Due to microscale effects, the segmented microchannels or micro pin fin heat sinks emerged as a h... more Due to microscale effects, the segmented microchannels or micro pin fin heat sinks emerged as a high thermal management solution. In this context, the present work analyzes the influence of different heights of square micro pin fins with an aligned array and investigates their influence on pressure drop and heat transfer behavior. The HFE-7100 is used as the working fluid, and the pressure drop and surface temperature behavior are analyzed for different mass fluxes and inlet subcooling. The single-phase flow was analyzed numerically using the computational fluid dynamics (CFD) software ANSYS FLUENT® for comparing the simulation results with the experimental data, showing that the highest micro pin fins configuration provides a more uniform and lowest wall temperature distribution compared to the lowest configuration. There is a good agreement between the experimental results and the numerical analysis, with a mean absolute error of 6% for all the considered parameters. For the two-p...
Effect of uniformly and nonuniformly coated Al2O3 nanoparticles over plain glass tube heater on p... more Effect of uniformly and nonuniformly coated Al2O3 nanoparticles over plain glass tube heater on pool boiling heat transfer was studied experimentally. A borosilicate glass tube coated with Al2O3 nanoparticle was used as test heater. The boiling behaviour was studied by using high speed camera. Result obtained for pool boiling shows enhancement in heat transfer for nanoparticle coated surface heater and compared with plain glass tube heater. Also heat transfer coefficient for nonuniformly coated nanoparticles was studied and compared with uniformly coated and plain glass tube. Coating effect of nanoparticles over glass tube increases its surface roughness and thereby creates more nucleation sites.
This paper deals with the numerical investigation of split hemispherical fins mounted staggered o... more This paper deals with the numerical investigation of split hemispherical fins mounted staggered over a base plate. The thermal and flow analyses have been carried out to evaluate the Nusselt number (Nu), pressure drop Δ P , and hydrothermal performance factor (HTPF) with air as a medium and Reynolds number ( Re = / 3000 to 15000). The cylindrical fin (CF) and hemispherical fin (HF, of radius R ) of the same volume and height have been formed and placed in the computational domain. Results reveal that the Nu for CF compared to HF is 1.3-1.4 times higher, with approximately 1.5 times higher Δ P for the given Re range. The value of HTPF for HF is greater than unity (/1.13-1.20) for all the considered Re values. Secondly, the HF gets split into longitudinal and transverse flow directions for better solid-fluid interaction. The geometrical parameters are transverse offset TO (/= 0 − R / 8 ), longitudinal offset LO (/= 0 − R / 8 ), and Re. Results show that the highest value of Nu (/=384....
ARTICLE INFO The bubble diameter at departure in nucleate pool boiling heat transfer using satura... more ARTICLE INFO The bubble diameter at departure in nucleate pool boiling heat transfer using saturated water affected by wall superheat, size of nucleation site etc. In this paper, effect of wall superheat in nucleate pool boiling heat transfer on single bubble dynamics using saturated water has been studied experimentally. Single bubble is generated using vertical hypodermic needle tip as a nucleation site. The hypodermic needles were used of inner diameters 0.603 mm with a constant depth of 25 mm. Single bubble dynamics was studied using PCO high speed camera operating at 100 frames per second at atmospheric pressure and at a wall superheat of 9 K to 30 K. Bubble growth in saturated water is studied at heat flux 430 kW/m 2 , 900 kW/m 2 , the results show that, bubble departure diameter increases with increase in wall superheat at 430 kW/m 2. The bubble release frequency increases with increase in wall superheat at 900 kW/m 2 .
The present work is focused on energy conservation for the pool boiling applications with and wit... more The present work is focused on energy conservation for the pool boiling applications with and without eco-friendly red areca nut as an additive in the deionized water. The aqueous red areca nut solutions having concentration 100–600 ppm is considered to quantify the effect on pool boiling heat transfer and bubble phenomenon. It is observed that as the concentration increases and goes up to 500 ppm, it shows the increase in heat transfer rate with the smaller wall superheat. The critical heat flux observed at 908.24 kW/m2 with a minimum wall superheat at 63.5 °C and the further increase in concentration, the wall superheat is also increased which shows the loss of heat energy in pool boiling experiments. The similar result is obtained for bubble phenomenon that an increase in concentration has a decrease in bubble diameter and increase in velocity compared to deionized water. It is also observed that the relative heat transfer coefficient with additive solutions shows 80% enhancement in the performance of heat transfer as compared to deionized water only.
International Journal of Global Technology Initiatives, 2012
For researchers, it is a challenge to carry processes which will consume less energy, using some ... more For researchers, it is a challenge to carry processes which will consume less energy, using some efficient and effective techniques. Pool boiling process is used in various industries and in day to day life. It is need to augment the heat transfer rate in pool boiling applications for saving the energy required to complete the process as well as time required to boil if reduced can have good impact on productivity of the process. There are different techniques used for the enhancement in heat transfer process in pool boiling. These are categorized as active, passive and compound techniques. An extensive survey of these techniques is carried in view to optimize the energy required for pool boiling processes. These techniques accelerate the bubble dynamics (i.e. bubble formation, its growth, mixing and departure) that optimize the energy required for processes. The addition of small amount additive in the solution is one of the cost effective technique and simple to handle. Environmen...
3RD INTERNATIONAL CONFERENCE ON FRONTIERS IN AUTOMOBILE AND MECHANICAL ENGINEERING (FAME 2020), 2020
The current study presents the hybrid Taguchi-Fuzzy technique to predict the heat transfer coeffi... more The current study presents the hybrid Taguchi-Fuzzy technique to predict the heat transfer coefficient in pool boiling of Copper surfaces with dissimilar coating layer of ZrO2 in the boiling experimental system with saturated water as boiling fluid. A hybrid Taguchi-Fuzzy technique was developed considering the coating thickness, voltage, concentration, and surface roughness as input variables and current, contact angle, wall superheat, heat transfer coefficient as output variables. The commendable correctness is found with the forecast optimal model findings with the experimental investigation in each test case. It is found that the highest performance with the Multi performance characteristics index value is 0.75 for the A4B4C4Dll case, which matched with the experimental result of S4 sample.
Abstract Nanofluid preparation and its deposition on metallic surfaces are in wide practice due t... more Abstract Nanofluid preparation and its deposition on metallic surfaces are in wide practice due to their enhancement capability in the pool boiling heat transfer. The effect of zirconia nanoparticles coated layer on pool boiling heat transfer has been investigated with de-ionized water. The turbidity, viscosity and stability test are conducted, and confirmed a better dispersion of nanoparticles. The synthesized zirconia nanofluid is deposited by nanofluid boiling nanoparticle technique at different concentrations on three copper samples. The conventional characterization techniques confirm the better structural behavior of the coating. The obtained results of non-coated copper sample fits well with Rohsenow correlation, which signifies the reliability and stability of the obtained results. Experimental results shows that sample with 200 nm coating thickness and 227 nm surface roughness improved the heat transfer coefficient by 31.52% compared to non-coated copper sample. The bubble behavior of the same has the highest velocity and lower bubble diameter compared to other at 785 kW/m2 of heat flux. Hence by this experimentation, it is found that the effect of surface characteristics of the zirconia coated layer on the copper surface enhances the pool boiling heat transfer coefficient at the maximum coating thickness and surface roughness by the considered coating technique.
Journal of the Brazilian Society of Mechanical Sciences and Engineering, 2020
One promising way to enhance the heat transfer coefficient (HTC) and the critical heat flux (CHF)... more One promising way to enhance the heat transfer coefficient (HTC) and the critical heat flux (CHF) is modifying the heating surface morphology by using machining techniques, coating, and chemical processes. Microstructured surfaces, i.e., surfaces with the presence of micropillars on the surface, provide small perturbations in the liquid, affecting the vapor bubbles dynamic. These structures increase the heating surface area and change the fluid flow. Microfins can have different shapes and sizes and can be arranged in different patterns to improve heat transfer. This study aims to evaluate experimentally the thermal performance of different microfin surfaces by using HFE-7100 as working fluid. Square micro-pillar arrays were etched on a plain copper surface through the micro-milling process. Square microfins of different length scales (i.e., height and side length) were uniformly spaced on the plain copper surface. The inter-fin space had the same value, 250 μm, for all surfaces in order to control the effective roughness, R eff , defined as the ratio of the area in contact with the liquid to the projected area. Microfin surfaces intensify the HTC as compared to plain surfaces and the number of fins is the main factor for the HTC enhancement; if the number of microfins is constant, the larger the effective roughness, the higher the heat transfer performance. Additionally, the capillary-wicking ability increases and it also improves the HTC and the dryout heat flux due to the prevention of hotspots in the microfin surface. Thus, the surface thermal behavior is a function of the surface morphology and its surface capillary wicking.
