A Fundamental Thermodynamic Study on the Effects of Engine Scale in Diesel Engines

2019 ◽  
Author(s):  
Kevin J. Burnett ◽  
Ashwani K. Gupta ◽  
Jim S. Cowart
Keyword(s):  
Heat Transfer ◽  
Surface Area ◽  
Wall Temperature ◽  
Diesel Engines ◽  
Cold Start ◽  
Cylinder Wall ◽  
Piston Speed ◽  
Heat Effects ◽  
Wide Range ◽  
Significant Difference

Abstract The Navy has a wide range of diesel engines with bore sizes varying by a factor of four. In general, diesel engines can have bore scaling over a full order of magnitude. As an engine cylinder gets larger its surface area to volume ratio reduces significantly, which in turn affects in-cylinder heat transfer. In this study, a fundamental generalized thermodynamic model of diesel engines was developed. The various key model effects were systematically analyzed along with engine bore size. Further, cylinder wall temperature was varied across a range of cold start to stabilized operating temperatures. The results of this study show that smaller bore diesel engines are always more sensitive to cold start conditions. The effect is reduced with increasing wall temperature yet smaller diesel engines have cooler end-of-compression temperatures as comparted to larger engines. The effects of engine speed, in which mean piston speed is held constant, tend to modestly reduce the differences between various size diesel engines due to non-linear heat transfer effects. When variable specific heat effects are correctly considered, end-of-compression air charge temperatures are only modestly different as a function of engine bore size. The most significant difference is the overall reduced heat transfer in larger engines due to the surface area to volume effect. A difference of a factor of three for in cylinder heat transfer relative to in-cylinder inducted air mass is predicted being much greater for the smaller engines. Higher exhaust temperatures are also characteristic of the larger bore engines. This allows more combustion work to be delivered to the piston with a correspondingly higher thermal efficiency for larger diesel engines. Future work will evaluate fuel effects on varying bore size.

Engine Cycle-by-Cycle Cylinder Wall Temperature Observer-Based Estimation Using Cylinder Pressure Signals

2011 ◽  
Author(s):  
Fengjun Yan ◽  
Junmin Wang
Keyword(s):  
Heat Transfer ◽  
Wall Temperature ◽  
Disturbance Observer ◽  
Fuel Injection ◽  
Cold Start ◽  
Estimation Methods ◽  
Frequency Noise ◽  
Cylinder Wall ◽  
Cylinder Pressure ◽  
Temperature Estimation

Estimating cylinder wall temperature before start of fuel injection in a dynamic and cycle-by-cycle way is important for advanced combustion mode engine control, particularly during cold-start and transient operations. In this paper, two methods for cylinder wall temperature estimation, based on disturbance observer designs, are proposed. The heat transfer through cylinder wall is viewed as a disturbance in total heat release. With disturbance observers, this heat transfer can be estimated in finite time and thus to calculate the cylinder wall temperature. To handle the high frequency noise issues in cylinder pressure signals, a robust disturbance observer is proposed and compared with a typical design method. The effectiveness of such cylinder wall temperature estimation methods are demonstrated and compared with engine experimental data obtained during a cold-start process.

ENTRANCE EFFECTS OF THERMAL CREEP ON FLUID HEATING IN RECTANGULAR MICROCHANNELS

2013 ◽  
Vol 24 (08) ◽  
pp. 1350054 ◽  
Author(s):  
ALI AMIRI-JAGHARGH ◽  
HAMID NIAZMAND ◽  
METIN RENKSIZBULUT
Keyword(s):  
Heat Transfer ◽  
Wall Temperature ◽  
Temperature Jump ◽  
Velocity Slip ◽  
Temperature Gradients ◽  
Thermal Creep ◽  
Constant Wall Temperature ◽  
Rectangular Microchannels ◽  
Aspect Ratios ◽  
Wide Range

The effects of thermal creep on the development of gaseous fluid flow and heat transfer in rectangular microchannels with constant wall temperature are investigated in the slip-flow regime. Thermal creep arises from tangential temperature gradients, which may be significant in the entrance region of channels, and affects the velocity and temperature fields particularly in low Reynolds number flows. In the present work, the Navier–Stokes and energy equations coupled with velocity-slip and temperature-jump conditions applied at the channel walls are solved numerically using a control-volume technique. Despite the constant wall temperature, tangential temperature gradients form in the gas layer adjacent to the wall due to the temperature-jump condition. The effects of slip/jump and thermal creep on the flow patterns and parameters are studied in detail for a wide range of channel aspect ratios and, Knudsen and Reynolds numbers. Furthermore, the effects of variable properties on velocity-slip and, friction and heat transfer coefficients are also examined.

