Testing and analysis of immersed heat exchangers

Modelling of storage tanks with immersed heat exchangers

“…They both consist of a tank with an immersed serpentine heat exchanger placed at its bottom which introduces or removes energy from the tank following different patterns. Numerical results obtained with the methodology here described are validated by comparison to experimental data reported by Farrington et al (1986) and Mather et al (2002). Results are presented in figures reproducing the reporting criteria adopted by these authors to present their experimental data.…”

“…The Reynolds number Re m is calculated using the tank fluid physical properties, the average velocity of the fluid circulating through the node in which the serpentine control volume m is placed, and πD ext as characteristic length. The natural Nusselt number at the serpentine control volume m is obtained from a general expression proposed by Farrington et al (1986): 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 where the coefficients C N and n N are user defined. Farrington et al (1986) suggested to fit this values with experimental data.…”

“…The natural Nusselt number at the serpentine control volume m is obtained from a general expression proposed by Farrington et al (1986): 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 where the coefficients C N and n N are user defined. Farrington et al (1986) suggested to fit this values with experimental data. However, as addressed by Newton et al (1995) if this data is not available, the values of C N = 0.5 and n N = 0.25 can be used.…”

“…Experimental results and details of the test procedure are reported by Farrington et al (1986). The test starts with the storage tank with an initial temperature of T tnk ini = 25 o C. Then, fluid at T hx in =70 o C is circulated through the serpentine (inlet temperature), until the temperature difference between the inlet and outlet of the serpentine is below 0.1 o C. The test was preformed under different flow rates through the serpentine of 5, 10 and 15 l/min respectively.…”

Heat transfer characteristics of high temperature molten salt for storage of thermal energy

“…Since the density of the molten salt employed in this study varied significantly with temperature [5][6][7][8][9][10][11], the effect of natural convection was examined. During the heat storage stage, the two different directions of steam flow were tested for the coil type heat exchanger.…”