To identify the preferred rotation direction, a blower performance analysis is needed.
A blower is usually an enclosed multiblade rotor that compresses air to a higher discharge pressure. Blower is also known as fan, but, traditionally, blowers do not discharge air at low pressure as some fans do. Figure 1.6 – CENTRIFUGAL BLOWER
Dryers use centrifugal blower, where air is radially discharged from the impeller, (or fan wheel), so turns 90° from its inlet to its outlet (Figure 1.6).
Air enters the impeller at the blade inlet with an absolute velocity of v_1. As the fluid elements flow through the blade passage, they accelerate. Moreover, a guiding pressure is exerted on the fluid elements by the blades because of the rotation of the impeller. …show more content…
For a centrifugal blower of a specific type and size, at each impeller speed, there will be a set of different curves ∆p_t-V ̇,P-V ̇" and" η_t-V ̇, where P is the motor power consumption and η_t is total blower efficiency. The higher the speed, the greater V ̇,P "and" ∆p_t.
Figure 1.7 – VELOCITY TRIANGLES AT THE BLADE INLET AND OUTLET OF A BACKWARD CENTRIFUGAL BLOWER
Based on the rotation direction, centrifugal blowers can work in a backward mode or in a forward mode (Figure …show more content…
It is usually determined by the product of the duct velocity and the area of the duct connected to the blower inlet, according to the test standard Air Movement and Control Association (AMCA) Standard 210-85 and ASHRAE Standard 51-1985.
Blower volume flow rate is independent of air density ρ. However, blower total pressure is affected by air density. Therefore, the blower volume flow rate is normally rated at standard air conditions, i.e., dry air at an atmospheric pressure of 101,325 Pa abs, a temperature of 21.1°C, and a density 1.2 kg /m3.
Pressure
Blower total pressure ∆p_t, expressed in Pa, is the total pressure rise of a blower, i.e., the pressure difference between the total pressure at the blower outlet p_to and the total pressure at the blower inlet p_ti, both in Pa:
∆p_t=p_to-p_ti (1.5)
As shown in Figure 1.9, ∆p_t-V ̇ curve of a forward blower is flatter than that of the backward blower. Figure 1.9 – PRESSURE-VOLUME FLOW PERFORMANCE CURVES FOR CENTRIFUGAL BLOWER
Total
A blower is usually an enclosed multiblade rotor that compresses air to a higher discharge pressure. Blower is also known as fan, but, traditionally, blowers do not discharge air at low pressure as some fans do. Figure 1.6 – CENTRIFUGAL BLOWER
Dryers use centrifugal blower, where air is radially discharged from the impeller, (or fan wheel), so turns 90° from its inlet to its outlet (Figure 1.6).
Air enters the impeller at the blade inlet with an absolute velocity of v_1. As the fluid elements flow through the blade passage, they accelerate. Moreover, a guiding pressure is exerted on the fluid elements by the blades because of the rotation of the impeller. …show more content…
For a centrifugal blower of a specific type and size, at each impeller speed, there will be a set of different curves ∆p_t-V ̇,P-V ̇" and" η_t-V ̇, where P is the motor power consumption and η_t is total blower efficiency. The higher the speed, the greater V ̇,P "and" ∆p_t.
Figure 1.7 – VELOCITY TRIANGLES AT THE BLADE INLET AND OUTLET OF A BACKWARD CENTRIFUGAL BLOWER
Based on the rotation direction, centrifugal blowers can work in a backward mode or in a forward mode (Figure …show more content…
It is usually determined by the product of the duct velocity and the area of the duct connected to the blower inlet, according to the test standard Air Movement and Control Association (AMCA) Standard 210-85 and ASHRAE Standard 51-1985.
Blower volume flow rate is independent of air density ρ. However, blower total pressure is affected by air density. Therefore, the blower volume flow rate is normally rated at standard air conditions, i.e., dry air at an atmospheric pressure of 101,325 Pa abs, a temperature of 21.1°C, and a density 1.2 kg /m3.
Pressure
Blower total pressure ∆p_t, expressed in Pa, is the total pressure rise of a blower, i.e., the pressure difference between the total pressure at the blower outlet p_to and the total pressure at the blower inlet p_ti, both in Pa:
∆p_t=p_to-p_ti (1.5)
As shown in Figure 1.9, ∆p_t-V ̇ curve of a forward blower is flatter than that of the backward blower. Figure 1.9 – PRESSURE-VOLUME FLOW PERFORMANCE CURVES FOR CENTRIFUGAL BLOWER
Total