Abstract
Falling film type heat exchangers can realize the higher heat transfer even in the low temperature difference between working fluids. Therefore it can be applied to an evaporator in the power plant or an evaporator, absorber and generator in an absorption refrigerator. There are some types of the falling film type heat exchangers. This paper investigates a falling film type evaporator using horizontal tubes. When the flow rate of the working fluids is low, some factors such as the dry surface area on tubes decrease the heat transfer of the falling film type evaporator. In such cases, in order to improve the heat transfer, it is indispensable to use something to improve wettability or advanced surface tubes. Therefore this paper aims to clarify the method of improving film side heat transfer. The working fluids are water. As a result, it was revealed that the wettability of the tubes are greatly improved by the smoother we made in this study, and the heat transfer of CCS tube is about 4 times as large as that of smooth tube.
