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Experimental investigation of non-boiling gas-liquid two-phase flow in helically coiled micro-channel
(2026-05-15)
Benjawun, Phakkhanan
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Chingulpitak, Sakkarin
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Pratuyai, Kritsada
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Wongwises, Somchai
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Saisorn, Sira
The pressure drop (dP) and flow pattern are presented for two-phase flow in a helical micro-scale channel using an SS-304 tube of 1 mm diameter, having an equal coil pitch of 20 mm, and a coil pitch of 20 mm, all under constant surface heat flux situations. A flow visualization study was conducted, revealing various flow patterns, including bubbly flow, slug flow, churn flow, throat-annular flow, and annular flow. Additionally, the results demonstrated a higher pressure drop (dP) during churn flow in the channel.
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Characterization of diabatic air-water flow in helically coiled micro-channel
(2026-05-15)
Benjawun, Phakkhanan
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Chingulpitak, Sakkarin
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Pratuyai, Kritsada
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Wongwises, Somchai
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Saisorn, Sira
Experimental studies on flow patterns and heat transfer (HT) phenomena in a two-phase air-water system within a vertically helically coiled micro-scale tube were conducted using an SS-304 tube with a 1 mm diameter, a coil diameter of 50 mm, and a uniform coil pitch of 20 mm. The study investigated heat transfer characteristics under constant heat flux conditions. The superficial gas and liquid Reynolds numbers ranged from 290 to 3800 and 780 to 1170, respectively. The results indicated that throat-annular flow exhibited superior heat transfer performance compared to bubble flow, slug flow, churn flow, and annular flow. Finally, the observed flow regimes from the experiment were analyzed and compared with existing prediction methods.
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Experimental investigation of the secondary flow influencing on two-phase heat transfer and pressure drop characteristics in curved micro-tube
(2026-05-15)
Khauntakob, Suphattharachai
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Chingulpitak, Sakkarin
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Wongwises, Somchai
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Saisorn, Sira
This study investigates the flow behavior, heat transfer, and pressure drop in a helically coiled microchannel exposed to a range of heat flux levels. The analysis focuses on the effects of secondary flow and two-phase (phase-change) flow of R134a refrigerant under vertically upward conditions. The experiment involved fabricating a helically coiled channel with a 1 mm inner diameter. Experiments were conducted with a mass flux of 636 kg/m²·s, a saturation pressure of 0.9 MPa, and heat fluxes ranging from 0.1 to 10 kW/m². The experimental results demonstrated that the helical tubes enhance heat transfer through secondary flows and Dean vortices, which increase turbulence and disrupt the thermal boundary layer.
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Experimental study of adiabatic two-phase micro-scale up-flow in helical tube
(2026-05-15)
Chorprasert, Vissuta
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Chingulpitak, Sakkarin
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Wongwises, Somchai
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Saisorn, Sira
This research investigates the flow characteristics in a helical coil tube with a length of 850 millimeters, a coil diameter of 50 millimeters and an inner diameter of 1 millimeter, focusing on the adiabatic two-phase flow of water and air in a vertically upward direction. The test runs are done at a superficial velocity of gas and liquid varies between 0.86 to 12.86 m/s and 0.01 to 0.19 m/s, sequentially. Three flow patterns were observed: Annular flow, Throat-annular flow and Slug flow. A flow regime map was created and compared with data from other researchers. Additionally, the study examined the pressure drop in the two-phase flow within the micro-scale helical coil tube, finding that the pressure drop is low and gradually rises as the superficial gas velocity.
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Experimental investigation on flow pattern and void fraction for two-phase gas-liquid upflow in a vertical helically coiled micro-channel
(2025-03-01)
Saisorn, Sira
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Benjawun, Phakkhanan
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Suriyawong, Adirek
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Wongwises, Somchai
To contribute toward state-of-the-art microfluidic technology, our experiments were conducted to study gas-liquid adiabatic upflow phenomena in a helical micro-channel having a channel diameter of 0.87 mm, a coil diameter of 50 mm, and a helical pitch of 20 mm. The presence of centrifugal acceleration in the micro-scale flow is given as follows. The unique flow pattern having the throat-like gas-core flow generally detected in the straight micro-tube was still present in the curved test section. The void fraction characteristics were not able to match with the homogeneous flow model. The slip ratio data explicitly showed that the annular flow tended to be highly affected by the secondary flow when compared to the throat-annular flow. The prediction based on different approaches indicated that the data aligned well with drift flux model incorporating inertia and channel orientation effects.
