Experimental Study of Triple Pipe Heat Exchanger with Nanofluids

Abstract

Experimental study is worked out on experimental system in which a concentric triple pipe heat exchanger made of copper consist the main part of it. The triple pipe heat exchanger consists of inner tube of 2 m length with inner and outer diameters of 1.27 cm and 1.5 cm respectively, the intermediate pipe of 1.5 m length with inner and outer diameters of 2.22 cm and 2.54 cm respectively and the outer pipe of 1m length with inner and diameters of 3.81 cm and 4.13 cm respectively. Nano-silicon dioxide (SiO₂), nano-copper oxide (CuO) and nano-black iron oxide (Fe₃O₄) are used in different volume percent concentrations (0.1, 0.2, 0.3, 0.4 and 0.5) in water (base fluid), as a cooling (nano) fluid. The cooling (nano) fluid flows in different five-volume flow rates (100, 150, 200, 250 and 300 cm³/s) in inner and outer pipes counter currently to hot water flowing at constant volume flow rate of 50 cm³/s in the middle pipe of the triple pipe heat exchanger. Experimentally, there were a dual advantageous effect on the heat transfer coefficient consequently on heat transfer rates achieved, one due to, the contact surface area between the cold and hot fluids offered by the triple pipe heat exchanger compared with double pipe of heat exchanger, and the second due to, adding the nanomaterials to cold fluid. These effects, led to increase in heat transfer rates and overall heat transfer coefficients. The increment in heat transfer rates reached to 24.2, 28.3 and 31.8% with using SiO₂, CuO and Fe₃O₄ respectively. Whereas, the increment in combined overall heat transfer coefficients reached to 44.7, 53.9 and 62.2% with using SiO₂, CuO and Fe₃O₄ respectively. Wherefore, the effectiveness, reached to 63, 65 and 67% with using SiO₂, CuO and Fe₃O₄ respectively.