PIV Applications to Thermal Performance of LPG Cooking Burner BY USA MAKMOOL And PROF.SUMRERNG JUGJAI Assoc. PROF. SUVIT TIA
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
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
PIV Applications PIV technique = non-intrusive technique = measure 2-D instantaneous velocity field introduced to the combustion researches. important flame characteristics could be observed
2.METHODOLOGY 2.1 Performance Test - The test was performed basing on EN 203-1:1992 and EN 203-2:1995 2.2 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
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 2 1 100 Barometer Restrictor Sampling gas to analyzer Steam vent Hood CO @ 0% O 2 Combustion is checked within 15 minutes after ignition. LPG Bottom Gas flow meter (Wet-type) Vaporizer Pressure regulator Cooking burner
Burners Performance Burner type Radial flow (No.1) Radial flow (No.2) Vertical flow Swirling flow Thermal efficiency, % 41.6 51.7 54.2 56.2 CO, ppm 80 120 800 800 Free flame Impinging flame Self-aspirating burners, low-pressure type Heat capacity < 5 kw
PIV Diagnostics
Schematic diagram of the seeding system
PIV Experimental (Flow field visualization) Hot test - 280 mmh 2 O of LPG - Primary Air, seeded with TiO 2 (3µm φ) Nd :YAG laser Laser sheet Cooking burner Camera lens Seeding box
Radial flow No.1 η th = 41.6% CO =80 ppm Radial flow No.2 η th = 51.7% CO =120 ppm
Schematics of the cooking burner 1 2 3
Burner No.1 Flame images Burner No.2
Radial flow burner No.1 52 o 62 o Radial flow burner No.2
Pan s rim Pan s center Burner No.1 Burner No.2
Vertical flow burner η th = 54.2% CO =800 ppm Area of Interest
Impinging flame of vertical flow burner 90 o
Swirling Flow Burner η th = 56.2% CO =800 ppm Area of Interest
Averaged field of velocity magnitude of swirling flame 40 o
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) 0.53 0.63 0.67 0.68 Turbulent intensity 0.13 0.15 0.15 0.25 Vorticity -39.97-29.48-124.32-61.49 Strain rate 15.7 12.67 59.53 30.39
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
Thank you
Radial flow burner No.1 52 o Impinging flame 62 o Radial flow burner No.2
Impinging flame of vertical flow burner 90 o
Averaged field of velocity magnitude of swirling flame 40 o
(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
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.
Nd:YAG Laser 10 140 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 10 30 Hz pulse Repetition rate 532 nm Wavelength
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.
PIV testing room