Pool boiling heat transfer enhancement by using perforated twisted tape fins

2021 ◽  
pp. 1-10
Author(s):  
Parimesh Joshi ◽  
Anil Kumar Patil ◽  
Manoj Kumar
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Boiling Heat Transfer ◽  
Pool Boiling ◽  
Twisted Tape ◽  
Transfer Enhancement ◽  
Maximum Enhancement ◽  
Twist Ratio ◽  
Plain Surface ◽  
Considerable Enhancement

Abstract The application of twisted tape fins showed a considerable enhancement in pool boiling heat flux. The present study experimentally investigates the effect of solid and perforated twisted tape fins on pool boiling of water by varying the twist ratio (y) and perforation index (PI) from 3 - 4.3 and 5 - 10, respectively. An arrangement of five twisted tape fins with twist ratio of 3 showed 18.6% enhancement as compared to the plain surface whereas an arrangement of five perforated twisted tape fins having perforation index (PI) of 7 and twist ratio of 3 showed a maximum enhancement of 28.7%.

Effect of Heat Flux on Pool Boiling Heat Transfer Enhancement (Numerical Investigation Approach)

2020 ◽  
Author(s):  
T. S. Mogaji ◽  
O. A. Sogbesan ◽  
Tien-Chien Jen
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Heat Transfer Enhancement ◽  
Numerical Investigation ◽  
Boiling Heat Transfer ◽  
Pool Boiling ◽  
Nucleate Boiling ◽  
Transfer Enhancement

Abstract This study presents numerical investigation results of heat flux effect on pool boiling heat transfer enhancement during nucleate boiling heat transfer of water. The simulation was performed for five different heated surfaces such as: brass, copper, mild steel, stainless steel and aluminum using ANSYS simulation software at 1 atmospheric pressure. The samples were heated in a domain developed for bubble growth during nucleate boiling process under the same operational condition of applied heat flux ranged from 100 to 1000 kW/m2 and their corresponding heat transfer coefficient was obtained numerically. Obtained experimental data of other authors from the open literature result is in close agreement with the simulated data, thus confirming the validity of the CFD simulation method used in this study. It is found that heat transfer coefficient increases with increasing heat flux. The results revealed that in comparison to other materials tested, better heat transfer performance up to 38.5% and 7.11% is observed for aluminum and brass at lower superheated temperature difference conditions of 6.96K and 14.01K respectively. This behavior indicates better bubble development and detachment capability of these heating surface materials and could be used in improving the performance of thermal devices toward producing compact and miniaturized equipment.

Microporous Coatings to Maximize Pool Boiling Heat Transfer of Saturated R-123 and Water

2015 ◽  
Vol 137 (8) ◽  
Author(s):  
Joo Han Kim ◽  
Ajay Gurung ◽  
Miguel Amaya ◽  
Sang Muk Kwark ◽  
Seung M. You
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Boiling Heat Transfer ◽  
Pool Boiling ◽  
Nucleate Boiling ◽  
Transfer Coefficients ◽  
Maximum Heat ◽  
Microporous Coating ◽  
Plain Surface ◽  
Improved Performance

The present research is an experimental study for the enhancement of boiling heat transfer using microporous coatings. Two types of coatings are investigated: one that is bonded using epoxy and the other by soldering. Effects on pool boiling performance were investigated, of different metal particle sizes of the epoxy-based coating, on R-123 refrigerants, and on water. All boiling tests were performed with 1 cm × 1 cm test heaters in the horizontal, upward-facing orientation in saturated conditions at atmospheric pressure and under increasing heat flux. The surface enhanced by the epoxy-based microporous coatings significantly augmented both nucleate boiling heat transfer coefficients and critical heat flux (CHF) of R-123 relative to those of a plain surface. However, for water, with the same microporous coating, boiling performance did not improve as much, and thermal resistance of the epoxy component limited the maximum heat flux that could be applied. Therefore, for water, to seek improved performance, the solder-based microporous coating was applied. This thermally conductive microporous coating, TCMC, greatly enhanced the boiling performance of water relative to the plain surface, increasing the heat transfer coefficient up to ∼5.6 times, and doubling the CHF.

