scholarly journals Influence of Fins Number and Frosting on Heat Transfer through Longitudinal Finned Tubes of LNG Ambient Air Vaporizers

Energies ◽  
2022 ◽  
Vol 15 (1) ◽  
pp. 280
Author(s):  
Filip Lisowski ◽  
Edward Lisowski
Keyword(s):  
Power Supply ◽  
Cryogenic Temperature ◽  
Analytical Approach ◽  
Unit Length ◽  
Heat Rate ◽  
Ambient Air ◽  
Finned Tube ◽  
Ansys Software ◽  
Finned Tubes ◽  
Gaseous Form

The use of cryogenic liquefied gasses in industry is constantly increasing both for process purposes and for power supply needs. The liquefied natural gas (LNG) is stored at cryogenic temperature and its immediate use in gaseous form requires its evaporation. The heat needed to cause a phase change is usually delivered by means of vaporizers. This paper presents a numerical analysis of the influence of the fins number and frost accumulated within the fins surface on the heat transferred through the aluminum finned tubes of LNG ambient air vaporizers. The calculations were carried out applying finite element thermal analysis within Ansys software as well as using an analytical approach. As a result, the heat rate per unit length of the finned tube was obtained. The results were compared for different numbers of longitudinal fins both without frost and for total frosting of the tubes.

scholarly journals CFD analysis of air flow through the LNG ambient air vaporizer with longitudinal finned tubes

2021 ◽  
Vol 323 ◽  
pp. 00021
Author(s):  
Filip Lisowski ◽  
Edward Lisowski
Keyword(s):  
Air Flow ◽  
Ambient Air ◽  
Finned Tube ◽  
The Other ◽  
Wind Pressure ◽  
Cfd Analysis ◽  
Finned Tubes ◽  
Wind Velocities ◽  
Flow Through ◽  
Forced Air

Ambient air vaporizers, depending on their efficiency, can be up to several meters high. Therefore, they can have a large outside surface area exposed to the wind. Forced air flow through the vaporizer structure have a beneficial effect on improving heat transfer from the environment. On the other hand, if the vaporizer is placed in the region of significant wind velocities, the wind forces acting on the structure can be considerable. This paper presents CFD analysis of air flow through the structure of the ambient air vaporizer with a 6 x 6 finned tube array. The effect of changing wind direction on the wind pressure and wind velocity distributions is investigated.

scholarly journals Finite element analysis of heat flow through longitudinal finned tubes in the LNG ambient air vaporizer for a total frost case

2021 ◽  
Vol 323 ◽  
pp. 00020
Author(s):  
Filip Lisowski ◽  
Edward Lisowski
Keyword(s):  
Heat Transfer ◽  
Finite Element ◽  
Natural Gas ◽  
High Efficiency ◽  
Ambient Air ◽  
Element Analysis ◽  
Finned Tubes ◽  
Large Heat ◽  
Flow Through ◽  
Gaseous Form

Liquefied natural gas (LNG) is transported and stored in liquid state at temperature of -163C. In order to use natural gas directly in its gaseous form, LNG must be vaporized, which requires the input of heat. Ambient air vaporizers (AAVs) are commonly used for that purpose in LNG regasification stations. These heat exchangers consist of longitudinally finned tubes with a large heat transfer surface area, provide high efficiency and are virtually cost-free since the heat is taken from the ambient air. This paper presents the results finite element thermal analysis of heat transfer through the finned tubes of ambient air vaporizers under the conditions of total frosting.

Cracking Response of a Concrete Wall to Cryogenic Temperature

2015 ◽  
Vol 365 ◽  
pp. 71-76
Author(s):  
Lahlou Dahmani ◽  
Rabah Hammar ◽  
Mohamed Oussalem Mechiche
Keyword(s):  
Cryogenic Temperature ◽  
Heat Conduction Problem ◽  
Outer Wall ◽  
Distribution Data ◽  
Cryogenic Temperatures ◽  
The Finite Element Method ◽  
Ansys Software ◽  
Concrete Wall ◽  
Steel Tank ◽  
Concrete Tank

Liquefied natural gas (LNG) has the cryogenic temperature of –160°C to ensure the minimum storage volume when stored in LNG containers. Among various types of LNG storage containers, the full containment above-ground type with a double safety system (outer concrete tank and inner steel tank) is very common. Normally, the inner tank contains LNG, but when the LNG leaks from the inner tank, the outer concrete tank comes into contact with LNG. Under this accidental case, it is indispensable for the outer wall to keep the liquid tightness in order to safely contain the LNG before taking any countermeasure. It is, therefore, proposed to take up a heat conduction problem using the finite element method with the ANSYS software to obtain temperature distribution data of a concrete wall at cryogenic temperatures.

