Prediction and Comparison of Shell Condensers With Straight or Helical Channels for Underwater Vehicles

2019 ◽  
Vol 11 (5) ◽  
Author(s):  
Peiyu Chen ◽  
Gongnan Xie ◽  
Bengt Sunden
Keyword(s):  
Heat Transfer ◽  
Underwater Vehicles ◽  
Condensation Process ◽  
Inlet Temperature ◽  
Mass Rate ◽  
R Ratio ◽  
Universal Prediction ◽  
Inlet Conditions ◽  
Degree Of Condensation ◽  
Helical Channels

The shell condenser is one of the key components of underwater vehicles. To study its thermal performance and to design a more efficient structure, a computational model is generated to simulate condensation inside straight and helical channels. The model combines empirical correlations and a MATLAB-based iterative algorithm. The vapor quality is used as a sign of the degree of condensation. Three calculation models are compared, and the optimal model is verified by a comparison of simulated results and available experimental data. Several cases are designed to reveal the effects of various inlet conditions and the diameter-over-radius (Dh/R) ratio. The results show that the inlet temperature and mass rate significantly affect the flow and heat transfer in the condensation process, the heat transfer capabilities of the helical channels are much better than that of the straight channel, and both the heat transfer coefficient and total pressure drop increase with the decrease of Dh/R. This study may provide a useful reference for performance prediction and structural design of shell condensers used for underwater vehicles and may provide a relatively universal prediction model for condensation in channels.

Thermal Design and Performance Prediction of a Shell Condenser for Closed-Cycle Underwater Vehicles

2018 ◽  
Author(s):  
Peiyu Chen ◽  
Hongbin Yan ◽  
Gongnan Xie ◽  
Bengt Sunden
Keyword(s):  
Heat Transfer ◽  
Computational Model ◽  
Performance Prediction ◽  
Mass Velocity ◽  
Underwater Vehicles ◽  
Thermal Design ◽  
Condensation Process ◽  
Inlet Temperature ◽  
Straight Channel ◽  
Helical Channel

The shell condenser is a key component for the underwater vehicles. To study its heat transfer performance and flow characteristics and to design a more efficient structure, a mathematical model is generated to simulate condensation inside the straight and helical channels. The model combines empirical correlations and MATLAB based on an iterative algorithm. Here, quality is used as a sign of the degree of condensation. The computational model is verified by comparison of simulations and experiments. Several cases are designed to reveal the effects of the initial condition. The inlet temperature varies from 160 to 220°C and the inlet mass velocity ranges between 133 and 200 kg/m2·s. The results show that the inlet temperature and mass velocity significantly affect flow and heat transfer in the condensation process. In addition, comparisons of the straight channel and helical channel with different Dh/R indicate that the heat transfer capability of the helical channel is obviously better than that of the straight channel, and the heat transfer coefficient and total pressure drop increase with the decrease of Dh/R. This study may provide useful information for performance prediction and structure design of shell condensers, and provide a relatively universal computational model for condensation in channels.

scholarly journals Numerical Analysis of Laminar Convective Condensation with the Presence of Noncondensable Gas Flowing Downward in a Vertical Channel

2019 ◽  
Vol 2019 ◽  
pp. 1-15
Author(s):  
Mustapha Ait Hssain ◽  
Youness El Hammami ◽  
Rachid Mir ◽  
Sara Armou ◽  
Kaoutar Zine-Dine
Keyword(s):  
Heat Transfer ◽  
Numerical Analysis ◽  
Relative Humidity ◽  
Liquid Film ◽  
Vertical Channel ◽  
Dimensionless Temperature ◽  
Condensation Process ◽  
Inlet Temperature ◽  
Mixture Flow ◽  
Noncondensable Gas

The purpose of this paper is to study and perform a numerical analysis of the simultaneous processes of mass and heat transfer during the condensation process of a steam in the existence of noncondensable gas (NCG) inside a descending vertical channel. In this study, the flow of the vapor-air mixture is laminar and the saturation conditions are prevailing at the inlet of the channel. The coupled control equations for liquid film, interfacial conditions, and mixture flow are solved together using the approach of finite volume. Detailed and valuable results are presented both in the liquid condensate film and in the mixing regions. These detailed results contain the dimensionless velocity and dimensionless temperature profiles in both phases, the dimensionless mass fraction of vapor, the axial variation of the dimensionless thickness of the film liquid δ⁎, and the accumulated condensate rate Mr as well the local Nusselt number Nuy. The relative humidity at the inlet varies from 60% to 100% and the inlet temperature from 40°C to 80°C. The results confirm that a decrease in the mass concentration of NCG by the increasing the inlet relative humidity has a direct influence on the liquid film layer, the local number of Nusselt, and the variation of condensation rate accumulated through the channel. The results also designate that an increase of the inlet relative humidity and the inlet temperature ameliorates the condensation process. The comparison made for the coefficient of heat transfer due to condensation process and the condensate liquid film thickness with the literature results is in good concordance which gives more credibility to our calculation model.

Analysis on the Effect of a Non-Uniform Inlet Profile on Heat Transfer and Fluid Flow in Turbine Stages

2010 ◽  
Author(s):  
Salvadori Simone ◽  
Francesco Montomoli ◽  
Francesco Martelli ◽  
Kam S. Chana ◽  
Imran Qureshi ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Temperature Profile ◽  
Thermal Load ◽  
Thermal Loading ◽  
Radial Profile ◽  
Experimental Studies ◽  
Test Facility ◽  
Inlet Temperature ◽  
Inlet Conditions ◽  
Hot Streak

This paper presents an investigation of the aerothermal performance of a modern unshrouded high pressure (HP) aeroengine turbine subject to non-uniform inlet temperature profile. The turbine used for the study was the MT1 turbine installed in the QinetiQ Turbine Test Facility (TTF) based in Farnborough (UK). The MT1 turbine is a full scale transonic HP turbine, and is operated in the test facility at the correct non-dimensional conditions for aerodynamics and heat transfer. Datum experiments of aero-thermal performance were conducted with uniform inlet conditions. Experiments with nonuniform inlet temperature were conducted with a temperature profile that had a non-uniformity in the radial direction defined by (Tmax−Tmin)/T = 0.355, and a non-uniformity in the circumferential direction defined by (Tmax−Tmin)/T = 0.14. This corresponds to an extreme point in the engine cycle, in an engine where the non-uniformity is dominated by the radial distribution. Accurate experimental area surveys of the turbine inlet and exit flows were conducted, and detailed heat transfer measurements were obtained on the blade surfaces and end-walls. These results are analysed with the unsteady numerical data obtained using the in-house HybFlow code developed at the University of Firenze. Two particular aspects are highlighted in the discussion: prediction confidence for state of the art computational fluid dynamics (CFD) and impact of real conditions on stator-rotor thermal loading. The efficiency value obtained with the numerical analysis is compared with the experimental data and a 0.8% difference is found and discussed. A study of the flow field influence on the blade thermal load has also been detailed. It is shown that the hot streak migration mainly affects the rotor pressure side from 20% to 70% of the span, where the Nusselt number increases by a factor of 60% with respect to the uniform case. Furthermore, in this work it has been found that a nonuniform temperature distribution is beneficial for the rotor tip, contrary to the results found in the open literature. Although the hot streak is affected by the pressure gradient across the tip gap, the radial profile (which dominates the temperature profile being considered) is not fully mixed out in passing through the HP stage, and contributes significantly to cooling the turbine casing. A design approach not taking into account these effects will underestimate to rotor life near the tip and the thermal load at mid-span. The temperature profile that has been used in both the experiments and CFD is the first simulation of an extreme cycle point (more than twice the magnitude of distortion all previous experimental studies): it represents an engine-take-off condition combined with the full combustor cooling. The research was part of the EU funded TATEF2 (Turbine Aero-Thermal External Flows 2) programme.

Effect of NGV Lean Under Influence of Inlet Temperature Traverse

2013 ◽  
Author(s):  
A. Rahim ◽  
B. Khanal ◽  
L. He ◽  
E. Romero
Keyword(s):  
Heat Transfer ◽  
Computational Study ◽  
Navier Stokes ◽  
Tangential Displacement ◽  
Inlet Temperature ◽  
Heat Transfer Characteristics ◽  
Transfer Characteristics ◽  
Inlet Conditions ◽  
Hot Streak ◽  
The Impact

One of the most widely studied parameters in turbine blade shaping is blade lean, i.e. the tangential displacement of spanwise sections. However, there is a lack of published research that investigates the effect of blade lean under non-uniform temperature conditions (commonly referred to as a ‘hot-streak’) that are present at the combustor exit. Of particular interest is the impact of such an inflow temperature profile on heat transfer when the NGV blades are shaped. In the present work a computational study has been carried out for a transonic turbine stage using an efficient unsteady Navier-Stokes solver (HYDRA). The configurations with a nominal vane and a compound leaned vane under uniform and hot-streak inlet conditions are analysed. After confirming the typical NGV loading and aero-loss redistributions as seen in previous literature on blade lean, the focus has been directed to the rotor aerothermal behavior. Whilst the overall stage efficiencies for the configurations are largely comparable, the results show strikingly different rotor heat transfer characteristics. For a uniform inlet, a leaned NGV has a detrimental effect on the rotor heat transfer. However, once the hot-streak is introduced, the trend is reversed; the leaned NGV leads to favourable heat transfer characteristics in general and for the rotor tip region in particular. The possible causal links for the observed aerothermal features are discussed. The present findings also highlight the significance of evaluating NGV shaping designs under properly conditioned inflow profiles, rather than extrapolating the wisdom derived from uniform inlet cases. The results also underline the importance of including rotor heat transfer and coolability during the NGV design process.

Effect of Simulated Combustor Temperature Nonuniformity on HP Vane and Endwall Heat Transfer: An Experimental and Computational Investigation

2010 ◽  
Author(s):  
Imran Qureshi ◽  
Arrigo Beretta ◽  
Thomas Povey
Keyword(s):  
Heat Transfer ◽  
Guide Vane ◽  
Research Programme ◽  
Test Facility ◽  
Inlet Temperature ◽  
Computational Investigation ◽  
Nozzle Guide Vane ◽  
Inlet Conditions ◽  
Nozzle Guide ◽  
Computational Predictions

This paper presents experimental measurements and computational predictions of surface and endwall heat transfer for a high-pressure (HP) nozzle guide vane (NGV) operating as part of a full HP turbine stage in an annular rotating turbine facility, with and without inlet temperature distortion (hot-streaks). A detailed aerodynamic survey of the vane surface is also presented. The test turbine was the unshrouded MT1 turbine, installed in the Turbine Test Facility (previously called Isentropic Light Piston Facility) at QinetiQ, Farnborough UK. This is a short duration facility, which simulates engine representative M, Re, non-dimensional speed and gas-to-wall temperature ratio at the turbine inlet. The facility has recently been upgraded to incorporate an advanced second-generation combustor simulator, capable of simulating well-defined, aggressive temperature profiles in both the radial and circumferential directions. This work forms part of the pan-European research programme, TATEF II. Measurements of HP vane and endwall heat transfer obtained with inlet temperature distortion are compared with results for uniform inlet conditions. Steady and unsteady CFD predictions have also been conducted on vane and endwall surfaces, using the Rolls-Royce CFD code HYDRA to complement the analysis of experimental results. The heat transfer measurements presented in this paper are the first of their kind in the respect that the temperature distortion is representative of an extreme cycle point measured in the engine situation, and was simulated with good periodicity and with well defined boundary conditions in the test turbine.

Analysis on the Effect of a Nonuniform Inlet Profile on Heat Transfer and Fluid Flow in Turbine Stages

2011 ◽  
Vol 134 (1) ◽  
Author(s):  
Salvadori Simone ◽  
Francesco Montomoli ◽  
Francesco Martelli ◽  
Kam S. Chana ◽  
Imran Qureshi ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Temperature Profile ◽  
Thermal Load ◽  
Thermal Loading ◽  
Radial Profile ◽  
Experimental Studies ◽  
Test Facility ◽  
Inlet Temperature ◽  
Inlet Conditions ◽  
Hot Streak

This paper presents an investigation of the aerothermal performance of a modern unshrouded high-pressure (HP) aero-engine turbine subject to nonuniform inlet temperature profile. The turbine used for this study was the MT1 turbine installed in the QinetiQ turbine test facility based in Farnborough (UK). The MT1 turbine is a full scale transonic HP turbine, and is operated in the test facility at the correct nondimensional conditions for aerodynamics and heat transfer. Datum experiments of aerothermal performance were conducted with uniform inlet conditions. Experiments with nonuniform inlet temperature were conducted with a temperature profile that had a nonuniformity in the radial direction defined by (Tmax−Tmin)/T¯=0.355, and a nonuniformity in the circumferential direction defined by (Tmax−Tmin)/T¯=0.14. This corresponds to an extreme point in the engine cycle, in an engine where the nonuniformity is dominated by the radial distribution. Accurate experimental area surveys of the turbine inlet and exit flows were conducted, and detailed heat transfer measurements were obtained on the blade surfaces and end-walls. These results are analyzed with the unsteady numerical data obtained using the in-house HybFlow code developed at the University of Firenze. Two particular aspects are highlighted in the discussion: prediction confidence for state of the art computational fluid dynamics (CFD) and impact of real conditions on stator-rotor thermal loading. The efficiency value obtained with the numerical analysis is compared with the experimental data and a 0.8% difference is found and discussed. A study of the flow field influence on the blade thermal load has also been detailed. It is shown that the hot streak migration mainly affects the rotor pressure side from 20% to 70% of the span, where the Nusselt number increases by a factor of 60% with respect to the uniform case. Furthermore, in this work, it has been found that a nonuniform temperature distribution is beneficial for the rotor tip, contrary to the results found in open literature. Although the hot streak is affected by the pressure gradient across the tip gap, the radial profile (which dominates the temperature profile being considered) is not fully mixed out in passing through the HP stage, and contributes significantly to cooling the turbine casing. A design approach not taking into account these effects will underestimate the rotor life near the tip and the thermal load at midspan. The temperature profile that has been used in both experiments and CFD is the first simulation of an extreme cycle point (more than twice the magnitude of distortion of all previous experimental studies): It represents an engine-take-off condition combined with the full combustor cooling. This research was part of the EU funded Turbine AeroThermal External Flows 2 program.

