Development of the New Comprehensive Performance Evaluation Equipment for Enhanced Convective Heat Transfer Techniques
Based on the new performance evaluation criterion system (PECS) for enhanced convective heat transfer techniques, an evaluation equipment of enhanced heat exchange tube was developed. The equipment structure and functions, parameters measurement and control of auxiliary system were introduced in detail. The monitoring and control software was programmed with the Delphi 7.0, and be used to realize the data acquisition and processing, database operation and management, and many other functions. A kind of new type enhanced heat exchange tube was tested. The experience result shows that apparatus is feasible to evaluate the performance of enhanced convection techniques.
Survey and evaluation of techniques to augment convective heat transfer
Abstract : The report presents a survey and evaluation of the numerous techniques which have been shown to augment convective heat transfer. These techniques are: surface promoters, including roughness and treatment; displaced promoters, such as flow disturbers located away from the heat-transfer surface; vortex flows, including twisted-tape swirl generators; vibration of the heated surface or the fluid near the surface; electrostatic fields; and various types of fluid additives. Natural and forced convection situations for nonboiling, boiling, and condensation heat transfer are included. The conditions under which heat transfer is improved are summarized, and the efficiency of each technique is presented in terms of a performance criterion where possible. (Author)
Laminar heat or mass transfer in rectangular channels and in cylindrical tubes for fully developed flow: comparison of solutions obtained for various boundary conditions
Abstract A comparison is made of results obtained with various boundary conditions at the wall of the channels. By comparing blood Sherwood numbers for finite wall resistance with those for constant concentration boundary condition only a small variation is found for various points along the blood channel.