scholarly journals A Numerical Analysis of the Air-Cooling System of a Spark Ignition Aeronautical Engine

2020 ◽  
Vol 197 ◽  
pp. 06003
Author(s):  
Maria Faruoli ◽  
Annarita Viggiano ◽  
Paolo Caso ◽  
Vinicio Magi
Keyword(s):  
Heat Transfer ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Cooling System ◽  
Spark Ignition ◽  
Operating Conditions ◽  
Air Cooling ◽  
Air Mass ◽  
Air Cooling System

It is well known that spark ignition internal combustion engines for aeronautical applications operate within a specific temperature range to avoid structural damages, detonations and loss of efficiency of the combustion process. An accurate assessment of the cooling system performance is a crucial aspect in order to guarantee broad operating conditions of the engine. In this framework, the use of a Conjugate Heat Transfer method is a proper choice, since it allows to estimate both the heat fluxes between the engine walls and the cooling air and the temperature distribution along the outer wall surfaces of the engine, and to perform parametric analyses by varying the engine operating conditions. In this work, the air-cooling system of a 4-cylinder spark ignition engine, designed by CMD Engine Company for aeronautical applications, is analysed in order to evaluate the amount of the air mass flow rate to guarantee the heat transfer under full load operating conditions. A preliminary validation of the model is performed by comparing the results with available experimental data. A parametric study is also performed to assess the influence of the controlling parameters on the cooling system efficiency. This study is carried out by varying the inlet air mass flow rate from 1.0 kg/s to 1.5 kg/s and the temperature of the inner wall surfaces of the engine combustion chambers from 390 K to 430 K.

Heat Transfer Characteristics of a Rotor-Stator System With Small Radial Outflow

2012 ◽  
Author(s):  
Li Lin ◽  
Jing Ren ◽  
Hongde Jiang ◽  
Peter Childs
Keyword(s):  
Heat Transfer ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Cooling System ◽  
Small Mass ◽  
Eckert Number ◽  
Air Cooling ◽  
Air Cooling System ◽  
Radial Outflow

In some cases, the mass flow rate needed to prevent ingress through rim seals in turbine is smaller than that entrained by a free disk. In order to obtain the heat transfer features of the rotor-stator system at such a small mass flow rate, a combined computational and theoretical study has been carried out. It is found that the average Nusselt number (Nuav) on the rotor drops approximately linearly down to zero with decreasing turbulent flow parameter (λt) when λt is smaller than λt,c (λt,c < λt,fd), while Nuav almost keeps constant when λt is larger than λt,c. A correlation between Nuav and λt has been developed, which is expected to be useful in determining disk temperatures in the preliminary design of an internal air cooling system. The Eckert number, which can express the relationship between heat generated by windage and heat conducted through disk, turns out to be an important nondimensional number in describing the heat transfer features of such rotor-stator systems. Moreover, the effect of rotational speed on heat transfer when λt,c<λt<λt,fd has been studied, further identifying the significance of the Eckert number.

Comparative Study of Impinging Jet Array Heat Transfer on a Flat Plate Cooled by Superheated Steam and Air

2014 ◽  
Author(s):  
Chao Ma ◽  
Jianfei Wang ◽  
Shusheng Zang ◽  
Yongbin Ji
Keyword(s):  
Heat Transfer ◽  
Flat Plate ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Superheated Steam ◽  
Operating Conditions ◽  
Air Cooling ◽  
Promising Alternative ◽  
Spacing Ratio

In modern gas turbine, using superheated steam to cool the vane and the liner of combustion chamber is a promising alternative to traditional compressor air. Infrared camera was applied to measure the spatial distribution of the impingement heat transfer coefficient on a flat plate cooled by superheated steam and air in this paper. The experimental study revealed the distribution of local heat transfer coefficients over a flat plate cooled by steam and air in an array of 3×5 impinging jets module. Results showed that the impingement cooling heat transfer is enhanced by the increase of mass flow rate, and the superheated steam cooling could improve area averaged heat transfer performance 35.3∼83.0% more than air cooling in the same mass flow rate conditions in the experiment. The influence of the jet-to-plate spacing ratio (Zn/d) and the jet-to-jet spacing ratio (Yn/d) on heat transfer were also investigated. It was concluded that the heat transfer is enhanced with the increase of Yn/d or the decrease of Zn/d based on the same area. Furthermore, three-dimensional and steady state computations had been carried out for experimental operating conditions. The Numerical results and experimental data have good agreements with each other for both the area averaged Nu and the local Nu, so results of the numerical model are expecting reliable. Results based Numerical models showed detailed characteristics of the distribution of the velocity and turbulence level, which revealed underlying mechanisms of pressure loss and flow structure for steam cooing and air cooling respectively.