Tube Banks Heat Transfer Enhancement Using Conical Fins

2010 ◽  
Author(s):  
Ignacio Carvajal-Mariscal ◽  
Florencio Sanchez-Silva ◽  
Georgiy Polupan
Keyword(s):  
Heat Transfer ◽  
Heat Exchange ◽  
Pressure Drop ◽  
Finned Tube ◽  
Hot Water ◽  
Experimental Results ◽  
Tube Bank ◽  
Finned Tubes ◽  
Tube Banks ◽  
Annular Fins

In this work the heat transfer and pressure drop experimental results obtained in a two step finned tube bank with conical fins are presented. The tube bank had an equilateral triangle array composed of nine finned tubes with conical fins inclined 45 degrees in respect with the tube axis. The heat exchange external area of a single tube is approximately 0.07 m2. All necessary thermal parameters, inlet/outlet temperatures, mass flows, for the heat balance in the tube bank were determined for different air velocities, Re = 3400–18400, and one constant thermal charge provided by a hot water flow with a temperature of 80 °C. As a result, the correlations for the heat transfer and pressure drop calculation were obtained. The experimental results were compared against the analytical results for a tube bank with annular fins with the same heat exchange area. It was found that the proposed tube bank using finned tubes with conical fins shows an increment of heat transfer up to 58%.

Prediction of Heat Transfer Coefficients in Gas Flow Normal to Finned and Smooth Tube Banks

1981 ◽  
Vol 103 (4) ◽  
pp. 705-714 ◽  
Author(s):  
J. C. Biery
Keyword(s):  
Heat Transfer ◽  
Gas Flow ◽  
Finned Tube ◽  
Smooth Tube ◽  
Transfer Coefficients ◽  
Tube Bank ◽  
Finned Tubes ◽  
Heat Transfer Coefficients ◽  
High Reynolds ◽  
Tube Banks

A new method is presented to predict heat transfer coefficients for gas flow normal to smooth and finned tube tanks with triangular pitch. A transformation from the actual tube bank to an equivalent equilateral triangular pitch infinite smooth tube bank (ETP-I-STB) is made. A function of Ch(Ch = NSTNPR2/3NRe0.4) versus (Xt D0)Δ, ratio of transverse pitch to tube diameter for the ETP-I-STB, was developed. The Ch for the equivalent ETP-I-STP then applies to the actual tube bank. The method works with circular finned tubes, smooth tubes, continuous finned tubes, and segmented finned tubes with any triangular pitch. Also, fair predictions were made for in-line tubes with high Reynolds numbers.

scholarly journals Nghiên cứu ảnh hưởng của hiện tượng nghịch nhiệt đến hàm lượng bụi PM2.5 trong môi trường không khí tại Hà Nội

2018 ◽  
Vol 34 (3) ◽  
Author(s):  
Trinh Thi Tham
Keyword(s):  
Air Quality ◽  
Statistical Difference ◽  
Heat Rate ◽  
Ambient Air ◽  
Quality Monitoring ◽  
Air Quality Monitoring ◽  
Heat Temperature ◽  
Effects Of Temperature ◽  
Temperature Inversions ◽  
The Impact

In this study, we assessed effects of temperature inversions on air quality in Hanoi, is the capital of Vietnam with the business development speed also as urbanization high in year near here. Temperature inversions occur frequently in the cooler seasons, exacerbating the impact of emissions and diffusions from industry and traffic. This research used concentration of PM2.5 data gathered from 02 automatic air quality monitoring station located North Centre for Environmental Monitoring, Vietnam environment administration and U.S Embassy Hanoi. The data on the change of temperature in the depth was collected from the meteorological stations Hanoi in 2017 aimed to analyze the frequency of the temperature  rating of the Heat Rate of the Heat Temperature and the Heat of the temperature  inversions and impacts of that on concentration of PM2.5 in the atmosphere. The results also revealed that there was statistical difference (Sig. <0,05) between PM2.5 levels in the ambient air on the inversion days and those on the normal day.

