Evaporation Condensation and Heat transfer Part 3 docx

， ， ， [...]... of experiment and theory International Journal of Heat and Fluid Flow, pages 128- 139 Kew P.A and Cornwell K (1997) Correlations for the prediction of boiling heat transfer in small-diameter channels Applied Thermal Engineering, pages 705-715 94 Evaporation, Condensation and Heat Transfer Ledinegg M (1 938 ) Instability flow during natural forced circulation, Warme, 61(8) :891-898 P A Kew and K Cornwell... Ghiaasiaan S M., Jeter S M., and Quershi Z H.(February 2000) The onset of flow instability in uniformly heated horizontal microchannels Journal of Heat Transfer, 122:118–125 Qu W., Mudawar I (20 03) Flow boiling heat transfer in two-phase micro-channel heat sinks: Experimental investigation and assessment of correlations methods International Journal of Heat and Mass Transfer, 46 Brutin D and Tadrist L (October... existing model descriptions of heat transfer and the development of transient processes and crisis phenomena 96 Evaporation, Condensation and Heat Transfer The aim is to study the thermal stability and the evolution of temperature disturbances on the heat- releasing surface with different thermal properties and geometrical parameters at boiling under free convection and falling wave liquid films 2... intensification of heat and mass transfer Evaporation in the thin films of liquid provides high heat transfer rate at low cost and low temperature difference The topicality of this subject matter is relates, in particular, to the development of efficient and compact systems for cooling of the elements of electronics and computers and high-productivity graphical processors whose response and lifetime are... Tsat (11) On Fig 17, we show the evolution of the local wall temperature and the heat flux function of the minichannel length: Fig 17 Influence of gravity on the surface temperature and the heat flux along the minichannel (Qw =33 kW.m-2) 90 Evaporation, Condensation and Heat Transfer We observe that the temperature profile increases and that in microgravity, the values are higher The temperature rises,... intensive heat transfer to the linear size of the liquid meniscus at 98 Evaporation, Condensation and Heat Transfer the boundary of film boiling regime may change in wide range depending on the thermophysical properties of the heater, its thickness and the relative pressure, wich is illustrated in fig 3 For thin heaters and heaters of low heat conducting material, size of the width of the temperature front... 0.5 (2) 84 Evaporation, Condensation and Heat Transfer Frle = G2 2 ρl gD h The table below are useful to calculate the Fk number Fluid Water R-11 R-12 R-13B1 R-22 Nitrogen Neon Fluid Water R-11 Fk 1.00 1 .30 1.50 1 .31 2.20 4.70 3. 50 Fk 1.00 1 .30 Table 2 List of Fk values for different fluids 3. 4.2 Experimental results The results are in good agreement with the correlation (Fig 13) Concerning the range... at low superheat or low heat flux levels Fig 9 Flow boiling analysis in our minichannel using a fast cam The thermal study of the transfers confirms a higher heat transfer coefficient in the input minichannel during the phase of microgravity (Fig 13) This decrease is due to the decrease in size of the vapour bubbles 82 Evaporation, Condensation and Heat Transfer On Fig 10 and Fig 11, we plot the evolution... minichannel, the heat transfer coefficient decreases strongly to reach a level which characterizes a kind of vapour phase heat transfer Furthermore, as soon as the vapour completely fills the pipe, the heat exchange strongly falls because there is no more liquid boiling (Fig 18) but only heat transfer through the vapour (heat insulator) 4 .3 Reynolds number Fig 19 presents the evolution of the heat transfer. .. minichannel, the heat transfer coefficient decreases strongly to reach a level which characterizes a kind of vapour phase heat transfer Furthermore, as soon as the vapour completely fills the pipe, the heat exchange strongly falls (Fig 18) The thermal study of the transfers confirms a higher heat transfer coefficient in the input minichannel during the phase of microgravity 3. 4 Validation 3. 4.1 Kandlikar’s . Influence of Gravity Level on Local Boiling Heat Transfer 83 3. 3 Bubble behaviour To understand fully the role of microgravity on flow boiling and particularly on the bubbles patterns, we. of the vapour bubbles. Evaporation, Condensation and Heat Transfer 82 On Fig. 10 and Fig. 11, we plot the evolution of the flow in respectively terrestrial and microgravity phase during. evaporators and heat exchangers. They provide an effective method of fluid movement and they have large heat dissipation capabilities. In these situations, their compact size and heat transfer