Experimental evaluation and thermal performance analysis of a twisted tape with dimple configuration in a heat exchanger

Abstract

This contemporary experiment examines heat transfer and friction factor of liquid (water) going in a double pipe heat exchanger with twisted tape (TT) insert. Effect of twisted tape in DPHE inserts dimple configuration by providing a dimple protrusion surface only on the front face with a hole configuration placed adjacent to it over the tube length of 1500 mm and diverse dimple diameter (D) and dimple diameter-to-depth ratio (D/H) proceeding heat transfer and friction factor(f) characteristics are analysed in this work. Twist ratio for all cases is 5.5 for each twist, range of Reynolds number (Re) 6000–14,000, D of 2, 4, and 6 mm and (D/H) of 1.5, 3 and 4.5. Six twisted tapes with dimples were tested, and their performance was compared to that of twist with plain tube. It is discovered that the Nusselt number is the deviance with respect to Reynolds number of a plain tube (without twisted tape and dimples) with an inner tube diameter of d = 16 mm. It is evident from the plot that there is an increase in the rate of Nusselt number with a subsequent increase in the value of Reynolds number. Through experimental analysis conducted, Therefore, Optimum value for higher Nusselt number is standard for discussion at D/H = 3 for different diameter as it 111 (for Re = 13987) and 58 (for Re = 6180) using D = 4 mm. As a result of the investigation, it is determined that the depth and diameter of the dimple is directly proportional to the friction factor. Therefore, optimum value for lower friction factor is benchmarked for discussion at D/H = 4.5 for different diameter as it 0.1033 (for Re = 13987) and 0.1437 (for Re = 6180).

Keywords

• Double pipe heat exchanger
• Dimple configuration
• Twisted tape
• Plain twisted tapes
• Performance evaluation criteria (PEC)