Fuel Spray Trajectory in Diesel Engines

1978 ◽  
Vol 100 (2) ◽  
pp. 326-332 ◽  
Author(s):  
M. M. Elkotb ◽  
N. M. Rafat
Keyword(s):  
Heat Transfer ◽  
Theoretical Model ◽  
Working Conditions ◽  
Fuel Spray ◽  
Air Velocity ◽  
Spray Penetration ◽  
Injection Angle ◽  
Velocity Pattern ◽  
Spray Volume ◽  
Spray Velocity

A detailed investigation of the effect of the shape of an open combustion chamber for diesel engine on the air velocity pattern, and consequently, on the trajectory of the fuel spray is given in this paper. A theoretical model for the calculation of the spray penetration, taking into consideration the heat transfer to the droplet, the variation of the drag force with Reynolds number, and air velocity pattern, is suggested. The effect of some working conditions on the spray shape, trajectory, and penetration is experimentally studied to verify the theoretical model and to correlate the results of using different medium pressures, initial spray velocity, and injection angle on the magnitude of fuel spray diameter and spray volume.

Multivariate design and analysis of aircraft HEX under multiple working conditions within flight envelope

2021 ◽  
pp. 1-18
Author(s):  
Qihang Liu ◽  
G.Q. Xu ◽  
Jie Wen ◽  
Yanchen Fu ◽  
Laihe Zhuang ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Working Conditions ◽  
Design Method ◽  
Structural Parameters ◽  
Optimal Structure ◽  
Clear Correlation ◽  
Pressure Drops ◽  
Design Variables ◽  
Wide Range ◽  
Common Weight

Abstract This paper presents a multi-condition design method for the aircraft heat exchanger (HEX), marking with light weight, compactness and wide range of working conditions. The quasi-traversal genetic algorithm (QT-GA) method is introduced to obtain the optimal values of five structural parameters including the height, the tube diameter, the tube pitch, and the tube rows. The QT-GA method solves the deficiency of the conventional GA in the convergence, and gives a clear correlation between design variables and outputs. Pressure drops, heat transfer and the weight of the HEX are combined in a single objective function of GA in the HEX design, thus the optimal structure of the HEX suitable for all the working conditions can be directly obtained. After optimization, the weight of the HEX is reduced to 2.250 kg, more than 20% lower than a common weight of around 3 kg. Based on the optimal structure, the off-design performance of the HEX is further analyzed. Results show that the extreme working conditions for the heat transfer and the pressure drops are not consistent. It proves the advance of the multi-condition design method over traditional single-condition design method. In general, the proposed QT-GA design method is an efficient way to solve the multi-condition problems related to the aircraft HEX or other energy systems.

Research on Heat Transfer Performance of Water Film for Outside the Tubes of the Microscale Evaporative Condenser

2009 ◽  
Author(s):  
Minghui Hu ◽  
Dongsheng Zhu ◽  
Jialong Shen
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Heat Transfer Performance ◽  
Water Film ◽  
Transfer Performance ◽  
Air Velocity ◽  
Microscale Heat Transfer ◽  
High Heat Transfer ◽  
Spray Density

It is requested to develop a microscale and high performance heat exchanger for small size energy equipments. The heat transfer performance of the water film on the condensing coils of the microscale evaporative condenser was studied for a single-stage compressed refrigeration cycle system. Under various operation conditions, the effects of the spray density and the head-on air velocity on the heat transfer performance of the water film were investigated. The results show that the microscale heat transfer coefficient of the water film αw increases with the increase of spray density and decreases with the increase of head-on air velocity. The results indicate that the key factor affecting the microscale heat transfer of the water film is the spray density. As the results, it is measured that the present device attained high heat transfer quantity despite the weight is light. In addition, via regression analysis of the experimental data, the correlation equation for calculating the microscale heat transfer coefficient of the water film was obtained, its regression correlation coefficient R is 0.98 and the standard deviation is 7.5%. Finally, the correlations from other works were compared. The results presented that the experimental correlation had better consistency with the correlations from other works. In general, the obtained experimental results of the water film heat transfer are helpful to the design and practical operation of the microscale evaporative condensers.

