Experimental Analysis of Nucleation Triggering in a Thermal Energy Storage Based on Xylitol Used in a Portable Solar Box Cooker

Abstract

Sugar alcohols have interesting thermodynamic properties that make them good options as heat storage materials (HSMs) to be used in solar cookers. Among sugar alcohols, xylitol is affected by severe supercooling that can significantly alter its usefulness in thermal energy storage (TES) systems. To overcome the supercooling issue, in this work the thermal behavior of a xylitol-based TES installed in a portable solar box cooker was investigated experimentally. The solar cooker has a 4.08 concentration ratio and the TES is a double-pot system filled with 2.5 kg of commercial-grade xylitol. The TES includes a manual mixing device that can be used to trigger the nucleation of xylitol. The effectiveness of the TES system with and without triggering was assessed through several outdoor tests, divided into heating and cooling phases, using silicone oil as absorbing media. It was found that the average load cooling time, in the temperature range of the test fluid from 110 to 80∘C, increased by about 346% when the solar cooker was equipped with the xylitol-triggered TES. The mixing device can therefore be considered an effective solution for regarding xylitol as an actual and performing phase change material.

Enhancement the solar box cooker performance using steel fibers

“…In addition to the traditional method of improving the performance of SBC by adding a reflector(s), the performance of SBC is also improved by modifying the cooking pot [13][14][15][16][17] or adding materials to the inside of the cooker. [18][19][20][21][22][23] The performance of SBC is evaluated by several parameters, including Performance Characteristics, First and Second figures of merit, Time Boiling, Parameter Index, Standard Cooking Power, cooker optothermal ratio (COR), Thermal efficiency, and Exergy efficiency. [24][25][26][27] Mawire et al 28 compared two SBCs with a reflector and without a reflector by evaluating both energy efficiency and exergy efficiency with several water loads.…”

“…The second reason is subject to development and improvement, which prompted many researchers to search and investigate to raise the performance of SBC. In addition to the traditional method of improving the performance of SBC by adding a reflector(s), the performance of SBC is also improved by modifying the cooking pot 13–17 or adding materials to the inside of the cooker 18–23 . The performance of SBC is evaluated by several parameters, including Performance Characteristics, First and Second figures of merit, Time Boiling, Parameter Index, Standard Cooking Power, cooker optothermal ratio (COR), Thermal efficiency, and Exergy efficiency 24–27 .…”