7.5-i APPENDIX 7.5. BLOWER FAN CURVES TABLE OF CONTENTS 7.5.1 INTRODUCTION ................................................... 7.5-1 7.5.2 STATIC PRESSURE ................................................. 7.5-4 7.5.3 SHAFT POWER ..................................................... 7.5-4 LIST OF TABLES Table 7.5.1.1 Models Used For Virtual Furnace Blowers ........................... 7.5-1 Table 7.5.2.1 Coefficients to Calculate Pressure for Different Blower Sizes ............... 7.5-4 Table 7.5.3.1 Coefficients to Calculate Shaft Power for Different Blower Sizes ............ 7.5-5 LIST OF FIGURES Figure 7.5.1.1 Blower Fan Curves for Lau #DD9-8A ............................... 7.5-2 Figure 7.5.1.2 Blower Fan Curves for Lau #DD10-8A .............................. 7.5-2 Figure 7.5.1.3 Blower Fan Curves for Lau #DD10-10A ............................. 7.5-3 Figure 7.5.1.4 Blower Fan Curves for Lau #DD11-10AT ............................ 7.5-37.5-1 APPENDIX 7.5. BLOWER FAN CURVES 7.5.1 INTRODUCTION Blower manufacturers provide blower fan curves for both pressure and shaft power as functions of airflow. The Department chose four blowers from Lau Industries, a manufacturer that supplies blowers to the furnace industry, to match the four virtual model furnace blowers. The models DOE used for the different virtual furnace blowers are listed in Table 7.5.1.1. Table 7.5.1.1 Models Used For Virtual Furnace Blowers Airflow Capacity Blower Size Lau Industries Model 800 cfm (2 ton) 9 X 8 DD9-8A 1200 cfm (3 ton) 10 X 8 DD10-8A 1600 cfm (4 ton) 10 X 10 DD10-10A 2000 cfm (5 ton) 11 X 10 DD11-10AT Pressure and shaft power curves for these blowers are available in fan selection software from Lau Industries. 1 Figures 7.5.1.1 - 7.5.1.4 show the curves for these blowers. The Department fit polynomial equations of air flow to the static pressure and shaft power curves of these blowers. Knowing these equations permits the Department to calculate static pressure and shaft power at any airflow rate.7.5-2 0 0.5 1 1.5

0 1000 2000 3000 4000 5000 Q, Airflow (CFM)P, Static Pressure (in. w.g)

0 1 2 3H, Shaft Power (hp) P H

Figure 7.5.1.1 Blower Fan Curves for Lau #DD9-8A

0 0.5 1 1.5

0 1000 2000 3000 4000 5000 Q, Airflow (CFM)P, Static Pressure (in. w.g)

0 1 2 3H, Shaft Power (hp) P H

Figure 7.5.1.2 Blower Fan Curves for Lau #DD10-8A7.5-3 0 0.5 1 1.5

0 1000 2000 3000 4000 5000 Q, Airflow (CFM)P, Static Pressure (in. w.g)

0 1 2 3H, Shaft Power (hp) P H

Figure 7.5.1.3 Blower Fan Curves for Lau #DD10-10A

0 0.5 1 1.5

0 1000 2000 3000 4000 5000 Q, Airflow (CFM)P, Static Pressure (in. w.g)

0 1 2 3H, Shaft Power (hp) P H

Figure 7.5.1.4 Blower Fan Curves for Lau #DD11-10AT7.5-4

7.5.2 STATIC PRESSURE The coefficients for the polynomial equation for static pressure rise across the blower as a function of airflow are shown in Table 7.5.2.1. The speeds at which they were tested are included in the table as well. The coefficients vary depending on blower size. The equation used to fit static pressure is: P(Q) = c0 + c1 × ( Q/1000) + c2 × (Q/1000)^2 + c3 × (Q/1000)^3 + c4 × (Q/1000)^4 where: Q = airflow (cfm), P = static pressure (in.w.g.), and c0-c4 = coefficients. Table 7.5.2.1 Coefficients to Calculate Pressure for Different Blower Sizes Blower Size Speed c0 c1 c2 c3 c4 11 × 10* 1055 2.816408 -14.45755 50.06729 -79.1925 57.93131 10 × 10 1020 0.571842 0.952433 -0.40526 0.027687 0 10 × 8 1044 0.05092 2.51260 -1.96989 0.64310 -0.08909 9 × 8 1084 1.25829 -1.09850 1.17555 -0.56167 0.06693 * For this blower size, the coefficient Q was divided by 4000, not 1000 as shown in the equation. 7.5.3 SHAFT POWER Shaft power is the mechanical power input to the blower. It is the power required to rotate the blower wheel at the tested speed under the tested static pressure and airflow conditions. The Department determined shaft power using a second-order polynomial equation. The coefficients vary depending on blower size. Table 7.5.3.1 shows the different blower sizes and their corresponding coefficients that DOE used to determine shaft power. H(Q) = h0+ h 1 × ( Q/1000) + h2× (Q/1000) 2 where: Q = airflow (cfm), H = shaft power (hp), and h 0 , h 1, h2 = coefficients.7.5-5

Table 7.5.3.1 Coefficients to Calculate Shaft Power for Different Blower Sizes Blower size Speed h0 h1 h2 11 × 10 1055 0.02424 0.209691 0.073447 10 × 10 1020 0.052032 0.195255 0.072613 10 × 8 1044 0.012244 0.187546 0.086849 9 × 8 1084 0.044483 0.100756 0.1088437.5-6 REFERENCES 1. Lau Industries, Whirl Wind IV, Version 4.0, Fan Application Software . 2000. http://www.lau-ind.com/whirlwind.htm