Heat Transfer and Flow Friction Characteristics for Compact Cold Plates

2003 ◽  
Vol 125 (1) ◽  
pp. 104-113 ◽  
Author(s):  
Chang-Yuan Liu ◽  
Ying-Huei Hung
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Nusselt Number ◽  
Thermal Resistance ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Average Nusselt Number ◽  
Cold Plate ◽  
Air Mass

Both experimental and theoretical investigations on the heat transfer and flow friction characteristics of compact cold plates have been performed. From the results, the local and average temperature rises on the cold plate surface increase with increasing chip heat flux or decreasing air mass flow rate. Besides, the effect of chip heat flux on the thermal resistance of cold plate is insignificant; while the thermal resistance of cold plate decreases with increasing air mass flow rate. Three empirical correlations of thermal resistance in terms of air mass flow rate with a power of −0.228 are presented. As for average Nusselt number, the effect of chip heat flux on the average Nusselt number is insignificant; while the average Nusselt number of the cold plate increases with increasing Reynolds number. An empirical relationship between Nu¯cp and Re can be correlated. In the flow frictional aspect, the overall pressure drop of the cold plate increases with increasing air mass flow rate; while it is insignificantly affected by chip heat flux. An empirical correlation of the overall pressure drop in terms of air mass flow rate with a power of 1.265 is presented. Finally, both heat transfer performance factor “j” and pumping power factor “f” decrease with increasing Reynolds number in a power of 0.805; while they are independent of chip heat flux. The Colburn analogy can be adequately employed in the study.

The Study of the Effects of Gas Turbine Inlet Air Cooling on the Heat Recovery Boiler Performance

Volume 1 ◽  
2004 ◽  
Author(s):  
Mohammad Ameri ◽  
Hamidreza Shahbaziyan ◽  
Hadi Hosseinzadeh
Keyword(s):  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Flue Gas ◽  
Gas Turbines ◽  
Heat Recovery ◽  
Cooling System ◽  
Combined Cycle ◽  
Heat Recovery Boiler ◽  
Air Cooling

Heat recovery steam generators (HRSG) are widely used in industrial processes and combined cycle power plants. The quantity and the state of the produced steam depend on the flue gas temperature and its mass flow rate. Two key factors, which affect those parameters, are the ambient temperature and the load of the gas turbines. The output power of the gas turbines degrades considerably in hot days of summer. The use of the inlet air cooling system to eliminate this problem is rapidly increasing. One of the effective methods is cooling the inlet air to the compressor by Evaporative Coolers. The purpose of this paper is to study the effects of the evaporative inlet air cooling system on the performance of a heat recovery boiler in a combined cycle power plant. The heat and mass balance of a typical HRSG and its components including the superheaters, evaporators and economizers were calculated. To analyze the effects of the changes in ambient temperature and the flue gas flow, a numerical software has been used. The results have shown that using the evaporative cooler will increase the flue gas mass flow rate to the HRSG. Nevertheless, the exhaust gas temperature control system holds this temperature almost constant. Also, the results show that the produced steam temperature remains almost constant. However, the steam mass flow rate increases. Therefore the output power of the steam turbine of the combined cycle will increase. The effect of the increase in the humidity ratio is shown to be insignificant. In fact, it has negligible effect on the produced steam flow rate and the sulfuric acid dew point.

scholarly journals Study of Heat Transfer and the Hydrodynamic Performance of Gas–Solid Heat Transfer in a Vertical Sinter Cooling Bed Using the CFD-Taguchi-Grey Relational Analysis Method

Energies ◽  
2020 ◽  
Vol 13 (9) ◽  
pp. 2225
Author(s):  
Junpeng Fu ◽  
Jiuju Cai
Keyword(s):  
Heat Transfer ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Grey Relational Analysis ◽  
Hydrodynamic Performance ◽  
Inlet Temperature ◽  
Air Mass ◽  
Relational Analysis ◽  
Grey Relational

The vertical sinter cooling bed (VSCB) is a high-efficiency energy-saving and environmentally friendly waste heat recovery equipment. In this study, a computational fluid dynamics (CFD) convection model was established to reveal the typical factors on the thermodynamic performance in VSCB. Indeed, a multiple performance optimal algorithm based on the Taguchi-grey relational analysis (GRA) method was first applied to investigate the effects of geometric and operational factors, including the diameter of the bed, height of the bed, air mass flow rate, air inlet temperature, and sinter mass flow rate, on improving the heat transfer (Ex) and hydrodynamic performance (Pdrop) and obtain the optimum combination of each factor in VSCB. The results found that the diameter of the bed was the most influential factor contributing the multiple types of performance with a contribution rate of 70.51%, followed by the air mass flow rate (15.84%), while the height of the bed (0.27%) exerted a limited effect on the performance of multiple processes. The optimal combination of factors (A1B5C5D5E1) was compared with the initially selected parameters by performing a confirmation test. The performances of heat transfer and hydrodynamics were improved by the Taguchi with the GRA method.

