Thermal coupling between a helical pipe and a conducting volume

Abstract

a b s t r a c tHere we document the effect of flow configuration on the heat transfer performance of a spiral shaped pipe embedded in a cylindrical conducting volume. We considered several configurations with fixed volumes of fluid and solid. First, we optimized the geometry of two spiral pipes with varying spacing between the spiral turns and the vertical spacing between the two spirals. Next, we extended the method to three spiral pipes with varying the spacing between the spiral turns and the spacing between the spiral pipes, and changing the dimensions of the conducting volume. We found that optimal spacings between the spiral turns and spire planes exist, such that the volumetric heat transfer rate is maximal. The optimized features of the heat transfer architecture are robust.

Evolutionary Design of Heat Exchangers in Thermal Energy Storage

“…The configurations with a vertical pipe [15] is the less prone to morphing. The helical pipe [16] in a cylindrical PCM enclosure is fixed, but the ability to vary the number of turns and the diameter of each turn increases the system's freedom to morph. Finally, an advancing heat source line invading the PCM material aims at the theoretical design with the greatest freedom to morph [17].…”

“…The helical coil illustrated in Figure 4 is an alternative to the vertical pipe, and a geometry where the freedom to morph is larger because of the ability to change the helix diameter, number of turns and pitch angle. Alailami et al [16] explored the morphing ability of the system in its design stage to optimize the storage of energy analyzing two scales. The timescale of heat penetrating the storage material from the boundaries of the helical coil to the cylinder diameter, τ c ¼ D 2 =α; and the temperature difference, Tt ðÞÀT tf , scaled by the initial condition, T 0 ðÞ À T tf , with T tf as the temperature of the thermal fluid.…”

“…The timescale of heat penetrating the storage material from the boundaries of the helical coil to the cylinder diameter, τ c ¼ D 2 =α; and the temperature difference, Tt ðÞÀT tf , scaled by the initial condition, T 0 ðÞ À T tf , with T tf as the temperature of the thermal fluid. When Alailami et al [16] simulated the evolution of the scaled average temperature -T * avg ¼…”

“…[21] performed an experiment of this configuration to store energy in a PCM. The authors used unoptimized values for the helical coil (ζ≈0:7, ε≈0:2), from the Alailami et al [16] point of view. However, the PCM configuration showed promising results storing 20% more energy than its equivalent mass in water.…”

Current trends in constructal law and evolutionary design

“…The stream was assumed to be isothermal, and only heat transfer by conduction along the plate was considered. When the duct configuration is three dimensional (in a volume) rather than in a plane, the time‐dependent heat transfer can be improved by morphing the pipe configuration, as demonstrated in Alalaimi, Lorente, and Bejan . Such work is applicable to the design of underground heat exchangers, which was investigated in Kobayashi, Maeno, Lorente, and Bejan, where the single duct configuration consisted of two tree‐shaped networks positioned palm‐against‐palm (Figure ).…”