Chapter hvac engineering Fundamentals: Part 1 Introduction

Equipment: Part 2
355
Figure 10.29
Psychrometric chart for Fig. 10.28, without heat recovery.
Figure 10.30
Psychrometric chart for Fig. 10.28, with heat recovery.
Equipment: Part 2
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356
Chapter Ten
Figure 10.31
Heat-pipe energy recovery.
although some leakage and cross-contamination may occur. This may
be minimized by use of a
purge
section between the two halves and
by making the clean airstream ‘‘positive’’ with respect to the exhaust
airstream. Heat transfer may be sensible only or sensible plus latent,
depending on the type of heat transfer medium selected. Even the
sensible-heat-only design may involve some latent heat transfer if
there is a buildup of hygroscopic dust on the medium. Capacity may
be controlled by varying the rotational speed. This system requires
that exhaust and supply airstreams be contiguous at the exchanger,
which may pose problems. Remember that outside air intake and ex-
haust discharge louvers must have sufficient separation to avoid cross-
contamination.