An apparatus and method for creating enlarged particles in a flow. The apparatus includes a coiled tube having a tube diameter and a coil diameter, the tube having an input receiving the flow and an output, the tube having a length between the input and the output. A heater heats a first portion of the tube along a first, longitudinal portion of the tube, and a cooler cools a second, longitudinal portion of the tube along at least a second portion of the tube. The method includes heating a first portion of the tube along a first longitudinal portion of the tube, and simultaneously cooling a second portion of the tube along at least a second longitudinal portion of the tube. While heating and cooling, the method includes introducing a flow into an interior of the tube at an input, the flow moving the output.