ACTIVITY $21-3-$Heating Elements

Power is consumed when an electric heating element produces heat. To calculate the amount of power required to heat air, apply the formula:

$kW=\frac{cfmTR}{3000}$

where

$kW=$ power required to heat air $($in kilowatts$)$

$cfm=$ cubic feet per minute air flow $($measured at $70F$ inlet air and $14$ psi $)$

$TR=$ temperature rise $($in $F)$

$3000=$ constant

Complete Heating Air Power Requirements$*$ by determining the power required to heat the air.

$\backslash$table$[[29.,$HEATING AIR POWER REQUIREMENTS$*],[,$Temperature Rise $(F)],[\backslash$table$[[$Rate$],[($in cfm$)]],50,100,150,200,250,300,350,400],[100,,,,,,,,],[200,,,,,,,,],[300,,,,,,,,],[400,,,,,,,,],[500,,,,,,,,],[600,,,,,,,,],[700,,,,,,,,],[800,,,,,,,,]]$

The power required to heat liquid in a tank depends on the amount of tank insulation. Uninsulated tanks require additional power due to heat loss. To calculate the amount of power required to heat water in a tank that is adequately insulated, apply the formula: