The Effect of Linearly Increasing/Decreasing Pitch Ratio Twisted Tape with Various Progression rate and Nanofluid Towards the System Performance

2021 ◽  
pp. 100979
Author(s):  
A. Saadah ◽  
S. Abdullah ◽  
K. Sopian
Keyword(s):  
System Performance ◽  
Twisted Tape ◽  
Progression Rate ◽  
Pitch Ratio

scholarly journals Performance Study of a Cylindrical Parabolic Concentrating Solar Water Heater with Nail Type Twisted Tape inserts in the Copper Absorber Tube

2017 ◽  
Author(s):  
Amit K. Bhakta ◽  
Nitesh K. Panday ◽  
Shailenrda N. Singh
Keyword(s):  
Solar Energy ◽  
Thermal Performance ◽  
Water Flow Rate ◽  
Twisted Tape ◽  
Solar Water Heater ◽  
Performance Study ◽  
Water Heater ◽  
Solar Water ◽  
Pitch Ratio ◽  
Twist Pitch

This paper reports the overall thermal performance of a cylindrical parabolic concentrating solar water heater (CPCSWH) with inserting nail type twisted tape (NTT) in the copper absorber tube for the nail twist pitch ratios 4.787, 6.914 and 9.042 respectively. The experiments are conducted for a constant volumetric water flow rate and during the time period 9:00 h to 15:00 h. The useful heat gain, hourly solar energy collected and hourly solar energy stored of this solar water heater are found higher for nail twist pitch ratio 4.787. The above said parameters are found to be a peak at noon and observed to follow the path of variation of solar intensity. At the starting of the experiment, the value of charging efficiency is observed to be maximum. Whereas the maximum value of instantaneous efficiency and overall thermal efficiency are observed at noon. The key finding is that the nail twist pitch ratio enhances the overall thermal performance of the CPCSWH.

Identification of the Effective Control Parameter to Enhance the Progression Rate of Vibro-Impact Devices With Drift

2017 ◽  
Vol 140 (1) ◽  
Author(s):  
Van-Du Nguyen ◽  
Huu-Duc Ho ◽  
The-Hung Duong ◽  
Ngoc-Hung Chu ◽  
Quoc-Huy Ngo
Keyword(s):  
System Performance ◽  
Effective Control ◽  
Progression Rate ◽  
Phase Lag ◽  
Harmonic Force ◽  
Natural Motion ◽  
Excitation Period ◽  
Excitation Force ◽  
The Impact ◽  
Impact Mass

This paper presents an experimental study to find out an effective parameter which is useful to enhance the progression rate of drifting vibro-impact systems excited by a harmonic force. It is assumed that the system performance would be better if the excitation force stays in a harmonious relationship with the natural motion of the impact mass. This hypothesis has been numerically analyzed and then experimentally verified. The phase lag between the excitation force and the motion of the impact mass is used to identify the best situation, where the system progression rate is maximal. It has been found that the highest progression rate of the system can be obtained when the phase lag is around one-eighth of the excitation period.

scholarly journals Analysis and Implementation of Thermal Heat Exchanger Tube Performance with Helically Pierced Twisted Tape Inserts Using ANFIS Model

2021 ◽  
Vol 2021 ◽  
pp. 1-13
Author(s):  
Faisal Altarazi ◽  
Sunil Kumar ◽  
Gaurav Gupta ◽  
Muhammad Gulzar ◽  
Yaé Ulrich Gaba ◽  
...  
Keyword(s):  
Heat Exchanger ◽  
System Modeling ◽  
Diameter Ratio ◽  
Twisted Tape ◽  
Heat Exchanger Tube ◽  
Anfis Model ◽  
Inference System ◽  
Relative Pitch ◽  
Pitch Ratio ◽  
Exchanger Tube

The present work used ANFIS, an adaptive neuro-fuzzy inference system modeling to analyze the effect of the variable parameters of helically pierced twisted tape inserts on the Nusselt number, friction factor, and thermo-hydraulic heat exchanger tube performance. The experimental data utilized for ANFIS modeling considered a diameter ratio ranging from 0.57 to 0.80, a relative pitch ratio ranging from 0.046 to 0.107, a perforation index ranging from 5% to 20% as variable twisted tape parameters and flow parameters. The Reynolds number varies from 4000 to 30000. The analysis showed that the maximum thermo-hydraulic performance was obtained at a diameter ratio of 0.65, a relative pitch ratio of 0.085, and a perforation index equal to 10%. The result predicts that the ANFIS model and experimental results are in good agreement as they have only ±0.53% deviations.