Due to microscale effects, the segmented microchannels or micro pin fin heat sinks emerged as a h... more Due to microscale effects, the segmented microchannels or micro pin fin heat sinks emerged as a high thermal management solution. In this context, the present work analyzes the influence of different heights of square micro pin fins with an aligned array and investigates their influence on pressure drop and heat transfer behavior. The HFE-7100 is used as the working fluid, and the pressure drop and surface temperature behavior are analyzed for different mass fluxes and inlet subcooling. The single-phase flow was analyzed numerically using the computational fluid dynamics (CFD) software ANSYS FLUENT® for comparing the simulation results with the experimental data, showing that the highest micro pin fins configuration provides a more uniform and lowest wall temperature distribution compared to the lowest configuration. There is a good agreement between the experimental results and the numerical analysis, with a mean absolute error of 6% for all the considered parameters. For the two-p...
Effect of uniformly and nonuniformly coated Al2O3 nanoparticles over plain glass tube heater on p... more Effect of uniformly and nonuniformly coated Al2O3 nanoparticles over plain glass tube heater on pool boiling heat transfer was studied experimentally. A borosilicate glass tube coated with Al2O3 nanoparticle was used as test heater. The boiling behaviour was studied by using high speed camera. Result obtained for pool boiling shows enhancement in heat transfer for nanoparticle coated surface heater and compared with plain glass tube heater. Also heat transfer coefficient for nonuniformly coated nanoparticles was studied and compared with uniformly coated and plain glass tube. Coating effect of nanoparticles over glass tube increases its surface roughness and thereby creates more nucleation sites.
This paper deals with the numerical investigation of split hemispherical fins mounted staggered o... more This paper deals with the numerical investigation of split hemispherical fins mounted staggered over a base plate. The thermal and flow analyses have been carried out to evaluate the Nusselt number (Nu), pressure drop Δ P , and hydrothermal performance factor (HTPF) with air as a medium and Reynolds number ( Re = / 3000 to 15000). The cylindrical fin (CF) and hemispherical fin (HF, of radius R ) of the same volume and height have been formed and placed in the computational domain. Results reveal that the Nu for CF compared to HF is 1.3-1.4 times higher, with approximately 1.5 times higher Δ P for the given Re range. The value of HTPF for HF is greater than unity (/1.13-1.20) for all the considered Re values. Secondly, the HF gets split into longitudinal and transverse flow directions for better solid-fluid interaction. The geometrical parameters are transverse offset TO (/= 0 − R / 8 ), longitudinal offset LO (/= 0 − R / 8 ), and Re. Results show that the highest value of Nu (/=384....
ARTICLE INFO The bubble diameter at departure in nucleate pool boiling heat transfer using satura... more ARTICLE INFO The bubble diameter at departure in nucleate pool boiling heat transfer using saturated water affected by wall superheat, size of nucleation site etc. In this paper, effect of wall superheat in nucleate pool boiling heat transfer on single bubble dynamics using saturated water has been studied experimentally. Single bubble is generated using vertical hypodermic needle tip as a nucleation site. The hypodermic needles were used of inner diameters 0.603 mm with a constant depth of 25 mm. Single bubble dynamics was studied using PCO high speed camera operating at 100 frames per second at atmospheric pressure and at a wall superheat of 9 K to 30 K. Bubble growth in saturated water is studied at heat flux 430 kW/m 2 , 900 kW/m 2 , the results show that, bubble departure diameter increases with increase in wall superheat at 430 kW/m 2. The bubble release frequency increases with increase in wall superheat at 900 kW/m 2 .
The present work is focused on energy conservation for the pool boiling applications with and wit... more The present work is focused on energy conservation for the pool boiling applications with and without eco-friendly red areca nut as an additive in the deionized water. The aqueous red areca nut solutions having concentration 100–600 ppm is considered to quantify the effect on pool boiling heat transfer and bubble phenomenon. It is observed that as the concentration increases and goes up to 500 ppm, it shows the increase in heat transfer rate with the smaller wall superheat. The critical heat flux observed at 908.24 kW/m2 with a minimum wall superheat at 63.5 °C and the further increase in concentration, the wall superheat is also increased which shows the loss of heat energy in pool boiling experiments. The similar result is obtained for bubble phenomenon that an increase in concentration has a decrease in bubble diameter and increase in velocity compared to deionized water. It is also observed that the relative heat transfer coefficient with additive solutions shows 80% enhancement in the performance of heat transfer as compared to deionized water only.
International Journal of Global Technology Initiatives, 2012
For researchers, it is a challenge to carry processes which will consume less energy, using some ... more For researchers, it is a challenge to carry processes which will consume less energy, using some efficient and effective techniques. Pool boiling process is used in various industries and in day to day life. It is need to augment the heat transfer rate in pool boiling applications for saving the energy required to complete the process as well as time required to boil if reduced can have good impact on productivity of the process. There are different techniques used for the enhancement in heat transfer process in pool boiling. These are categorized as active, passive and compound techniques. An extensive survey of these techniques is carried in view to optimize the energy required for pool boiling processes. These techniques accelerate the bubble dynamics (i.e. bubble formation, its growth, mixing and departure) that optimize the energy required for processes. The addition of small amount additive in the solution is one of the cost effective technique and simple to handle. Environmen...
