A Model of a Buoyancy-Driven Heat Exchanger, with Implications for Optimal Design

TL;DR

This paper presents a first-principles model of a buoyancy-driven air-to-air heat exchanger, analyzing its steady-state behavior and efficiency-flow tradeoff for optimal design insights.

Contribution

It introduces a novel, physics-based model incorporating Bernoulli and pressure continuity boundary conditions for buoyancy-driven heat exchangers.

Findings

Numerical and asymptotic solutions agree well.

The model reveals the tradeoff between efficiency and airflow.

Insights for optimal heat exchanger design.

Abstract

In this paper, we introduce a model for a buoyancy-driven, air-to-air heat exchanger. This model, derived from first principles, features a conservative boundary condition at inflow based on the compressible Bernoulli equation, and a dissipative boundary condition at outflow based on pressure continuity. We solve for the steady-state behavior numerically and asymptotically, with excellent agreement between the two, and we study the tradeoff between the efficiency and air flow predicted by the model.