Building Design and Construction Handbook - Merritt - Ventech!

HEATING, VENTILATION, AND AIR CONDITIONING 13.69
TABLE 13.15d Second-Floor Office No. 2
Btu/hr
Heat gain through enclosures:
North wall, 103 � 0.25 � 15 386
North glass, 72 � 1.04 � 15 1,110
East wall, 132 � 0.25 � 15 495
Partition, 114 � 0.39 � 10 445
Door in partition, 18 � 0.46 � 10 83
Roof, 231 � 0.19 � 54 2,370
4,889
Occupants (sensible load), 5 � 255 1,275
Lights, 231 � 4 � 3.42 3,160
9,324
Fan hp 4% 373
Total internal sensible load 9,697
Fresh air (sensible load), 77 � 1.08 � 15 1,250
Total sensible load 10,947
Occupants (latent load), 5 � 255 1,275
Fresh air (latent load), 77 � 0.67(99 � 77) 1,140
Total latent load 2,415
Total load 13,362
Cooling and supply-air requirements for the building are summarized in Table
13.16.
13.21 REFRIGERATION CYCLES
Figure 13.29 shows the basic air-conditioning cycle of the direct-expansion type.
The compressor takes refrigerant gas at a relatively low pressure and compresses
it to a higher pressure. The hot gas is passed to a condenser where heat is removed
and the refrigerant liquefied. The liquid is then piped to the cooling coil of the airhandling
unit and allowed to expand to a lower pressure (suction pressure). The
liquid vaporizes or is boiled off by the relatively warm air passing over the coil.
TABLE 13.16 Cooling-Load Analysis for Building in Fig. 13.3 (p. 13.43)
Space Tons
Flow with ducted
fresh air, ft 3 /min
Flow without
ducted fresh air,
ft 3 /min
First-floor store 7.25 2842 3052
First-floor office 0.35 137 164
Second-floor office No. 1 3.50 1737 1887
Second-floor office No. 2 1.13 499 563
12.23 5215 5666