99/03958 Variable air volume ventilation control strategies analysed in six climate zones

1999 ◽  
Vol 40 (6) ◽  
pp. 415
Energies ◽  
2020 ◽  
Vol 13 (18) ◽  
pp. 4947
Author(s):  
Nina Szczepanik-Scislo ◽  
Jacek Schnotale

This study aimed to develop a new concept for an air terminal device for a VAV (variable air volume) ventilation system that would improve overall ventilation efficiency under a varying air supply volume. In VAV systems, air volume is modified according to the thermal load in each ventilated zone. However, lowering the airflow may cause a lack of proper air distribution and lead to the degradation of hygienic conditions. To combat this phenomenon, an air terminal device with an adapting geometry to stabilize the air throw, such that it remains constant despite the changing air volume supplied through the ventilation system, was designed and studied. Simulations that were performed using the RNG k–ε model in the ANSYS Fluent application were later validated on a laboratory stand. The results of the study show that, when using the newly proposed terminal device with an adaptive geometry, it is possible to stabilize the air throw. The thermal comfort parameters such as the PMV (predicted mean vote) and PPD (predicted percentage of dissatisfied) proved that thermal comfort was maintained in a person-occupied area regardless of changing airflow though the ventilation system.


Energies ◽  
2019 ◽  
Vol 12 (3) ◽  
pp. 347 ◽  
Author(s):  
Behzad Rismanchi ◽  
Juan Zambrano ◽  
Bryan Saxby ◽  
Ross Tuck ◽  
Mark Stenning

In a commercial building, a significant amount of energy is used by the ventilation systems to condition the air for the ‎indoor environments to satisfy the required quantity (temperature ‎and humidity) and quality (amount of fresh air). For many years, Variable Air Volume ‎‎(VAV) systems have been considered as the most efficient solutions by balancing the airflow volume based on the demand making them energy efficient when compared with the traditional Constant Air Volume (CAV) systems. However, the setpoints in VAV systems are ‎often misread by the sensors due to stratification and formation of pollutant pockets and ‎responding to design levels that overestimate the real-time demand conditions, which result in ‎waste of energy, thermal discomfort and unhealthy air. In general, VAV devices are expensive, complicated and prone to failures and ‎they are used only in medium and large projects. More recently, new technologies have evolved to solve this issue. In one of the new solutions, VAV motors terminals are replaced with flaps which are simpler and less expensive thus, they can be implemented ‎in a wider range of projects. In systems, balancing and supplying the optimal airflow ‎to reduce the energy consumption while delivering ideal thermal and Indoor Air Quality (IAQ) levels are the ‎main challenges. In this paper, a comparison of the recent technologies with traditional VAV systems is presented to be used as a guild line for researchers and designers in the field of Heating Ventilation Air Conditioning (HVAC)‎.


Author(s):  
Froylan E. Sifuentes ◽  
Taylor Keep

Increasing penetration of intermittent renewable electricity into the grid, coupled with development of new communication and control strategies, is creating challenges and opportunities for demand response (DR) to balance the grid. This paper presents a model characterization of a controllable buildings Variable Air Volume HVAC (VAV HVAC) system capable of implementing control strategies that provide flexibility to the grid. A Model Predictive Controller (MPC) capable of reliably varying the modeled power by ±20%, or up to ±2 GW on a national scale, every five minutes without compromising occupants comfort was built. A climate analysis was performed in order to assess the availability of controllable resources in sixteen cities. It is found that this control strategy could be implemented up to 99% of the time in the hottest regions, but as low as 10% of the time in the coldest.


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