تحلیل انرژی و اگزرژی عملکرد یک موتور اشتعال جرقه‌ای با استفاده از مدل احتراق دوناحیه‌ای

نوع مقاله : مقاله پژوهشی

نویسندگان

دانشکده فنی مهندسی، دانشگاه اصفهان، اصفهان، ایران

چکیده

امروزه با تکیه بر روش‌های عددی می‌توان عملکرد موتور را با دقت بسیار مناسبی شبیه‌سازی نمود و راهکارهای بهینه سازی عملکرد موتور را بررسی کرد. با توجه به این که در موتور حدود 30 درصد از انرژی سوخت از طریق انتقال حرارت  به دیواره‌های سیلندر هدر می‌رود، به دست آوردن نتایج مناسب از یک مدل شبیه سازی نیازمند محاسبه انتقال حرارت با دقت بالا است. مدل ترمودینامیکی ارائه شده در این مقاله، با هدف بهینه‌سازی یک موتور اشتعال جرقه‌ای، سیکل موتور را به صورت دو‌ناحیه‌ای، که برای موتور اشتعال جرقه‌ای مناسب است، شبیه سازی می‌نماید. جهت انتخاب بهترین مدل برای انتقال حرارت در موتور احتراق جرقه‌ای، مدل‌های مختلف در شبیه‌سازی استفاده شده و پس از مقایسه نتایج هر مدل با نتایج تجربی موتور مورد مطالعه، مدل هوهنبرگ به عنوان مدل مناسب برای انتقال حرارت موتورهای اشتعال جرقه‌ای معرفی گردیده است. نتایج نشان‌داد که با افزایش نسبت تراکم به میزان 18 درصد، تلفات اگزرژی از اگزوز موتور و انتقال حرارت از بدنه تقریباً 2 درصد کاهش می‌یابد در حالی که توان خروجی بیش از 4 درصد افزایش می یابد. همچنین، بیشینه راندمان انرژی و اگزرژی در هنگامی که احتراق 5 درجه قبل از نقطه مرگ بالا رخ دهد، حاصل می شود.

کلیدواژه‌ها

موضوعات


عنوان مقاله [English]

Energy and Exergy Analyses of the Performance of a Spark Ignition Engine Using Two-Zone Combustion Model

نویسندگان [English]

  • Ehasn Baniasadi
  • Hamidreza Abbasi Varzaneh
Assistant Professor / University of Isfahan
چکیده [English]

Relying on numerical methods, it is possible to estimate the performance of an engine precisely, and to evaluate the optimization methods of the engine. Almost 30% of the fuel energy is dissipated through the cylinder walls, therefore, accurate calculation of heat transfer rate is necessary to yield reliable results from the simulation model. The thermodynamic model in this paper, that is developed to optimize the performance of a spark ignition engine, utilizes the two-zone combustion model that is suitable for this type of engine. Different models for heat transfer in the engine are used in simulation and compared with available experimental data, and the Hohenberg model is identified as the most precise heat transfer model for spark ignition engine. The results indicate that increase of the compression ratio by 18% leads to almost 2% lower exergy destruction due to engine exhaust and heat transfer to the enegin body, however, the engine power output increases by about 4%. Also, it is concluded that the maximum energy and exergy efficiencies are obtained when combustion takes place 5 degree before top dead center.

کلیدواژه‌ها [English]

  • Thermodymaic model
  • Spark ignition engine
  • Energy and Exergy analysis
  • Heat ransfer and burning rate
  • Two-zone model
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