Data from: Simplified models of the symmetric single-pass parallel-plate counterflow heat exchanger: a tutorial

The heat exchanger is important in practical thermal processes, especially
those of (i) the molten-salt storage schemes, (ii) compressed air energy
storage schemes, and (iii) other load-shifting thermal storage presumed to
undergird a Smart Grid. Such devices, although central to the utilization
of energy from sustainable (but intermittent) renewable sources, will be
unfamiliar to many scientists, who nevertheless need a working knowledge
of them. This tutorial paper provides a largely self-contained conceptual
introduction for such persons. It begins by modelling a novel quantized
exchanger , impractical as a device, but useful for comprehending the
underlying thermophysics. It then reviews the one-dimensional steady-state
idealization which demonstrates that effectiveness of heat transfer
increases monotonically with (device length)/(device throughput). Next it
presents a two-dimensional steady-state idealization for plug flow and
from it derives a novel formula for effectiveness of transfer; this
formula is then shown to agree well with a finite-difference time-domain
(FDTD) solution of the two-dimensional idealization under Hagen-Poiseuille
flow. These results are consistent with a conclusion that effectiveness of
heat exchange can approach unity, but may involve unwelcome tradeoffs
amongst device cost, size, and throughput.