Question

A ten story office building has a floor plate of 200 x 175 Story height: 12 ft. Use a circulation factor of 15 % Ceiling height- 9 1t Assume 350 ft iton a.) Size the chiller b.) Size the Cooling Tower c.) Size the AHU's on each floor (tns) e) Size the pump for the condenser water flow (assum

Answer 1

Ans a) Floor plate area = 200 x 175

= 35000 ft²

Given that per ft² required 1 ton, hence 35000 ft² require : 35000/350 ton

= 10 ton per floor

For 10 story , chiller ton = 10 x 10

= 100 ton

Ans b) Chiller ton = GPM x $\Delta T$ /24..........(1)

Cooling tower ton = GPM x $\Delta T$/30...........(2)

From eqn 1 ,

GPM x $\Delta T$ =24 x 10

Cooling tower ton = 24 x 10 /30

= 8 ton /floor

For 10 story , chiller ton = 8 x 10

= 80 ton

Ans c) Total volume of single story = 200 x 175 x 12

= 420000 cfm

Assume one AHU of 60000 cfm

Number of AHU required = 420000/60000

= 7 units

Ans d) Assume total dynamic head as  60 ft and flow as 4 gallon/min

Pump power required = $\rho$gQh  

=1000 x 9.81 x 18.75 x 0.000252

= 463.52 W