Abstract :
Efficiency of domestic ventilation waste heat
recovery systems (WHRS) depends not only on the amount
of waste heat recovered, but also on the energy involved in
running fans to drive air through the system. Computational
fluid dynamics (CFD) can be a powerful tool for
analysing WHRS losses (thus predicting fan energy usage),
but the computational effort involved can limit the value of
CFD as a practical design tool. This study presents a range
of assumptions and simplifications that can be applied to
reduce the computational effort associated with the CFD
analysis of a WHRS. The importance of experimental
validation to assess the effect of errors introduced by the
simplifying assumptions is discussed. In an example case,
application of the methods presented have allowed total
pressure losses (excluding the fixed losses through the heat
exchanger) to be reduced by over 50 % in comparison with
an initial prototype design, with proportional reduction in
fan energy usage. This highlights the value of sufficiently
simplified CFD analyses within a typical WHRS product
development cycle.
