On miniaturisation of spirally wound tubular heat exchanger

Spirally coiled multilayer, Giauque-Hampson type heat exchangers, the classical examples of early generation cryogenic heat transfer devices, are best known for their unique and favourable features. These exchangers are capable of handling multiple fluid streams in different phases in a single unit, typically meant for high Ntu applications, operational over a wide range of temperature and pressure with minimum thermal stress development. On the negative part, they belong to the non-compact class of heat exchangers. As the trend of miniaturisation is gradually diffusing into almost every engineering discipline, the development of a compact system is the call of the present era. While probing the prospect of miniaturising multilayer spirally wound tubular (Giauque-Hampson) heat exchangers satisfying the compactness criteria, this article presents the design, fabrication, and testing of a miniature, compact, laboratory-scale prototype. Initially, the pros and cons of miniaturisation have been studied based on the 'goodness factors'. Subsequently, a step-by-step methodology is proposed to design a compact and miniature heat exchanger geometry, subjected to design constraints. Description of critical fabrication steps is followed by the experimental performance evaluation of the prototype. The heat exchanger effectiveness is calculated based on the steady-state experimental data. Performance degradation is linked to the prevailing non-ideal operating conditions causing external heat ingress. The analysis including heat leak shows good agreement between the experimental results and theoretical predictions.