Date: 2021-08-16 20:03:54
AMCA Asia Update
Note: This article appears in the 2020 edition of AMCA inmotion magazine.
By MDM SL GOH
On May 29, 2020, China published an update of mandatory national standard GB 19761, Minimum Allowable Values of Energy Efficiency and Energy Efficiency Grades for Fan, which will take effect June 1, 2021. Compared with the current (2009) version of the standard, GB 19761-2020 reduces some target efficiencies.
Under the standard, fan type, pressure coefficient, and speed are considered for centrifugal fans, while fan type and hub ratio are considered for axial fans. Based on peak efficiency, impeller efficiency for centrifugal and axial fans, and overall (combination of fan and drive) efficiency for forward-curved fans with external rotors, fan efficiency is classified into three grades in the updated standard: Grade 1, Grade 2, and Grade 3, of which Grade 3 represents the minimum allowable values for fan energy efficiency. Additionally, the metric for evaluating energy conservation for Grade 2 fans in the 2009 version has been removed.
Perhaps the most significant change concerns centrifugal fans. The pressure-coefficient ranges in tables 1 (0.95 to 1.55) and 2 (0.25 to 0.95) for general-purpose centrifugal fans and Table 4 (1.0 to greater than 1.4) for forward-curved centrifugal fans with external rotors were adjusted. Additionally, for some centrifugal-fan types, the deduction of a certain percentage from the target efficiency in Table 1 or Table 2 will be allowed. For double-inlet centrifugal fans and centrifugal fans for HVAC, the deduction will be 1 percent for grades 1 and 2 and 3 percent for Grade 3. The standard also defines fan inlet boxes’ effect on energy performance. The deduction from the target efficiency for centrifugal fans with inlet boxes in tables 1 and 2 will be 4 percentage points for all grades.
There also will be some special provisions for axial fans. For example, for axial fans with inlet boxes, a 3-percentage-point deduction from the target efficiency in Table 3 will be allowed for each grade. Additionally:
- In recognition of the impact of outlet diffusers on axial-fan efficiency, all axial fans with outlet diffusers will be required to meet the requirements in the fan-size-greater-than-or-equal-to-10 and 0.55-to-0.75 hub-ratio columns in Table 3. The target efficiency for axial fans without outlet diffusers in Table 3, on the other hand, will be 2 percentage points higher.
- For dynamic-pitch-angle-adjustable axial fans without inlet boxes and diffusers, the limitation on fan efficiency for grades 1, 2, and 3 will be 89.5 percent, 87 percent, and 82 percent, respectively.
- The target efficiency for reversible axial fans will be allowed to be 8 percentage points lower than the corresponding value in Table 3.
It should be noted that the 2009 version of the standard defines term-of-service range as the operation range in which fan efficiency is no less than 90 percent of peak efficiency, or the performance range specified in the fan catalog. In the 2020 version of the standard, the term has been replaced with “stable operation range.”
Standard GB 19761-2020 can be purchased in English and Chinese here.
Mdm SL Goh is executive director of Asia AMCA.