Methodology for the Evaluation of Natural Ventilation in ... - Cham

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Figure 44. Heaters and Zones for a) single zone case, b) two zone case, and c) full modelIn order to scale the data for application in the full-scale model predictions, the referencetemperature differences for both the scale model and the full-scale prototype had to beascertained. Once the reference temperature differences were known, then the full-scaletemperature difference, inlet to outlet, for the prototype building was determined. By selectingan ambient temperature, the resulting internal temperature distributions were obtained.Table 27. Variables and Calculated Reference Temperature Difference for Model Case and Full-Scale BuildingFull-ScaleBuildingSingle ZoneAir ModelTwo-ZoneAir ModelFull AirModelQ (Watts) 35,000 500 1,000 2,000A (m 2 ) 1,800 2.16 4.32 8.64rho (kg/m 3 ) 1.2 1.2 1.2 1.2c p 1007 1007 1007 1007g 9.8 9.8 9.8 9.8Beta (1/K) 0.0033 0.00314 0.00314 0.00314H (m) 15 1.2 1.2 1.2ΔTref (°C) 0.083 0.997 0.997 0.997118
7.1 Buoyancy-Driven Ventilation ResultsThe results for the three buoyancy-driven ventilation experiments, single zone, two zone and fullmodel, are presented along with the comparisons to the numerical simulations.7.1.1 Single Heated Zone CaseThe simplified model with a single heated zone connected to the atrium was investigated usingonly the lower windows initially, and then using only the upper windows. This allowed viewingthe effect of window location on the flow patterns and resulting temperature distribution withinthe heated zone. The physical model was then created as a CFD simulation using PHOENICS.The single heated zone model was evaluated for temperature distribution, air flow rate throughthe model, and heat loss through the envelope. The temperature distribution was evaluated inboth the heated zone and within the atrium space. Additional temperature measurements wererecorded at the inlet and outlet conditions.The measured temperature data within the physical model provided insight into the influence ofwindow location on the internal temperature distribution. The data for the upper windows opencase and lower windows open case were compared using the situation with seven windows andthree stacks open for each case in Figure 45 through 47 below. The data recorded from thephysical model were non-dimensionalized and scaled for use in predicting the full buildingtemperatures. The full building temperatures and corresponding height within the space arepresented, using 20°C as the ambient conditions for the full building case. At the column,located at the edge of the heated zone where it connects to the atrium, the temperaturedistribution was similar for both the upper and lower window case (Figure 45). This was similarto the atrium temperature distribution, shown in Figure 47, where the location of inlet windowsdid not significantly affect the temperature stratification. The maximum temperature differencebetween the upper and lower window measurements for both the scaled column and atriummeasurements was 0.13°C.In the heated zone, the temperature patterns were somewhat different between the upper andlower window locations. When the upper windows were used, the temperature measurementclosest to the floor and ceiling were higher than for the lower window case at the mid-point ofthe heated zone, where the vertical temperature measurements were taken. For the lowerwindow experiments, the temperatures within the heated zone were very similar for the upperfour points, and then increased closer to the floor, which was located 3 cm above the heatedaluminum plate. The maximum temperature difference of 0.45°C occurred at a height of 1.1m(9.5cm as measured in the model) from the floor.119
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Thesis Committee:Leon R. Glicksman,
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Table of ContentsTable of Contents
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7.1.3 Full Model Case .............
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Figure 41. Wind Direction Data for
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List of TablesTable 1. Energy End U
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Table 64. Comparison of Dimensionle
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Chapter 1.0IntroductionEnergy consu
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insulated building envelopes with t
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energy usage and efficient design.
