Figure 8 Wall temperature measurements for different pure water mass fluxes, (a) channel 1 and (b) channel 41. Afterward, the heat https://www.selleckchem.com/products/VX-770.html transfer parameters can be calculated depending on the previous Equations 1, 2, and 3. Figure 9a,b,c,d shows the local surface temperature, local heat flux, local heat transfer coefficient, and the local vapor quality, respectively, along the flow direction for different pure water mass fluxes. OICR-9429 manufacturer Experimental data show a strong dependence of the local heat transfer coefficient and local heat flux on the liquid’s mass flux and on the x location. They possess

almost the same shapes with decreasing local heat transfer coefficient and local heat flux, with the increase of x and decrease of liquid’s mass flux. For the same mass flux, the surface temperature at the downstream flow is smaller and the local heat transfer coefficient is greater than those at the upstream flow. At the channel’s inlet, the nucleate boiling dominates causing a high heat transfer coefficient and low surface temperature. But while moving

toward upstream flow, the vapor covers the major part of the flow outlet and prevents the contact between liquid flow and the channels’ surface causing a partial dry out and blockage mechanisms which, in turn, causes a decrease in the local heat transfer coefficient and an increase in the surface temperature. As shown in Figure 9d, BTSA1 price the local vapor quality increases along the channel’s length and with smaller water mass fluxes. Figure 9 Heat transfer parameters

for different mass fluxes. (a) Local heat transfer coefficient, (b) local heat flux, (c) surface temperature, and (d) vapor quality. Comparison of experimental data with the existing correlations for flow boiling heat transfer In order to validate the experimental procedure, experimental results obtained in the present work for boiling water in minichannels are compared to predictions of various correlations from literature. These existing correlations are proposed for convective boiling heat transfer in microchannels and macrochannels (Table 2). Of these predictive correlations, those for boiling flow in the rectangular minichannels defined by Warrier et al. [27], Kandlikar and Balasubramanian [28], Sun and Mishima [29] and Bertsch et al. [30] are employed. Cytidine deaminase On the other hand, Fang et al. [8] compared experimental data for convective boiling of R113 in minichannels with the predictions from 18 correlations defined for flow boiling heat transfer. They found that the best predictions of the average boiling heat transfer coefficient are found with a mean absolute relative deviation of 36% by the correlations of Lazarek and Black [31] and Gungor and Winterton [32], which are developed for convective boiling in macrochannels. Predictions from these two correlations are also compared to the experimental data.