification on the energy accumulation and release. Using a test particle code coupled to these MHD simulations, ion and electron acceleration are investigated, taking into account Coulomb collisions.

Based on these numerical models, we investigate spatial distributions and temporal variations of thermal and non-thermal emission in different configurations, and compare them with observational data.