Abstract
Heat Exchange Networks (HENs) and Mass Exchange Networks (MENs) have been widely adopted and extensively studied for heat and material recovery to save energy and other resources. However, work recovery can also result in significant energy savings in for example oil refineries, petrochemical plants and cryogenic processes, such as the production of liquefied natural gas (LNG). The concept of Work Exchange Networks (WENs) was first proposed and identified as a new research topic in Process Synthesis in 1996. This research area has broadened considerably during the last 5-10 years, and it covers both flow work (material streams) and shaft work (energy streams or non-flow processes). More recently, there has also been considerable development in the combined problem of Work and Heat Exchange Networks (WHENs). Two research directions have developed for WHENs; one with a focus on work integration accounting for heat effects, and one focusing on heat integration accounting for heating and cooling produced by compression and expansion. The field of WENs and WHENs can be classified as follows: (1) Pressure Integration (flow work), (2) Power (or Work) Integration (shaft work), and (3) Work and Heat Integration (mechanical and thermal energies). The present review will cover WENs (both flow work and shaft work) and WHENs (with a focus on both mechanical energy and thermal energy) from both a pinch technology based and a mathematical programming (optimization) based perspectives.
