Enhancement of Coolant Side Heat Transfer in Water Cooled Engines by Using Finned Cylinder Heads

2005 ◽  
Author(s):  
Mohamed Y. E. Selim ◽  
S. M. S. Elfeky ◽  
A. Helali
Keyword(s):  
Heat Transfer ◽  
Cast Iron ◽  
Flow Velocity ◽  
Forced Convection ◽  
Cylinder Head ◽  
Cast Steel ◽  
Bulk Temperature ◽  
Subcooled Boiling ◽  
Iron Specimen ◽  
Fin Length

An experimental investigation has been carried out for almost the first time to examine the heat transfer by forced convection and subcooled boiling from a finned water-cooled engine cylinder head using steady state technique. Cast iron and cast steel specimens with and without fins have been used in the present work. The effects of flow velocity, coolant bulk temperature, fin length, fin number and fin material have been examined. It has been found that the use of finned cylinder head surface greatly improves the forced convection heat transfer coefficient and subcooled boiling heat flux as the fin length and number influenced the heat transfer process. The cast iron specimen exhibited better heat transfer characteristics over the cast steel one. The effects of bulk flow velocity and temperature for flat and finned specimens have been evaluated for forced convection and subcooled boiling. A correlation has been developed to relate the Nusselt number with Reynolds’ number, Prandtl number, viscosity ratio and fin length ratio, for forced convection from the cast iron specimen, which read: Nu=0.023Re0.697Pr0.33μr0.14(1+A)0.623

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 Experimental study on the correlation of subcooled boiling flow in horizontal tubes

2020 ◽  
pp. 339-339
Author(s):  
Qi Jing ◽  
QingGuo Luo
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Flow Velocity ◽  
Cylinder Head ◽  
Nucleate Boiling ◽  
Coolant Flow ◽  
Inlet Temperature ◽  
Subcooled Boiling ◽  
Water Jacket ◽  
System Pressure

Subcooled boiling is the most effective form of heat exchange in the water jacket of the cylinder head. Chen's model is the most widely used correlation for predicting boiling heat transfer, but the selection of the correlation for the nucleate boiling is controversial. The work of this paper is to simulate the heat transfer process in the water jacket of the cylinder head with a horizontal rectangular channel that is heated on one side. Using the coolant flow velocity, inlet temperature and system pressure as variables, the heat flux and heat transfer coefficient were obtained. The results show that the increase of the coolant flow velocity can effectively promote the convection heat transfer, and the change of inlet temperature and system pressure will affect the occurrence of nucleate boiling. However, the Chen?s model predictions doesn?t fit well with the experimental data. Four nucleate boiling correlations were selected to replace Chen's model nucleate boiling correlation. The correlation proposed by Pioro coincides best with the experimental data. The mean error after correction is 18.2%.

Transient Internal Forced Convection Under Arbitrary Time-Dependent Heat Flux

2013 ◽  
Author(s):  
M. Fakoor-Pakdaman ◽  
M. Andisheh-Tadbir ◽  
Majid Bahrami
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Nusselt Number ◽  
Forced Convection ◽  
Analytical Model ◽  
Time Dependent ◽  
Bulk Temperature ◽  
Fluid Temperature ◽  
Flux Boundary Condition ◽  
Arbitrary Time

A new all-time model is developed to predict transient laminar forced convection heat transfer inside a circular tube under arbitrary time-dependent heat flux. Slug flow condition is assumed for the velocity profile inside the tube. The solution to the time-dependent energy equation for a step heat flux boundary condition is generalized for arbitrary time variations in surface heat flux using a Duhamel’s integral technique. A cyclic time-dependent heat flux is considered and new compact closed-form relationships are proposed to predict: i) fluid temperature distribution inside the tube ii) fluid bulk temperature and iii) the Nusselt number. A new definition, cyclic fully-developed Nusselt number, is introduced and it is shown that in the thermally fully-developed region the Nusselt number is not a function of axial location, but it varies with time and the angular frequency of the imposed heat flux. Optimum conditions are found which maximize the heat transfer rate of the unsteady laminar forced-convective tube flow. We also performed an independent numerical simulation using ANSYS to validate the present analytical model. The comparison between the numerical and the present analytical model shows great agreement; a maximum relative difference less than 5.3%.

