A Model for Drilled Cooling in the Valve Bridge of Cylinder Head

2011 ◽  
Vol 52-54 ◽  
pp. 338-342
Author(s):  
Xiao Liu ◽  
Wei Zheng Zhang ◽  
Chang Hu Xiang
Keyword(s):  
Heat Transfer ◽  
Mathematical Model ◽  
Heat Transfer Coefficient ◽  
Diesel Engine ◽  
Theoretical Analysis ◽  
Transfer Coefficient ◽  
Cylinder Head ◽  
3D Model ◽  
Numerical Study ◽  
The Mathematical Model

To evaluate the efficiency of drilled cooling in the valve bridge of cylinder head, theoretical analysis for the drilled cooling is carried out, and a mathematical model for the enhanced cooling is presented based on a simplified 3D model. The mathematical model is validated by numerical study on the heat transfer with and without drilled cooling, which is carried out through fluid-solid coupling. The correlation between the velocity in the drilled passage and heat transfer coefficient was also analyzed. The results can be used to solve the heat transfer in enhanced diesel engine.

Measurement and Calculation of Heat Exchanger Performance Using Film Method

Volume 3 ◽  
2004 ◽  
Author(s):  
Che´rif Bougriou ◽  
Rachid Bessai¨h ◽  
Kerstin Eckert ◽  
Mahfoud Kadja
Keyword(s):  
Heat Transfer ◽  
Mathematical Model ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Computer Code ◽  
Method Of Calculation ◽  
Finned Tubes ◽  
The Mathematical Model ◽  
The Heat Transfer Coefficient ◽  
Film Method

In this paper, we present a method of calculation by partial or total condensation of the water vapor contained in the humid air, over the smooth or finned tubes-heat recupurators. This study presents an implantation of the film method in a computer code developed here. The mathematical model used is validated by our experimental approach, using tubes bundles in staggered and aligned arrangements. The heat transfer coefficient by convection around the fin is supposed too be constant. The computer code predicts the heat flux exchanged in a range of 20% and 5%, in wet and dry regime, respectively. The apparent heat transfer coefficient by condensation can exceed 10 times the value of the heat transfer coefficient. The mathematical model used is validated with the experimental data obtained in this study.

Study of Convective Heat Transfer Coefficient of High Pressure Water Descaling

2014 ◽  
Vol 599-601 ◽  
pp. 1976-1980
Author(s):  
Peng Gao
Keyword(s):  
Heat Transfer ◽  
Mathematical Model ◽  
High Pressure ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Convective Heat Transfer Coefficient ◽  
Pressure Water ◽  
The Mathematical Model

In order to improving the product quality of hot rolled plate, the iron scale was removed by high pressure water descaling before hot rolling. The billet temperature dropped when a large amount of high pressure water injected on the billet surface. Establishing reasonably mathematical model of temperature field was very important, because it was related to formulate correctly rolling technology. High pressure water descaling convection heat transfer coefficient was an important parameter in the mathematical model of the temperature field. This paper calculated the high pressure water convection heat transfer coefficient by the method of numerical simulation, and regressed the mathematical model of the high pressure water coefficient of convective heat transfer by nonlinear regression method. The author used this mathematical model for finite element analysis in a steel mill, the results showed that the simulation results agreed with the experimental results, the mathematical model of high pressure water descaling convective heat transfer coefficient was reasonable.

scholarly journals On Heat Transfer enhancement in Diesel Engine Cylinder Head Using γ-Al2O3/water nanofluid with different nanoparticle sizes

2020 ◽  
Vol 12 (1) ◽  
pp. 168781401989750 ◽  
Author(s):  
Mohsen Salem Radwan ◽  
Hosam E Saleh ◽  
Youssef Ahmed Attai ◽  
Mohamed Salah Elsherbiny
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Diesel Engine ◽  
Transfer Coefficient ◽  
Flow Velocity ◽  
Cylinder Head ◽  
Operating Conditions ◽  
Bulk Temperature ◽  
Engine Cylinder ◽  
Nanoparticle Sizes

In the current work, an experimental investigation of γ-Al2O3/water characteristics nanofluid was performed for convective cooling of engine cylinder head for fully developed turbulent regime. Nanoparticles of different sizes were mixed in distilled water with constant volume fraction of 1% through the experiments. The cylinder head was simulated as a rectangular duct, of an aspect ratio of 0.8, with a cast iron test specimen from actual cylinder head of diesel engine. The effect of different nanoparticle sizes (30, 100, and 150 nm), bulk temperature (60°C, 70°C, and 80°C), and flow velocity (1, 1.5 and 2 m/s) were investigated at variable heat fluxes. The experimental results revealed that the obtained enhancement of convective heat transfer coefficient is inversely proportional to both nanoparticle diameter and bulk temperature and directly proportional to the coolant flow velocity. Also, the highest achieved enhancement over the pure base fluid in heat transfer coefficient is 88.74% at 30 nm particle size. The γ-Al2O3/water nanofluid showed promising results for intensive study with different operating conditions.

scholarly journals Study on diesel cylinder-head cooling using nanofluid coolant with jet impingement

