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Experimental study of an intermittent ventilation system
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STUDIE S I N T HE RE S E ARCH PROF IL E B U I LT EN V I R O N MEN T. DOCT ORAL T HE S IS N O 3, Experimental study of, an intermittent ventilation system. in high occupancy spaces, Alan Kabanshi, G vle University Press. Alan Kabanshi 2017, G vle University Press, ISBN 978 91 88145 11 6. ISBN 978 91 88145 12 3 pdf, urn nbn se hig diva 23754. Distribution, University of G vle, Faculty of Engineering and Sustainable Development.
SE 801 76 G vle Sweden, 46 26 64 85 00, www hig se. Print Ineko AB K llered 2017, Tryckt p FSC m rkt papper. a rational calculation of heating and air conditioning systems. must begin with the conditions for comfort, PROF P O FANGER 1934 2006. Spaces with high occupancy density like classrooms are challenging to ven. tilate and require a lot of energy to maintain comfort Usually a compromise. is made between low energy use and good Indoor Environmental Quality. IEQ of which poor IEQ has consequences for occupants health produc. tivity and comfort Alternative strategies that incorporate elevated air speeds. can reduce cooling energy demand and provide occupant s comfort and. productivity at higher operative temperatures A ventilation strategy Inter. mittent Air Jet Strategy IAJS which optimizes controlled intermittent air. flow and creates non uniform airflow and non isothermal conditions critical. for sedentary operations at elevated temperatures is proposed herein. The primary aim of the work was to investigate the potential of IAJS as a. ventilation system in high occupancy spaces Ventilation parameters such as. air distribution thermal comfort and indoor air quality were evaluated and. the system was compared with a traditional system specifically mixing ven. tilation MV A 3 part research process was used 1 Technical objective. evalua tion of IAJS in comparison to MV and displacement ventilation DV. systems 2 An occupant response study to IAJS 3 Estimation of the cool. ing effect under IAJS and its implications on energy use All studies were. conducted in controlled chambers, The results show that while MV and DV creates steady airflow condi. tions IAJS has cyclic airflow profiles which results in a sinusoidal tempera. ture profile around occupants Air distribution capability of IAJS is similar to. MV both having a generic local air quality index in the occupied zone. On the other hand the systems overall air change rate is higher than a MV. Thermal comfort results suggest that IAJS generates comfortable thermal. climate at higher operative temperatures compared to MV Occupant re. sponses to IAJS show an improved thermal sensation air quality perception. and acceptability of indoor environment at higher temperatures as compared. to MV A comparative study to estimate the cooling effect of IAJS shows that. upper HVAC setpoint can be increased up to 2 3 4 5 oC for a neutral thermal. sensation compared to a MV This implies a substantial energy saving poten. tial on the ventilation system In general IAJS has a potential to be used as. an energy efficient ventilation system in high occupancy spaces. Keywords Intermittent airflow Indoor air quality Perceived air quality. Thermal sensation thermal comfort Air movement acceptability Convec. tive cooling Cooling effect, Sammanfattning, Lokaler d r m nga m nniskor vistas som t ex klassrum r ofta sv ra att.
