One of the most common problems related to brake discs is overheating, which negatively affects braking performance especially under the continuous braking conditions of vehicles. Ventilation applications on brake discs can significantly improve the brake system performance by reducing the heating of the discs. In this study, the thermal behaviors of ventilated brake discs using three different configurations were investigated at continuous brake conditions in terms of heat generation and thermal stresses with finite element analysis. The results were compared with a solid disc. Heat generation on solid brake discs reduced to a maximum of 24% with ventilation applications. The experimental study indicated finite element temperature analysis results in the range between 1.13% and 10.87%. However, thermal stress formations were higher with ventilated brake discs in comparison to those with solid discs.

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This article has been retracted at the request of the Editor-in-chief, since substantial parts of this article were previously published in Tribology in Industry: A. Belhocine , N.M. Ghazali, O.I. Abdullah. Structural and Contact Analysis of a 3-Dimensional Disc-Pad Model with and without Thermal Effects. 2014. Tribology in Industry 36(4): 406—418 (2014).

Geleneksel gama tipi Stirling motorlarında iki silindir mevcut olup silindirlerden birisi aracılığı ile çalışma gazının sıkıştırılması ve genişletilmesi işlemleri, diğeri aracılığı ile çalışma gazının sabit hacimde ısıtılması ve soğutulması işlemleri gerçekleştirilmektedir. Geleneksel gama tipi motorlarda soğuk ve sıcak hacimlerin aynı silindirde bulunması nedeni ile sıcak uçtan soğuk uca iletimle önemli bir miktarda ısı kaybı olmaktadır. Ayrıca dispileyser’ in yapımı oldukça külfetli bir iştir. Bu problemleri yok etmek için, son zamanlarda sıcak ve soğuk hacimleri ayrı ayrı silindirlerde bulunan üç silindirli gama tipi bir motor modeli tanıtılmıştır. Bu motorlarda bulunan silindirlerden birisi sıcak hacim olarak bir diğeri soğuk hacim olarak üçüncüsü de güç silindiri olarak görev yapmaktadır. Bu motorların termodinamik süreçleri geleneksel gama tipi motorunkine çok benzediği için bunlara üç silindirli gama tipi motor adı verilmiştir. Her üç silindirin içerisinde alışılmış tipten pistonlar çalışmaktadır. Bu araştırmada geleneksel gama tipi bir motorun ve üç silindirli gama tipi bir motorun nodal termodinamik analizleri yapılarak performansları kıyaslanmıştır. Motorların çevrimlik işlerinin ve verimlerinin birbirine çok yakın olduğu görülmektedir. Yüksek hızlarda ve yüksek basınçlarında geleneksel gama tipi motorun, yüksek sıkıştırma oranında ise üç silindirli gama tipi motorun az miktarda avantajlı olduğu görülmektedir.

Theoretical and experimental investigations indicate that at high loads such as 3/4 throttling or more and high speeds such as 3000 rpm or more, the exhaust gas temperatures of the Internal Combustion engines are about 900-1000 K. The amount of heat wasted with exhaust gas of the Internal Combustion engines is equivalent to the power of them. By considering this feature of the Internal Combustion engines, a Hybrid engine consisting of an Internal Combustion (IC) engine and a gamma type Stirling engine was proposed and analyzed from the thermodynamic point of view. Hybrid engine is formed by combining the Stirling and IC engines via a common crankshaft and a common cylinder. The Internal Combustion engine may be a four stroke Diesel engine having an unconventional piston consisting of a crown and a rod. Via using this kind of pistons, two chambers are created in the same cylinder where one of them take part at above of the piston crown, while the other is taking part at below of the piston crown. In the combined engine presented here, the chamber at below of the piston crown is used as the expansion volume of the Stirling engine while the other chamber is being used as operational volume of the Diesel engine. In this study the thermodynamic performance of the Hybrid engine was investigated via using statistical values of common Diesel engines. For Stirling engine; 800 K heater surface temperature, 392 K cooler surface temperature, 800 W/m2K heat transfer coefficient in regenerator, 300 W/m2K heat transfer coefficient in cooler and heater, 250 rad/s engine speed and 12.5 bar air charging pressure were used as principal inputs. The output power of the Diesel engine was assumed to be 120 kW which provides 120 kW heat to Stirling engine. The heat transfer areas of cooler, heater and regenerator were optimized as 0.33 m2, 0.6 m2 and 4.6 m2 respectively. The optimum thermal efficiency and power of the Stirling engine were determined as 47 % and 24 kW. The total thermal efficiency of the combined engine is expected to increase 6 % compared to the stand-alone Internal Combustion engine. For 12.5 bar average gas pressure in the cylinder of Diesel engine, the working fluid mass in the Stirling engine was determined as 17g