Study on Free Convection Heat Transfer in a Finned Tube Array

2015 ◽  
Vol 23 (01) ◽  
pp. 1550007 ◽  
Author(s):  
Ryoji Katsuki ◽  
Tsutomu Shioyama ◽  
Chikako Iwaki ◽  
Tadamichi Yanazawa
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Heat Exchanger ◽  
Transfer Coefficient ◽  
Finned Tube ◽  
Average Heat Transfer Coefficient ◽  
Average Heat ◽  
Finned Tubes ◽  
Air Cooled Heat Exchanger ◽  
The Heat Transfer Coefficient

We have been developing a free convection air cooled heat exchanger without power supply to improve economic efficiency and mechanical reliability. However, this heat exchanger requires a larger installation area than the forced draft type air cooled heat exchanger since a large heating surface is needed to compensate for the small heat transfer by natural convection. Therefore, we have been investigating a heat exchanger consisting of an array of finned tubes and chimney to increase the heat transfer coefficient. Since the heat transfer characteristics of finned tube arrays have not been clarified, we conducted experiments with a finned tube array to determine the relation between the configuration of finned tubes and the heat transfer coefficient of a tube array. The results showed that the average heat transfer coefficient increased with pitch in the vertical direction, and became constant when the pitch was over five times the fin diameter. The average heat transfer coefficient was about 1.4 times higher than that of a single finned tube in free space. The ratio of the average heat transfer coefficient of the finned tube array with chimney to that of a single finned tube was found to be independent of the difference in temperature between the tube surface and air.

Static configuration of liquid films on horizontal tubes with low radial fins: implications for condensation heat transfer

1987 ◽  
Vol 410 (1838) ◽  
pp. 125-139 ◽  
Keyword(s):  
Heat Transfer ◽  
Liquid Films ◽  
Finned Tube ◽  
Tube Surface ◽  
Maximum Heat ◽  
Finned Tubes ◽  
Horizontal Tubes ◽  
Maximum Heat Transfer ◽  
Fluid Properties ◽  
Static Conditions

The configuration of a liquid film retained by surface tension forces on horizontal low-finned tubes has been analysed. It has been shown that liquid is retained on the upper parts of the tube surface previously regarded as 'unflooded'. The meniscus in a radial plane has been shown to approximate to a circular arc, with radius dependent only on the distance from the bottom of the tube, fluid properties and gravity. Four ‘flooding’ conditions are identified for trapezoidal-section fins and the positions around a tube at which these occur have been determined. Experimental measurements, for condensation of three fluids on tubes with rectangular-section fins, suggest that maximum heat-transfer en­hancement occurs when the spacing between the fins (the only geometric variable in these tests) is such as to maximize the ‘unblanked’ (by retained liquid under static conditions) finned tube surface area. The ‘unblanked’ or ‘active’ area is increased by using a radiused fillet at the fin root rather than a sharp corner. This might also be expected to give a corresponding increase in heat-transfer enhancement during condensation.

The Flow Characteristics of Flue Gas Between the Fins of a Single Spiral Finned Tube

2005 ◽  
Author(s):  
Fengzhong Sun ◽  
Yuetao Shi ◽  
Zhihang Han ◽  
Yang Liu ◽  
Xinyuan Huang ◽  
...  
Keyword(s):  
Experimental Research ◽  
Flue Gas ◽  
Heat Exchangers ◽  
Flow Characteristics ◽  
Finned Tube ◽  
Finned Tubes ◽  
Cold State ◽  
State Test

The spiral finned tubes are used as the substitute of bare tubes in heat exchangers, which is an effective method to reduce abrasion and fouling in boilers. The cold state test with PDA system has been made to study the distribution of granule concentration between fins. This experimental research has laid the foundation of analysis for further study why the spiral finned tube can reduce abrasion and fouling.

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