Design and finite volume evaluation of a counterflow recuperative spiral heat exchanger for additive manufacturing

Abstract

There is an ever-increasing demand to find alternatives to carbon based fuel sources and move to renewable electric propulsion systems. Recent advances in additive manufacturing have enabled the manufacturing of complex geometries enabling the potential for higher efficiencies for smaller, more compact designs. The aviation sector is a critical aspect of the transition to electrical population and one that cannot be proactively solved with traditional electric motors. To this end, the use of a superconducting electric motors has been proposed to achieve higher efficiencies and make application within aircraft a viable alternative. The investigation of a cryocooling component, specifically, the ability to pump cryogenic fluid through the electrical systems to maintain the superconducting state is critical to determine the viability of such a design.

This paper considers the application of a warm pump in combination with a recuperative heat exchanger to fulfil the cryogenic circulation requirement. The utilisation of additive manufacturing to design complex geometries and ANSYS fluent to verify the effectiveness of the design can result in a superior solution. This paper proposes the use of homogenised heat transfer within the design to achieve both a room temperature output and a cryogenic output. To achieve this, two critical design requirements were proposed; a low thermally conductive intermediate layer to ensure controlled homogenised heat transfer and fixed temperature inlets, one being room temperature and the other at cryogenic temperature. The high temperature gradient across the recuperative heat exchanger, in combination with a low thermally conductive intermediate layer allows for an even heat transfer cumulating in the reversal of the inlet temperatures at an efficiency between 95 and 98 percent.