PR2017

CFD simulations were conducted to assess turbulent forced convection heat transfer and pressure drop through a ventilation channel using a stack of panels with different ridge configurations containing Phase Change Material (PCM). First, an experimental rig using an existing commercial panel provided by a PCM manufacturer validates the model simulated in Ansys FLUENT. After that, 3D simulations with different designs were tested until the optimum configuration in terms of heat transfer and pressure drop was achieved.

The aim was to study how the cooling jet from the ceiling, with individual control over the airflow, is perceived and how it affects the thermal comfort in warm office environment. 32 undergraduate university students participated in the experiment. Two thermal conditions were tested: (1) no cooling jet and (2) adjustable cooling jet from the ceiling. Subjects were able to use a controller with seven different settings to adjust the airflow coming from the nozzles so that the target velocity varied from 0.3 m/s to 1.5 m/s. The cooling jet was directed into the upper body.

For testing of general ventilation filters, a completely new standard is now available and is going to replace EN 779 (2012) since the parts 1 to 4 of ISO 16890 (2017) have been adopted in August 2016 and published in 2017 at both international and European levels. With this new standard, the fractional efficiency of the new and the conditioned (24 hours to isopropanol vapour) filters is measured between 0.3 and 10 μm.

Shopping centres currently design has included a small portion of automated windows sized for smoke ventilation. Their presence is mandatory for fire regulation and they are usually operated just in case of fire. Nevertheless, these buildings can potentially take advantage of those openable windows to exploit the potential of natural ventilation to guarantee the minimum air change rate required by IAQ standards and for ventilative cooling purpose reducing cooling and electrical consumption.

Wind pressure and thermal forces are driving forces for pressure difference on the building envelope. In European and German standards infiltration is calculated using wind speed, temperature difference and wind pressure coefficients result-ing from upstream and downstream flow on the building envelope. This long term measurements shall present measured pressure differences on the building envelope in comparison to those calculations.

In high density occupation rooms, it is necessary to control indoor air quality (IAQ) combined with other comfort parameters. An adequate IAQ in classrooms enhances children learning and academic results are improved.

Renewable energy sources for heating and cooling buildings usually have temperatures close to room temperature and therefore a limited convertibility potential, i.e. they are of low value. To exploit low-valued energy sources Low Temperature Heating and High Temperature Cooling (LTH-HTC) systems must be developed.

Displacement ventilation (DV) is an alternative to conventional mixing ventilation in various types of rooms. DV is superior to mixing ventilation when it comes to removing contaminants and surplus heat in a room if designed and applied correctly. In the design process of a space with DV it is necessary to have design methods and simulation tools that can predict the vertical contaminant stratification that arise.

In 2008 the State of California adopted new building codes that required the use of mechanical ventilation systems in homes that meet the requirements of ASHRAE Standard 62.2. The standard requires both a dwelling unit mechanical ventilation system and exhaust fans in kitchens and bathrooms. A field study was undertaken to evaluate the IAQ and ventilation performance of homes built to these requirements. For ventilation system performance, the airflows of all mechanical ventilation systems were measured and their use was monitored for a one-week period.

A key aspect of achieving acceptable indoor air quality is source control. Cooking has been recognized as a significant source of pollutants for health impacts (e.g., PM2.5 and NO2) as well as moisture and odour. A common method of controlling this pollutant source is by using a range (or cooker) hood that vents to outside. However, field and laboratory experiments have shown highly variable performance for these devices. We use the capture efficiency metric (the fraction of the pollutants that are exhausted to outside at steady state) to characterize the range hood performance.