Integration of Thermochemical Material (TCM) and Phase Change Material (PCM): hybrid 3 in 1 system for advanced thermal energy storage applications

Download Statistics

Downloads

Downloads per month over past year

Trujillo, Anabel Palacios (2021). Integration of Thermochemical Material (TCM) and Phase Change Material (PCM): hybrid 3 in 1 system for advanced thermal energy storage applications. University of Birmingham. Ph.D.

Preview

Trujillo2021PhD.pdf
Text - Accepted Version
Available under License All rights reserved.
Download (19MB) | Preview

Abstract

Energy has become the most valuable good in our modern society, dictating our living conditions and social status. In this energy scenario with increasing demand, energy storage has the potential to change the way we live by bringing flexibility into the energy systems and decentralising the network. Thermal Energy Storage (TES) is seen as one of the main key players, but TES needs significant research efforts to address some fundamental challenges to reach its full potential. System hybridisation, which integrates different energy storage sources such as TES technologies, can significantly boost the system efficiency and drive TES deployment offering a highly effective solution to these challenges. This thesis aims to firstly look beyond the three traditional Thermal Energy Storage technologies proposing a novel co-working storage concept where the materials’ components are not acting individually but synergistically to maximise the outputs: the 3 in 1 TES system. This has never been attempted before and constitutes the paving way of a new paradigm in Thermal Energy Storage.

The 3 in 1 system integrates the three known thermal storage methods of sensible heat, latent heat and thermochemical based TES into one system, providing three different operational configurations with cascading, charging integrated and discharging integrated working conditions. These different configurations offer controllability of TES charge/discharge processes while enhancing system-level efficiency. The TES materials are theoretically selected through a comprehensive literature review on the area. The candidates are then experimentally validated, and relevant properties not measured in the literature are taken into account. The candidates are narrowed down to five TCMs (MgSO\(_{4}\)∙7H\(_{2}\)O, MgCl\(_{2}\)∙6 H\(_{2}\)O, CaCl\(_{2}\)∙6H\(_{2}\)O, SrBr\(_{2}\)∙6 H\(_{2}\)O and K\(_{2}\)CO\(_{3}\)∙1.5 H\(_{2}\)O), seven PCMs (6 polymers: high-density polyethylene (HDPE), 4,40-diphenylmethane diisocyanate (MDI), polyethylene oxide (PEO), polyethylene glycols (PEG) 1,000, 600 and 35,000 MW) and one sugar alcohol: erythritol (E)), one matrix cellulose (CLU) and two gels as additives (polyacrylamide (PA) and guar gum (GG)). These materials will be combined to form working pairs according to the three different operational conditions. The working pairs are then studied in two main blocks; SSPCM and SLPCM-gel. The energy stored and the chemical stability of SSPCM/TCM being studied, while the compatibility/synergies between TCM/PCM-gel working pairs are investigated for the SLPCM. The use of gels in the formulation process proofs its potential for thermochemical synthesis as it reduces the leakage and enhances the cycling stability even of pure TCMs. The final working pairs selected for the proof of concept and scale-up study are MgSO\(_{4}\)/E/PA and MgSO\(_{4}\)/HDPE for charging integrated, MgSO\(_{4}\)/MDI for cascade system and MgSO\(_{4}\)/CLU, MgCl\(_{2}\)/PEO and MgCl\(_{2}\)/MDI and MgCl\(_{2}\)/HDPE for discharging integrated. The reliability of the MgSO\(_{4}\)/HDPE composites containing 75–90 wt.% of TCM was studied after 40 cycles tests; mechanical integrity, stability, energy stored and reaction kinetics was monitored. The results show that the new composite has a great potential for storing heat, up to 2 GJ∙m−3 and offers a wide working temperature range, from 30 °C to ~150 °C. The PCM/TCM combination give the composites mechanical integrity while accommodating the volume change and maintaining the structural stability during the thermal cycles.

This novel idea addresses some key technology gaps in TES technologies, particularly TCM degradation (increases life-span), cost-effectiveness and TCM flexibility of the based technology. Thus, it offers a paradigm shift to thermal energy storage technology.

Type of Work:

Thesis (Doctorates > Ph.D.)

Award Type:

Doctorates > Ph.D.

Supervisor(s):