Experimental Study With Analytical Validation of Energy Parameters in Parabolic Trough Collector With Twisted Tape Insert

2020 ◽  
Vol 142 (3) ◽  
Author(s):  
U. C. Arunachala
Keyword(s):  
Experimental Study ◽  
Performance Evaluation ◽  
Analytical Model ◽  
System Performance ◽  
Operating Conditions ◽  
Twisted Tape ◽  
Hydraulic Efficiency ◽  
Parabolic Trough ◽  
Parabolic Trough Collector ◽  
Maximum Percentage

Abstract Thermo-hydraulic performance evaluation of parabolic trough collector is important while introducing heat transfer augmentation techniques to it. In the present outdoor experimental study, the role of twisted tape is justified in laminar flow-based parabolic trough collector. For the Re range of 544–1742 and solar beam radiation of 400–750 W/m2, the use of twisted tape (twist ratios: 5.2, 4.1, and 2.7) resulted in maximum instantaneous efficiency of 22.3%, 29.5%, and 40%, respectively, against 19.1% with plain receiver. The effect of pressure drop rise on system performance due to twisted tape is found to be insignificant as effective thermo-hydraulic efficiency recorded are 21.8%, 29.3%, and 39.7%, respectively, with maximum uncertainty involved of 1.01%. In view of the importance of system performance evaluation over a wide range of operating parameters and limitation of outdoor experiments, an analytical model has been developed which followed the similar trend. The model takes into account various operating conditions, viz. laminar, twisted tape-based laminar and turbulent flow condition as well as air-in-annulus and evacuated receiver cases. Using the model (laminar region) in both plain and twisted tape cases, the maximum percentage deviation in the prediction of exit fluid temperature (in °C) and effective thermo-hydraulic efficiency are 1.6 and 13.3, respectively. Further, for a turbulent case, the maximum percentage deviation in exit temperature (in °C) noticed is 2.9. Hence, the developed analytical model is having a good agreement with the experimental outcomes.

scholarly journals Numerical and Experimental Analysis of the Thermal Performances of SiC/Water and Al2O3/Water Nanofluid Inside a Circular Tube with Constant-Increased-PR Twisted Tape

Energies ◽  
2020 ◽  
Vol 13 (8) ◽  
pp. 2095 ◽  
Author(s):  
Saadah Ahmad ◽  
Shahrir Abdullah ◽  
Kamaruzzaman Sopian
Keyword(s):  
Experimental Analysis ◽  
Volume Fraction ◽  
Swirling Flow ◽  
Circular Tube ◽  
Simulation Analysis ◽  
Twisted Tape ◽  
Ansys Fluent ◽  
Twisted Tapes ◽  
Pitch Ratio ◽  
Heat Transfer System

The simultaneous use of two passive methods (twisted tape and a nanofluid) in a heat transfer system will increase the average Nusselt number (Nu) of the system. However, the presence of inserts and nanoparticles inside the tube will create higher pressure drop (ΔP) in the system, which can eventually affect the overall enhancement ratio (η), especially at higher Reynolds numbers (Re). Several modifications of twisted tapes have been made to reduce ΔP, but most showed a decreasing trend of η as Re increased. The objective of this study is to design a new geometry of twisted tape that yields a larger value of Nu and a smaller value of ΔP, which can result in a larger value of η especially at higher Re. A simulation and experimental analysis are conducted in which Re ranges from 4000–16,000 with two types of nanofluids (SiC/Water and Al2O3/Water) at various values of the volume fraction, (φ) (1–3%). ANSYS FLUENT software with the RNG k-ɛ turbulent model is adopted for the simulation analysis. Three types of twisted tape are used in the analysis: classic twisted tape with a pitch ratio of 2 (TT PR2), constant-increasing-pitch-ratio twisted tape (TT IPR) and constant-decreasing-pitch-ratio twisted tape (TT DPR). The use of TT IPR generates a stronger swirling flow at the inlet of the tube and smaller ∆P, especially near the outlet region. The highest value of η is obtained for 3% SiC/Water nanofluid that is flowing through a smooth circular tube with TT IPR inserts at Re of 10,000.

Influence of twisted tape fins on heat transfer and friction factor characteristics for impinging jet solar air heater

2021 ◽  
pp. 095440892199528
Author(s):  
MM Matheswaran ◽  
TV Arjunan ◽  
Mukesh K Sahu
Keyword(s):  
Heat Transfer ◽  
Friction Factor ◽  
Impinging Jet ◽  
Operating Conditions ◽  
Design Parameters ◽  
Twisted Tape ◽  
Solar Air Heater ◽  
Air Heater ◽  
Twist Ratio ◽  
Pitch Ratio