Experimental Study on Heat Pipe Radiator in Cooling Electronic Apparatus

2012 ◽  
Vol 197 ◽  
pp. 216-220
Author(s):  
Zhong Chao Zhao ◽  
Rui Ye ◽  
Gen Ming Zhou
Keyword(s):  
Heat Transfer ◽  
Experimental Study ◽  
Heat Pipe ◽  
Heat Dissipation ◽  
Heat Transfer Performance ◽  
Electronic Device ◽  
Transfer Performance ◽  
Air Velocity ◽  
Electronic Apparatus ◽  
Operational Temperature

To solve the cooling problem in modern electronic device, a kind of heat pipe radiator was designed and manufactured in this paper. The heat transfer performance of heat pipe radiator and its relationship with air velocity were investigated by experimental method. The experimental results show that the heat pipe radiator can meet the temperature requirement of electronic device with the power range from 40W to 160W. To keep the operational temperature of electronic device with power of 160W under 75°C，the air velocity should be keep at 1.7m/s. The heat dissipation performance of heat pipe radiator was enhanced with the air velocity increased from 0.2m/s to 1.7m/s.for the electronic equipment with power of 160W.

A Pulsed Wire Probe for the Measurement of Velocity and Flow Direction in Slowly Moving Air

1984 ◽  
Vol 106 (1) ◽  
pp. 72-78 ◽  
Author(s):  
D. E. Olson ◽  
K. H. Parker ◽  
B. Snyder
Keyword(s):  
Heat Transfer ◽  
Theoretical Model ◽  
Spatial Resolution ◽  
Flow Direction ◽  
Three Dimensional ◽  
Velocity Fields ◽  
Transport Time ◽  
Wire Probe ◽  
Circular Pipes ◽  
Measured Flow

This report describes the theory and operation of a pulsed-probe anemometer designed to measure steady three-dimensional velocity fields typical of pulmonary tracheo-bronchial airflows. Local velocities are determined by measuring the transport time and orientation of a thermal pulse initiated at an upstream wire and sensed at a downstream wire. The transport time is a reproducible function of velocity and the probe wire spacing, as verified by a theoretical model of convective heat transfer. When calibrated the anemometer yields measurements of velocity accurate to ±5 percent and resolves flow direction to within 1 deg at airspeeds ≥10 cm/s. Spatial resolution is ±0.5 mm. Measured flow patterns typical of curved circular pipes are included as examples of its application.

Experimental Modeling of Air Temperature and Velocity Distribution in an Engine Compartment

2006 ◽  
Author(s):  
A. A. Mozafari ◽  
M. H. Saidi ◽  
J. Neyestani ◽  
A. E. Sany
Keyword(s):  
Heat Transfer ◽  
Velocity Distribution ◽  
Air Temperature ◽  
Gasoline Engine ◽  
Point Of View ◽  
Vehicle Body ◽  
Air Distribution ◽  
Wind Effect ◽  
Engine Compartment ◽  
Air Velocity

Investigation of air distribution and wind effect on a vehicle body from the point of view of underhood heat transfer effect and proper positioning of vehicle elements such cooler, condenser and engine configuration is an important area for engine researchers and manufacturers as well. In this research, the effect of air velocity distribution and wind effect around a vehicle is simulated and temperature and velocity distribution around engine block which is influenced by the wind effect is investigated. Thermal investigation of the engine compartment components is performed using results of underhood air temperature and velocity distribution. The heat transfer from engine surface is calculated from the engine energy balance in which their input data are obtained from a comprehensive experimental study on a four cylinder gasoline engine.