scholarly journals Analysis of Enhanced Pool Boiling Heat Transfer on Laser—Textured Surfaces

Energies ◽  
2020 ◽  
Vol 13 (11) ◽  
pp. 2700 ◽  
Author(s):  
Łukasz J. Orman ◽  
Norbert Radek ◽  
Jacek Pietraszek ◽  
Marcin Szczepaniak
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Boiling Heat Transfer ◽  
Pool Boiling ◽  
Textured Surfaces ◽  
Transfer Enhancement ◽  
Modified Model ◽  
Copper Surfaces ◽  
Pool Boiling Heat Transfer ◽  
The Impact

Enhancement of pool boiling heat transfer can be attained with a number of passive and active techniques. The paper experimentally analyses the impact of laser treatment of the copper surfaces on pool boiling heat transfer of distilled water and ethyl alcohol. The samples were modified with a laser beam to produce longitudinal grooves of highly developed microstructures in the laser textured area. Specimens of different groove depths, groove widths and micro-fin widths were produced. The results indicate a significant influence of laser processing on heat flux dissipated from the surfaces and heat transfer enhancement for all the samples tested. The experimental results have been generalized in the form of a heat flux correlation based on a modified model of enhanced pool boiling heat transfer.

Pool Boiling Heat Transfer Characteristics of Inclined pHEMA-Coated Surfaces

2017 ◽  
Vol 139 (11) ◽  
Author(s):  
Abdolali Khalili Sadaghiani ◽  
Ahmad Reza Motezakker ◽  
Alsan Volkan Özpınar ◽  
Gözde Özaydın İnce ◽  
Ali Koşar
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Boiling Heat Transfer ◽  
Bubble Dynamics ◽  
Pool Boiling ◽  
Nucleate Boiling ◽  
Surface Orientation ◽  
Maximum Enhancement ◽  
Pool Boiling Heat Transfer ◽  
Coated Surfaces

New requirements for heat exchangers offered pool boiling heat transfer on structured and coated surfaces as one of the promising methods for effective heat removal. In this study, pool boiling experiments were conducted on polyhydroxyethylmethacrylate (pHEMA)-coated surfaces to investigate the effect of surface orientation on bubble dynamics and nucleate boiling heat transfer. pHEMA coatings with thicknesses of 50, 100, and 200 nm were deposited using the initiated chemical deposition (iCVD) method. De-ionized water was used as the working fluid. Experiments were performed on horizontal and inclined surfaces (inclination angles of 10 deg, 30 deg, 50 deg, and 70 deg) under the constant heat flux (ranging from 10 to 80 kW/m2) boundary condition. Obtained results were compared to their plain surface counterparts, and heat transfer enhancements were observed. Accordingly, it was observed that the bubble departure phenomenon was affected by heat flux and wall superheat on bare silicon surfaces, while the supply path of vapor altered the bubble departure process on pHEMA-coated surfaces. Furthermore, the surface orientation played a major role on bubble dynamics and could be considered as a mechanism for fast vapor removal from surfaces. Bubble coalescence and liquid replenishment on coated surfaces had a promising effect on heat transfer coefficient enhancement on coated surfaces. For horizontal surfaces, a maximum enhancement of 25% relative to the bare surface was achieved, while the maximum enhancement was 105% for the inclined coated surface under the optimum condition. iCVD was proven to be a practical method for coating surfaces for boiling heat transfer applications due to the obtained promising results.

