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Performance evaluation of the miniaturized catalytic combustion type hydrogen sensor

Evaluation of a fast-response hydrogen sensor for early detection of leaks in hydrogen stations, focusing on response time, durability, and accuracy. The study compares a miniaturized hydrogen sensor to conventional ones in detecting hydrogen leakage. Key features and experimental results are outlined.

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Performance evaluation of the miniaturized catalytic combustion type hydrogen sensor

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  1. October, 2015 ICHS, Yokohama Performance evaluation of the miniaturized catalytic combustion type hydrogen sensor Hiroshi Miyazaki, Hiromasa Tanjyoh, Kengo Suzuki, Tomoaki Iwami New Cosmos Electric, Co., Ltd., Osaka, Japan

  2. Outline 1. Background 2. Structure and characteristic of the miniaturizedhydrogen sensor 3. Evaluation of response property by the hydrogen diffusion experiment 4. Summary

  3. Backgrounds New Cosmoselectricdevelops, manufactures, andprovides of hydrogen safety-related products and maintenance Key point of hydrogen alarm systems Early detection of the hydrogen leak accident emergency • Higher performance hydrogen sensor is required • detection range • response time • Accuracy • Long life • High durability Hydrogen alarm systems Our gas alarm system has been adopted in 22 hydrogen stations in Japan

  4. Purpose of this study Compressor unit on the hydrogen station =container with forced ventilation Hydrogen leaks out ⇒ hydrogen concentration keep low ⇒ Trouble detection is late http://www.iwatani.co.jp/jpn/newsrelease/detail.php?idx=1178 Early detection of the trouble = even such a condition must detect hydrogen Confirmed the influence that a leak point and the ventilation rate gave in the hydrogen sensor output by a hydrogen diffusion experiment

  5. Structure of the m-CS sensor The Fast-Response Hydrogen Sensor “μ-CS Sensor” miniaturized Φ0.2mm Φ0.7mm Conventional Detector Element m-CS Detector Element Catalytic technology Micro-fabrication technology Pd – Pt Catalyst Φ10mm Pt wire Alumina Micro Heater Coil Catalyst material

  6. Characteristic of the m-CS sensor 1. Fast response : 90％ Response time < 1 sec. 2. Fast stand-up : Warm-up time < 1 sec. 3. Very low power consumption : < 65mW 4. Resistance to silicone compound : Deterioration rate ≦10％ 　　　　　 5. Wide temperature / humidity range : -35 to 100℃ / 0 to 100%RH 6. Long life : Sensitivity decrease rate less than 10% / 15years 7. High durability : High tolerance to vibration and impact strength. m-CS sensor Φ0.2mm

  7. Evaluation result of the silicone poisoning and the life time Silicone poisoning test Life time test 90 H2 40000ppm 80 70 H2 30000ppm 60 +10% 50 H2 20000ppm Sensor output / mV -10% 40 30 H2 10000ppm 20 H2 4000ppm 10 Air 0 -10 14 2 4 6 8 10 12 0 Evaluation result of silicone poisoning Time / year Evaluation result of long-term stability Test result of resistance to Silicone Poisoning at 1% HMDSO*1 for 20h exposure. The μ-CS sensor life span can be expected for 15 years The μ-CS sensor have durability to even high-concentration silicone vapor. *1HMDSO = Hexamethyldisiloxane

  8. Evaluation of the response properties T90 response time (= 90% arrival time to saturated output) μ-CS sensor = 0.7 sec. Conventional sensor = 3.5 sec. Figure. Constitution outline of the response evaluation setup 1sec. cycle 10sec. cycle 6000 6000 m-CS sensor m-CS sensor Conventional sensor Conventional sensor 5000 5000 4000 4000 Sensor output Sensor output (H2 concentration conversion) / ppm 3000 3000 (H2 concentration conversion) / ppm 2000 2000 1000 1000 0 0 1sec. 10sec. 5 9 0 20 40 60 80 100 0 1 2 3 4 6 7 8 10 11 12 Time / sec. Time / sec. The response properties to 5000ppm hydrogen comparison between the μ-CS sensor and the conventional sensor.

  9. The hydrogen diffusion experiment Experiment method Figure. The setup simulating unit The ventilation rate on this condition is about1.1times/min, in other words, an air in the container is substituted at the rate of 1.1 times for 1min.

  10. The hydrogen diffusion experiment Result 1-1 TEST-1 H2 Leakage:2L/min 12000 10000 8000 m-CS sensor 6000 Alarm level (H2 concentration conversion) / ppm Sensor output 4000 2000 Conventional sensor Start 0 30s 3.8s -2000 0 5 10 15 20 25 30 35 40 45 50 Time / sec. μ-CS sensor output sharply fluctuate. The fluctuation of the conventional sensor output was smaller than μ-CS sensor. Warning time of μ-CS sensor is 3.8sec. and the conventional sensor is 30sec.. The fast response sensor is useful for the early detection of the hydrogen leak.

