Effect of tube diameter on boiling heat transfer and flow characteristic of refrigerant R32 in horizontal small-diameter tubes |
| |
| Affiliation: | 1. National High Magnetic Field Laboratory, 1800 East Paul Dirac Drive, Tallahassee, FL 32310, USA;2. Mechanical Engineering Department, Florida State University, Tallahassee, FL 32310, USA;1. Chinese Academy of Sciences, Key Laboratory of Cryogenics, Technical Institute of Physics and Chemistry, Beijing 100190, China;2. University of Chinese Academy of Sciences, Beijing 100049, China;1. Air Conditioning and Refrigeration Center, Department of Mechanical Engineering and Science, University of Illinois at Urbana-Champaign, 1206 W Green St, Urbana, IL, USA;2. Building Equipment Group, Oak Ridge National Laboratory, 1 Bethel Valley Rd, Oak Ridge, TN, USA;3. CTS-Creative Thermal Solutions, 2209 Willow Rd, Urbana, IL, USA |
| |
| Abstract: | This study investigated the effect of tube diameter on flow boiling characteristics of refrigerant R32 in horizontal small-diameter tubes with 1.0, 2.2, and 3.5 mm inner diameters. The boiling heat transfer coefficient and pressure drop were measured at 15 °C saturation temperature. The effects of mass velocity, heat flux, quality, and tube diameter were clarified. The flow pattern of R32 for adiabatic two-phase flow in a horizontal glass tube with an inner diameter of 3.5 mm at saturation temperature of 15 °C was investigated. Flow patterns such as plug, wavy, churn, and annular flows were observed. The heat transfer mechanisms of forced convection and nucleate boiling were similar to those in conventional-diameter tubes. In addition, evaporation heat transfer through a thin liquid film in the plug flow region for low quality, mass velocity, and heat flux was observed. The heat transfer coefficient increased with decreasing tube diameter under the same experimental condition. The fictional pressure drop increased with increasing mass velocity and quality and decreasing tube diameter. The experimental values of the heat transfer coefficient and frictional pressure drop were compared with the values calculated by the empirical correlations in the open literature. |
| |
| Keywords: | |
| 本文献已被 ScienceDirect 等数据库收录！ |
|