An Experimental Study of Surface Tension-Dependent Pool Boiling Characteristics of Carbon Nanotubes-Nanofluids

2009 ◽  
Author(s):  
S. M. Sohel Murshed ◽  
Denitsa Milanova ◽  
Ranganathan Kumar
Keyword(s):  
Heat Transfer ◽  
Carbon Nanotubes ◽  
Surface Tension ◽  
Heat Flux ◽  
Boiling Heat Transfer ◽  
Heated Surface ◽  
Pool Boiling ◽  
Heat Fluxes ◽  
Maximum Enhancement ◽  
Heater Wire

This paper reports an experimental investigation of the pool boiling heat transfer characteristics of single-walled carbon nanotubes (SWCNTs)-nanofluids. Two main characteristics were studied to identify their influence on boiling heat transfer: one is the surface tension through the addition of surfactant and the other is the chemical treatment of nanotubes sidewalls (i.e. oxidized and untreated sidewalls). A Transmission Electron Microscope was used to study the morphology of the functionalized nanotubes and their deposition on heater wire. The maximum enhancement of both the critical and burnout heat fluxes of this nanofluid over those of the pure deionized water are found to be 492% and 265%, respectively at a surfactant to carbon nanotubes concentration ratio of 1:5. This indicates that high enhancement of heat flux is possible and would depend on the concentration of the surfactants. Present results also demonstrate that CNT-nanofluids in a pool boiling environment can extend the saturated boiling regime and the burnout of the heated surface. The burnout heat flux is found to be a strong function of the relaxation of nanofluid surface tension with the base fluid. Based on the best fit of experimental data, an empirical correlation between the burnout heat flux of nanofluid and its relaxation of surface tension is introduced.

Orientation Effects on Pool Boling of Microporous Coating in Water

2017 ◽  
Vol 139 (2) ◽  
Author(s):  
Seongchul Jun ◽  
Jinsub Kim ◽  
Hwan Yeol Kim ◽  
Seung M. You
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Bubble Growth ◽  
Boiling Heat Transfer ◽  
Pool Boiling ◽  
Nucleate Boiling ◽  
Copper Surface ◽  
Large Bubble ◽  
Microporous Coating ◽  
Plain Surface

Copper HTCMC (High-temperature, Thermally Conductive Microporous Coating) with a coating thickness of ~300 µm was created by sintering 67 µm copper particles onto a flat copper surface. This was shown to be the optimum particle size and thickness combination, in terms of boiling heat transfer enhancement with water, during a prior pool boiling study conducted by Jun et al. [1]. The effects of orientation of pool boiling heat transfer in saturated distilled water at 1 atm were tested experimentally and compared with a plain copper surface. An SEM image (top left) shows the porous structure of HTCMC demonstrating reentrant cavities which promote nucleate boiling and lead to significant critical heat flux (CHF) enhancement compared to the plain copper surface (top right). The nucleate boiling incipience heat flux of HTCMC was demonstrated to be 5 kW/m2, which was an 8x reduction when compared to a plain copper surface which was found to have an incipience heat flux of 40 kW/m2. At this same 40 kW/m2 heat flux, the activated nucleation site density of HTCMC was extremely high, and each bubble appeared much smaller compared to a plain surface. This can be seen in the first row of images, captured with a high speed camera at 2,000 fps. The bubble growth times and departing bubble sizes of 0° and 90° are comparable for both HTCMC and plain surfaces with the order of 10 milliseconds and 100 micrometers. However, when oriented at 180°, the bubble growth time was the order of 100 milliseconds for both HTCMC and plain surface, and the departing bubble size was the order of 10 millimeters. This is due to the growth of a large bubble which coalesced with adjacent bubbles to become a relatively huge bubble which was stretched by buoyance forces before the bubble departed.

Pool boiling heat transfer enhancement by twisted-tape fins

2018 ◽  
Vol 135 ◽  
pp. 170-177 ◽  
Author(s):  
Massoud Ebrahimi-Dehshali ◽  
Seyyed Zagros Najm-Barzanji ◽  
Ali Hakkaki-Fard
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Enhancement ◽  
Boiling Heat Transfer ◽  
Pool Boiling ◽  
Twisted Tape ◽  
Transfer Enhancement ◽  
Pool Boiling Heat Transfer
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