3RD INTERNATIONAL CONFERENCE ON FRONTIERS IN AUTOMOBILE AND MECHANICAL ENGINEERING (FAME 2020), 2020
The current study presents the hybrid Taguchi-Fuzzy technique to predict the heat transfer coeffi... more The current study presents the hybrid Taguchi-Fuzzy technique to predict the heat transfer coefficient in pool boiling of Copper surfaces with dissimilar coating layer of ZrO2 in the boiling experimental system with saturated water as boiling fluid. A hybrid Taguchi-Fuzzy technique was developed considering the coating thickness, voltage, concentration, and surface roughness as input variables and current, contact angle, wall superheat, heat transfer coefficient as output variables. The commendable correctness is found with the forecast optimal model findings with the experimental investigation in each test case. It is found that the highest performance with the Multi performance characteristics index value is 0.75 for the A4B4C4Dll case, which matched with the experimental result of S4 sample.
Abstract Nanofluid preparation and its deposition on metallic surfaces are in wide practice due t... more Abstract Nanofluid preparation and its deposition on metallic surfaces are in wide practice due to their enhancement capability in the pool boiling heat transfer. The effect of zirconia nanoparticles coated layer on pool boiling heat transfer has been investigated with de-ionized water. The turbidity, viscosity and stability test are conducted, and confirmed a better dispersion of nanoparticles. The synthesized zirconia nanofluid is deposited by nanofluid boiling nanoparticle technique at different concentrations on three copper samples. The conventional characterization techniques confirm the better structural behavior of the coating. The obtained results of non-coated copper sample fits well with Rohsenow correlation, which signifies the reliability and stability of the obtained results. Experimental results shows that sample with 200 nm coating thickness and 227 nm surface roughness improved the heat transfer coefficient by 31.52% compared to non-coated copper sample. The bubble behavior of the same has the highest velocity and lower bubble diameter compared to other at 785 kW/m2 of heat flux. Hence by this experimentation, it is found that the effect of surface characteristics of the zirconia coated layer on the copper surface enhances the pool boiling heat transfer coefficient at the maximum coating thickness and surface roughness by the considered coating technique.
Journal of the Brazilian Society of Mechanical Sciences and Engineering, 2020
One promising way to enhance the heat transfer coefficient (HTC) and the critical heat flux (CHF)... more One promising way to enhance the heat transfer coefficient (HTC) and the critical heat flux (CHF) is modifying the heating surface morphology by using machining techniques, coating, and chemical processes. Microstructured surfaces, i.e., surfaces with the presence of micropillars on the surface, provide small perturbations in the liquid, affecting the vapor bubbles dynamic. These structures increase the heating surface area and change the fluid flow. Microfins can have different shapes and sizes and can be arranged in different patterns to improve heat transfer. This study aims to evaluate experimentally the thermal performance of different microfin surfaces by using HFE-7100 as working fluid. Square micro-pillar arrays were etched on a plain copper surface through the micro-milling process. Square microfins of different length scales (i.e., height and side length) were uniformly spaced on the plain copper surface. The inter-fin space had the same value, 250 μm, for all surfaces in order to control the effective roughness, R eff , defined as the ratio of the area in contact with the liquid to the projected area. Microfin surfaces intensify the HTC as compared to plain surfaces and the number of fins is the main factor for the HTC enhancement; if the number of microfins is constant, the larger the effective roughness, the higher the heat transfer performance. Additionally, the capillary-wicking ability increases and it also improves the HTC and the dryout heat flux due to the prevention of hotspots in the microfin surface. Thus, the surface thermal behavior is a function of the surface morphology and its surface capillary wicking.
Saturated nucleate boiling of aqueous ammonium chloride on a nichrome wire heater has been experi... more Saturated nucleate boiling of aqueous ammonium chloride on a nichrome wire heater has been experimentally investigated. The boiling performance is enhanced by using of ammonium chloride as an additive. The maximum level of enhancement is observed up to 2,600 ppm concentration of additive. For concentrations more than 2600 ppm, significant enhancement is not recorded. Enhancement observed is due to the change in the thermophysical properties of the aqueous solution. It is observed that as ammonium chloride is added to distilled water, the surface tension of the mixture considerably reduces. The experiment is carried out above critical heat flux to observe the behavior of boiling at higher heat flux.
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