Minimum airflow reset of single duct VAV terminal boxes

2017

Sustainability

Self Cite

Abstract:The objective of this study was to propose a control method with a ventilation requirement of variable air volume (VAV) system in multi-zone. In order to control the VAV system inmulti-zone, it is essential to control the terminal unit installed in each zone. A VAV terminal unit with conventional control method using a fixed minimum air flow can cause indoor air quality (IAQ) issues depending on the variation in the number of occupants. This research proposes a control method with a ventilation requirement of the VAV terminal unit and AHU inmulti-zone. The integrated control method with an air flow increase model in the VAV terminal unit, AHU, and outdoor air intake rate increase model in the AHU was based on the indoor CO 2 concentration. The conventional and proposed control algorithms were compared through a TRNSYS simulation program. The proposed VAV terminal unit control method satisfies all the conditions of indoor temperature, IAQ, and stratification. An energy comparison with the conventional control method showed that the method satisfies not only the indoor thermal comfort, IAQ, and stratification issue, but also reduces the energy consumption.

Section: Proposed Control Methods Of a Vav Systemmentioning

confidence: 99%

Section: (3) Ventilation Modementioning

confidence: 99%

A Study on a Control Method with a Ventilation Requirement of a VAV System in Multi-Zone

Kim

2017

Sustainability

Self Cite

“…In addition, the relationship between the supply air volume and temperature that minimizes energy consumption was suggested through proper supply temperature, stratification and energy analysis according to the load, which can minimize energy consumption. 3) In the ASHRAE Standard 55, stratification that results in an air temperature at the head level that is higher than at the ankle level can cause thermal discomfort. 4) The difference between the room and supply air temperature should not exceed 8.4°C to avoid excessive temperature stratification.…”

Section: Introductionmentioning

confidence: 99%

“…2) Cho et al (2009) reported the relationship between the supply air temperature and minimum air flow. In addition, the relationship between the supply air volume and temperature that minimizes energy consumption was suggested through proper supply temperature, stratification and energy analysis according to the load, which can minimize energy consumption.…”

Section: Introductionmentioning

confidence: 99%

A Study on the Control Method Without Stratification of Single Duct VAV Terminal Units

Kim

Kang²,

Journal of Asian Architecture and Building Engineering

2015

Self Cite

The objective of this study was to propose a stratification control method for the minimum air flow of a variable air volume (VAV) terminal unit. The minimum air flow rate of the VAV terminal unit is the key factor affecting thermal comfort, indoor air quality (IAQ), stratification and energy consumption depending on the operating mode of the VAV system. Therefore, selecting the proper minimum air flow is very important. In this study, a building simulation was conducted to evaluate the indoor thermal comfort, stratification, IAQ and energy consumption according to the fixed minimum air flow rate of the VAV terminal units. In addition, an algorithm was proposed considering the stratification and variable minimum air flow rate depending on the indoor load. The results of the fixed minimum air flow rate simulation showed that the minimum air flow rate considering stratification satisfies all the conditions of indoor thermal comfort, IAQ and without stratification. The proposed method was found to be more effective than the existing control method. The energy comparison with the existing control method showed that the proposed method reduces the energy consumption.

“…Unfortunately, some engineers apply these values as a standard for every space, regardless of the thermal conditions 4) . Cho et al (2009) developed optimal control algorithms for single duct VAV terminal boxes. The terminal box can automatically identify the minimum heating airflow under actual working conditions with improved control algorithms.…”

Section: Introductionmentioning

confidence: 99%

Evaluation of the Impact of Minimum Airflow on the Energy Consumption of Single Duct VAV Terminal Boxes

Journal of Asian Architecture and Building Engineering

Liu³

2014

Self Cite

Terminal boxes are critical components of variable air volume (VAV) systems. The minimum airflow of terminal boxes is a key factor for comfort, indoor air quality (IAQ) and energy cost. If the minimum airflow is higher than needed, terminal boxes will have significantly more simultaneous heating and cooling, and airhandling units (AHUs) will consume more fan power. Buildings will have IAQ problems if the minimum airflow is less than required. A dynamic building simulation and field experiment were carried out to evaluate the impact of minimum airflow on the energy consumption of single duct VAV terminal boxes. A comparison of the simulation data with the existing constant setpoint revealed 20% annual energy savings in the improved minimum airflow setpoint. The experiment showed that the room air temperature can be maintained stably and the vertical difference in the room air temperature is lower than the comfort value when the improved minimum airflow setpoint is applied. Measurements of the CO 2 levels also revealed no indoor air quality problems.