pressure drop

The risen awareness of improved indoor air quality has resulted in an increased energy demand for HVAC systems due to higher air exchange rates and the additional operation of air purifiers. Therefore, the need for energy-efficient methods to improve indoor air quality has grown. In this experimental study, we develop an innovative wet scrubber concept to remove solid particles from the airflow. In contrast to conventional wet scrubbers, this concept uses a perforated plate and the hydrostatic pressure to feed water droplets into the air stream.

Building airtightness requirements are becoming more and more common in Europe (Leprince, Carrié, & Kapsalaki, 2017). However, airtight buildings require an efficient ventilation system to ensure good indoor air quality. In France, the inspection of ventilation system (Jobert, 2012) has revealed many noncompliance. They are mainly due to bad conception, poor implementation, and lack of maintenance. This often leads to reduced ventilation flowrates and poor indoor air quality. Leaky ductwork is one of the reasons for this noncompliance.

The real performances of ventilation systems on site remains a challenge in practice. One of the most common reasons for complaints by the building occupants is the acoustic discomfort. Mechanical ventilation often produces too high levels of noise, mainly coming from the fans. 

Although several good practice recommendations are theoretically known to limit the noise generation by mechanical ventilation systems, the acoustical performance of real ventilation systems on site seems uncontrolled and unexpected.  

Cyclone purifier has been conventionally used for separating particles from exhaustion. This paper, however, tried to develop a cyclone purifier for fresh air treatment in ventilation. Simulations were carried out based on continuity equation, momentum equation, RNG k-epsilon turbulent flow equation and Discrete Phase Model; the discrete griddings were both structural and non-structural; the software used was FLUENT. The separation efficiencies, pressure drops and the flow patterns of air in the cyclone purifier were simulated.

When planning ventilation systems for energy efficient housing, an appropriate design of the overflow elements between rooms is important as it influences ventilation losses, indoor air quality and sound attenuation between rooms. Based on calculation results of the natural in- or exfiltration rates through the building envelope as a function of the overflow element’s flow resistance, this work proposes a maximal pressure drop of 2-3Pa for overflow elements in energy efficient buildings.

When conducting airtightness tests of buildings, you must ensure that all building parts to be measured have air connection, so that the test object can be considered as one single zone. This also applies to large buildings like office buildings, schools, old people homes, indoor pools, etc. with several floors and rambling floor plans. Openings that are too small for a constant air flow from the leakages to the measuring device can prevent an even pressure distribution.

The aim of that study was to evaluate the effect of compression on pressure drop in flexible, spiral wire helix core ducts used in residential and light commercial applications. Tests on ducts of 6, 8, 10 in. nominal diameters were conduted under different compression configurations following ANSI/ASHRAE standard 120-1999. That study suggests potential improvements to that standard and gives new data for duct design.

New equations derived from the recent ASHRAE-sponsored research project RP-1026 will enable HVAC system designers to better predict aero-acoustic performance of sheet metal plenums. This paper deals primarily with the aerodynamic performance of flow-through plenums and presents new
total pressure drop equations for some of the most common plenum configurations. Comparisons are made between these equations, computational fluid dynamics (CFD) analyses, and hand-calculation methods. The practical uses of plenums are discussed along with prescriptive rules of thumb to help

A model for air flow inside ducts with leakages has been established from the equations governing the variation of total pressure and velocity along the duct. It was found that duct performance could be expressed as a function of two dimensionless constants, allowing the calculation of the required total pressure and velocity in the duct.

Pressure loss coefficients were measured for several flat oval tee and lateral fittings. The paper gives measurement results and pressure loss curves.