  11. The hydrogen diffusion experiment Result 1-2 TEST-1 H2 Leakage:1L/min 5000 4000 m-CS sensor 3000 Sensor output (H2 concentration conversion) / ppm 2000 1000 Conventional sensor Start 0 -1000 0 10 20 30 40 50 60 70 Time / sec. TEST-1 H2 Leakage:0.1L/min 500 400 m-CS sensor Sensor output 300 (H2 concentration conversion) / ppm 200 100 Start Conventional sensor 0 -100 0 10 20 30 40 50 60 70 Time / sec. The fluctuation of μ-CS sensor's output was observed even the lower H2 leakage rate.

  12. The hydrogen diffusion experiment Result 2 TEST-2 H2 Leakage:2L/min 6000 m-CS sensor 5000 Alarm level 4000 (H2 concentration conversion) / ppm 3000 Conventional sensor Sensor output 2000 1000 Start 0 -1000 0 5 10 15 20 25 30 35 40 45 50 Time / sec. In the case of high ventilation rate Hydrogen leaks out ⇒ Hydrogen concentration keep low μ-CS sensor output reached the alarm level Useful for the construction of the hydrogen alarm system

  13. The hydrogen diffusion experiment Result 3 TEST-3 H2 Leakage:2L/min 12000 m-CS sensor 10000 8000 Alarm level (H2 concentration conversion) / ppm Sensor output 6000 4000 2000 Start Conventional sensor 0 -2000 0 5 10 15 20 25 30 35 40 45 50 Time / sec. The fluctuation of the μ-CS sensor output was extreme. The local hydrogen concentrations greatly fluctuate under the influence of the complicated air flow. The μ-CS sensor can detect a change of local hydrogen concentration at the real time.

  14. 5000 m-CS sensor 4000 3000 Conventional sensor Sensor output (H2 concentration conversion) / ppm 2000 1000 Start 0 -1000 0 10 20 30 40 50 60 70 80 Time / sec. The hydrogen diffusion experimentResult 4 TEST-4 H2 Leakage:0.1L/min In the case of Fan OFF = Poor ventilation (natural ventilation) Hydrogen concentration = proportional to quantity of leakage The μ-CS sensor and conventional sensor can detect

  15. Summary • We had been developed the miniaturized catalytic combustion type hydrogen sensor (μ-CS) . • The μ-CS sensor’s life was estimated more than 15 years. Furthermore, μ-CS sensor had the high durability to the silicone vapor mixture conditions. • We confirmed by a diffusion experiment that a fast response sensor was suitable for the hydrogen detection under the high ventilation. • The μ-CS sensor was able to detect a change of local hydrogen concentration inreal time. • We conclude that the μ-CS sensor is useful for the future hydrogen safety managements. • We would apply the μ-CS sensor to a hydrogen alarm system and a hydrogen detector for the fuel cell vehicle in future.

  16. Product of m-CS sensor Wearable gas detector XP-380 Hydrogen detector for FCV KSV-50/51

  17. The hydrogen diffusion experiment Compressor unit The setup simulating unit Compressor unit on the hydrogen station =container with forced ventilation

  18. Diffusion experiment results Leakage = 1 L/min Leakage = 2 L/min 12000 12000 10000 10000 m-CS sensor 8000 8000 6000 6000 m-CS sensor (H2 concentration conversion) / ppm (H2 concentration conversion) / ppm Sensor output Sensor output 4000 4000 2000 2000 conventional sensor conventional sensor 0 0 Start Start 0 10 20 30 40 50 0 10 20 30 40 50 Time / sec. Time / sec.

  19. Diffusion experiment results TEST-1 and 2 H2 Leakage:2L/min 12000 12000 Leakage = 2 L/min Leakage = 2 L/min 10000 10000 m-CS sensor 8000 8000 m-CS sensor 6000 6000 (H2 concentration conversion) / ppm (H2 concentration conversion) / ppm Sensor output Sensor output 4000 4000 2000 2000 conventional sensor conventional sensor 0 0 Start Start 0 10 20 30 40 50 0 10 20 30 40 50 Time / sec. Time / sec.

  20. TEST-1 and 4 H2 Leakage:0.1L/min(the slow leak mode) Natural ventilation Forced ventilation m-CS sensor Conventional sensor m-CS sensor Conventional sensor Start Start Diffusion experiment results 5000 5000 4000 4000 3000 3000 2000 2000 (H2 concentration conversion) / ppm (H2 concentration conversion) / ppm Sensor output Sensor output 1000 1000 0 0 -1000 -1000 0 10 20 30 40 50 60 70 0 10 20 30 40 50 60 70 Time / sec. Time / sec.

  21. The hydrogen diffusion experiment Experiment method Hydrogen concentration simulation result based on the uniform diffusion model. In this condition, H2 concentration is in 300ppm equilibrium at H2 leak rate 2L/min..

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