Publication detail

A New Numerical Approach for Exergy Targets and Losses Determination in Sub-Ambient Processes

Hamsani, M.N. Liew, P.Y. Walmsley, T.G.

Original Title

A New Numerical Approach for Exergy Targets and Losses Determination in Sub-Ambient Processes

Type

conference paper

Language

English

Original Abstract

Sub-ambient processes such as a refrigeration system are a highly energy intensive area in chemical industries. Refrigeration systems require a high level of process cooling using a combination of compression and expansion operations. It is, therefore, crucial to optimise heat transfer between the utility system and the process streams including the placement of compression and expansion operations to minimise the exergy losses and work as much as possible. This paper demonstrates how heat integration tools such as Pinch Analysis and Exergy Analysis can be applied to determine exergy losses and exergy targets for sub-ambient processes. In this study, a numerical approach, the Exergy Problem Table Algorithm (Ex-PTA), is proposed as an improved method compared to the graphical method based on the Extended Pinch Analysis and Design (ExPAnD) methodology. The methodology is applied to a literature case study of a refrigeration system to prove its validity. For the new numerical method, the minimum exergy requirement above the Exergy Pinch is 2.67 kW, while the maximum exergy rejection below the Exergy Pinch is 1.33 kW. The result shows that the total exergy loss for the process is 4.74 kW. In contrast, the maximum exergy rejection and minimum exergy requirement obtained in ExPAnD are 0.46 kW and 5.38 kW while the total exergy loss is 6.72 kW. These new targets assume so-called horizontal heat transfer is allowed between process and utility streams, whereas the ExPAnD method assumes vertical heat transfer between process and utility and, therefore, results in less optimistic targets.

Keywords

Chemical analysis; Chemical industry; Cooling systems; Heat transfer; Numerical methods; Refrigeration; Exergy Analysis; Graphical methods; Heat integration; Numerical approaches; Pinch analysis; Process streams; Refrigeration system; Utility systems; Exergy;

Authors

Hamsani, M.N.; Liew, P.Y.; Walmsley, T.G.

Released

1. 10. 2017

Publisher

Italian Association of Chemical Engineering - AIDIC

ISBN

978-88-95608-51-8

Book

Chemical Engineering Transactions

ISBN

2283-9216

Periodical

Chemical Engineering Transactions

Number

61

State

Republic of Italy

Pages from

1225

Pages to

1230

Pages count

6

BibTex

@inproceedings{BUT146094,
  author="Hamsani, M.N. and Liew, P.Y. and Walmsley, T.G.",
  title="A New Numerical Approach for Exergy Targets and Losses Determination in Sub-Ambient Processes",
  booktitle="Chemical Engineering Transactions",
  year="2017",
  journal="Chemical Engineering Transactions",
  number="61",
  pages="1225--1230",
  publisher="Italian Association of Chemical Engineering - AIDIC",
  doi="10.3303/CET1761202",
  isbn="978-88-95608-51-8",
  issn="2283-9216"
}