| Status | 已發表Published |
| Laminar-transition-turbulent forced and mixed convective heat transfer correlations for pipe flows with different inlet configurations | |
Ghajar A.J.; Tam L.M.
| |
| 1991-12-01 | |
| Source Publication | American Society of Mechanical Engineers, Heat Transfer Division, (Publication) HTD
 |
| Volume | 181 |
| Pages | 15-23 |
| Abstract | Local heat transfer (under constant wall heat flux conditions) were measured along a 6.1 m long stainless steel horizontal circular straight tube with two different kinds of entrance configurations (re-entrant and square-edged). The test section has 26 thermocouple stations with four thermocouples placed around the periphery (90 degrees apart) at each station. For the heat transfer measurements the Reynolds number varied from about 280 to 51500. In these experiments the test fluid was either distilled water or a mixture of ethylene-glycol and distilled water which gave a Prandtl number range from about 3 to 160. The experimental results clearly indicate that the development of local heat transfer coefficient along the tube and the start and end of the transition region are significantly affected by the type of inlet configuration used. In addition, natural convection was found to be a major factor in laminar flow. However, over the range of parameters considered in this study, natural convection had no effect on the forced convective heat transfer for flows with Reynolds number greater than 3000. Based on the obtained experimental data, heat transfer correlations for each flow regime were developed. The heat transfer correlations proposed for the mixed laminar and forced turbulent regions are applicable to both inlets and predict the experimental data with an average absolute deviation of 6 and 4%, respectively. In the transition region a modified version of Churchill's correlation was used. Due to strong influence of inlet configuration on the start and end of transition, same general correlation but with two different sets of constants for each inlet configuration is proposed. The proposed correlations for this region predict the experimental data with an average absolute deviation of about 10%. The experimental data were also used to construct a flow regime map similar to the one developed by Metais and Eckert for constant wall temperature boundary condition. With a knowledge of Re and the parameter Gr Pr at a particular x/D location, the flow regime map can be used to identify the convection heat transfer flow regime in horizontal tubes under constant wall heat flux boundary condition. |
| URL | View the original |
| Language | 英語English |
| Fulltext Access | |
| Document Type | Conference paper |
| Collection | University of Macau |
| Affiliation | Oklahoma State University - Stillwater |
| Recommended Citation GB/T 7714 | Ghajar A.J.,Tam L.M.. Laminar-transition-turbulent forced and mixed convective heat transfer correlations for pipe flows with different inlet configurations[C], 1991, 15-23. |
| APA | Ghajar A.J.., & Tam L.M. (1991). Laminar-transition-turbulent forced and mixed convective heat transfer correlations for pipe flows with different inlet configurations. American Society of Mechanical Engineers, Heat Transfer Division, (Publication) HTD, 181, 15-23. |
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