Boiling Behavior of Iso-Butane on a Horizontal Plain Tube

2021 ◽  
pp. 23-32
Author(s):  
Ashok K. Dewangan ◽  
Sanjeev K. Sajjan
Keyword(s):  
Plain Tube

Thermal Performance Assessment of Turbulent Flow Through Dimpled Tubes

2010 ◽  
Author(s):  
Pornchai Nivesrangsan ◽  
Somsak Pethkool ◽  
Kwanchai Nanan ◽  
Monsak Pimsarn ◽  
Smith Eiamsa-ard
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Friction Factor ◽  
Heat Transfer Rate ◽  
Thermal Performance ◽  
Transfer Rate ◽  
Staggered Arrangement ◽  
Plain Tube ◽  
Pitch Ratio ◽  
Surface Patterns

This paper presents the heat transfer augmentation and friction factor characteristics by means of dimpled tubes. The experiments were conducted using the dimpled tubes with two different dimpled-surface patterns including aligned arrangement (A-A) and staggered arrangement (S-A), each with two pitch ratios (PR = p/Di = 0.6 and 1.0), for Reynolds number ranging from 9800 to 67,000. The experimental results achieved from the dimpled tubes are compared with those obtained from the plain tube. Evidently, the dimpled tubes with both arrangements offer higher heat transfer rates compared to the plain tube and the dimpled tube with staggered arrangement shows an advantage on the basis of heat transfer enhancement over the dimpled tube with aligned arrangement. The increase in heat transfer rate with reducing pitch ratio is due to the higher turbulent intensity imparted to the flow between the dimple surfaces. The mean heat transfer rate offered by the dimpled tube with staggered arrangement (S-A) at the lowest pitch ratio (PR = 0.6), is higher than those provided by the plain tube and the dimpled tube with aligned arrangement (A-A) at the same PR by around 127% and 8%, respectively. The empirical correlations developed in terms of pitch ratio (PR), Prandtl number (Pr) and Reynolds number, are fitted the experimental data within ±8% and ±2% for Nusselt number (Nu) and friction factor (f), respectively. In addition, the thermal performance factors under an equal pumping power constraint of the dimple tubes for both dimpled-surface arrangements are also determined.

Buoyancy Force on a Plain or Perforated Portion of a Pipe

2021 ◽  
Author(s):  
Eric Cayeux ◽  
Sigmund Stokka
Keyword(s):  
Buoyancy Force ◽  
Construction Operations ◽  
Drilling Operation ◽  
Drill Stem ◽  
Shallow Wells ◽  
Plain Tube ◽  
End Caps ◽  
Drag Models ◽  
The One ◽  
Perforated Tube

Abstract Torque and drag models have been used for many decades to calculate tensions and torques along drill-strings, casing strings and liner strings. However, when applied to sand-screens, it is important to check that all the initial hypotheses used for torque and drag calculations are still valid. In particular, it should be checked whether the buoyancy force on a perforated tube may differ from the one applied to a plain tube. The buoyancy force applied on a pipe, contributes to the sum of efforts at the contact between the pipe and the borehole and therefore influences torque and drag calculations. This contact force is local and should account for localized effects as well as the material internal forces, torques and moments on each side of the contact. As the buoyancy force is the result of the gravitational component of the pressure gradient on the surface of the pipe that is in contact with the fluid, the presence of holes in the pipe also influences the buoyancy force. When applied to a portion of a pipe, buoyancy does not have contributions at the end caps of that portion of the drill-stem since these end caps are not in contact with the fluid, except at positions with a change of diameter. Therefore, one shall be cautious when calculating the local buoyancy force either on a plain or a perforated tube. The paper describes how to calculate the local buoyancy force on a portion of a drill-stem by application of the Gauss theorem accounting for the necessary corrections arising from the end caps not being exposed to the fluid. An experimental setup has been built to verify that the tension inside a pipe subject to buoyancy does follow the derived mathematical calculations. With complex well construction operations, for instance during extended reach drilling or when drilling very shallow wells with high kick-off rates, the slightest error in torques and drag calculations may end up in jeopardizing the chance of success of the drilling operation. It is therefore important to check that all initial calculation hypotheses are still valid in those contexts and that for instance, sand-screens may be run in hole safely after a successful drilling operation.

