Abstract
The performance of three different confluent jets ventilation (CJV) supply devices was evaluated in a classroom environment concerning thermal comfort, indoor air quality (IAQ) and energy efficiency. The CJV supply devices have the acronyms: high-momentum confluent jets (HMCJ), low-momentum confluent jets (LMCJ) and low-momentum confluent jets modified by varying airflow direction (LMCJ-M). A mixing ventilation (MV) slot jet (SJ) supply device was used as a benchmark. Comparisons were made with identical set-up conditions in five cases with different supply temperatures (TS) (16–18 °C), airflow rates (2.2–6.3 ACH) and heat loads (17–47 W/m2). Performances were evaluated based on DR (draft rating), PMV (predicted mean vote), ACE (air change effectiveness) and heat removal effectiveness (HRE). The results show that CJV had higher HRE and IAQ than MV and LMCJ/LMCJ-M had higher ACE than HMCJ. The main effects of lower Ts were higher velocities, DR (HMCJ particularly) and HRE in the occupied zone as well as lower temperatures and PMV-values. HMCJ and LMCJ produce MV conditions at lower airflow rates (<4.2 ACH) and non-uniform conditions at higher airflow rates. LMCJ-M had 7% higher HRE than the other CJV supply devices and produced non-uniform conditions at lower airflow rates (<3.3 ACH). The non-uniform conditions resulted in LMCJ-M having the highest energy efficiency of all devices.
Highlights
Heating, ventilation, and air conditioning (HVAC) systems account for about 50% of the total building energy use and more than 10% of total national energy use [1]
One ofreferred the CJ supply devices has nozzles with 28 mm diameter, resulting in rates low jet velocity, to as low momentum confluent jets in (LMCJ), and the resulting in low jet exit velocity, referred to as low momentum confluent jets (LMCJ), and the other supply device has nozzles with 5 mm in diameter and about six times higher jet exit velocity, called other supply device has nozzles with 5 mm in diameter and about six times higher jet exit velocity, high momentum confluent jets (HMCJ)
The results show that if different CJ supply devices are mounted in the same position and use the same airflow and supply temperature, the configuration of the nozzles will have a great impact on the velocities in the occupied zone, which results in differing energy efficiency, air quality and thermal comfort
Summary
Ventilation, and air conditioning (HVAC) systems account for about 50% of the total building energy use and more than 10% of total national energy use [1]. Lowering airflow rates naturally implies low energy use and is less costly. Low airflow rates per person (L/(s·p)) of supply air in public buildings are connected to several issues regarding health [2,3,4], cognitive abilities [4,5,6], academic performance [5,7,8,9], work and economic productivity [3,10,11]. Recent studies on the implementation of VAV in office buildings, shows that VAV has a great potential to improve the indoor air quality (IAQ) and occupant health [13], and greatly reduce the HVAC energy use [13,14], reducing building operational costs [14,15,16]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
