Control Strategies in Multi-Zone Air Conditioning Systems

Abstract

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)‎.

Precise Explicit Approximations of the Colebrook-White Equation for Engineering Systems

“…∞, the curvature (9) goes to zero. Therefore, the root corresponds to the maximum curvature (8). In the range (5), the curvature monotonically decreases: j max = 0.080752349164383260460 j 0.…”

“…Due to increasing energy efficiency, modern systems are highly automated. A significant amount of research is devoted to the appropriate air distributors [3][4][5][6] or optimal control strategies [7][8][9]. However, the simulation of hydraulic and aerodynamic conditions [10] is no less important.…”

Energy Recovery in Air Conditioning Systems: Comprehensive Review, Classifications, Critical Analysis, and Potential Recommendations

“…The main reason for this was due to the HVAC systems in those buildings [12,13]. HVAC accounts for almost 50 to 82% of the energy, of which 40% of the world's overall final energy is spent in buildings [14]. While in non-industrial buildings, HVAC is responsible for around 18-35% of the total energy consumption [15], in commercial buildings HVAC accounts for approximately 30% of energy consumption [16,17].…”

Improving Building Energy Performance Using Dual VAV Configuration Integrated with Dedicated Outdoor Air System

“…As such, it is crucial to design these systems in a safe and efficient manner while minimizing energy consumption. In the last decade, a significant amount of research has been carried out to achieve better performance and improve the efficiency of such systems [3]. Previously, heating, ventilation, and air conditioning (HVAC) systems were designed to control the temperature with constant air volume (CAV) which did not satisfy the requirements of every zone in a building.…”

“…Previously, heating, ventilation, and air conditioning (HVAC) systems were designed to control the temperature with constant air volume (CAV) which did not satisfy the requirements of every zone in a building. Variable air volume (VAV) was later introduced to the systems as a novel solution to control the temperatures in multiple zones [3]. Consequently, Variable air volume (VAV) air conditioning systems have proven to be more economical than other alternatives due to their ability to adjust in response to load variations.…”