2015 ◽  
Vol 19 (6) ◽  
pp. 2025-2037 ◽  
Author(s):  
Zhong-Gen Su ◽  
Wei Zheng ◽  
Zhen-Dong Zhang
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Diesel Engine ◽  
Transfer Coefficient ◽  
Cylinder Head ◽  
Heat Transfer Performance ◽  
Jet Impingement ◽  
Good Effect ◽  
Transfer Performance ◽  
Engine Cylinder

To improve the heat-transfer performance of a diesel-engine cylinder head, nanofluid coolant as a new fluid was investigated, and jet impingement technology was then used to study on how to better improve heat-transfer coefficient at the nose bridge area in the diesel-engine cylinder head. Computational fluid dynamic simulation and experiments results demonstrated that using the same jet impingement parameters, the different volume shares of nanofluids showed better cooling effect than traditional coolant, but the good effect of the new cooling method was unsuitable for high volume share of nanofluid. At the same volume share of nanofluid, different jet impingement parameters such as jet angles showed different heat-transfer performance. This result implies that a strong association exists between jet impingement parameters and heat-transfer coefficient. The increase in coolant viscosity of the nanofluid coolant using jet impingement requires the expense of more drive-power cost.

Numerical Study on the Influence of Trench Width on Film Cooling Characteristics of Double-Wave Trench

2017 ◽  
Author(s):  
Bo-lun Zhang ◽  
Li Zhang ◽  
Hui-ren Zhu ◽  
Jian-sheng Wei ◽  
Zhong-yi Fu
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Film Cooling ◽  
Numerical Study ◽  
Leading Edge ◽  
Cooling Effectiveness ◽  
Film Cooling Effectiveness ◽  
Blowing Ratio ◽  
Trench Width

Film cooling performance of the double-wave trench was numerically studied to improve the film cooling characteristics. Double-wave trench was formed by changing the leading edge and trailing edge of transverse trench into cosine wave. The film cooling characteristics of transverse trench and double-wave trench were numerically studied using Reynolds Averaged Navier Stokes (RANS) simulations with realizable k-ε turbulence model and enhanced wall treatment. The film cooling effectiveness and heat transfer coefficient of double-wave trench at different trench width (W = 0.8D, 1.4D, 2.1D) conditions are investigated, and the distribution of temperature field and flow field were analyzed. The results show that double-wave trench effectively improves the film cooling effectiveness and the uniformity of jet at the downstream wall of the trench. The span-wise averaged film cooling effectiveness of the double-wave trench model increases 20–63% comparing with that of the transverse trench at high blowing ratio. The anti-counter-rotating vortices which can press the film on near-wall are formed at the downstream wall of the double-wave trench. With the double-wave trench width decreasing, the film cooling effectiveness gradually reduces at the hole center-line region of the downstream trench. With the increase of the blowing ratio, the span-wise averaged heat transfer coefficient increases. The span-wise averaged heat transfer coefficient of the double-wave trench with 0.8D and 2.1D trench width is higher than that of the double-wave trench with 1.4D trench width at the high blowing ratio conditions.

Conjugate Heat Transfer From a Heated Disk to a Thin Liquid Film Formed by a Controlled Impinging Jet

1993 ◽  
Vol 115 (1) ◽  
pp. 116-123 ◽  
Author(s):  
A. Faghri ◽  
S. Thomas ◽  
M. M. Rahman
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Conjugate Heat Transfer ◽  
Numerical Study ◽  
Heated Surface ◽  
Thin Liquid Film ◽  
Impinging Jet ◽  
Numerical Predictions ◽  
Heated Disk

An experimental and numerical study of the heat transfer from a heated horizontal disk to a thin film of liquid is described. The liquid was delivered to the disk by a collar arrangement such that the film thickness and radial velocity were known at the outer radius of the collar. This method of delivery is termed as a controlled impinging jet. Flow visualization tests were performed and heat transfer data were collected along the radius of the disk for different volumetric flow rates and inlet temperatures in the supercritical and subcritical regions. The heat transfer coefficient was found to increase with flow rate when both supercritical and subcritical regions were present on the heated surface. A numerical simulation of this free surface problem was performed, which included the effects of conjugate heat transfer within the heated disk and the liquid. The numerical predictions agree with the experimental results and show that conjugate heat transfer has a significant effect on the local wall temperature and heat transfer coefficient.

