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Abstract: The influence of the pressure drop in Plate Heat Exchangers (PHE) in the boiling temperature of LiBr–H2O and NH3–H2O solutions is studied. For the NH3–H2O solution, the pressure drop-temperature saturation relationship estates that high pressure drops can be allowed in the solution with negligible changes in the saturation temperature, and in the PHE performance. Besides, in the case of the LiBr–H2O solution, as the working pressure is usually very low, the analysis of the pressure drop must be taken as a main limiting parameter for the use of Plate Heat Exchangers as vapour generators. In this case, the pressure drop may considerably change the boiling temperature of the solution entering the heat exchanger and therefore a higher heating fluid temperature may be required. A guideline to design these systems is proposed. [ABSTRACT FROM AUTHOR]

Abstract: This work presents an experimental analysis of the hydrodynamic and thermal performance of micro-heat exchangers. Two micro-heat exchangers, characterized by microchannels of 100×100 and 200×200μm square cross-sections, were designed for that purpose. The fluid used was deionized water and there was no phase change along the fluid circuit. The fluid pressure drop along the heat exchanger and the heat transfer were measured and corrections were made to isolate the contribution of the microchannels. The results were compared with the predictions of the classical viscous flow and heat transfer theory. The main conclusions show that the experimental results fit well with these theories. No effects of heat transfer enhancement or pressure drop increase were observed as a consequence of the small scale of the microchannels. [Copyright &y& Elsevier]

This work describes the behaviour of the standard deviation of pressure fluctuations, σ, in fluidized beds for group B particles in the bubbling regime. An empirical-theoretical function, which depends on the gas velocity, is proposed for predicting the pressure signal fluctuations, and the corresponding values of are calculated. The differences in the standard deviation of pressure fluctuations obtained for absolute or differential sensors are analyzed and compared to experimental values corresponding to different bed dimensions, pressure probe positions and particle properties. [ABSTRACT FROM AUTHOR]