This section describes the most important energy efficiency opportunities for fans and blowers. Choose the right fan Important considerations when selecting a fan are (US DOE, 1989): Noise Rotational speed Air stream characteristics Temperature range Variations in operating conditions Space constraints and system layout Purchase costs, operating costs (determined by efficiency and maintenance), and operating …
Typically, once a fan system is designed and installed, the fan operates at a constant speed. There may be occasions when a speed change is desirable, i.e., when adding a new run of duct that requires an increase in air flow (volume) through the fan. There are also instances when the fan is oversized and …
The term “system resistance” is used when referring to the static pressure. The system resistance is the sum of static pressure losses in the system. The system resistance is a function of the configuration of ducts, pickups, elbows and the pressure drops across Fans and Blowers equipment-for example bagfilter or cyclone. The system resistance varies …
Fan Performance Evaluation and Efficient System Operation System Characteristics Read More »
Imagine a fan selected with great care to provide exactly the performance required in the specifications. Once installed, the air balancer reports that air performance is considerably lower than required. What went wrong? The answer is probably system effect. The system effect is the change in system performance that results from the interaction of system …
Most fans are sized to handle the largest expected peak design condition. Because normal operating conditions are often well below these design conditions, air-moving equipment is often oversized, operating below its most efficient point and creating several types of problems. Among these problems are high energy costs, high system pressures and flow noise, and, in …
Roof Exhaust Fans Figures below illustrate how roof exhausters are tested; AMCA refers to Fig#1 setup as “Type A: Free inlet, free outlet”. Fig # 2&3 illustrate roof exhaust fan installations having system effects. Fig # 3 illustrates the worst case, because the damper is located in a turbulent airstream. To improve on installations where …
In order to generate the fan performance data used in the analysis DOE(Department of Energy) applied the following procedure (the 3-ton baseline PSC motor for non-weatherized (non-condensing) gas furnaces is used as an example): STEP 1: Using the coefficients to generate for airflow (cfm) vs. pressure and watts/cfm vs. pressure curves at each airflow speed …
How to Determine the Fan Curves for Each Efficiency Level and Product Class Read More »