scholarly journals ANALISIS PERPINDAHAN KALOR KONDENSOR PADA PROSES DISTILASI BIOETANOL SEBAGAI BIOFUEL DARI CAMPURAN LIMBAH BUAH SALAK DENGAN LIMBAH AIR KELAPA

2018 ◽  
Vol 2 (2) ◽  
pp. 43
Author(s):  
Muhammad Idris Hutasuhut
Keyword(s):  
Heat Transfer ◽  
Alternative Fuels ◽  
Fossil Fuels ◽  
Convection Heat Transfer ◽  
Cooling Water ◽  
Condensation Process ◽  
Convection Heat ◽  
Mass Rate ◽  
Alternative Sources ◽  
Bioethanol Fuel

<p class="JudulAbstrakEnglish"> </p><p class="JudulAbstrakEnglish">Cadangan bahan bakar fosil Indonesia akan segera habis. Indonesia harus segera melakukan inovasi dan temuan bahan bakar alternative untuk menggatikan bahan bakar fosil tersebut untuk menghindari krisis dan isu lingkungan. Biomassa sebagai salah satu sumber bahan bakar alternative yang tersedia dalam jumlah banyak di Indonesia. Melalui beberapa tahapan proses biomassa dapat dirubah menjadi bahan bakar bioethanol. Salah satu proses yang dimaksud dengan cara termokimia yaitu distilasi. Distilasi merupakan proses pemisahan fasa berdasarkan titik didih fasa itu sendiri. Uap mengalir dalam pipa masuk ke dalam kondensor dengan ukuran Ø 8.89x10<sup>-2</sup> m dan panjang L 3.4 x10<sup>-2</sup>. Didalam kondesnor terjadi perpindahan panas secara konveksi. Perbedaan temperature pada proses kondensasi antara fluida uap yang mengalir dalam pipa dengan fluida air pendingin yang mendinginkan dinding kondesor direkam menggunakan perankat akuisisi. Oleh karena itu, penelitian ini bertujuan untuk menganalisis perpindahan panas konveksi pada kondensor dan mengitung hasil luaran bioethanol secara teoritis berdasarkan massa kondensat uap fermentor. Dari hasil analisis diperoleh perpindahan panas konveksi sebesar 0.2752 kW. Laju massa uap fermentor 1.192 x 10<sup>-4</sup> kg/s, koefisien perpindahan kalor kondensasi 340.7161 W/m<sup>2 O</sup>C, laju massa kondensat 1.01x 10<sup>-5</sup> kg/s. Laju massa kondensat yang diperoleh 8% merupakan hasil luaran biofuel atau bioethanol.</p><p><strong><em><br /></em></strong></p><p class="JudulAbstrakEnglish"><strong>Abstract</strong></p><p class="Howtocite">Indonesia's fossil fuel reserves will soon run out. Indonesia must immediately innovate and search alternative fuels to replace fossil fuels to avoid crises and environmental issues. Biomass as one of the alternative sources of fuel available in large quantities in Indonesia. Through several stages, the process of biomass can be converted into bioethanol fuel. One of the processes referred to by thermochemical methods is distillation. Distillation is a phase separation process based on the boiling point itself. Steam flows in the pipe into the condenser with a size of Ø 8.89x10-2 m and length L 3.4 x10-2. In the condenser, there is convection heat transfer. The temperature difference in the condensation process between the vapor fluid flowing in the pipe and the cooling water fluid that cools the condenser wall is recorded using the acquisition role. Therefore, this study aims to analyze the convection heat transfer in the condenser and to calculate the bioethanol output theoretically based on the mass of the fermentor vapor condensate. From the analysis results obtained convection heat transfer of 0.2752 kW. The fermentor vapor mass rate is 1,192 x 10-4 kg / s, the condensation heat transfer coefficient is 340.7161 W / m2 OC, the condensate mass rate is 1.01x 10-5 kg / s. The condensate mass rate obtained by 8% is the result of biofuel or bioethanol output.</p><p class="Howtocite"> </p><p><strong><em><br /></em></strong></p>