Heat Transfer in Liquid-Liquid Taylor Flow in a Mini-Scale Tube With Constant Wall Temperature

2015 ◽  
Author(s):  
W. M. Adrugi ◽  
Y. S. Muzychka ◽  
K. Pope
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Enhancement ◽  
Wall Temperature ◽  
Silicone Oil ◽  
Transfer Enhancement ◽  
Constant Wall Temperature ◽  
Flow Rates ◽  
Taylor Flow ◽  
Low Viscosity ◽  
Wide Range

In this paper, heat transfer enhancement using liquid-liquid Taylor flow is examined. The experiments are conducted in mini-scale tubes with constant wall temperature. The segmented flow is created using several fractions of low viscosity silicone oil (1 cSt) and water for a wide range of flow rates and segment lengths. The variety of liquids and flow rates change the Prandtl, Reynolds, and capillary numbers. The dimensionless mean wall flux and the dimensionless thermal flow length are used to analyze the experimental heat transfer data. The comparison shows the heat transfer rate for Taylor flow is higher than in single-phase flow. The heat transfer enhancement occurs due to internal circulation in the fluid segments.

Theoretical Distributions of Heat Transfer Downstream of a Backstep in Supersonic Turbulent Flow

1972 ◽  
Vol 94 (1) ◽  
pp. 87-94 ◽  
Author(s):  
J. P. Lamb ◽  
C. G. Hood
Keyword(s):  
Heat Transfer ◽  
Flow Field ◽  
Turbulent Flow ◽  
Wall Temperature ◽  
Control Volume ◽  
Convective Transport ◽  
Transport Processes ◽  
Independent Variables ◽  
Test Conditions ◽  
Wide Range

A physically perceptive model is presented for the flow field and convective transport processes in the vicinity of reattachment of a planar, supersonic, turbulent flow. Control volume methods are utilized extensively in the analysis and the restating integral equations are solved by various numerical search techniques. The analysis enables one to determine significant parameters in the flow field as well as the heat transfer distribution and associated wall temperature of the reattachment surface. Also presented is a general correlation of predicted results for the convection process in terms of pertinent independent variables. The correlated results are shown to agree with measurements for a wide range of test conditions.

scholarly journals Review of the Wall Temperature Prediction Capability of Available Correlations for Heat Transfer at Supercritical Conditions of Water

2013 ◽  
Vol 2013 ◽  
pp. 1-13 ◽  
Author(s):  
Dhanuskodi Ramasamy ◽  
Arunagiri Appusamy ◽  
Anantharaman Narayanan
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Wall Temperature ◽  
Mass Flux ◽  
Flux Ratio ◽  
Temperature Prediction ◽  
Heat Transfer Deterioration ◽  
Error Band ◽  
Wide Range ◽  
Data Points

The validity of the wall temperature predictions by 18 correlations available in the literature for supercritical heat-transfer regimes of water was verified for 12 experimental datasets consisting of 355 data points available in the literature. The correlations were ranked based on criteria like % data with <5% error, % data with <10°C error and minimum error band in temperature prediction. Details of the best fitting correlations were tabulated. The analysis indicated that for normal heat-transfer conditions, most of the correlations give close predictions. However, at deteriorated heat transfer regimes, only very few prediction points are closer to experimental value. Also, in the ranking process, the first position keeps varying, and no one correlation shall be said as the best for all experiments. Evaluation of the applicability of heat flux to mass-flux-ratio-based prediction of heat-transfer deterioration indicated 75% agreement. The empirical formulae linking mass flux for the prediction of the starting heat flux for heat-transfer deterioration indicated 58.33% of agreement. This review indicated that continued precise experimentation covering wide range of parameter conditions near pseudocritical regime and development of correlations is felt necessary for the accurate prediction of supercritical fluid heat transfer.

scholarly journals Monitoring of the states of malfunction of the EGR system in TDCi engines fueled with Ekodiesel Ultra and B10 fuel

2013 ◽  
Vol 153 (2) ◽  
pp. 83-93
Author(s):  
Bogusław Cieślikowski ◽  
Janusz Jakóbiec
Keyword(s):  
Heat Transfer ◽  
Infrared Spectroscopy ◽  
Mass Exchange ◽  
Diesel Engines ◽  
Diesel Oil ◽  
Energy Dispersive ◽  
Formal Description ◽  
X Ray ◽  
Intake System ◽  
Wide Range

