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Heat transfer enhancement is used in many applications including heat exchangers, air conditioning, and refrigeration systems; hence many researchers have conducted experimental and numerical researches on heat transfer enhancement and have developed various techniques and methods. As a passive heat transfer technique, twisted tapes are widely used in various industries for their cost savings, lower maintenance requirements and the fact that they are easily set up. This paper introduces the principle of heat transfer enhancement of twisted tapes and reviews some of the experimental works done by researchers on this technique in recent years. The variously modified twisted tape inserts are widely researched and used to enhance heat transfer efficiency for heat exchangers. Twisted tapes perform better in low Re conditions and in square tubes. However, they could also cause higher pressure drops. Twisted tapes have great potential and profound implications if they can be used in traditional heat exchangers. Besides this, some correlations between the Nusselt number and friction factors are presented in this paper.

This paper introduces a data transmission and processing system for the speed governor test-bed. And the design employed the Internet of things (IOT) technology, added the WIFI communication module on the traditional speed governor test-bed, as well as combined the database and WEB server, which enabled the data measured by the speed governor test-bed to be stored in the database in real-time. In addition, the experimenter can remotely retrieve and view historical experimental data and view the direct results of data processing. It solved the issue that the data and information in the process of governor testing can be transferred and transmitted efficiently and reliably among all levels and layers, and accordingly enhanced the ability of data storage and fast retrieval in the process of governor testing.

Numerical simulations and experiments are carried out in this paper to research about characteristics of heat transfer, frictional resistance and comprehensive performance of turbulent water flow (3000

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