Effect of Simulated Combustor Temperature Nonuniformity on HP Vane and End Wall Heat Transfer: An Experimental and Computational Investigation

2010 ◽  
Vol 133 (3) ◽  
Author(s):  
Imran Qureshi ◽  
Arrigo Beretta ◽  
Thomas Povey
Keyword(s):  
Heat Transfer ◽  
Guide Vane ◽  
Test Facility ◽  
Inlet Temperature ◽  
Wall Heat Transfer ◽  
Computational Fluid Dynamics Cfd ◽  
Inlet Conditions ◽  
Nozzle Guide ◽  
End Wall ◽  
Computational Predictions

This paper presents experimental measurements and computational predictions of surface and end wall heat transfer for a high-pressure (HP) nozzle guide vane operating as part of a full HP turbine stage in an annular rotating turbine facility, with and without inlet temperature distortion (hot streaks). A detailed aerodynamic survey of the vane surface is also presented. The test turbine was the unshrouded MT1 turbine, installed in the Turbine Test Facility (previously called Isentropic Light Piston Facility) at QinetiQ, Farnborough, UK. This is a short-duration facility, which simulates engine-representative M, Re, nondimensional speed, and gas-to-wall temperature ratio at the turbine inlet. The facility has recently been upgraded to incorporate an advanced second-generation combustor simulator, capable of simulating well-defined, aggressive temperature profiles in both the radial and circumferential directions. This work forms part of the pan-European research program, TATEF II. Measurements of HP vane and end wall heat transfer obtained with inlet temperature distortion are compared with results for uniform inlet conditions. Steady and unsteady computational fluid dynamics (CFD) predictions have also been conducted on vane and end wall surfaces using the Rolls-Royce CFD code HYDRA to complement the analysis of experimental results. The heat transfer measurements presented in this paper are the first of their kind in that the temperature distortion is representative of an extreme cycle point, and was simulated with good periodicity and with well-defined boundary conditions in the test turbine.

scholarly journals Numerical Investigation of Inlet Thermodynamic Conditions on Solid Fuel Ramjet Performances

2021 ◽  
Vol 2021 ◽  
pp. 1-20
Author(s):  
Weixuan Li ◽  
Dan Zhao ◽  
Xiong Chen ◽  
Liang Zhu ◽  
Siliang Ni
Keyword(s):  
Heat Transfer ◽  
Chemical Reaction ◽  
Solid Fuel ◽  
Swirl Flow ◽  
Navier Stokes ◽  
Inlet Temperature ◽  
Combustion Heat ◽  
Flow Recirculation ◽  
Flow Field Characteristics ◽  
Inlet Conditions

In this work, 2D numerical RANS (Reynolds Average Navier-Stokes) simulations were carried out to investigate the thermodynamic performance of a solid fuel ramjet (SFRJ) with different inlet conditions. This is achieved by using an in-house FORTRAN code to simulate a 2D turbulent, reacting, unsteady flow in the ramjet engine. The inlet conditions are characterized by three key parameters: (1) swirl number ( S N ), (2) mass flow rate ( m ̇ air ), and (3) inlet temperature ( T in ). With the code numerically validated by benchmarking with a number of computed cases, it is applied to perform systematic studies on the turbulent flow recirculation, combustion, and heat transfer characteristics. It is found that increasing S N , m ̇ air , or T in can dramatically enhance the combustion heat release rate, regression rate, and combustor average temperature. Furthermore, the analysis on the chemical reaction intermediate (CO) reveals that the chemical reaction is more sufficient with increased m ̇ air , but S N = 0 . In addition, a secondary vortex is generated at the corner of the backward facing step in the presence of a swirl flow resulting from the instability of the shear layer. Finally, the nonlinear correlations between the heat transfer, combustion characteristics, and flow field characteristics and the corresponding inlet thermodynamic parameters are identified.

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