scholarly journals Effects of Louvered Parameters on Exergetic Performance of Louvered Finned Solar Air Heater

2021 ◽  
Vol 39 (5) ◽  
pp. 1649-1658
Author(s):  
Subhash Chand ◽  
Prabha Chand
Keyword(s):  
Heat Transfer ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Operating Conditions ◽  
High Mass ◽  
Solar Air Heater ◽  
Air Heater ◽  
Pitch Ratio ◽  
Exergy Performance

The aim of the present study to improve the performance of solar air heater because of low thermo-physical properties of air. In the current work, an attempt has been made to improve the performance of the heater by employing louvered fins to the absorber plate, as it not only enhances heat transfer coefficient but also improve heat transfer area. The effect of exergy performance on the geometrical parameters of louvered fin i.e., louvered angle, louvered pitch and louvered length has been studied and analyzed. The results are compared to plane solar air heater (PSAH) to evaluate the effectiveness of louvered finned solar air heater (LFSAH). The exergy efficiency of LFSAH is comparatively higher for all the operating conditions except for higher mass flow rate where it may even go below that of PSAH; possibly due to the higher pressure drop and more loss of exergy at high mass flow rate. In addition, the results conclude that for louvered parameters viz., louvered angle 20°, fin pitch to louvered pitch ratio 0.75 and louvered length to louvered pitch ratio 1.25, high exergy performance of SAH is obtained as compared to other louvered parameter values.

Three-Dimensional Forced Air Cooling System Analysis of a Scooter Engine

2002 ◽  
Author(s):  
Ennio Carnevale ◽  
Giacomo Migliorini ◽  
Stefano Zecchi ◽  
Bart Olmi
Keyword(s):  
Mass Flow ◽  
Noise Level ◽  
Cooling System ◽  
Three Dimensional ◽  
Low Noise ◽  
Air Cooling ◽  
Air Mass ◽  
Air Cooling System ◽  
Flow Demand ◽  
Forced Air

Internal combustion engines must match several requirements such as good efficiency and low fuel consumption rate; when they are applied on scooter they are subject to some other restrictions. Nowadays, both low pollutant emissions and low noise level are requested for this engine since scooters are usually city vehicles. To match these requirements several aspects must be investigated: one of these may be the cooling system. There are usually three cooling methods, i.e. free stream air cooling, liquid cooling and forced air cooling. The first one is usually not employed in scooter engines because of its arrangement inside the scooter body (due to functionality and aestheticism). The second one may present some plant complications caused by the heat exchanger and ducts. A forced air cooling system presents usually lower complication, lower weight and greater reliability. Nevertheless, in order to keep engine temperatures below lubricant and structural limit, high mass flow rate may be necessary since air has smaller coolant efficiency compared to liquids. Moreover cooling air, supplied by a fan, requires high pumping power which may be excessive at high rotational speed; the fan itself may produce excessive noise reducing comfort. Sometimes, it may be hard to define the air flow demands in order to properly cool the critical parts (i.e. cylinder head); poor design may result in an excessive air mass flow demand and high pressure losses. Consequently the fan requires an excessive power and emits high noise level. Proper coolant distribution around the cylinder and the engine head reduces the overall air mass flow demand, rising indirectly engine efficiency. Usually the geometry of a forced air cooled engine is quite complex because of fins and other internal passages. To study coolant distribution and heat transfer a three-dimensional approach is then required. Computational fluid dynamic calculations, provided by commercial codes, can give useful suggestions about flow distribution around a finned cylinder. This paper will show an analysis of a typical air cooled scooter engine. Air mass flows and cooling efficiency are shown at several engine rotational speeds.

