Restricted accessResearch articleFirst published online 2020-2
Mathematical and experimental analysis of the thermal effectiveness of an oscillating jet with side-to-side swing louvers in a cassette split type air conditioner
The impact of air supply control strategies (louvers movement) on indoor thermal environment were evaluated in this study. The temperature uniformity was evaluated by: (i) the air distribution performance index (ADPI) to determine the air diffusion performance in heating mode; (ii) the air draught rate (DR%) on the face to determine the local discomfort due to cold draught; (iii) the mathematically determined vertical temperature stratification in a room with Beta distributions. A comparison of the conventional type with three different oscillating type airflows (louvers swing angle ±20°, ±40° and ±60°) were experimentally analysed to determine appropriate air supply control strategies. The results indicated that Beta distributions could capture the overall trend of the oscillating airflow, to establish the acceptable thermal uniformity and higher thermal effectiveness. The oscillating airflow as generated by the side-to-side swing type delivery louvers mounted inside a cassette split type air conditioner could shorten heating time by 20% to attain room temperature from 9°C. The data reveal that oscillating airflow can provide a better thermal sensation to feeling warm in the heating mode at both ankle and neck level. The ADPI is approximately 85% in the occupied zone. The actual draught rates on the face ranged 0–35%.
FarrowATaylorHGoldingJ.Time spent in the home by different family members. Environ Technol1997;
18: 605–613.
2.
SilvaMAWolterbeekHTAlmeidaSM.Elderly exposure to indoor air pollutants. Atmos Environ2014;
85: 54–63.
3.
BrascheSBischofW.Daily time spent indoors in German homes – baseline data for the assessment of indoor exposure of German occupants. Int J Hyg Environ Health2005;
208: 247–253.
4.
LombardLPOrtizJPoutC.A review on buildings energy consumption information. Energy Build2008;
40: 394–398.
5.
KimJTYuC.Sustainable development and requirements for energy efficiency in buildings – the Korean Perspectives. Indoor Built Environ2018;
27: 734–751.
6.
LiXYuC.China’s building energy efficiency targets: challenges or opportunities?Indoor Built Environ2012;
21: 609–613.
7.
ShibuyaTCroxfordB.The effect of climate change on office building energy consumption in Japan. Energy Build2016;
117: 149–159.
8.
Strategy for energy conservation of Japan 2016. Ministry of Economy, Trade and Industry. Renewable Energy Department, www.meti.go.jp/english/press/2016/0916_02.html (accessed 5 May 2019).
9.
FanYQItoK.Energy consumption analysis intended for real office space with energy recovery ventilator by integrating BES and CFD approaches. Build Environ2012;
52: 57–67.
10.
FanYQItoK.Integrated BES-CFD simulation for estimating the energy saving effect of energy recovery ventilator with CO2 demand-control ventilation system in office space. Indoor Built Environ2014;
23: 785–803.
11.
FanYQItoK.Field-based study on the energy-saving effects of CO2 demand controlled ventilation in an office with application of energy recovery ventilators. Energy Build2014;
68: 412–422.
12.
ChowWWongL.Experimental studies on air diffusion of a linear diffuser and associated thermal comfort indices in an air-conditioned space. Build Environ1994;
29: 523–530.
13.
RheeKNShinMSChoiSH.Thermal uniformity in an open plan room with an active chilled beam system and conventional air distribution systems. Energy Build2015;
93: 236–248.
14.
CalayRBorresenBHoldøA.Selective ventilation in large enclosures. Energy Build2000;
32: 281–289.
15.
GilaniSMontazeriHBlockenB.CFD simulation of stratified indoor environment in displacement ventilation: validation and sensitivity analysis. Build Environ2016;
95: 299–313.
16.
WangXHuangCCaoWGaoXLiuW.Experimental study on indoor thermal stratification in large space by under floor air distribution system (UFAD) in summer. Eng2011;
3: 384–388.
17.
XueYChenQ.Influence of floor plenum on energy performance of buildings with UFAD systems. Energy Build2014;
79: 74–83.
18.
TianLLinZWangQ.Experimental investigation of thermal and ventilation performances of stratum ventilation. Build Environ2011;
46: 1309–1320.
