View/Open

List of Figures
Figure 1.1 Obstructive sleep apnea [4] .......................................................................... 1
Figure 1.2 Mandibular repositioning device[9] .............................................................. 2
Figure 1.3 tongue retaining device[10] .......................................................................... 3
Figure 1.4 CPAP machine ............................................................................................. 5
Figure 1.5 Schematic diagram of a CPAP system in use [19] ........................................ 5
Figure 1.6 CPAP treatment of sleep apnea[20] .............................................................. 6
Figure 2.1 CPAP HC600 by Fisher and Paykel Healthcare Co. Ltd. ............................ 11
Figure 2.2 CPAP system ............................................................................................. 12
Figure 2.3 Controlled volume analysis of tube flow .................................................... 13
Figure 2.4 The blower and the connecting duct ........................................................... 16
Figure 2.5 Experimental set up for positive direction flow ADU outlet pressure
measurement ....................................................................................................... 16
Figure 2.6 Pressure sensor - Honeywell Precision Pressure Transducer ....................... 17
Figure 2.7 Flowmeter - NDD Ultrasonic Flow Sensor ................................................. 17
Figure 2.8 Measuring pressure at the blower outlet ..................................................... 18
Figure 2.9 Experimental set up for ADU outlet pressure measurement with reverse flow
............................................................................................................................ 18
Figure 2.10 Connecting adapter between two CPAPs .................................................. 18
Figure 2.11 ADU outlet pressure at different pressure settings and different flow rate . 19
Figure 2.12 Experimental set up for connecting duct air flow velocity and pressure drop
measurement ....................................................................................................... 21
Figure 2.13 Pressure tubes inserted for measuring pressure drop on the connecting duct
............................................................................................................................ 21
Figure 2.14 Connecting duct pressure drop vs. airflow velocity ................................... 22
Figure 2.15 Corrugated wall of the HADT [19] .......................................................... 24
Figure 2.16 controlled volume analysis of airflow in HADT ....................................... 24
Figure 2.17 Nasal mask type “FlexFit407” and Full face mask type “FlexFit432” 26
Figure 2.18 Full face mask and the non-rebreathing valve ........................................... 27
Figure 2.19 The shape of bias vent holes ..................................................................... 28
Figure 2.20 Diluting curve in the mask........................................................................ 33
Figure 3.1 CPAP in the Vötsch C4-340 Environment Control Chamber for testing ..... 37
Figure 3.2 Air temperature at the blower outlet measurement ...................................... 37
Figure 3.3 Airflow only comes out from bias vent holes.............................................. 38
Figure 3.4 Thermal enthalpy gain of airflow between CPAP inlet and the chamber ..... 39
Figure 3.5 Humidifier diagram .................................................................................... 40
Figure 3.6 Heating element beneath heating plate........................................................ 41
Figure 3.7 Humidifier thermal balance flow chart ....................................................... 42
Figure 3.8 Chamber water heat balance ....................................................................... 43
Figure 3.9 Heating plate heat balance .......................................................................... 47
Figure 3.10 Temperature at wall 1 ............................................................................... 49
Figure 3.11 Airflow direction in the chamber .............................................................. 51
xiii