scholarly journals In-Cylinder Heat Transfer Characteristics of Hydrogen Fueled Engine: A Steady State Approach

2010 ◽  
Vol 6 (2) ◽  
pp. 124-129 ◽  
Author(s):  
Rahman
Author(s):  
Agarwal A ◽  
◽  
Molwane O.B ◽  
Letsatsi M.T ◽  
◽  
...  

During braking process, the kinetic energy of vehicle reduces and gets converted in thermal energy due to friction between disk and brake pads. The disk brake is used to retard the motion of vehicle by pressing brake pads against disk rotors. The frequent braking or panic braking results in overheating of brake disks which may result in brake fade. It is therefore essential to test newer materials which are more effective and possess better heat transfer characteristics than conventional cast iron material. The current research investigates the application of Al MMC material for ATV disk brake using experimental and numerical techniques. The numerical analysis is conducted on both conventional cast iron and Al MMC disk brake under steady state conditions and dynamic conditions. The dynamic condition testing involved testing of disk brake with externally flowing air at 2.5m/s and 5m/s using techniques of Computational Fluid Dynamics (CFD). The CAD model of ATV disk brake is developed in Creo design software and CFD analysis is conducted using ANSYS CFX. The turbulence model used for analysis is RNG k-epsilon. The temperature and heat flux are determined for disk brake under steady state and dynamic conditions. The results have shown that disk brake made from Al MMC possess better heat transfer characteristics as compared to conventional cast iron and cooling time also reduces with increase in external air speed.


Author(s):  
C. Y. Lee ◽  
C. J. Fang ◽  
C. H. Peng ◽  
T. W. Lin ◽  
Y. H. Hung

An effective method of design of experiments combined with Central Composite Design for exploring the heat transfer characteristics for a confined rotating Multi-Chip Module (MCM) disk with round jet array impingement has been successfully developed. The relevant parameters influencing heat transfer performance include the steady-state Grashof number (Grs), ratio of jet separation distance to nozzle diameter (H/d), jet Reynolds number (Rej) and rotational Reynolds number (Rer). Their effects on heat transfer characteristics have been systematically explored. An axisymmetrical temperature distribution is ensured for various Grs, Rej, Rer and H/d ratios. As compared with the mutual effects of jet array impingement and disk rotation cause a more non-uniform distribution of chip temperatures. For heat transfer behavior, a new correlation of stagnation Nusselt number for jet array impingement at r/R = 0 in terms of Rej and H/d is presented. As compared with the experimental steady-state data of single round jet impingement, the average heat transfer enhancement at stagnation point r/R = 0 of jet array impingement is 607%. For the rotating MCM disk cases, the highest chip heat transfer occurs at the MCM disk rim, and decreases sharply along the distance from the surface edge toward the surface center.


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