The paper discusses the identification of malfunctions in the EGR system based on a list of OBD II error codes. The authors monitored EGR systems of vehicles fitted with DURATORQ TDCi engines. The Analysis of the processes of heat transfer and mass exchange in the engine intake system drew attention to a number of simplifications in the formal description introducing a wide range of tolerance for the instantaneous recirculation rate. The aim of this study was to determine the influence of diesel oil, Ekodiesel Ultra with biocomponents and B10 fuel used for the fueling of diesel engines on the formation of deposits in the EGR system. The analysis was performed in a laboratory utilizing the methods of energy dispersive X-ray fluorescence and infrared spectroscopy.

Experimental Study of Heat Transfer in a Direct Injection Diesel Engine

2020 ◽  
Vol 12 (1) ◽  
Author(s):  
P. Raghu ◽  
R. Sundarrajan ◽  
R. Rajaraman ◽  
M. Ramaswamy ◽  
B. Sathyanaryanan
Keyword(s):  
Heat Transfer ◽  
Experimental Study ◽  
Diesel Engine ◽  
Heat Transfer Rate ◽  
Transfer Rate ◽  
Engine Speed ◽  
Direct Injection ◽  
Cylinder Wall ◽  
Direct Injection Diesel Engine ◽  
Wide Range

An experimental study has been established to understand the effective cylinder wall heat transfer rate and temperature of a direct injection diesel engine. Temperatures were calculated under a wide range of load at different locations in the cylinder block and cylinder head of the engine using pre-arranged thermocouples to acquire the temperature gradient and consequently realize the equivalent heat transfer rate, cylinder wall temperatures, heat transfer co-efficient and engine speed. Diesel and biodiesel blends (B20 and B100) are used as fuels and the temperature readings are found using a ‘k-type’ thermocouple and temperature readings are noted. Raise in the cylinder temperature is observed as the engine torque increases for the diesel and biodiesel. As the engine speed increases, the exhaust gas velocity involved in and out of the engine will increases and this lead to an increase in the heat transfer co-efficient for diesel and biodiesel.

Similarity Solution of Unaxisymmetric Heat Transfer in Stagnation-Point Flow on a Cylinder With Simultaneous Axial and Rotational Movements

2008 ◽  
Vol 130 (5) ◽  
Author(s):  
Asghar B. Rahimi ◽  
Reza Saleh
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Stagnation Point ◽  
Wall Temperature ◽  
Similarity Solution ◽  
Free Stream ◽  
Wall Heat Flux ◽  
Cylinder Wall ◽  
Local Coefficient ◽  
Unsteady Viscous Flow

Similarity solution of unaxisymmetric heat transfer of an unsteady viscous flow in the vicinity of an axisymmetric stagnation point of an infinite circular cylinder with simultaneous axial and rotational movement along with transpiration Uo is investigated when the angular velocity, axial velocity, and wall temperature or wall heat flux vary arbitrarily with time. The impinging free stream is steady and with a strain rate of k¯. The results presented are found by numerical integration. The local coefficient of heat transfer (Nusselt number) is found to be independent of time and place, though the cylinder wall temperature or wall heat flux are functions of both time and place.

An Analysis of Laminar Free and Forced Convection between Finite Vertical Parallel Plates

1973 ◽  
Vol 95 (1) ◽  
pp. 53-59 ◽  
Author(s):  
J. Quintiere ◽  
W. K. Mueller
Keyword(s):  
Heat Transfer ◽  
Forced Convection ◽  
Wall Temperature ◽  
Parallel Plates ◽  
Constant Property ◽  
Uniform Wall Temperature ◽  
Approximate Analytical Solutions ◽  
Wide Range ◽  
Free And Forced Convection ◽  
Prandtl Numbers

Approximate analytical solutions are presented for constant-property laminar free- and forced-convection flows between finite vertical parallel plates. For free convection, the thermal boundary conditions considered include the thermally symmetric channel with uniform wall temperature or step change in wall temperature and the unsymmetric channel with uniform but unequal wall temperatures. For forced convection and combined free and forced convection, the thermally symmetric and uniform thermal boundary condition is considered. Where possible, results are compared with available numerical and experimental results. Particular attention is given to heat-transfer results, which cover a wide range of Rayleigh and Prandtl numbers. For combined convection the heat-transfer results are related to the impressed pressure difference and flow rate.

Sign in / Sign up

Export Citation Format

Share Document