Compact heat Exchanger

Generally, compact heat exchangers are used in heat integrating processes and provide advantages over shell-and-tube heat exchangers, such as compactness, large surface area per volume ratio, low temperature differential, and can be applied as MHEX. Compact plate-fin heat exchangers are one type of compact exchanger, and they are normally used in MHEX systems because they have the ability to handle a large number of hot and cold streams in the same unit. However, the MHEX structure is complex because it contains many channels for a number of hot and cold streams to flow through an interaction between them.

Picon-Nunez et al. (1999) demonstrated a methodology for designing compact plate-fin heat exchangers with the objective of minimising pressure drop. A thermo-hydraulic model was developed and the volume performance index (VPI) corresponding to Reynolds number was used to select the best fin surface. According to Reynolds number assumptions, fin selection could not provide effective results. Picon-Nunez et al. (2002) then proposed the thermal design of a multi-stream plate-fin heat exchanger.

(2015). Basic fin geometries were treated as continuous variables to reduce computational time compared to the discrete design problem from previous work, and thermal hydraulic performance was applied together with it to minimise the total volume. In this study, we present a methodology for designing multi-stream plate-fin heat exchangers by considering pressure drop utilisation, optimising basic fin geometry and minimising the total volume of the exchanger by using uniform block heights and widths across all block sections.

The following are the most common types of CHE:

– Plate heat exchangers (PHE) use metal plates to transfer heat between two fluids over a much larger surface area. The thin, corrugated plates used in PHE are either brazed, welded or gasketed together depending on the application. As a result of the compression of the plates in a rigid frame, parallel flow channels with alternating hot and cold fluids are formed. Adding or removing plates from the stack increases and decreases heat transfer area.

– Plate-fin heat exchangers (PFHE) transfer heat between fluids using finned chambers and plates. In a PFHE, corrugated sheets are separated by flat metal plates which form a series of finned chambers. A series of hot and cold fluid streams flow through alternating layers of the HE and are enclosed by side bars. Additionally, the fins increase the structural strength of the PFHE, allowing it to withstand high pressures while providing extended heat transfer areas.

– Spiral heat exchangers (SHE) are composed of two flat surfaces that are coiled together in a counter-flow arrangement, such as helical/coiled tubes. The space she uses is highly efficient, so she has a small footprint and low capital costs. She is commonly used for handling slurries. SHEs use three main types of flow patterns: (1) spiral-spiral flow used for all heating and cooling services, (2) spiral-cross flow (one fluid is in spiral flow while the other is in cross flow) used for condensers and reboilers, and (3) distributed vapour-spiral flow that can condense and subcool in the same unit.