Plate-Fin Heat Exchangers for Cryogenic Applications with Special Emphasis on Two-Phase Flow

Abstract

Brazed aluminium plate-fin heat exchangers are commonly used in cryogenic and low temperature industrial applications [1–3]. These applications include air separation, processing of liquefied petroleum and liquefied natural gas, manufacture of hydrogen and helium. etc. Some of the unique features of plate-fin heat exchangers, which make them suitable for these applications, include - Ability to work effectively at very low temperatures because of their aluminium based construction Multistream ability which means that the concept of process integration can be used to the fullest extent to save energy, capital and operating costs High thermal effectiveness arising from high heat transfer coefficients and ability to incorporate large heat transfer area, both primary as well as secondary. High thermal effectiveness means that the exchangers can be operated for duties involving very close temperature approaches In this paper these unique features of plate-fin heat exchangers are discussed in detail. Furthermore the paper also focuses on the two-phase flow heat transfer characteristics of the plate-fin passages . Also, studies related to two-phase flow heat transfer in small diameter channels, including tubes, are discussed because of their relevance to plate-fin passages, with their inherently small hydraulic diameters.