Optimisation and analysis of a heat pipe assisted low-energy passive cooling system

Abstract

14Passive cooling using windcatchers have been utilised in the past by several Middle East countries to 15 capture wind and provide indoor ventilation and comfort without using energy. Recently, researchers 16 have attempted to improve the cooling performance of windcatchers by incorporating heat pipes. The 17 present work encompasses existing research by optimising the arrangement of heat pipes in natural 18 ventilation airstreams using numerical and experimental tools. The airflow and temperature profiles 19 were numerically predicted using Computational Fluid Dynamics (CFD), the findings of which were 20 quantitatively validated using wind tunnel experimentation. Using a source temperature of 314K or 21 41°C and an inlet velocity of 2.3m/s, the streamwise distance-to-pipe diameter ratio was varied from 22 1.0 to 2.0 and the emergent cooling capacities were established to comprehend the optimum 23 arrangement. The results of this investigation indicated that the heat pipes operate at their maximum 24 efficiency when the streamwise distance is identical to the diameter of the pipe as this formation 25 allows the incoming airstream to achieve the maximum contact time with the surface of the pipes. In 26 addition, the findings showed that any increase in streamwise spacing leads to the formation of a 27 second bell curve representing an increase in air velocity which simultaneously reduces the contact 28 time between the airstream and the heat pipes, decreasing its effectiveness. The study quantified that 29 the optimum streamwise distance was 20mm at which the Sd/D (streamwise distance-to-pipe 30 diameter) ratio was 1.0. The thermal cooling capacity was subsequently found to decrease by 10.7% 31 from 768W to 686W when the streamwise distance was increased to 40mm (Sd/D ratio of 2.0). The 32 technology presented here is subject to an international patent application (PCT/GB2014/052263). 33

Numerical Investigation on Heat Pipe Spanwise Spacing to Determine Optimum Configuration for Passive Cooling of Photovoltaic Panels

“…Theoretical modelling was carried out by Chaudhry et al [14] using water as the liquid medium for ventilation works and utilizing a water flow rate of 0.25 m/s. The study used various spacing from 1D to 4D with a maximum of 80 mm down to 20 mm.…”

“…Further investigation by Chaudhry et al [14] included optimization of the heat pipe arrangement for natural ventilation using CFD and the wind tunnel method. The airflow and temperature profiles were numerically predicted, the findings of which were quantitatively validated using wind tunnel experimentation.…”

“…The technology presented was subjected to an international patent application (PCT/GB2014/052263). Therefore, Chaudhry et al [14] works were used as a benchmark methodology for the current study.…”

“…The independent variables were identified as flow rate, heat pipe (HP) spacing, and design installations and are shown in Table 2. All heat pipe parameters, which include diameter, working fluid, and operating temperature, were taken from the previous works of Chaudhry et al [9,14], as part of the research team's earlier works. The dependent variables were PV temperature and energy efficiency.…”