Conceptual Approach on Feasible Hydrogen Contents for Retrofit of CNG to HCNG under Heavy-Duty Spark Ignition Engine at Low-to-Middle Speed Ranges

Bum Youl Park,Ki-Hyung Lee,Jungsoo Park

doi:10.3390/en13153861

Bum Youl Park, Ki-Hyung Lee + Show 1 more

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https://doi.org/10.3390/en13153861

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Journal: Energies	Publication Date: Jul 28, 2020
Citations: 3	License type: CC BY 4.0

Affiliation: Hanyang University, Chosun University

Abstract

Hydrogen-based engines are progressively becoming more important with the increasing utilization of hydrogen and layouts (e.g., onboard reforming systems) in internal combustion engines. To investigate the possibility of HICE (hydrogen fueled internal combustion engine), such as an engine with an onboard reforming system, which is introduced as recent technologies, various operating areas and parameters should be considered to obtain feasible hydrogen contents itself. In this study, a virtual hydrogen-added compressed natural gas (HCNG) model is built from a modified 11-L CNG (Compressed Natural Gas) engine, and a response surface model is derived through a parametric study via the Latin hypercube sampling method. Based on the results, performance and emission trends relative to hydrogen in the HCNG engine system are suggested. The operating conditions are 1000, 1300, and 1500 rpm under full load. For the Latin hypercube sampling method, the dominant variables include spark timing, excess air ratio (i.e., λCH4+H2), and H2 addition. Under target operating conditions of 1000, 1300, and 1500 rpm, the addition of 6–10% hydrogen enables the virtual HCNG engine to reach similar levels of torque and BSFC (brake specific fuel consumption) compared to same lambda condition of λCH4. For the relatively low 1000 rpm speed under conditions similar to those of the base engine, NOx formation is greater than base engine condition, while a similar NOx level can be maintained under the middle speed range (1300 and 1500 rpm) despite hydrogen addition. Upon addition of 6–10% hydrogen under the middle speed operation range, the target engine achieves performance and emission similar to those of the base engine.

Highlights

Sustainable and renewable energy sources are currently employed for powering mechanical systems
This study investigated the effect of varying the spark advance timing and excess air ratio on the combustion and emission of nitrogen oxide (NOx) in a hydrogen-fueled spark ignition engine under part load conditions
The analysis indicates that when the hydrogen-added compressed natural gas (HCNG) heavy-duty engine runs at 1000 rpm, a distinct tradeoff between torque or fuel economy and NOx emission exists; on considering the torque loss when lean combustion is achieved by increasing the hydrogen fraction, the foregoing suggests that brake specific NOx (BSNOx) formation can be reduced

Summary

Introduction

Sustainable and renewable energy sources are currently employed for powering mechanical systems. Biogases are used as alternative fuels, either alone or blended with conventional fossil fuels or H2 additives [1,2]. As a combustion enhancer, can improve flame speed and range upon being added to fuels because of its favorable properties [3]. In this regard, many experimental and numerical studies yielding common results have been reported. It is widely known that as the hydrogen content of fuels increases, the in-cylinder pressure and temperatures increase during combustion and thereby enhance engine torque [4,5].

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