| 1 |
Upper water distribution section and water
filter section |
| 2 |
Tube core assemblies (2 minimum-8 maximum) |
| 3 |
Lower water pan assembly (basin) |
| 4 |
Each unit contains an upper water distribution
section, a lower water pan assembly (basin), and mounting rails. Two eight core assemblies
may be selected per unit. The pump float valve, water filtration media, and water
distribution systems are furnished with the unit. A water bleed line, to control scaling
is factory provided to the overflow connection. External piping is minimal. The pump is
externally mounted. |
Selection of
cores
The number of cores selected is based on the quantity of
air to be cooled and the desired cooling capacity. Maximum cooling capacity is achieved
with a selection at minimum CFM per core. Nominal selection is 1 000 CFM per core.
Core selection example
| Required: |
Pre-cool 7000 CFM with one VARI-COOL unit |
|
|
| Trial selection: |
7000 CFM / 1000 CFM/core = 7 cores - select 7
cores |
|
|
| Trial selection: |
(7000 CFM) / (2000 CFM/core)= 3.5 cores-
select 4 cores |
|
|
| Selecting: |
For maximum cooling capacity and minimum
static pressure loss select a 7 core unit Model 7S For
minimum unit sizing select a 4 core unit Model 4S |
Selecting
The I/D™ System
I/D two and three stage systems are selected to achieve the
required supply air temperature to satisfy the system cooling load at the calculated
supply air quantity. The following is a step by-step process to determine the two stage
system supply air temperature and, if required, the third stage standby or booster
refrigeration capacity:
| Step#l - |
From the cooling load calculation determine
the required supply air temperature and quantity. |
| Step #2 - |
The l 977 ASHRAE Handbook of Fundamentals,
chapter 23, has the 1 O/o, 21/2%, and 5% suggested design dry-bulb and mean coincident
wet-bulb temperatures for most major cities in the United States. From this data, or other appropriate weather data, select a
design condition (DB & WB'F). |
| Step #3 - |
The recommended selection efficiency is6O%
for the indirect unit and 90% for the direct unit. The standard I/D package selection is as follows:
| I/D-2 S |
= |
2000 CFM |
| I/D-3 S |
= |
3000 CFM |
| I/D-4 S |
= |
4000 CFM |
| I/D-5 S |
= |
5000 CFM |
| I/D-6 S |
= |
6000 CFM |
| I/D-7 S |
= |
7000 CFM |
| I/D-8 S |
= |
8000 CFM |
Multiples of these units or paralleled
packages can be selected to achieve the total CFM required. |
|