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Two-phase flow structures in a helically coiled microchannel: An experimental investigation
(2023-10-01)
Saisorn, Sira
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Benjawun, Phakkhanan
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Suriyawong, Adirek
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Asirvatham, Lazarus Godson
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Mondal, Pranab Kumar
At the microfluidic scale, the utilization of helically coiled channels (HCCs), also known as a spiral channel, for two-phase flow offers numerous advantages in various applications. Existing articles mainly focus on the macro-scale transport, examining secondary flows induced in curved channels. The increasing demand, however, for innovative miniature equipment for thermal energy management emphasizes the importance of comprehending gas-liquid micro-scale flow in curved channels. Unfortunately, despite a vast body of literature on this paradigm, there is still a lack of systematic investigations into the underlying facets of two-phase micro-scale transport in HCCs. To address this gap, our study conducted experiments on adiabatic two-phase air-water flow inside an up-flow helical micro-scale tube. The tube had a hydraulic diameter of 0.87 mm, a coil diameter of 50 mm, and a helical pitch of 20 mm. The primary aim was to explore the impact of centrifugal force on flow pattern, void fraction, and frictional pressure drop characteristics. Additionally, we carefully examined the phase separation phenomenon influenced by the secondary flows induced by the curved channel. In particular, we compared the gas-core flow pattern (either throat-annular flow or annular flow), void fraction, and frictional pressure drop obtained from our experiments on the helical tube with corresponding results based on straight micro-scale channel configurations for an Eötvös number of approximately 0.01. In summary, this study delves deep into the crucial aspects of two-phase micro-scale transport in HCCs, contributing to a better understanding of these systems for future advancements in micro-channel applications.
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An investigation of horizontal and vertical flow boiling in a single channel with a confinement number beyond the threshold of micro-scale flow
(2021-11-01)
Saisorn, Sira
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Suriyawong, Adirek
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Srithumkhant, Pochai
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Wongpromma, Pakorn
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Wongwises, Somchai
The gravitational force effect is of concern when designing flow boiling systems deployed on Earth and in space. A study of the R-134a flow boiling inside the horizontal and vertical channels was experimentally performed to explore the flow orientations' effect on flow pattern and heat transfer characteristics. The test section was a 0.5 mm diameter tube from which the corner effect was excluded. The single channel was used to avoid disturbances that flow maldistribution could possibly cause in the multiple channels. The experimental two-phase flow corresponded to a 1.75 confinement number, which was above the threshold for micro-scale flow. The results indicated the flow regime map, which was less affected by the channel orientation except for that slug flow pattern that was unable to survive during the vertical downflow and vertical upflow. Also, based on the present micro-scale flow, the heat transfer results were mostly independent of the gravitational force effect, and the nucleate boiling and convective mechanisms tended to govern them.
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Management of air conditioning system in electronics housing by using thermoelectric Peltier module
(2021-09-15)
Suriyawong, Adirek
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Saisorn, Sira
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Suwanpayak, Nathaporn
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Wongwises, Somchai
The study was the conditioning system of the electronic case by using thermoelectric Peltier module. The Peltier module is used based on the temperature difference of the hot and cold sides, with input electric power in the thermoelectric Peltier module. The hot side of the Peltier module was installed on a side of the heat sinks with heat removing from a Peltier module into a surrounding while the cold side of the Peltier module was installed on the other side of the heat sinks with the heat absorption of the computer case. The electronic case volume is 450x395x240 mm³. The device of cooling loads was installed in the electronic case. The cooling loads were tested with various power of 0, 60, 120, 180, and 240 Watt. The results indicated that the coefficient of performance (COP) increased with the cooling load. Furthermore, the experimental results indicated that the temperature inside the electronic case increased with cooling load because the temperature of the electronic case increased with decreasing the temperature difference between the hot and the cold sides.
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An experimental study of adiabatic two-phase gas-liquid flow in helical micro-tube
(2021-09-15)
Suriyawong, Adirek
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Pratuyai, Kritsada
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Wongwises, Somchai
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Saisorn, Sira
The development of two-phase flow patterns in helical micro-tube was experimentally investigated. The adiabatic gas-liquid two-phase flow regime maps were presented based on a 0.87 mm inner diameter tube which was helical glass channel. Working fluid in the helically coiled tube was air-water mixture flowing in vertical upward direction. The diameter of the helical coil and the relevant pitch were, respectively, 50 mm and 20 mm. Flow visualization was carried out at different positions along the micro-tube length in order to examine the significance of the centrifugal force existing in addition to the conventional force vectors. In this work, slug flow, churn flow, throat-annular flow, and annular flow were observed and compared to the existing flow transition boundaries developed from micro-channel configurations.

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