Dr. Krishpersad Manohar & Kimberly Ramroop International Journal of Engineering (IJE), Volume: 4, Issue: 4 268 A Comparison of Correlations for Heat Transfer from Inclined Pipes Krishpersad Manohar kmanohar@eng.uwi.tt Department of Mechanical and Manufacturing Engineering The University of the West Indies St. Augustine, Trinidad and Tobago West Indies Kimberly Ramroop kimberlyramroop@gmail.com Department of Mechanical and Manufacturing Engineering The University of the West Indies St. Augustine, Trinidad and Tobago West Indies Abstract A review of literature on heat transfer coefficients indicated very little work reported for cross-flow pipe arrangement at various angles of inclination. In this study forced airflow at 1.1 m/s and 2.5 m/s across 2 steel pipes of diameters 0.034m and 0.049m were examined with pipe orientation inclined at 30 and 60 degrees to the horizontal position. A comparison of the experimentally determined u N and the conventional method using existing correlations for horizontal pipes in cross-flow showed that at 30 degrees inclination, 1.1 m/s, u N values were in good agreement. However, there were large differences at 60 degrees inclination, 2.5 m/s. Comparing experimental data with the correlations of Churchill, Zhukaukas, Hilpert, Fand and Morgan showed that for 30 degrees inclination the deviation from experimental u N at 1.1 m/s ranged from 2% to 18% and 2% to 8% for the 0.034m and 0.049m pipes, respectively, while at 2.5 m/s the deviation ranged from 12 % to 31% and 20% to 41% for the 0.034m and 0.049m diameter pipes, respectively. At 60 degrees inclination the deviation from experimental u N at 1.1 m/s ranged from 19% to 45% and 27 % to 41% for the 0.034m and 0.049m pipes, respectively, while at 2.5 m/s the deviation ranged from 48% to 65% and 29% to 52% for the 0.034m and 0.049m diameter pipes, respectively. Keywords: Convective heat transfer, Inclined pipes, Heat transfer correlations. 1. INTRODUCTION In the study of thermodynamics the average heat transfer coefficient, h , is used in calculating the convection heat transfer between a moving fluid and a solid. This is the single most important factor for evaluating convective heat loss or gain. Knowledge of h is necessary for heat transfer design and calculation and is widely used in manufacturing processes, oil and gas flow processes and air-conditioning and refrigeration systems. The heat transfer coefficient is critical for designing and developing better flow process control resulting in reduced energy consumption and enhanced energy conservation. Application of external flow forced convection heat transfer coefficient range from the design of heat exchangers and aircraft bodies to the study of forced convection over pipes.