PIV Applications to Thermal Performance of LPG

Transcription

1 PIV Applications to Thermal Performance of LPG Cooking Burner BY USA MAKMOOL And PROF.SUMRERNG JUGJAI Assoc. PROF. SUVIT TIA

2 1. Rational/ Problem Statement LPG consumption of Household sector (Thailand, 2005) - 53% of the total LPG consumption - increasing rate 5.3% Domestic cooking burner production - basing on experience and copying rather than scientific reason. - Burners performance? => No standardization

3 1.2 Objectives To apply PIV technique to investigate the flow field of the domestic LPG cooking burner ( available in Thailand) The corresponding flow field Burner s performance

4 PIV Applications PIV technique = non-intrusive technique = measure 2-D instantaneous velocity field introduced to the combustion researches. important flame characteristics could be observed

5 2.METHODOLOGY 2.1 Performance Test - The test was performed basing on EN 203-1:1992 and EN 203-2: PIV Diagnostics - To compare flow field of the two Radial flow burner but with difference performance. - To investigate the impingements flow field of high thermal performance (i.e. swirling flow and vertical flow) burners

6 Performance tests (EN 203-1:1992, EN 203-2:1995) Thermal efficiency is given by: η th M = C V P C ( t t ) H Barometer Restrictor Sampling gas to analyzer Steam vent Hood 0% O 2 Combustion is checked within 15 minutes after ignition. LPG Bottom Gas flow meter (Wet-type) Vaporizer Pressure regulator Cooking burner

7 Burners Performance Burner type Radial flow (No.1) Radial flow (No.2) Vertical flow Swirling flow Thermal efficiency, % CO, ppm Free flame Impinging flame Self-aspirating burners, low-pressure type Heat capacity < 5 kw

8 PIV Diagnostics

9 Schematic diagram of the seeding system

10 PIV Experimental (Flow field visualization) Hot test mmh 2 O of LPG - Primary Air, seeded with TiO 2 (3µm φ) Nd :YAG laser Laser sheet Cooking burner Camera lens Seeding box

11 Radial flow No.1 η th = 41.6% CO =80 ppm Radial flow No.2 η th = 51.7% CO =120 ppm

12 Schematics of the cooking burner 1 2 3

13 Burner No.1 Flame images Burner No.2

14 Radial flow burner No.1 52 o 62 o Radial flow burner No.2

15 Pan s rim Pan s center Burner No.1 Burner No.2

16 Vertical flow burner η th = 54.2% CO =800 ppm Area of Interest

17 Impinging flame of vertical flow burner 90 o

18 Swirling Flow Burner η th = 56.2% CO =800 ppm Area of Interest

19 Averaged field of velocity magnitude of swirling flame 40 o

20 Dynamic properties at the impingement region Dynamic properties Overall impinging region (5 mm thickness) Radial No.1 Radial No.2 Vertical Swirl Velocity magnitude (m/s) Turbulent intensity Vorticity Strain rate

21 1. Performance tests 4. Conclusion maximum 1. => Swirling flow 2. => vertical 3. => radial flow No.2 minimum 4. => radial flow No.1 2. PIV technique = A powerful technique to investigate the burner performance. Fluid mechanics => well correlated with burner performances

22 Thank you

23 Radial flow burner No.1 52 o Impinging flame 62 o Radial flow burner No.2

24 Impinging flame of vertical flow burner 90 o

25 Averaged field of velocity magnitude of swirling flame 40 o

26 (η =41.6%) Radial flow burner No.1 (η=51.7%) Radial flow burner No.2 (η =54.2%)Vertical flow burner (η =56.2%)Swirling flow burner

27 PIV principle The flow is seeded The field of interest is illuminated A double exposure is recorded The picture is evaluated The velocity vector field and associated flow properties were calculated from the particle image displacements.

28 Nd:YAG Laser mj per pulse 4 20 ns pulse duration - freezes the particle images Wide range of ΔT - to measure flow velocities from mm/s to supersonic speeds Hz pulse Repetition rate 532 nm Wavelength

29 A successful PIV measurements 1.) Selection of appropriate tracer particles - Particle size must be large enough to scatter sufficient light for image acquisition. - Particle size must be small enough for faithfully tracking the flow. 2.) Proper seeding of tracer particle: - Homogeneous and uniform seeding. - No severe particle aggregation. - Particle seeding concentration must be 1. high enough for data processing 2. low enough for not disturbing the flow field.

30 PIV testing room