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Figure 3. European Patent Office Bu
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selecting boundary conditions) to e
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2.2.1 Buoyancy-Driven VentilationVe
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Figure 7. Neutral Pressure Level fo
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Combined wind-buoyancy flow is more
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design. The depth of natural ventil
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of cooling required by 30 percent o
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considered when determining how the
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environmental conditions are examin
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As natural ventilation is prevalent
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Chapter 3.0Evaluation of Prototype
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Figure 12. Interior Atrium ViewFigu
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Table 8. Prototype Building Window
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Figure 15. HOBO® H8 Series Tempera
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Finally, airflow visualization was
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only is the airflow almost never at
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Table 10. Window Bag Device Measure
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Mon 7-21Tue 7-22Wed 7-23Thu 7-24Fri
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12:00 AM1:00 AM2:00 AM3:00 AM4:00 A
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27-Jul27-Jul28-Jul28-Jul29-Jul30-Ju
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A range of air exchange rates was f
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the windows on the second floor, or
Page 67 and 68: Total Electric (kWh/m2)Total Gas (k
Page 69 and 70: movement, Houghton Hall has much le
Page 71 and 72: Chapter 4.0Modeling and Visualizati
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Page 75 and 76: lower and upper openings and natura
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Page 79 and 80: applications involving full-scale b
Page 81 and 82: digital camera with both manually o
Page 83 and 84: Chapter 5.0Dimensional Analysis and
Page 85 and 86: u oHgHT2uocu Hpo1Re Ar1Re Pr(5.7)(5
Page 87 and 88: X HM X HP(5.16)5.3.2 Kinematic Sim
Page 89 and 90: Radiation was found to have an impa
Page 91: height is used for the full-scale b
Page 94 and 95: 6.3 Model Descriptions6.3.1 Physica
Page 96 and 97: Figure 30. Floor Plan of the Protot
Page 98 and 99: Figure 31. North Facade of Model wi
Page 100 and 101: Monitoring data collected from the
Page 102 and 103: By default, there was no accounting
Page 104 and 105: 40-location card inserted into the
Page 106 and 107: 6.5 ExperimentsTo evaluate the mode
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Page 110 and 111: Figure 39. Two Heated Zone ModelWit
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Page 114 and 115: Figure 42. Cross-Section of Wind-Ge
Page 116 and 117: Table 25. Wind-Assisted Ventilation
Page 120 and 121: Height from Floor (m)Height from Fl
Page 122 and 123: Where V is the outlet velocity, A o
Page 124 and 125: Table 32. Conduction Heat Loss for
Page 126 and 127: a) Air Modelb) Water ModelFigure 50
Page 128 and 129: Height from Floor (m)The temperatur
Page 130 and 131: Height from Floor (m)In the atrium
Page 132 and 133: First NorthUpper Window 0.17 m/s -0
Page 134 and 135: Height from Floor (m)the column at
Page 136 and 137: Height from Floor (m)Height from Fl
Page 138 and 139: Height from Floor (m)3.53.02.52.01.
Page 140 and 141: was less than 12 percent. These val
Page 142 and 143: Table 39. Variation of Outlet Wind
Page 144 and 145: temperature of the air was the same
Page 146 and 147: 3.532.521.55m/s4m/s3m/s2m/s1m/s1.5m
Page 148 and 149: 3.532.521.55m/s4m/s3m/s2m/s1m/s1.5m
Page 150 and 151: The average and exhaust internal bu
Page 152 and 153: Table 43. Calculated Wind and Buoya
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Page 156 and 157: Figure 80. CFD Simulation of the Te
Page 158 and 159: uoyancy case the air from the groun
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Bordass, W.T., A.K.R. Bromley and A
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Linddament, M. 1996. Why CO2? Air I
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172
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MODEL: K20-8SERIAL: 10047RECORDER_I
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2 Boiler-3 50.00 C1 N1 1.0 ON ON OF
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|PW|DESCRIP |KW |KWH|KVA|KVH|------
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2:5 ;day_ofYr17:P30 ;EOT = 0.000075
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2:3136:P30 ;DUM2 = -0.040891:-4.089
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;7:21 ;input location;8:0 ;mulptipl
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;79:P22 ;EXC w/DELAY (only for dela
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1:45 ;port5 (homeSense)2:31 ;exit l
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13:P95 ;ENDIF14:P95 ;ENDIF15:P3 ;pu
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2:20 ;RH30:P70 ;sample1:12:20 ;RH31
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194
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Five Windows Open: Upper versus Low
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One Window Open: Upper versus Lower
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25 cm / 3 m 24.33 26.62 22.68 22.93
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25 cm / 3 m 24.07 25.26 22.65 22.78
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Two Stacks Open Temperature Stratif
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Stacks Closed Temperature Stratific
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2.3 24.31 24.65 24.781.4 23.35 23.6
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0.6 20.56 20.67 20.94 21.22 21.41 2
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