To use the spreadsheet simply input basic information about the house in question (i.e., house and pad dimensions), the number of tunnel fans, the theoretical tunnel air moving capacity of the fans at various static pressures (available from BESS Laboratory websitewww.bess.uiuc.edu), and the general condition of the house’s evaporative cooling pads (1 to 5 scale) and fans (1 to 4 scale). Using this information the spreadsheet ...calculates the increase in static pressure as the air moves through the pads, tunnel doors, into the cross-section of the house and along the length of the house to determine the total static pressure the tunnel fans are working agains. Once the total static pressure is calculated the air moving capacity of the tunnel fans are then estimated using the inputted fan performance information, taking into account their condition. The total air moving capacity of the tunnel fans is then divided by the cross-sectional area of the house to obtain an average tunnel air velocity.
In addition to estimating the average air speed and total static pressure the spreadsheet shows how each area of the house (i.e, pad, tunnel doors/curtain opening, etc.) contributes to the total pressure the tunnel fans are working against. The spreadsheet also allows the addition of new fans to an “existing” house to aid in determining how many additional fans would be required to obtain, for instance, an average air speed of 600 ft/min and illustrating how increasing pad area is beneficial when adding fans.