Quasi-stationary modelling of solidification in a latent heat storage comprising a plain tube heat exchanger

2018 ◽  
Vol 20 ◽  
pp. 551-559 ◽  
Author(s):  
A. Stamatiou ◽  
S. Maranda ◽  
F. Eckl ◽  
P. Schuetz ◽  
L. Fischer ◽  
...  
Keyword(s):  
Heat Exchanger ◽  
Latent Heat ◽  
Heat Storage ◽  
Latent Heat Storage ◽  
Tube Heat Exchanger ◽  
Plain Tube

scholarly journals PENGARUH SUDUT LOUVERED STRIPS TERHADAP LAJU PERPINDAHAN PANAS PADA COUNTER FLOW HEAT EXCHANGER

2011 ◽  
Vol 8 (2) ◽  
Author(s):  
Nyoman Arya Wigraha
Keyword(s):  
Heat Exchanger ◽  
Performance Ratio ◽  
Counter Flow ◽  
Tube Heat Exchanger ◽  
Plain Tube ◽  
Flow Heat

Pengaruh turbulator Louvered strips terhadap laju perpindahan kalor dan faktor gesekan aliran turbulen pada double tube heat exchanger dapat memecah (partitioning) dan mengganggu (blockage) pola streamline dari fluida yang mengalir ke saluran pipa dalam (inner tube) sehingga mengakumulasi aliran turbulensi dan meningkatkan laju perpindahan kalor dalam pipa. Louvered strips memiliki variasi sudut serang (q = 15°, 25°, 30°) yang terpasang ditengah-tengah pipa bagian dalam dan searah aliran fluida masuk. Laju aliran fluida (air) panas di bagian pipa dalam diteliti dengan interval 400 lt/jam sampai 900 lt/jam dan laju aliran air dingin di bagian pipa luar konstan 900 lt/jam. Data hasil pengujian dari masing – masing sudut serang turbulator ini dibandingkan data tanpa turbulator (plain tube),  secara keseluruhan terjadi peningkatan laju perpindahan kalor sebesar 26 % sampai 58 % dari pada tanpa turbulator serta menghasilkan faktor gesekan dari 25 % sampai 40 %. Dengan performance ratio rata –rata tertinggi pada turbulator dengan sudut 30O sebesar 0,948.   Kata kunci:  Louvered strips, Heat Exchanger, Counter flow, turbulensi, faktor gesekan, turbulator, efektifitas

scholarly journals Efficacy of autologous platelet rich fibrin matrix in the management of non-healing ulcers

2019 ◽  
Vol 5 (4) ◽  
pp. 686
Author(s):  
Prachi V. Gole ◽  
Naziya Muhammed ◽  
Siddhi R. Patadia
Keyword(s):  
Therapeutic Option ◽  
Venous Blood ◽  
Middle Layer ◽  
Complete Healing ◽  
Duration Of Treatment ◽  
Platelet Rich Fibrin ◽  
Average Percentage ◽  
Fibrin Matrix ◽  
Plain Tube ◽  
Healing Wounds

<p class="abstract"><strong>Background:</strong> Non healing ulcers have a worldwide prevalence of 1.9%-13.1% with lower extremity being the commonest site. They are difficult to manage for the physician and frustrating for the patient due longer duration of treatment, cost, unsatisfactory outcomes and impairment caused due to them. Standard conventional management may fail at times and hence growth factors derived from platelets have been tried in the management of these ulcers. The purpose of our study was to evaluate the efficacy of platelet rich fibrin matrix (PRFM) in treatment of these ulcers.</p><p class="abstract"><strong>Methods:</strong> Twelve patients with fifteen non-healing ulcers more than 3 months duration were included in the study. 10cc of venous blood was withdrawn in plain tube without anti-coagulants and centrifuged at 1500 rpm for 14 minutes as early as possible as per advanced PRF protocol. Middle layer of PRFM was applied to the clean ulcer followed by a secondary dressing. All patients received PRFM sittings every 7-10 days or till ulcer healed. Baseline photographs and measurements of length, breadth and depth were taken to calculate the area of ulcer at every sitting.<strong></strong></p><p class="abstract"><strong>Results:</strong> The average percentage reduction in area and volume of the ulcer was 95.84% and 98.18% respectively at the end of six sittings. Twelve out of fifteen ulcers showed complete healing by 6 weeks, while three ulcers showed significant improvement but did not heal completely. The procedure was safe, well tolerated without any side effects.</p><p class="abstract"><strong>Conclusions:</strong> Platelet rich fibrin matrix is a novel modality and an ideal, safe, affordable therapeutic option for non-healing wounds of varied causes.</p>

scholarly journals PENGARUH SUDUT LOUVERED STRIPS TERHADAP LAJU PERPINDAHAN PANAS PADA COUNTER FLOW HEAT EXCHANGER

2011 ◽  
Vol 8 (2) ◽  
Author(s):  
Nyoman Arya Wigraha
Keyword(s):  
Heat Exchanger ◽  
Performance Ratio ◽  
Counter Flow ◽  
Tube Heat Exchanger ◽  
Plain Tube ◽  
Flow Heat