In this work, an experimental study was carried out to investigate the enhancement of heat transfer and friction factor characteristics of an impinging jet solar air heater integrated with twisted tape fins. During the analysis, the Reynolds number fin design parameters namely twist ratio (Y), and pitch ratio (py) are varied from 3500 –13500, 5.5–9.5, and 0.1–0.3, respectively. During the experimentation, the constant heat flux of 1000 W/m2 was maintained on the absorber plate. From the results, it was observed that the heat transfer rate increases while increasing the twist ratio up to 7.5 and further increase in twist ratio diminishes the performance. It was also concluded that the rise in pitch ratio (py) deteriorates the rate of heat transfer. The present work enhances the heat transfer and friction factor by the maximum of 1.9 and 1.81 times as compared with the conventional jet impingement solar air heater at identical operating conditions.

scholarly journals Review on Heat Transfer Enhancement by Insert Devices

2020 ◽  
Vol 5 (4) ◽  
pp. 130-147
Author(s):  
Md. Shamim Ahmed ◽  
Mohammad Zoynal Abedin
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Enhancement ◽  
Twisted Tape ◽  
Transfer Enhancement ◽  
Helical Tube ◽  
Twist Ratio ◽  
Different Types ◽  
Considerable Impact ◽  
Wire Coil ◽  
Pitch Ratio

The scientists revise the heat transfer enhancement techniques time to time to achieve better performance and to obtain optimized designs of heat exchangers. The present study reviews the performance and techniques of heat transfer enhancement using various insert devices such as twisted tape and wire coil insert as well as completely different forms of other inserts like air-foil shape inserts, X-shaped twisted tape inserts, baffles and V-winglets inserts with various types of medium and nanofluids. According to the summary of recent significant researches  on the heat transfer enhancement by using different types of  inserts and combinations of these inserts with various nanofluids showed that insert can indicatively enhance the heat transfer rate by modifying its geometry or configurations like twist ratio, length ratio, pitch ratio, segmented tape, perforated tape, angle of arrangements and insert quantities and so on which caused a considerable impact on performance characteristics of heat transfer enhancement along with the pressure drop and friction factor. It is revealed through reviewing the related literature that the highest value of equivalence heat transfer enhancement is as maximum as 400%, 300% and 9% for the twisted tape insert with helical tube, the air foil shaped inserts and for the wire coil inserts, respectively when compared with the smooth tube. In the case of baffles in nanofluids, as maximum as 255% equivalence heat transfer enhancement could be achieved when compared with that of baffles without nanofluids.

C-reactive protein as a marker of progression of carotid atherosclerosis in subjects with type 2 diabetes mellitus

VASA ◽  
2017 ◽  
Vol 46 (3) ◽  
pp. 187-192 ◽  
Author(s):  
Aleš Pleskovič ◽  
Marija Šantl Letonja ◽  
Andreja Cokan Vujkovac ◽  
Jovana Nikolajević Starčević ◽  
Katarina Gazdikova ◽  
...  
Keyword(s):  
Diabetes Mellitus ◽  
Carotid Atherosclerosis ◽  
Inflammatory Marker ◽  
Progression Rate ◽  
C Reactive Protein ◽  
Reactive Protein ◽  
Hs Crp ◽  
Unstable Plaques

Abstract. Background: This prospective study was designed to evaluate the effect of inflammatory markers on the presence and progression of subclinical markers of carotid atherosclerosis in a 3.8-year follow-up period in patients with type 2 diabetes mellitus (T2DM). Patients and methods: A total of 595 subjects with T2DM were enrolled. Subclinical markers of carotid atherosclerosis (carotid intima media thickness (CIMT), plaque thickness, and plaques presence) were assessed with ultrasound at the time of recruitment and again after 3.8 years. Subjects with T2DM were divided into 2 groups according to the plasma high sensitive C-reactive protein (hs-CRP) levels (subjects with hs-CRP ≥ 2 mg/L and subjects with hs-CRP below 2 mg/L). Results: Subjects with T2DM and hs-CRP levels ≥ 2 mg/L had higher CIMT in comparison with subjects with T2DM and hs-CRP levels below 2 mg/L, and higher incidence of plaques/unstable plaques in comparison with subjects with T2DM and hs-CRP levels below 2 mg/L. Multivariate logistic regression analysis found the association between the HDL cholesterol level and presence of plaques, whereas the inflammatory marker hs-CRP was not associated with subclinical markers of progression of carotid atherosclerosis. Multiple linear regression analysis found the association between the hs-CRP levels and either CIMT progression rate or a change in the number of sites with plaques in a 3.8-year follow-up. Conclusions: We demonstrated an association between the inflammatory marker hs-CRP and either CIMT or incidence of plaques/unstable plaques at the time of recruitment in Caucasians with T2DM. Moreover, we found the association between hs-CRP levels and either CIMT progression rate or a change in the number of sites with plaques in a 3.8-year follow-up in subjects with T2DM.

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