• 동력기계공학회지
• /
• 제5권4호
• /
• pp.18-23
• /
• 2001

This paper is to present the results of a comprehensive study on heat transfer in annuli with spirally corrugated inner tubes in the turbulent regime. Tube surface-temperature measurements were used to explain the enhancement phenomena in the annuli with several different corrugated tubes. Nusselt numbers were between 1.1 and 2 times the smooth annulus values. These enhancement values can be used to determine the appropriate range of applicability for spirally corrugated annuli.

• 한국마린엔지니어링학회:학술대회논문집
• /
• 한국마린엔지니어링학회 2001년도 춘계학술대회 논문집
• /
• pp.100-105
• /
• 2001

The present paper is to present the results of studied of pressure drop in annuli with corrugated and spirally fluted inner tubes for the turbulent flow regime. To understand the underlying physical phenomena responsible for heat transfer enhancement, flow mechanism documented elsewhere are combined with pressure drop measurements to confirm the friction factors obtained from the annuli with the grooved inner tubes for the Reynolds number of 1000 to 8000. Friction factors were found to be functions of trough depth, pitch and angle, and the annulus radius ratio. friction factor increases in the spirally fluted tubes were larger than those in the corrugated tubes.

• 설비공학논문집
• /
• 제14권8호
• /
• pp.683-689
• /
• 2002

This paper is to present the results of a comprehensive study on heat transfer in annuli with spirally corrugated inner tubes in the turbulent regime. Tube surface-temperature measurements were used to explain the enhancement phenomena in the annuli with several different corrugated tubes. Nusselt numbers were between 1.1 and 2 times the smooth annulus values. These enhancement values can be used to determine the appropriate range of applicability for spirally corrugated annuli.

• 설비공학논문집
• /
• 제13권9호
• /
• pp.803-809
• /
• 2001

The present paper presents the experimental results of pressure drip of water flow in annuli with spirally corrugated inner tubes in the turbulent flow regime. To understand the underlying physical phenomena responsible for heat transfer enhancement, pressure drop data documented elsewhere are combined to compare with those obtained from the present experiment for the Reynolds numbers of 1,000 to 8,000. Friction factors were found to be functions of trough depth, pitch and angle, and the annulus radius ratio. Friction factor increases in the spirally fluted tubes were larger than those in the corrugated tubes.

• International Journal of Air-Conditioning and Refrigeration
• /
• 제12권4호
• /
• pp.198-205
• /
• 2004

An experimental study was carried on the characteristics of fluid flow and heat transfer in a fluidized bed shell-and-tube type heat exchanger with corrugated tubes. Seven different solid particles having same volume were circulated in the tubes. The effects of vari­ous parameters such as water flow rates, particle geometries and materials, and geometries of corrugated tubes on relative velocities and drag coefficients were investigated. The present work showed that the drag force coefficients of particles in the corrugated tubes were usually lower than those in the smooth tubes, meanwhile the relative velocities between particles and water in the corrugated tubes were little higher than those in the smooth tubes except the particles of glasses.

• Journal of Mechanical Science and Technology
• /
• 제20권2호
• /
• pp.212-226
• /
• 2006

This paper is a continuation of the authors' previous work on spiral coil heat exchangers. In the present study, the heat transfer characteristics and the performance of a spirally coiled finned tube heat exchanger under wet-surface conditions are theoretically and experimentally investigated. The test section is a spiral-coil heat exchanger which consists of a steel shell and a spirally coiled tube unit. The spiral-coil unit consists of six layers of concentric spirally coiled finned tubes. Each tube is fabricated by bending a 9.6 mm diameter straight copper tube into a spiral-coil of four turns. The innermost and outermost diameters of each spiral-coil are 145.0 and 350.4 mm, respectively. Aluminium crimped spiral fins with thickness of 0.6 mm and outer diameter of 28.4 mm are placed around the tube. The edge of fin at the inner diameter is corrugated. Air and water are used as working fluids in shell side and tube side, respectively. The experiments are done under dehumidifying conditions. A mathematical model based on the conservation of mass and energy is developed to simulate the flow and heat transfer characteristics of working fluids flowing through the heat exchanger. The results obtained from the present model show reasonable agreement with the experimental data.

• 한국초전도ㆍ저온공학회논문지
• /
• 제10권4호
• /
• pp.33-37
• /
• 2008

The main objective of this study is to identify the pressure drop characteristics of coolant flow passages of 154kV/1GVA High Temperature Superconducting (HTS) power cable, experimentally. The passages were consisted of two parts, the one is the circular path with spiral ribs in the core to cool the cable conductor layer and the other is annular path with spirally corrugated outer wall to cool the shield layer. Thus the experiments to acquire the pressure drop data were performed with two types of circular spiral tubes and eight types of the concentric annuli in various range of Reynolds number. The pressure drops in the core tubes and the annuli were much higher than those in the tubes with smooth surface. Therefore, modified correlations to present the experimental results in each flow passage were suggested.