A process for heating articles in a heating system includes passing an article in a carrier through a heating chamber that is at least partially filled with a liquid medium to form a liquid bath. The process further includes heating the article in the carrier by at least partially submerging the article into the liquid bath during heating, the heating being performed, at least in part, using microwave energy. The process further includes one or more of adding fluid into and removing fluid from at least one location in the heating chamber to maintain a temperature profile across the heating chamber. In one implementation, the temperature of the liquid bath at an inlet area of the heating chamber is at least 10° C. cooler than a temperature of the liquid bath at an outlet area of the heating chamber.