Nonequilibrium modeling of heat transfer in a gas-saturated powder layer subject to a short-pulsed heat source

Heat transfer in a gas-saturated powder layer subject to a short-pulsed volumetric heat source is modeled using a two-temperature model. The energy equations for the powder particles and gas in the powder layer are coupled by an interphase coupling coefficient. The effect of the heat source pulse width, particle diameter, and the heat source fluence on the powder and gas temperatures are investigated. The results show that the nonequilibrium is significant when the heat source pulse width is less than 1 s, and therefore heat transfer during nanosecond laser-powder interaction should be modeled using a nonequilibrium model. For the case with long pulse width, on the other hand, the equilibrium model is valid.