International Appliance Manufacturing 2008 - (Page 32) an integrated approach to fan and motor design. A further advantage of PAX fans is reduced air turbulence before, during, and after contact with the fan. This reduces loading on the fan. Since axial fan speed increases with decreasing back pressure, a PAX fan naturally tends to run a bit faster than its baseline counterparts. This typically improves a PAX fan’s operating position on the speedtorque curve of the motor. Results - on Bench Evaporator fans are typically either 100mm or 110mm in diameter, with the majority being 100mm. A production tooled 100mm PAX fan tests favorably when compared to a sampling of three different 100mm fan designs currently in the market. A prototype 110mm PAX fan also shows improvements when compared to a production baseline 110mm fan. Due to the aforementioned importance that closely matching pressure/flow characteristics has on refrigerator performance, specific motor matches have been developed to allow the PAX fan with a family of A. O. Smith motors to properly replace the baseline evap systems. In all, there are four baseline systems reported here whose performance has been matched by a PAX fan/A. O. Smith motor combination, three using 100mm fans and one using a 110mm fan. The baseline systems are referred to as “Baseline 1-4.” Pictures of the fans corresponding to these baseline systems are shown in figures 4-7 below. These fans are representative of what is commonly found in evap systems today. Figure 3: C-frame efficiency curve A single 100mm PAX fan and one 110mm PAX fan are used on a variety of A. O. Smith motors to properly match performance of these baseline evap systems. These systems are referred to as “PAX/AO 1-4.” When tested on a wind tunnel flow chamber, 0.02” - 0.03” H2O of static pressure is a region commonly considered a simulation of in-unit performance for evap systems using a 100mm fan. 0.03” H2O is often chosen as the operating point with 50-60 cubic feet per minute (CFM) typically considered a desirable airflow range at that static pressure. 60-80 CFM at 0.03” H2O is typical for evap systems with 110mm fans. These are general guidelines since refrigeration systems are similar but unique. In cases where the baseline systems deviated from these guidelines, performance matches were based on test data, not the guidelines. Data from a wind tunnel in Figure 8 shows plots of pressure and power vs. airflow for “Baseline 1” and “PAX/AO 1”, both 100mm evap motor/fan systems. The PAX fan with A. O. Smith motor shows similar airflow to the baseline throughout the curve and is nearly identical around the operating region (0.03” static). Also, a considerable reduction in motor/fan power required is noted throughout the curve. Tests were run at 115 volts and results are corrected to standard temperature and pressure. Both motors have 3/8” lamination stack heights. Table 1 is a summary of discrete data taken from Figure 8. At the rated pressure and airflow the 32 International Appliance Manufacturing 2008
For optimal viewing of this digital publication, please enable JavaScript and then refresh the page. If you would like to try to load the digital publication without using Flash Player detection, please click here.