16.01.2013 Views

Handbook of air conditioning and refrigeration / Shan K

Handbook of air conditioning and refrigeration / Shan K

Handbook of air conditioning and refrigeration / Shan K

SHOW MORE
SHOW LESS

Create successful ePaper yourself

Turn your PDF publications into a flip-book with our unique Google optimized e-Paper software.

28.10 CHAPTER TWENTY-EIGHT<br />

changeover problems, <strong>and</strong> lower in operating cost than a two-pipe system. On the other h<strong>and</strong>, it has<br />

a higher initial cost; <strong>and</strong> if reverse return pipe is used, many pipes must be squeezed into the ceiling<br />

plenum. Four-pipe fan-coil systems are most widely used.<br />

Dedicated Ventilation System<br />

FIGURE 28.3 Four-pipe fan-coil unit system: (a) common coil; (b) separate coil.<br />

The dedicated ventilaton system in a four-pipe fan-coil system must provide minimum outdoor <strong>air</strong><br />

V˙<br />

p,<br />

in cfm (L/s), specified for occupants according to ASHRAE St<strong>and</strong>ard 62-1999, served by each<br />

fan coil. The estimated cooling capacity Qcpn, in Btu/h (W), provided by the minimum outdoor <strong>air</strong><br />

to <strong>of</strong>fset the space cooling load can be calculated as<br />

Q cpn � 60V˙ p� ps(h r � h ps)<br />

(28.4)

Hooray! Your file is uploaded and ready to be published.

Saved successfully!

Ooh no, something went wrong!