Heat Transfer for Forced Convection Past Coiled Wires

1990 ◽  
Vol 112 (4) ◽  
pp. 921-925 ◽  
Author(s):  
M. Dietrich ◽  
R. Blo¨chl ◽  
H. Mu¨ller-Steinhagen
Keyword(s):  
Heat Transfer ◽  
Forced Convection ◽  
Measured Data ◽  
Subcooled Boiling ◽  
Transfer Coefficients ◽  
Heat Transfer Coefficients ◽  
Coil Geometry ◽  
Coil Diameter ◽  
Wide Range ◽  
Laminar And Turbulent Flow

Heat transfer coefficients were measured for forced convection of isobutanol in crossflow past coiled wires with different coil geometries. Flow rate and heat flux have been varied over a wide range to include laminar and turbulent flow for convective sensible and subcooled boiling heat transfer. To investigate the effect of coil geometry on heat transfer, the wire diameter, coil diameter, and coil pitch were varied systematically. The measured data are compared with the predictions of four correlations from the literature.

On The Correlation and Presentation of Information on Turbulent Variable Property Heat Transfer in Tubes

1962 ◽  
Vol 66 (618) ◽  
pp. 397-400 ◽  
Author(s):  
A. J. Ward Smith
Keyword(s):  
Heat Transfer ◽  
Flow Velocity ◽  
Forced Convection ◽  
Subject Matter ◽  
Variable Property ◽  
General Terms ◽  
The Subject ◽  
Thermal Entrance ◽  
Compressibility Effects

This note is concerned with the correlation and presentation of information on heat transfer under conditions of turbulent forced convection for the flow of gases in tubes. Discussion will be confined to the region where thermal entrance effects are absent and, furthermore, it will be assumed that the flow velocity is sufficiently low for compressibility effects to be neglected.The subject matter will be discussed in general terms only and it is not intended to produce quantitative conclusions, which may, however, be found in reference 11.

scholarly journals Investigation of the effect of different materials on convective heat transfer

2020 ◽  
Vol 14 (2) ◽  
pp. 6642-6651
Author(s):  
Abdulwehab Ibrahim ◽  
Perk Lin Chong ◽  
Vicnesvaran Rajasekharan ◽  
Mohamed Muzuhin Ali ◽  
Omar Suliman Zaroong ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Cast Iron ◽  
Natural Convection ◽  
Flat Plate ◽  
Forced Convection ◽  
Air Flow ◽  
Convection Heat Transfer ◽  
Simulation Software ◽  
Convection Flow ◽  
Flow Temperature

Conventionally, the study of convection heat transfer merely focuses on the behavior of air flow without considering the conductive effect of the horizontal flat plate. However, it is expected that the conductive effect of the horizontal plate somewhat affects the air flow temperature across the flat plate. Therefore, it is motivated to study the variation of air flow temperature across different materials of flat plate in various time frame. The materials used in this study are aluminium, stainless steel and cast iron. Infrared camera and FloEFD simulation software are used to measure the upper surface temperature of the flat plate. For forced convection, the study is carried out within the range of 103 £ Re £ 104 and within the range of 1 × 107 £ Ra < 2.2 × 107 for natural convection. Flow velocity of 2.3 m/s, 4.1 m/s and 5.2 m/s are used for the forced convection. The results showed that aluminium plate cools down faster than the other two metal plates used in all scenarios. Stainless steel’s temperature goes down faster compared to cast iron. These results were supported by the fact that aluminium has higher heat transfer rate of other metals. For forced convection, the discrepancies of temperatures between experimental and simulation studies are below 10%, which demonstrates that the results are reasonably acceptable. For natural convection, even though the discrepancies between simulation and experimental results on temperature variations are relatively large, the temperatures varied in similar pattern. This indicates that the results are reliable.

