Nucleate boiling of FC-87/FC-72 zeotropic mixtures on a horizontal copper disc

Schlindwein, A. R.; Martin, Florian; Misale, Mario; Passos, J.C.

doi:10.1007/s00231-008-0404-6

Cited by 6 publications

(4 citation statements)

References 12 publications

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“…HTC degradation results from mass transfer resistance (a phenomenon discussed in greater details by [21][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36]. During phase change, the more volatile fluid evaporates first and at a higher velocity rate than the less volatile.…”

Section: Proposed Correlationsmentioning

confidence: 99%

“…According to Venter [21] the degradation becomes more pronounced for higher pressure and heat flux. In order to obtain the HTC correlations for blends that take into account the HTC degradation authors [17,22,35,36] have used a methodology in which a reduction factor is applied to the correlations for pure fluids. The reduction factor applied on the nucleate boiling has the following functional form:…”

Section: Proposed Correlationsmentioning

confidence: 99%

See 1 more Smart Citation

Optimized heat transfer correlations for pure and blended refrigerants

Porto

Pedro

Machado

et al. 2015

International Journal of Heat and Mass Transfer

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Section: Proposed Correlationsmentioning

confidence: 99%

Section: Proposed Correlationsmentioning

confidence: 99%

Optimized heat transfer correlations for pure and blended refrigerants

Porto

Pedro

Machado

et al. 2015

International Journal of Heat and Mass Transfer

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“…A popular solution to tackle these problems is the dielectric fluids, which are compatible with direct electronics cooling, are usually less harmful with ozone layer, and have a wide range of boiling points. Following this line, in recent years, new engineering fluids have been promoted and investigated, such as fluorocarbons [19][20][21] and NOVEC fluids [22][23][24] manufactured by the company 3M. However, the studies on both fluorocarbons and NOVEC fluids are limited, and there are large discrepancies in the results on boiling heat transfer parameters [5].…”

Section: Introductionmentioning

confidence: 99%

“…However, the studies on both fluorocarbons and NOVEC fluids are limited, and there are large discrepancies in the results on boiling heat transfer parameters [5]. Schlindwein et al [19] studied different binary mixtures of F-87 and F-72 to test the heat transfer coefficients and compare them with different correlations commonly applied in nucleate boiling. Ho et al [20] analyzed the performance of FC-72 on pool boiling experiments with plain and microstructured copper surfaces and evaluated the Rohsenow's coefficients for the different surfaces tested.…”

Section: Introductionmentioning

confidence: 99%

Experimental Study on the Stability and Transient Behavior of a Closed-Loop Two-Phase Thermosyphon (CLTPT) Charged with NOVEC 649

et al. 2021

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Currently, the growing need for efficient refrigeration resources in the industrial sector has led to an increasing interest in finding technologies with a higher heat removal potential and better cooling performance. Along these lines, two-phase liquid cooling appears to be a very interesting solution, with the CLTPT (closed-loop two-phase thermosyphon) being one of the leading alternatives. Most works in the scientific literature study loop thermosyphons that work in flow boiling conditions in steady state. The present paper analyzes the transient thermal behavior of a pool boiling CLTPT gravitational channel as a passive cooling system using NOVEC 649 as working fluid. The evaporator works with two submerged cylindrical heaters that represent different heat sources located in different positions. The initial transient behavior and consequent instabilities of a laboratory-scale facility were studied, followed by a stability analysis for various power inputs. Parameters such as temperature and pressure along the experimental setup were monitored, and the effects of internal pressure and room conditions were also tested. The results show some instabilities in the process to start the flow circulation and a relative stability and quick adaptation to changes when circulation is reached. The temperature in the evaporator chamber was highly homogeneous during the whole process; however, the temperature changes in the riser and the loop top were delayed with respect to the evaporator zone. The analysis shows several pressure and temperature raises before the vapor flux reaches the condenser. When the flow circulation is established, the system becomes highly stable and thermally homogeneous, decreasing the thermal resistance when increasing the power input. The stability analysis also showed that, when the system reaches the steady state, the changes in the power input produce a transient increase in the pressure and temperature of the fluid, followed by a quick decrease of the previous steady state values. The heat transfer analysis in the evaporator shows a higher heat flux on the upper heater caused by the buoyancy flow that rises from the lower heater. It was also observed that the lower heater reaches the CHF point with a lower heat flux.

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