Cooling System Optimization in an Air-Cooled CNG Engine Using 3-D CFD Technique

• Main Authors: Nain, Ajay, Nene, Devendra, Unnithan, Sarat
• Format: Report
• Language: English
• Subjects: Conjugate heat transfer; Finite element analysis; Heat transfer coefficient; Moving reference frame
• ISSN: 0148-7191; 2688-3627
• DOI: 10.4271/2022-01-0206

Aluminium alloy material cylinder head is a popular choice for any air-cooled internal combustion engine. But when it is exposed to higher temperature, it is vulnerable for its loss in strength. It becomes imperative to maintain cylinder head temperature well below acceptable temperature limit. Efficient cooling system play a vital role to achieve this objective. In the present work, an air-cooled diesel engine is converted into compressed natural gas (CNG) engine configuration for 25kVA genset configuration. A 1D gas-exchange model is created to generate the thermal boundary conditions required for Computational Fluid Dynamics (CFD) analysis. A steady-state 3D Conjugate Heat Transfer (CHT) model, that uses the predicted in-cylinder temperatures as a spatially varying boundary condition, is created to predict the convective heat transfer between engine fins and cooling air. A Blower Fan is modelled using the Moving Reference Frame (MRF) approach. Liner and Cylinder Head Fin temperature predicted using conjugate heat transfer method is validated for a baseline case with the experimental data. Base model HTCs and temperatures are considered limits for new CNG configurations and optimum cooling air flow rates are evaluated. This new cooling system is also experimentally verified for its effectiveness.