We investigate effects of wall heat transfer on the structure of pressure driven flow in micro/nanochannels using the Direct Simulation Monte Carlo method. The effects of non-zero wall heat flux on the pressure distribution, velocity profiles, heat flow patterns and the mass flow rate are reported. The simulation results show that cooling decreases slip at the wall and pressure along the channel. Cooling changes the heat flow direction along the channel while heating does not. At higher degree of rarefaction, the direction of the heat flow is mainly axial along the channel. An existence of cold-to-hot heat transfer process is demonstrated in the cooling wall case. Cooling can also create a heat singularity point in the domain. There is a critical Knudsen number about unity for which heating or cooling does not affect the mass flow rate through the channel. Below the critical Knudsen number, heating decreases and cooling increases the mass flow rate. Above it, heating increases and cooling decreases the mass flow rate.

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