19.
van HoofJ.Forty years of Faner’s model of thermal comfort: comfort for all?Indoor Air2008;
18: 182–201.
20.
CaoGAwbiHBYaoRFanYQSirénKKosonenRZhangJJ.A review of the performance of different ventilation and airflow distribution systems in buildings. Build Environ2014;
73: 171–186.
21.
JanbakhshSMoshfeghB.Experimental investigation of a ventilation system based on wall confluent jets. Build Environ2014;
80: 18–31.
22.
ChenHJanbakhshSLarssonUMoshfeghB.Numerical investigation of ventilation performance of different air supply devices in an office environment. Build Environ2015;
90: 37–50.
23.
OzakiMChikamotoTOtaR.Personal air-conditioning system with outlet can be switched directivity or diffusivity. Trans Architect Instit Japan Kinki Branch2013;
53: 113–116. (in Japanese)
24.
YouRChenJShiZLiuWLinCHWeiDChenQ.Experimental and numerical study of airflow distribution in an aircraft cabin mock-up with a gasper on. J Build Perform Simulat2016;
9: 555–566.
25.
YouRChenJLinCHWeiDChenQ.Investigating the impact of gaspers on cabin air quality in commercial airliners with a hybrid turbulence model. Build Environ2017;
111: 110–122.
26.
KarimipanahTAwbiHB.Theoretical and experimental investigation of impinging jet ventilation and comparison with wall displacement ventilation. Build Environ2002;
37: 1329–1342.
27.
FanYQToyoshimaMSaitoM.Energy conservation and thermal environment analysis of room air conditioner with intermittent supply airflow. Int J Low-Carbon Technol2018;
13: 84–91.
28.
AwbiHB.Ventilation of buildings.
London:
Spon Press, Taylor & Francis Group, 2003.
29.
AwbiHB.Ventilation for good indoor air quality and energy efficiency. Energy Proc2017;
112: 277–286.
30.
Almesri AwbiHBFodaESirénK.An air distribution index for assessing the thermal comfort and air quality in uniform and nonuniform thermal environments. Indoor Built Environ2013;
22: 618–639.
31.
ChenQ.Ventilation performance prediction for buildings: a method overview and recent applications. Build Environ2009;
44: 848–858.
FanYQToyoshimaM.Performance evaluation of different air distraction system on thermal uniformity and energy saving: a case study of a Japanese detached house. Indoor Built Environ2019;
28: 186–194.
35.
WangLZhangXQiD.Indoor thermal stratification and its statistical distribution. Indoor Air2019; 29(2): 157-363. https://doi.org/10.1111/ina.12520
ASHRAE. Handbook – HVAC applications.
Atlanta GA:
American Society of Heating, Refrigerating and Air Conditioning Engineers, 2009.
38.
ASHRAE. ASHRAE handbook – fundamentals.
Atlanta GA:
American Society of Heating, Refrigerating and Air Conditioning Engineers, 2009.
39.
MillerPLNashRT.A further analysis of room air distribution performance. ASHRAE Trans1971;
3: 205–212.
40.
EN ISO 7730:2005. Ergonomics of the thermal environment – analytical determination and interpretation of thermal comfort using calculation of the PMV and PPD indices and local thermal comfort criteria.
Geneva:
International Organization for Standardization, 2005.
41.
LiuSCJordanCNovoselacA.Air diffusion performance index of overhead-air-distribution at low cooling loads. Energy Build2017;
134: 271–284.
42.
LiuSCNovoselacA.Air diffusion performance index (ADPI) of diffusers for heating mode. Build Environ2015;
87: 215–223.
43.
HoughtenFCGutberletCWitkowskiE.Draft temperature and velocities in relation to skin temperature and feeling of warmth. ASHRAE Trans1938;
44: 289–308.
44.
FangerPOMelikovAKHanzawaHRingJ.Air turbulence and sensation of draught. Energy Build1988;
12: 21–39.
45.
WuYLiuHLiBZChenYTanDYFangZS.Thermal comfort criteria for personal air supply in aircraft cabins in winter. Build Environ2017;
125: 373–382.
46.
PorrasACMazarrónFRCañasI.Study of the vertical distribution of air temperature in warehouses. Energies2014;
7: 1193–1206.