ventilera Att uppr tth lla en bra termisk komfort kr ver en h g energian. v ndning Vanligtvis blir det en kompromiss mellan l g energianv ndning. och bra kvalitet p inomhusmilj n IEQ D lig IEQ f r konsekvenser f r. m nniskors h lsa produktivitet och komfort Alternativa ventilationsstrategier. som anv nder f rh jda lufthastigheter kan minska kylbehovet och d rmed. energianv ndningen I denna avhandling utv rderas en ny ventilations. strategi Intermittenta luftstr lar IAJS d r korta perioder med h g lufthas. tighet genererar en svalkande effekt n r rummets temperatur upplevs som. Det prim ra syftet med arbetet var att unders ka potentialen hos IAJS. som ett ventilationssystem f r klassrum d r den termiska lasten ofta r h g. Strategin j mf rs mot traditionella ventilationsprinciper som omblandande. ventilation MV och deplacerande ventilation DV Parametrar som luftdis. tributionsindex termisk komfort luftkvalitet och energibesparing har utv r. derats Alla studier utf rdes i klimatkammare, Resultaten visar att medan MV och DV skapar konstanta luftfl desf r. h llanden genererar IAJS cykliska hastighetsprofiler samt en sinusformad. temperaturvariation i vistelsezonen IAJS klarar att bibeh lla ett bra termiskt. klimat vid h gre operativa temperaturer j mf rt med MV I en j mf relse. med ett traditionellt HVAC system visar ber kningar att dess b rv rde kan. h jas fr n 2 3 till 4 5 C med bibeh llen termisk komfort Detta indikerar en. avsev rd energibesparingspotential vid anv ndande av IAJS. Nyckelord Intermittent luftfl de Luftstr lar Upplevd luftkvalitet Termisk. komfort Acceptans av luftr relser Konvektiv kylning Kyleffekt. Acknowledgements, I am thankful for the opportunity to do my doctoral studies at the University. of Gavle I owe my deepest gratitude to numerous people who provided sup. port and encouragement that contributed significantly to the completion of. my studies, I express my sincere gratitude to my supervisors Professor Patrik. S rqvist Dr Hans Wig and Dr Robert Ljung for their unwavering support. positive attitude enthusiasm guidance and advice on my research and on. matters beyond research that has contributed tremendously to my professional. and personal development, I am grateful to Professor Mats Sandberg my secret supervisor for his. comments suggestions and discussions that inspired many research ideas for. this and other projects On this note I owe a debt of gratitude to Dr Bin Yang. for his contribution through discussions suggestions and comments Professor. Edward Arens and Dr Stefano Schiavon for inviting me to work at CBE as. a visiting research student and providing comments on my research Dr. Dusan Licina for being a brother for dreaming with me Kudos to dreams. deferred and for the support and advice during my studies Dr Despoina Teli. for reviewing and commenting on my thesis, I would like to thank colleagues and friends at the University of G vle.
whose names are too numerous to mention lest I forget some your support. companionship and the wonderful discussions during lunch and Fika made. G vle a homely environment This also extends to friends and colleagues at. UC Berkeley Veronika Soazig and Caroline I am grateful for the reception. my family received during our stay To friends across the world I am grateful. for your support tolerance and the welcome social distraction during this pe. riod Indeed it has been a journey worth a tale, I am thankful to the staff at the University of G vle for the help and sup. port that I received during my studies Much gratitude is owed to all the re. search engineers at the University lab who helped during my experimental. Finally to my wife Mpanga and my son Mp Ala all that should be said. is that you two are the spark that makes my life bright Thank you. List of Appended Papers, This thesis is based on the following papers which are referred to in the text. by Roman numerals, Kabanshi A Wig H Sandberg M 2016 Experimental evaluation. of an intermittent air supply system Part 1 Thermal comfort and ventilation. efficiency measurements Building and Environment 95 240 250. Kabanshi A Wig H Ljung R S rqvist P 2016 Experimental. evaluation of an intermittent air supply system Part 2 Occupant perception. of thermal climate Building and Environment 108 99 109. Kabanshi A Yang B S rqvist P Sandberg M Accepted, Occupant perception of air movements and air quality in a classroom with an. intermittent air supply system Indoor and Built Environment. Kabanshi A Wig H Ljung R S rqvist P 2016 Human perception. of room temperature and intermittent air jet cooling in a classroom. Indoor and Built Environment Prepublished January 28. DOI 10 1177 1420326X16628931, Kabanshi A Wig H 2016 Experimental Evaluation of Intermittent.
Air Jet Ventilation Strategy Cooling effect and the associated energy savings. The 14th International Conference on Indoor Air Quality and Climate. Ghent Belgium July 2 9 2016, Reprints were made with permission from the publishers. Nomenclature, Symbols Description Unit, do Nozzle diameter mm. S Spacing between nozzle centerline mm, M Metabolic rate met or W m2. W Effective mechanical power W m2, Icl Clothing insulation clo or m2 K W. fcl Clothing surface area factor, ta Room air temperature C.
r or tr Mean radiant temperature C, var Relative air velocity m s. pa Water vapor partial pressure Pa, hc Convective heat transfer coefficient W m2 C. tcl Clothing surface temperature C, T Temperature C. V Mean air velocity m s, V Room volume m3, TI Turbulence intensity. ts Supply temperature C, tex Exhaust temperature C.
tg Vertical temperature gradient C, Manikin equivalent temperature C. Local air change index, Nominal time constant h, Local mean age of air h. Volumetric airflow rate m3 s, Air change efficiency. Room mean age of air h, Abbreviations, IAJS Intermittent air jet strategy. MV Mixing ventilation, DV Displacement ventilation.
