Infrared analysis of the two phase flow in a single closed loop pulsating heat pipe

Mangini, Daniele; Marengo, Marco; Araneo, L.; Mameli, Mauro; Fioriti, Davide; Filippeschi, Sauro

doi:10.1016/j.expthermflusci.2018.04.018

Cited by 34 publications

(10 citation statements)

References 25 publications

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“…7. It is the typical tendency of the PHP as reported in the previous studies [13,14,17]. The resistance of the PHP with natural convection cooling is, at least, 1 K/W lower than that in forced convection cooling, under the same heat input conditions.…”

Section: Thermal Resistancesupporting

confidence: 80%

“…A copper wire heater (Pirelli, electrical resistance 1 Ω) is wrapped around the evaporator and fixed by aluminium tape so that the electrical heat load was uniform in the section. The loop is heated up non-symmetrically with respect to the gravitational force to induce a circulation flow and improve the overall thermal performance as the past studies have suggested [14,15]. The electrical power was applied and increased in stepwise by the DC power supply (JO POWER ALP6010) until the operating limit are reached .…”

Section: Methodsmentioning

confidence: 99%

“…In general, the heat transfer performance of the PHP is evaluated by means of thermal resistance [13,14,17]. The thermal resistance R is evaluated adopting the following equation:…”

Section: Thermal Resistancementioning

confidence: 99%

“…In this study, a single metallic loop is tested focusing on the effect of the adopted cooling methods in the condenser section. Single loops are the simplest configuration of PHP, therefore they have been used in research to understand their thermal and fluid behaviour [13][14][15]. Ethanol is used as the working fluid due to suitable operating temperature and availability.…”

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Effect of Different Cooling Methods on Thermal Performance of Single Loop Pulsating Heat Pipe

Iwata

Bozzoli

Cattani

et al. 2022

J. Phys.: Conf. Ser.

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A pulsating heat pipe (PHP) is a promising two-phase passive thermal device that consists of a capillary tube meandering between an evaporator and a condenser. Heat is transferred from the evaporator to the condenser by the self-excited oscillation of vapor and liquid. The complete knowledge of the heat transport mechanisms, particularly at the operating limit of PHPs, is far from satisfactory. In PHP, the phase-change acts as a driving force of the self-excited oscillation of the fluid. In this context, the condensation highly affects the performance of PHPs, while few studies have investigated the effect of the sink temperature or the cooling methods. In this study, a single metallic loop is tested to understand the local phenomena focusing on the impact of cooling methods of the condenser section: natural convection and forced air convection. Regardless of the cooling methods, the PHP showed the intermittent and unstable oscillation at low power input just after the start-up, and then continued to operate stably until the heater turned off after the evaporator temperature exceeds 140 °C. The resistance of natural convection cooling is more than 1 K/W lower than that of forced convection cooling, for the same heat input conditions. However, the resistance of both cooling methods at the same evaporator temperature shows a good agreement. The resistance is inversely proportional to the evaporator temperature as well as the heat input.

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Section: Thermal Resistancesupporting

confidence: 80%

Section: Methodsmentioning

confidence: 99%

“…In general, the heat transfer performance of the PHP is evaluated by means of thermal resistance [13,14,17]. The thermal resistance R is evaluated adopting the following equation:…”

Section: Thermal Resistancementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Effect of Different Cooling Methods on Thermal Performance of Single Loop Pulsating Heat Pipe

Iwata

Bozzoli

Cattani

et al. 2022

J. Phys.: Conf. Ser.

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show abstract

“…The test cell adopted in this work is a simplified geometry of a PHP originally described by Mangini et al [30], able to preserve the peculiar functioning characteristic of the PHP while reducing its complexity and the number of involved parameters. It consists of a closed loop pipe, with four 90 degrees turns, designed to facilitate high speed imaging and high-accuracy, high-frequency pressure investigation, coupled with temperature measurements.…”

Section: Test Cellmentioning

confidence: 99%

Developing flow pattern maps for accelerated two-phase capillary flows

Pietrasanta

Mameli

Mangini

et al. 2020

Experimental Thermal and Fluid Science

Self Cite

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The prediction of flow pattern transitions is extremely important to understand the coupling of thermal and fluid dynamic phenomena in two phase systems and it contributes to the optimum design of heat exchangers. Two phase flow regimes have been extensively studied under controlled mass flow rate and velocity. On the other hand, less effort has been spent in the literature on the cases where the flow motion is purely thermally induced and consequently the mass flow rate or the velocity of the phases are not known a priori. In the present work, flow pattern transitions and bubble break-up and coalescence events have been investigated in a passive two phase wickless capillary loop, where the mass flow rate is intrinsically not controllable. Modified Froude, Weber and Bond numbers have been introduced, considering the actual acceleration of the fluid and the length of the bubble as merit parameters for the transitions. The proposed nondimensional investigation was developed by analysing experimental data obtained with ethanol and FC-72, as working fluids, different heat input levels (from 9 to 24 W) as well as three different gravity levels (through a parabolic flight campaign). A new empirical diabatic flow pattern map for accelerated two-phase capillary flows is presented, together with quantitative criteria for the calculation of the flow regime transitions, defining the physic limits for the bubble coalescence and break-up. This kind of new regime maps will be useful to the further development of comprehensive designing tools for passive two-phase wickless heat transfer devices.

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Effect of graphene/hydrofluoroether (HFE-7100) nanofluids on start-up and thermal characteristics of pulsating heat pipe

Ali

Qayoum

Shahid

et al. 2023

J Therm Anal Calorim

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Infrared analysis of the two phase flow in a single closed loop pulsating heat pipe

Cited by 34 publications

References 25 publications

Effect of Different Cooling Methods on Thermal Performance of Single Loop Pulsating Heat Pipe

Effect of Different Cooling Methods on Thermal Performance of Single Loop Pulsating Heat Pipe

Developing flow pattern maps for accelerated two-phase capillary flows

Effect of graphene/hydrofluoroether (HFE-7100) nanofluids on start-up and thermal characteristics of pulsating heat pipe

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