STULZ, Mirus, ebm-papst to host webinar on harmonic mitigation in data centres

FREDERICK, Maryland, 26 September 2021: STULZ, Mirus International and ebm-papst will be conducting part 2 of a e-discussion on harmonic mitigation in data centres, STULZ said through a Press release. The webinar is on September 28, the company added.

To improve energy efficiencies in today’s modern custom air handlers, highly efficient electronically commutated (EC) fans are often incorporated for air movement, STULZ said. This is because the fan systems can improve efficiencies over conventional AC motors equipped with variable frequency drives (VFDs) by 30% or more, it said. An EC fan incorporates a brushless DC permanent magnet motor (BLDC) controlled by an integrated rectifier, inverter and smart electronics.

BLDC motors, with efficiencies greater than 90%, provide a more effective ventilation system, so that ‘free cooling’ becomes more easily achievable, which contributes to the energy savings potential, it said. Also, air distribution can be improved with multiple fan arrays allowing upstream or downstream components, such as filters or heat exchangers, to receive a more even airflow, thereby improving air filtering and heat transfer efficiency, it added.

In striving towards reliable and efficient systems, one significant factor sometimes overlooked is electrical harmonic distortion, STULZ said. One of the few things common with AC/VSD and EC fan systems is that they are both harmonic generating, non-linear loads, it said.

Without proper harmonic mitigation, non-linear loads can distort the AC power distribution and possibly expose a mission-critical facility to electrical issues, such as overheating distribution equipment and failure of sensitive equipment connected to the same electrical bus, it added.

The speakers include Dave Meadows, Director of Technology, STULZ USA; Tony Hoevenaars, President and CEO, Mirus International; and Joe Landrette, Director, VAC & Data Centers and Digital Solutions, ebm-papst. According to STULZ, the webinar, scheduled for a 2pm (Eastern Time, US and Canada) start, will be useful to electrical engineers, mechanical engineers and end-users.

ASHRAE releases core recommendations for reducing airborne infectious aerosol exposure

ATLANTA, Georgia, 14 January 2021: The ASHRAE Epidemic Task Force has released new guidance to address control of airborne infectious aerosol exposure and recommendations for communities of faith buildings, ASHRAE said through a Press release.

An infectious aerosol is a suspension in air of fine particles or droplets containing pathogens, such as the SARS-CoV-2 virus, which can cause infections when inhaled, ASHRAE said. They can be produced by breathing, talking, sneezing and other as well as by flushing toilets and by certain medical and dental procedures, it added.

ASHRAE’s Core Recommendations for Reducing Airborne Infectious Aerosol Exposure concisely summarize the main points found in the detailed guidance documents produced by the ASHRAE Epidemic Task Force, it said. They are based on the concept that ventilation, filtration and air cleaners can be combined flexibly to achieve exposure reduction goals, subject to constraints that may include comfort, energy use and costs, it added.

“This guidance outlines a clear approach for lessening the risk of infectious aerosol exposure for building occupants that can be applied in a wide range of applications, from homes to offices, to mobile environments, such as vehicles and ships,” said William Bahnfleth, Chair, ASHRAE Epidemic Task Force. “ASHRAE’s Core Recommendations are based on an equivalent clean air supply approach that allows the effects of filters, air cleaners, and other removal mechanisms to be added together to achieve an exposure reduction target.”

 According to ASHRAE, specific recommendations include the following:

• Public health guidance
  • Follow all regulatory and statutory requirements and recommendations.
• Ventilation, filtration, air cleaning 
  • Outdoor airflow rates guidance for ventilation, as specified by applicable codes and standards.
  • Recommendations on filters and air cleaners that achieve MERV 13 or better levels of performance.
  • The use of air cleaners.
  • Control options that provide desired exposure reduction while minimizing associated energy penalties.
  • Air distribution.
  • Promote the mixing of space air.
• HVAC system operation
  • Maintain temperature and humidity design set points.
  • Maintain equivalent clean air supply required for design occupancy.
  • Operate systems for a time required to achieve three air changes of equivalent clean air supply.
  • Limit re-entry of contaminated air.
• System commissioning
  • Verify that HVAC systems are functioning as designed.

 According to ASHRAE, the task force’s Communities of Faith Buildings guidance offers recommendations on conducting worship services under epidemic conditions. 

Rick Karg, ASHRAE Epidemic Task Force member, said: “The intent of the Communities of Faith guidance is to offer those who operate and care for buildings used for worship a plan for implementing short- and long-term HVAC strategies to reduce the possibilities of transmission of the SARS-CoV2-2 virus. The document also helps communities move toward a new ‘normal’ operation after this public health emergency nears an end.”

According to ASHRAE, recommendations for Communities of Faith include the following:

• Identify HVAC system characteristics. Compile and review operation and maintenance manuals and schedules.
• Verify HVAC systems are well maintained and operating as intended. For maintenance, follow the requirements of ASHRAE Standard 180 – 2018, Standard Practice for the Inspection and Maintenance of Commercial HVAC Systems.
  • Consider PPE when maintaining HVAC systems, including filters, coils and drain pans.
• Operate HVAC systems, if present, with system fan set to run continuously when building is occupied for services or cleaning.
• Operate the system for a time required to achieve three equivalent air changes of outdoor air (effect of outdoor air, filtration and air cleaners) before the first daily occupancy and between occupied periods, if appropriate. Three equivalent air changes can be calculated using ASHRAE’s Building Readiness Guide.

 To view the complete ASHRAE Core Recommendations For Reducing Airborne Infectious Aerosol Exposure and Communities of Faith Building guidance, ASHRAE suggested visiting ashrae.org/COVID-19.