PAQ Perceived air quality, IAQ Indoor air quality, ADI Air distribution index. PMV Predicted mean vote, MTV Mean thermal vote, OTS Overall thermal sensation. PSAM Percentage satisfied with air movements, PPD Predicted percentage dissatisfied. PD Percentage dissatisfied, SET Standard effective temperature. IEQ Indoor environmental quality, HVAC Heating ventilation and air conditioning.
AHU Air handling unit, AJD Air jet diffuser, MD mixing diffuser. D Diffuser, CO2 Carbon dioxide, PCS Personal comfort systems. EU European Union, IPCC Intergovernmental panel on climate change. CBE Center for the built environment, CTA Constant temperature anemometers. ANOVA Analysis of variance, EAC Environmental advisory council.
HRE Heat removal effectiveness, CP Cooling power, CFD Computational fluid dynamics. P Measurement point, PLC Programmable logic controller. PID Proportional integral derivative, Table of Contents. Abstract iii, Sammanfattning iv, Acknowledgements v. List of Appended Papers vi, Nomenclature vii, 1 Introduction 1.
2 Literature review 3, 2 1 Indoor Environment 3, 2 2 Ventilation 3. 2 2 1 Local air change index 4, 2 2 2 Air change efficiency 4. 2 2 3 Indoor air Quality IAQ 5, 2 2 4 Thermal Comfort 6. 2 3 Elevated air movements and indoor climate 8, 2 3 1 Characteristics of air movements and human comfort 10. 2 3 2 Air movements and perceived air quality 11, 2 4 Ventilation Strategies 12.
2 4 1 Mixing ventilation strategy 12, 2 4 2 Displacement ventilation strategy 12. 2 4 3 Alternative ventilation strategy 13, 2 5 Confluent Jets 14. 2 6 Knowledge gap 14, 2 7 Motivation of the study 14. 2 8 Aim and research process 15, 2 9 Outline of the appended papers 15. 3 Methods 18, 3 1 Research methods 18, 3 2 IAJS System description 18.
3 3 Experimental facilities 19, 3 4 Measurements 20. 3 4 1 Objective measurements 20, 3 4 2 Subjective measurements 23. 3 5 Estimation of the cooling effect of IAJS 25, 3 5 1 Manikin based cooling effect 25. 3 5 2 Cooling power analysis 25, 3 6 Limitations and Validity aspects 26. 4 Results and discussion 28, 4 1 Objective study 28.
4 1 1 Air speed and temperature characteristics, in the occupied zone 28. 4 1 2 Ventilation performance Air distribution indices 31. 4 1 3 Ventilation performance Thermal comfort 32, 4 2 Subjective study 34. 4 2 1 Case study 1 34, 4 2 2 Case study 2 40, 4 3 Cooling effect of IAJS 42. 4 3 1 Manikin Based Cooling Effect 42, 4 3 2 Cooling power analysis 43. 5 General discussion 45, 5 1 Implications on occupant comfort and building energy use 45.
5 2 System applicability 46, 5 3 Limitations and future work 47. 6 Conclusion 49, 7 Miscellaneous publications 51, 7 1 Journal articles 51. 7 2 Conference articles 51, References 52, Appendix A 63. 1 MTV scale 63, 2 Case study 1 questionnaire 63, Appendix B 72. Appendix C 73, 1 Introduction, Energy has become an international political issue that threatens global wel.
fare and regional security The concerns over exhaustion of energy resources. and environmental impacts are ever becoming serious and disquieting The. rapid growth in energy demand is apparent in the building sector which has. become the largest energy demanding sector Taking the European Union. EU as an example the built environment uses about 40 of the total re. gional energy and accounts for about 36 of the regions total CO2 emissions. Burman et al 2014 European Commission 2008, There are calls to reduce energy demand and improve energy efficiency. in the built environment This is reflected in the European Union EU. energy and climate change strategy da Gra a Carvalho 2012 The EU has. given directives 2010 31 EU and 2012 27 EU to its member states to. improve on building energy performance and energy efficiency European. parliament council 2010 2012 In Sweden the national board of housing. building and planning Boverket regulated the energy use in buildings with. regard to location and type of heating Boverket 2008 Earlier the Envi. This implies a substantial energy saving poten tial on the ventilation system In general IAJS has a potential to be used as an energy efficient ventilation system in high occupancy spaces Keywords Intermittent airflow Indoor air quality Perceived air quality Thermal sensation thermal comfort Air movement acceptability Convec

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