Thermal Performance of Multi-Fluid Heat Exchangers

Multi-fluid heat exchangers harness multi-stream configurations to achieve efficient thermal exchange among three or more fluid circuits. Benefits include compactness, enhanced interfacial area and simultaneous energy recovery at different temperature levels. Such devices employ concentric tube arrangements, spiral or plate geometries, and modular assemblies that support counter-flow, co-current and cross-flow modes. Thermal performance depends on fluid properties, flow regimes, channel geometry and surface treatments. Advances in theoretical modelling and computational fluid dynamics allow accurate prediction of outlet temperatures, overall heat transfer coefficients and pressure drops. Current research emphasises entropy generation minimisation, optimal mass flow distribution and fouling mitigation strategies. Applications span domestic heating, industrial process integration, renewable energy systems and waste-heat recovery, highlighting the vital role of multi-fluid exchangers in global decarbonisation and energy-efficiency drives.

Research from Nature Portfolio

Recent studies have delivered rigorous theoretical frameworks for convective processes within multi-phase and multi-fluid systems. A three-dimensional energy transfer theory has yielded analytical expressions for convective heat transfer coefficients in both laminar and turbulent flows, completing Newton’s cooling law by defining consistent formulae for heat flux and entropy flux vectors. This work elucidates the relationship between temperature differences and entropy generation, informing the design of heat exchangers with optimised thermal management. Foundational research on compressible flows has introduced unifying three-dimensional formulae for advective heat flux vectors, demonstrating that mass transport driven by temperature differentials can be characterised by a ‘potential temperature’. These insights reveal a novel thermal driving force and enable precise prediction of heat transfer in forced and natural convection regimes, opening new directions for multi-fluid heat exchanger design and control.

Thermal Performance of Multi-Fluid Heat Exchangers publication trend

The graph below shows the total number of articles in thermal performance of multi-fluid heat exchangers across all publications each year (not limited to Nature Index journals).

Technical terms

Multi-fluid heat exchanger: A device enabling simultaneous heat exchange among three or more fluid streams within distinct channels or circuits.

Nusselt number: Dimensionless parameter representing the ratio of convective to conductive heat transfer across a fluid–solid interface.

Convective heat transfer coefficient: Quantifies the rate of heat transfer between a solid surface and a fluid per unit surface area per unit temperature difference.

Entropy generation: Measure of irreversibility in a thermal process, indicating energy lost to inefficiencies.

Potential temperature: Reference temperature of a compressible fluid parcel when brought adiabatically to a standard pressure, used to characterise thermal driving forces.

References

1. Integrity of Newton’s cooling law based on thermal convection theory of heat transfer and entropy transfer. Scientific Reports (2022).
2. Derivation of unifying formulae for convective heat transfer in compressible flow fields. Scientific Reports (2021).
3. Modeling and optimization of triple tube heat exchangers. Theoretical formulation, CFD model and experimental contrast. Thermal Science and Engineering Progress (2024).
4. Performance Investigation of a Three Fluid Heat Exchanger Used in Domestic Heating Applications. International Journal of Automotive and Mechanical Engineering (2022).