Fs. Neto et Rm. Cotta, DYNAMIC ANALYSIS OF DOUBLE-PIPE HEAT-EXCHANGERS SUBJECTED TO PERIODICINLET TEMPERATURE DISTURBANCES, Warme- und Stoffubertragung, 28(8), 1993, pp. 497-503
A mixed lumped-differential formulation is employed to model the trans
ient energy equations for fully developed laminar-laminar or laminar-t
urbulent flow situations in concurrent or countercurrent double-pipe h
eat exchangers. The temperature distribution in the outer annular chan
nel is radially lumped, providing a more general boundary condition fo
r the inner channel differential energy equation, coupled through the
interface condition. The case of periodically varying inlet temperatur
es is more closely considered, and the dynamic response of the exchang
er is established in terms of the governing dimensionless parameters,
such as heat capacity flow rate ratio, dimensionless inlet temperature
oscillation frequency, and relative wall thermal resistence. The idea
s in the generalized integral transform technique are extended to yiel
d analytical solutions to the related periodic problem defined in the
complex domain, and offer highly accurate numerical results for quanti
ties of practical interest, such as fluids bulk temperatures.