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.
Least dissipation principle of heat transport potential capacity and its application in heat conduction optimization
In the viewpoint of heat transfer, heat transport potential capacity and its dissipation are defined based on the essence of heat transport phenomenon. Respectively, their physical meanings are the overall heat transfer capability and the dissipation rate of the heat transfer capacity. Then the least dissipation principle of heat transport potential capacity is presented to enhance the heat conduction efficiency in the heat conduction optimization. The principle is, for a conduction process with the constant integral of the thermal conductivity over the region, the optimal distribution of thermal conductivity, which corresponds to the highest heat conduction efficiency, is characterized by the least dissipation of heat transport potential capacity. Finally the principle is applied to some cases in heat conduction optimization.
Carbon Dioxide Elimination from Circle Systems
Ten various circle systems were studied in model experiments. All the experiments were performed using a Waters cannister containing 675–685 g of Durasorbr̀. 300 ml of carbon dioxide were supplied to the system per min. The efficacy of these systems was expressed as the time taken to demonstrate a concentration of 0.6% carbon dioxide in the gas mixture supplied to the patient connection during each respiratory cycle. The carbon dioxide elimination was studied at a gas flow of 2, 4 and 6 1 per min. All the systems showed an effective carbon dioxide elimination for 6 h or more at a flow of 2 1. An increasing efficacy was found with increasing flow, but to a varying extent.