Two Phase Flow Simulation for Nucleate Boiling Heat Transfer Calculation in Waterjacket of Diesel Engine

2011 ◽  
Author(s):  
Arash Mohammadi ◽  
Hossein Hashemi ◽  
Ali Jazayeri ◽  
Mahdi Ahmadi
Keyword(s):  
Heat Transfer ◽  
Temperature Field ◽  
Diesel Engine ◽  
Transfer Coefficient ◽  
Cylinder Head ◽  
Boiling Heat Transfer ◽  
Cooling System ◽  
Nucleate Boiling ◽  
Two Phase ◽  
Phase Mixture

Basic understanding of the process of coolant heat transfer inside an engine is an indispensable prerequisite to devise an infallible cooling strategy. Coolant flow and its heat transfer affect the cooling efficiency, thermal load of heated components, and thermal efficiency of a diesel engine. An efficient approach to study cooling system for diesel engine is a 3D computational fluid dynamics (CFD) calculation for coolant jacket. Therefore, computer simulation can analyze and consequently optimize cooling system performance, including complex cooling jacket. In this paper a computational model for boiling heat transfer based on two-phase Mixture model flow is established. Furthermore, the phenomenon of nucleate boiling, its mathematical modeling, and its effect on heat transfer is discussed. Besides, the static, total and absolute pressure, velocity and stream lines of the flow field, heat flux, heat transfer coefficient and volume fraction of vapor distribution in the coolant jacket of a four-cylinder diesel engine is computed. Also, comparison between experimental equation (Pflaum/Mollenhauer) and two-phase Mixture model for boiling hat transfer coefficient is done and good agreement is seen. In conclusion, it is observed that at high operating temperatures, nucleate boiling occurs in regions around the exhaust port. Numerical simulation of boiling heat transfer process of cooling water jacket and temperature field in the cylinder head of the diesel engine is compared with the data measured on the engine test bench. The calculated results indicate that this method can reflect the impact of boiling heat transfer on water jacket rather accurate. Therefore, this method is benefit to improve the computational precision in the temperature field computation of a cylinder head.

Thermal modelling of modern diesel engines: proposal of a new heat transfer coefficient correlation

2011 ◽  
Vol 225 (11) ◽  
pp. 1544-1560 ◽  
Author(s):  
C A Finol ◽  
K Robinson
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Heat Transfer Coefficient ◽  
Diesel Engine ◽  
Transfer Coefficient ◽  
Diesel Engines ◽  
Internal Combustion Engines ◽  
Operating Conditions ◽  
Boost Pressure ◽  
Simple Relationship

Existing methods for predicting heat fluxes and temperatures in internal combustion engines, which take the form of correlations to estimate the heat transfer coefficient on the gas-side of the combustion chamber, are based on methodology developed over the past 50 years, often updated in view of more recent experimental data. The application of these methods to modern diesels engines is questionable because key technologies found in current engines did not exist or were not widely used when those methods were developed. Examples of such technologies include: high-pressure common rail and variable fuel injection strategies including retarded injection for nitrogen oxides emission control; exhaust gas re-circulation; high levels of intake boost pressure provided by a single- or double-stage turbocharger and inter-cooling; multiple valves per cylinder and lower swirl; and advanced engine management systems. This suggests a need for improved predicting tools of thermal conditions, specifically temperature and heat flux profiles in the engine block and cylinder head. In this paper a modified correlation to predict the gas-side heat transfer coefficient in diesel engines is presented. The equation proposed is a simple relationship between Nu and Re calibrated to predict the instantaneous spatially averaged heat transfer coefficient at several operating conditions using air as gas in the model. It was derived from the analysis of experimental data obtained in a modern diesel engine and is supported by a research methodology comprising the application of thermodynamic principles and fundamental equations of heat transfer. The results showed that the new correlation adequately predicted the instantaneous coefficient throughout the operating cycle of a high-speed diesel engine. It also estimated the corresponding cycle-averaged heat transfer coefficient within 10 per cent of the experimental value for the operating conditions considered in the analysis.

Experimental and Numerical Study on the Convective Heat Transfer and Pressure Loss in Rectangular Ducts With Inclined Pin-Fin on a Wavy Endwall

2012 ◽  
Author(s):  
K. Takeishi ◽  
Y. Oda ◽  
Y. Miyake ◽  
Y. Motoda
Keyword(s):  
Heat Transfer ◽  
Mass Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Pressure Loss ◽  
Numerical Study ◽  
Average Heat Transfer Coefficient ◽  
Average Heat ◽  
Pin Fin ◽  
Pin Fins

Local endwall heat transfer characteristics and overall pressure loss of normal and inclined pin fins arrayed in rectangular ducts with flat and wavy endwalls have been investigated to improve the cooling efficiency of jet engine combustor liners. The detailed time-mean local Nusselt number profiles were measured using a naphthalene sublimation method based on the heat/mass transfer analogy. Four kinds of angled pin fins (−45, 0, and +45 degrees with a flat endwall, and −45 degrees with a wavy endwall) were tested and compared with each other. As a result, the average heat transfer coefficient on the flat endwall of normal pin fins was higher than that of the angled pin fins. The average heat transfer coefficient of −45-degree inclined pin fins with a wavy endwall is the same or a little higher than the heat transfer coefficient of those with a flat endwall; however, the pressure loss of the −45-degree inclined pin fins with a wavy endwall is less than the pressure loss of those with a flat endwall. Corresponding numerical simulations using Large Eddy Simulation (LES) with the Mixed Time Scale (MTS) model have been also conducted at Red = 1000 for fully developed regions, and the results have shown good quantitative agreement with mass transfer experiments. It can be concluded that wavy endwalls can realize better heat transfer with less pressure loss as long as the aim consists in enhancing endwall heat transfer in inclined pin-fin channels.

Sign in / Sign up

Export Citation Format

Share Document