Experimental Study About ONB and Subcooled Boiling Heat Transfer

2004 ◽  
Author(s):  
Changhong Peng ◽  
Aye Myint ◽  
Yun Guo ◽  
Dounan Jia
Keyword(s):  
Heat Transfer ◽  
Boiling Heat Transfer ◽  
Single Phase ◽  
Flow Boiling ◽  
Nucleate Boiling ◽  
Bulk Temperature ◽  
Subcooled Boiling ◽  
Subcooled Flow Boiling ◽  
Subcooled Flow ◽  
Vertical Annuli

Water subcooled boiling heat transfer were experimentally investigated in the vertical annuli with narrow gap. Subcooled flow boiling covers the region from the location where the bubbles forms on the wall to the location where the bulk temperature reaches saturated temperature. Three locations in the subcooled flow boiling have been identified by the earlier researcher as the onset of nucleate boiling (ONB), the beginning of fully developed boiling, the location where the thermodynamic quality is zero that is attained from the enthalpy balance equation. The heat transfer regions are identified as single-phase heat transfer prior to ONB, partial boiling (PB) and fully developed boiling (FDB). In this study, the available models for predicting heat transfer in the different regions and the modified correlation can predict our experimental data.

Forced Convection Heat Transfer in a Finitely Conducting Externally Finned Pipe

1988 ◽  
Vol 110 (3) ◽  
pp. 571-576 ◽  
Author(s):  
F. Moukalled ◽  
S. Acharya
Keyword(s):  
Heat Transfer ◽  
Forced Convection ◽  
Numerical Study ◽  
Convection Heat Transfer ◽  
Axial Direction ◽  
Bulk Temperature ◽  
Convection Heat ◽  
Forced Convection Heat Transfer ◽  
Nusselt Numbers ◽  
Wall Conductivity

A numerical study to determine the influence of axial wall conduction on forced convection heat transfer in an externally finned pipe has been made. The effects of wall conductivity, interfin spacing, and external heat transfer coefficient are examined by comparing the results with the corresponding solutions obtained assuming negligible wall conduction. Results indicate that the axial conduction in the pipe walls has a significant influence on the heat transfer behavior. The bulk temperature or the heat transferred to the fluid is underestimated when wall conduction is ignored. At high wall conductivity values, the wall temperatures and Nusselt numbers exhibit a monotonic variation in the axial direction, with the behavior becoming increasingly nonmonotonic as the wall conductivity value is decreased.

Fluid-to-Fluid Conjugate Heat Transfer for a Vertical Pipe—Internal Forced Convection and External Natural Convection

1980 ◽  
Vol 102 (3) ◽  
pp. 402-407 ◽  
Author(s):  
E. M. Sparrow ◽  
M. Faghri
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Nusselt Number ◽  
Natural Convection ◽  
Forced Convection ◽  
Wall Temperature ◽  
Bulk Temperature ◽  
Vertical Pipe ◽  
Uniform Wall Temperature ◽  
Uniform Wall

An analysis is made of the interactive heat transfer problem involving forced convection flow in a vertical pipe and natural convection boundary layer flow external to the pipe. Both flows are laminar. Solutions of the conservation equations for mass, momentum, and energy were obtained numerically by an iterative scheme which deals successively with the internal and external flows. Remarkably rapid convergence was achieved by adopting a procedure whereby information is transferred between the two flows via heat transfer coefficients rather than via the wall or bulk temperatures or the heat flux. Results are presented for the axial distributions of the internal and external Nusselt numbers, of the wall temperature, and of the bulk temperature of the internal flow—all as a function of three parameters. It was found that at any (dimensionless) axial station, the pipe Nusselt number is insensitive to the parameters and is bounded between the values for uniform wall temperature and uniform wall heat flux. On the other hand, the external natural convection Nusselt number is highly sensitive to the parameters and departs substantially from the standard uniform wall temperature results.

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