Gas Turbine Power Augmentation Using Fog Inlet Air-Cooling System

Volume 1 ◽  
2004 ◽  
Author(s):  
Mohammad Ameri ◽  
Hamid Nabati ◽  
Alireza Keshtgar
Keyword(s):  
Power Plant ◽  
Gas Turbine ◽  
Mass Flow Rate ◽  
Air Temperature ◽  
Flow Rate ◽  
Power Output ◽  
Gas Turbines ◽  
Cooling System ◽  
Air Cooling ◽  
Air Cooling System

Gas turbines are almost constant volume machines at a specific rotating speed, i.e., air intake is limited to a nearly fixed volume of air regardless of ambient air conditions. As air temperature rises, its density falls. Thus, although the volumetric flow rate remains constant, the mass flow rate is reduced as air temperature rises. Power output is also reduced as air temperature rises because power output is proportional to mass flow rate. This power output reduction is from 0.5% to 0.9% of the ISO output power for every 1°C rise in the ambient temperature. The solution of this problem is very important because the peak demand season also happens in the summer. One of the useful methods to overcome this problem is to apply the fog inlet air cooling system for the gas turbines. In this paper the Rey Power Plant site climate conditions in the summer have been studied. The design conditions regarding the dry bulb temperature and relative humidity have been selected. The different inlet air cooling systems have been studied and the Fog system has been chosen. The economical study has shown that this system is very cheap in comparison with the installation of the new gas turbines. The capital cost is estimated to be 40 $/KW. The pay back period is around 1.5 year. The testing of this system has shown that the average power capacity of the power plant is increased by 19 MW and prevented the installation of a new gas turbine.

Experimental Investigation on Compact Heat Exchanger in Aluminum Foam

2015 ◽  
Author(s):  
Luca Cirillo ◽  
Oronzio Manca ◽  
Lorenzo Marinelli ◽  
Sergio Nardini
Keyword(s):  
Heat Transfer ◽  
Experimental Investigation ◽  
Heat Exchanger ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Aluminum Foam ◽  
Hot Water ◽  
Compact Heat Exchanger ◽  
Air Mass

In this paper an experimental investigation on forced convection in a compact heat exchanger made up with an aluminum foam plate of 212.5mm × 212.5mm with a thickness of 40 mm and a single array with five circular tubes is presented. The foam has a porosity of 0.93 with 20 pores per inch and the tubes in aluminum have internal and external diameters equal to 9.5 mm and 12.5 mm. The test rig consists of an open air channel and a closed water cycle and the aluminum foam plate is placed inside the channel. The performances of the compact heat exchanger are evaluated for assigned hot water mass flow rate and different hot water inlet temperatures and air mass flow rate. Results are given in terms of heat transfer rates and pressure drops as a function of air velocity and Reynolds numbers. The evaluation of dimensionless, thermal resistance, Colburn factor and Nusselt number is performed for different air mass flow rates and hot water inlet temperatures. The performance evaluation criteria is considered in terms of ratio between the heat transfer rate inside the heat exchanger and the pumping power of the air fan.

Thermal Power Of The TS-300B Refrigerator in the Aspects of Statistical Research / Moc Cieplna Chłodziarki TS-300B W Aspekcie Badań Statystycznych

2015 ◽  
Vol 60 (3) ◽  
pp. 715-728
Author(s):  
Bernard Nowak ◽  
Rafał Łuczak
Keyword(s):  
Linear Regression ◽  
Flow Rate ◽  
Statistical Models ◽  
Cooling System ◽  
Thermal Power ◽  
Volumetric Flow Rate ◽  
Operating Conditions ◽  
Air Cooling ◽  
Independent Variables ◽  
Air Cooling System

Abstract The article discusses the improvement of thermal working conditions in underground mine workings, using local refrigeration systems. It considers the efficiency of air cooling with direct action air compression refrigerator of the TS-300B type. As a result of a failure to meet the required operating conditions of the aforementioned air cooling system, frequently there are discrepancies between the predicted (and thus the expected) effects of its work and the reality. Therefore, to improve the operating efficiency of this system, in terms of effective use of the evaporator cooling capacity, quality criteria were developed, which are easy in practical application. They were obtained in the form of statistical models, describing the effect of independent variables, i.e. the parameters of the inlet air to the evaporator (temperature, humidity and volumetric flow rate), as well as the parameters of the water cooling the condenser (temperature and volumetric flow rate), on the thermal power of air cooler, treated as the dependent variable. Statistical equations describing the performance of the analyzed air cooling system were determined, based on the linear and nonlinear multiple regression. The obtained functions were modified by changing the values of the coefficients in the case of linear regression, and of the coefficients and exponents in the case of non-linear regression, with the independent variables. As a result, functions were obtained, which were more convenient in practical applications. Using classical statistics methods, the quality of fitting the regression function to the experimental data was evaluated. Also, the values of the evaporator thermal power of the refrigerator, which were obtained on the basis of the measured air parameters, were compared with the calculated ones, by using the obtained regression functions. These statistical models were built on the basis of the results of measurements in different operating conditions of the TS-300B refrigerator, both on the test stand in the manufacturer’s laboratory and in the workings of underground mines. The evaluation of the measurement data distributions, as well as an analysis of the basic descriptive statistics of the mentioned variables were carried out, determining their measures of central tendency, location, dispersion and asymmetry.

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