Experimental Investigation on Heat Transfer Performance in an Underground Dam Tunnel of Hydropower Station

2011 ◽  
Vol 374-377 ◽  
pp. 494-497
Author(s):  
Yi Rong Dang ◽  
An Gui Li ◽  
Hai Guo Yin
Keyword(s):  
Heat Transfer ◽  
Surface Roughness ◽  
Air Temperature ◽  
Heat Transfer Performance ◽  
Transfer Characteristic ◽  
Hydropower Station ◽  
Transfer Performance ◽  
Air Velocity ◽  
Underground Dam ◽  
Ventilation Method

This paper presents an energy efficient ventilation method—dam tunnel air handling for hydropower station ventilation. The heat transfer characteristic between supply air and the dam tunnel is studied by model experiment. Supply air velocity, air temperature and dam tunnel surface roughness are chosen as the mainly influencing factors, the air temperature distribution along airflow direction are measured and analyzed in detail. The results show that the heat transfer performance in dam tunnel is improved as the increased of supply air temperature and the dam tunnel surface roughness, or maintained the supply air velocity at a lower level. This experimental study and its results are helpful to develop alternative and efficient systems for hydropower station ventilation.

Design of a Microfin Array Heat Sink Using Flow-Induced Vibration to Enhance the Heat Transfer Rate in the Laminar Flow Regime

2001 ◽  
Author(s):  
Jeung Sang Go ◽  
Geunbae Lim ◽  
Hayong Yun ◽  
Sung Jin Kim ◽  
Inseob Song
Keyword(s):  
Heat Transfer ◽  
Laminar Flow ◽  
Heat Transfer Enhancement ◽  
Flow Regime ◽  
Heat Transfer Rate ◽  
Heat Sink ◽  
Transfer Rate ◽  
Transfer Enhancement ◽  
Air Velocity ◽  
Flow Induced Vibration

Abstract This paper presented design guideline of the microfin array heat sink using flow-induced vibration to increase the heat transfer rate in the laminar flow regime. Effect of the flow-induced vibration of a microfin array on heat transfer enhancement was investigated experimentally by comparing the thermal resistances of the microfin array heat sink and those of a plain-wall heat sink. At the air velocities of 4.4m/s and 5.5 m/s, an increase of 5.5% and 11.5% in the heat transfer rate was obtained, respectively. The microfin flow sensor also characterized the flow-induced vibration of the microfin. It was determined that the microfin vibrates with the fundamental natural frequency regardless of the air velocity. It was also shown that the vibrating displacement of the microfin is increased with increasing air velocity and then saturated over a certain value of air velocity. Based on the numerical analysis of the temperature distribution resulted from microfin vibration and experimental results, a simple heat transfer model (heat pumping model) was proposed to understand the heat transfer mechanism of a microfin array heat sink. Under the geometric and structural constraints, the maximum heat transfer enhancement was obtained at the intersection of the minimum thickness of the microfin and constraint of the bending angle.

Boiling Heat Transfer With Binary Mixtures: Part I—A Theoretical Model for Pool Boiling

1998 ◽  
Vol 120 (2) ◽  
pp. 380-387 ◽  
Author(s):  
S. G. Kandlikar
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Theoretical Model ◽  
Transfer Coefficient ◽  
Binary Mixtures ◽  
Boiling Heat Transfer ◽  
Present Model ◽  
Pool Boiling ◽  
Interface Temperature ◽  
Pool Boiling Heat Transfer

Experimental evidence available in the literature indicates that the pool boiling heat transfer with binary mixtures is lower than the respective mole- or mass-fraction-averaged value. Although a few investigators have presented analytical work to model this phenomenon, empirical methods and correlations are used extensively. In the present work, a theoretical analysis is presented to estimate the mixture effects on heat transfer. The ideal heat transfer coefficient used currently in the literature to represent the pool boiling heat transfer in the absence of mass diffusion effects is based on empirical considerations, and has no theoretical basis. In the present work, a new pseudo-single component heat transfer coefficient is introduced to account for the mixture property effects more accurately. The liquid composition and the interface temperature at the interface of a growing bubble are predicted analytically and their effect on the heat transfer is estimated. The present model is compared with the theoretical model of Calus and Leonidopoulos (1974), and two empirical models, Calus and Rice (1972) and Fujita et al. (1996). The present model is able to predict the heat transfer coefficients and their trends in azeotrope forming mixtures (benzene/methanol, R-23/R-13 and R-22/R-12) as well as mixtures with widely varying boiling points (water/ethylene glycol and methanol/water).

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