Development of a Low-Cost Exhaust H2 Measurement Method for In-Use Vehicles
Notice bibliographique
Résumé
Abstract Port-injected hydrogen (H2) can be used as a partial substitution of diesel fuel in compression-ignition engines to reduce GHG emissions. For port-injected H2 systems, incomplete combustion or valve overlap can result in H2 slip, which increases the brake-specific fuel consumption. In this study, a low-cost method is developed to measure the H2 slip in the exhaust of a heavy-duty truck under real-world operating conditions. The truck is equipped with a 2016 15L Detroit diesel engine converted to run in dual-fuel mode with port-injected H2 ignited by directly injected diesel. Existing H2 detecting methods used for steady-state laboratory tests either have slow response time or require well-controlled testing environments. To develop a method suitable for transient on-road H2 measurements, we utilized a low-cost semiconductor sensor. The output of the sensor is potentially influenced by temperature, relative humidity (RH), gas flow rate, as well as the sensor’s resistance in the ambient air (R0) and the pre-heating strategy. Firstly, the characteristics of R0 was investigated in controlled benchtop tests, where pre-heating time, gas temperature, and RH were monitored. Then, the sensor was calibrated using a standard gas mixture of H2 and nitrogen. Finally, a Portable Emission Measurement System (PEMS) was developed to control the conditions of the sample gas. The sensor output was recorded using a low-cost Raspberry Pi Data Acquisition (DAQ) system in combination with an analog HAT (Hardware attached on top) module at a frequency of 4Hz. The results from the benchtop tests show that RH and flow rate both have significant influences on the sensor’s output. To ensure a stable R0, thirty minutes of pre-heating time is required. After calibration, the sensor’s readings are within 15% difference compared with the actual values. Data from the on-road tests demonstrated the applicability of the system for in-use vehicle’s exhaust H2 measurement. It was found from this data that the sensor’s average response time to rising H2 concentrations is 4.5s, but that the response to decreasing concentrations is much slower. The exhaust H2 concentrations, together with the engine operating data, were used to generate H2 emission maps, which provide insight into the relationship between the engine load, engine speed and the H2 slip. With further sensor development and sample gas control, this method can achieve high accuracy and extended application in in-use vehicle’s H2 emission measurements.
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Comment cette classification a été obtenuedéplier
Prédiction distillée sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Apprise à partir de 10 348 étiquettes directes de Codex et de 10 348 étiquettes directes de Gemma. Le mode candidate est l'union des têtes enseignantes seuillées; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont ni des étiquettes humaines ni des étiquettes directes de modèles de pointe.
Scores Codex et Gemma par catégorie
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,000 | 0,000 |
| Méta-épidémiologie (sens strict) | 0,000 | 0,000 |
| Méta-épidémiologie (sens large) | 0,000 | 0,000 |
| Bibliométrie | 0,000 | 0,000 |
| Études des sciences et des technologies | 0,000 | 0,000 |
| Communication savante | 0,000 | 0,000 |
| Science ouverte | 0,000 | 0,000 |
| Intégrité de la recherche | 0,000 | 0,000 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,000 | 0,000 |
Scores machine (provisoires)
Les deux têtes enseignantes du modèle étudiant, lues sur ce travail. Un score ordonne la base pour la relecture; il n'affirme jamais une catégorie, et le statut de validation accompagne chaque rangée tel quel.
Scores de référence d'un modèle non mature (critères de maturité non atteints, 7 itérations). Un score ordonne; il n'affirme jamais une catégorie.
score_only:v0-immature-baseline · tel quel depuis la passe de notation : score_only signifie que le nombre peut ordonner les travaux, et qu'aucune étiquette de catégorie n'en découleClassification
machine, non validéePrédiction automatique; un appel candidat d’une seule tête enseignante, pas un consensus.
Le détail, modèle par modèle et score par score, se trouve en fin de page sous « Comment cette classification a été obtenue ».