Pengaruh turbulator Louvered strips terhadap laju perpindahan kalor dan faktor gesekan aliran turbulen pada double tube heat exchanger dapat memecah (partitioning) dan mengganggu (blockage) pola streamline dari fluida yang mengalir ke saluran pipa dalam (inner tube) sehingga mengakumulasi aliran turbulensi dan meningkatkan laju perpindahan kalor dalam pipa. Louvered strips memiliki variasi sudut serang (q = 15°, 25°, 30°) yang terpasang ditengah-tengah pipa bagian dalam dan searah aliran fluida masuk. Laju aliran fluida (air) panas di bagian pipa dalam diteliti dengan interval 400 lt/jam sampai 900 lt/jam dan laju aliran air dingin di bagian pipa luar konstan 900 lt/jam. Data hasil pengujian dari masing – masing sudut serang turbulator ini dibandingkan data tanpa turbulator (plain tube),  secara keseluruhan terjadi peningkatan laju perpindahan kalor sebesar 26 % sampai 58 % dari pada tanpa turbulator serta menghasilkan faktor gesekan dari 25 % sampai 40 %. Dengan performance ratio rata –rata tertinggi pada turbulator dengan sudut 30O sebesar 0,948.   Kata kunci:  Louvered strips, Heat Exchanger, Counter flow, turbulensi, faktor gesekan, turbulator, efektifitas

Influence of Short Helical Tape on Local Convective Heat Transfer and Thermal Performance Characteristics in Turbulent Decaying Swirl Flow

2010 ◽  
Vol 8 (1) ◽  
Author(s):  
Smith Eiamsa-ard ◽  
Vichan Kongkaitpaiboon ◽  
Khwanchit Wongcharee
Keyword(s):  
Heat Transfer ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Thermal Performance ◽  
Swirl Flow ◽  
Transfer Rates ◽  
Friction Factors ◽  
Plain Tube ◽  
Uniform Wall ◽  
Uniform Wall Heat Flux

This paper reports the experimental investigation of local convective heat transfer enhancement, flow friction and thermal performance factor behaviors in the tube fitted with the short helical tapes (SHTs) acting as decaying swirl flow generators. The tapes with three different helical tape angles (? = 90°, 135° and 180°) and three different channel numbers (N = 2, 3 and 4 channels) were tested under the uniform wall heat flux condition. The performance of each tape is compared with the performance of the plain tube subject to the same pumping power. The experimental results show that the heat transfer rates and friction factors of the tube with SHTs are respectively in range of 1.15 to 1.9 and 1.49 to 2.31 times of those in the plain, corresponding to thermal performances between 0.98 and 1.46. The correlations for Nusselt number (Nu) as a function of Reynolds number (Re), Prandtl number (Pr), helical tape angle (?) and the number of channel (N) are also developed.

Acid freezes uricolysis in addition to glycolysis: Utility of fluoride-EDTA-citrate tube in the measurement of uric acid for patients administered rasburicase

2022 ◽  
pp. 000456322110662
Author(s):  
Tejas Kalaria ◽  
Jonathan Fenn ◽  
Richard Whitmill ◽  
Clare Ford ◽  
Rousseau Gama
Keyword(s):  
Uric Acid ◽  
Ethylenediaminetetraacetic Acid ◽  
Ex Vivo ◽  
Metal Chelators ◽  
Sample Tube ◽  
Serum Pool ◽  
Plain Tube ◽  
Ice Water ◽  
Edta Tube ◽  
Uricase Activity

Background In samples from patients administered rasburicase, ex vivo uricolysis leads to spuriously low uric acid results. The manufacturer’s recommendation of storing the sample in ice-water until analysis, however, does not fully arrest uricolysis. Since uricase activity is affected by pH and metal chelators, we assessed uricolysis inhibition in sodium fluoride-ethylenediaminetetraacetic acid (EDTA)-citrate sample tube (FC Mix tube, Greiner) used primarily for plasma glucose. Method A serum pool was spiked with rasburicase and uric acid measured at 15, 45, 90, 150, 240 and 1080 min in a lithium heparin tube in ice-water, plain tube at room temperature (RT), EDTA tube at RT, FC Mix tube in ice-water, FC Mix tube at RT and FC Mix tube at RT prepared by dissolving FC Mix in serum. Results The rate of urate decay was lowest in the FC Mix tube independent of temperature, then lithium heparin tube in ice-water, then EDTA tube at RT and highest in the plain tube at RT. Uric acid concentrations in the prepared FC Mix tube at RT and heparin tube in ice-water were, respectively, 98.2% and 93.8% of control values at 90 min, 97.1% and 89.3% of control values at 4 h, and remained higher in the prepared FC Mix tube at all time points. Conclusion NaF-EDTA-citrate mixture largely arrested rasburicase mediated ex vivo uricolysis without the need for sample cooling. We propose that sample tubes containing NaF-EDTA-citrate be used for the measurement of uric acid in patients administered rasburicase.

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