Parametric investigation of a non-constant cross sectional area air to air heat exchanger. (25th February 2017)

• Record Type: Journal Article
• Authors: Cárdenas, Bruno; Garvey, Seamus; Kantharaj, Bharath; Simpson, Michael
• Is Part Of: Applied thermal engineering. Volume 113(2017:Feb.)
• Page Start: 278
• Page End: 289
• Publication Date: 2017-02-25
• Subjects: Gas to gas heat exchanger -- High exergy efficiency heat exchanger -- Non-constant cross sectional area -- Heat exchanger additive manufacturing -- Heat exchanger cost optimization; Heat engineering -- Periodicals; Heating -- Equipment and supplies -- Periodicals; Periodicals; 621.40205
• DOI: 10.1016/j.applthermaleng.2016.10.209
• Languages: English
• ISSNs: 1359-4311

Abstract

Highlights: Evaluation of complex geometry aimed at minimizing volume per unit of exergy transfer. The use of a non-constant cross-section for the heat exchanger is proposed. The performance gains attainable via modern manufacturing techniques are discussed. The trade-off between overall exergy efficiency and cost is thoroughly analysed. A quadratic proportion between volume and characteristic dimension has been found. Abstract: The present article addresses the design, mathematical modelling and analysis of a novel highly exergy-efficient air to air heat exchanger. An intricate design based on an hexagonal mesh is proposed for the cross-sectional area of the heat exchanger with aims to explore the performance gains that can be obtained by exploiting the capabilities and benefits offered by modern fabrication techniques such as additive manufacturing. Special attention is paid to understanding the relationship or trade-off that exists between the overall exergy efficiency of the heat exchanger and its cost. The iterative algorithm used to find the geometrical parameters that yield the best performance in terms of volume of material required per unit of exergy transfer at a certain level of efficiency, as well as the assumptions and simplifications made, are comprehensively explained. It has been found through the analyses carried out performed, which are thoroughly discussed throughout the paper, that if the characteristic dimension of the heat exchanger is scaled up by a factor of n, the volume of material per kW of exergy transfer at certain exergy efficiency will increase by a factor of n squared. This is a very important observation, possibly applicable to other types of heat exchangers, that indicates that performance improves dramatically at smaller scales. The overall performance of the case study presented is satisfactory, a volume of material as low as 84.8 cm 3 for one kW of exergy transfer can be achieved with a 99% exergy efficiency.