Abstract: A multi tube heat exchanger with a bundle of small tubes surrounded by one large shell tube is provided. Each small tube has a smaller tube in the center. Product flows in the multiple annular spaces between the tubes while heating or cooling medium flows in the shell side. This arrangement provides high shear rate and results into high heat transfer rates and while still resulting in lower pressure drops for thick food products like tomato paste, catsup, sugar syrups and similar products.