The generation of domestic hot water from SIM (Salt in Matrix) technologies

KEY OBJECTIVES AND AIMS OF THE PROJECT:
The provision of heat accounts for approximately half of the total energy consumed in the UK, with 434 TWh (~57%) of this total consumed within domestic homes via space heating and hot water usage. The primary source for this energy is the combustion of gas, a methodology which unsustainable in the long term due to depleting resources, rapid approaching climate change targets and a ban on the installation of gas boilers in UK new build homes. Between 20 and 50% of industrial waste heat is vented to the atmosphere, losing a huge amount of energy that could potentially be reused to provide heat for process or space heating applications.

SUSTAIN and SPECIFIC IKC are currently working with the UK steel industry to capture and reuse this waste heat via Thermochemical storage (TCS) and release technologies, that could be used to impact on the above issues through the provision of domestic heating with limited primary energy production requirements. These storage materials, such as SIM (Salt in Matrix) technologies, have been researched for a number of years as an Inter-seasonal storage option, operate via the dehydration and rehydration of the chemical salt, utilising the associated endo- and exothermic reactions to provide the storage and release of thermal energy with the output currently focused upon the delivery of hot air.

THE RESEARCH QUESTION TO BE ADDRESSED:
The focus of the current project will be to investigate and optimise the discharge of novel SIM material sets to allow the production of hot water compatible with a UK domestic scenario. This will cover both the material characterisation and assessment along with the development of novel systems to generate hot water.

The research engineer will:
Perform short- and long-term discharge tests of SIM materials varying moisture inputs, flow rates and material constituents
Investigate pulsed cycles using combinations of hydrated and dry air inputs
Investigate the generation of domestic hot water from the developed material sets
Characterise the material changes as a result of the varying input parameters using microscopy, XRD and other suitable techniques
Support ongoing industrial projects looking to capture and utilise industrial waste heat.

THE NOVEL ENGINEERING THAT PLACES IT WITHIN EPSRC REMIT:
Current thermochemical storage research has focused on the production of heat for building heating only. This would potentially provide low carbon heating, but ignores the domestic demand for hot water which typically can make up 10% of the thermal energy demand in winter and almost 100 % in the summer. The project will determine the feasibility of using thermochemical materials for the provision of hot water in a domestic setting. This will map total thermal energy density and peak temperature requirements to individual salt hydrates, identifying novel single and composite salt systems which meet the thermodynamic, economic and practical (e.g. corrosion, toxicity, abundance) requirements. Both theoretical and experimental methods will be used to determine suitable material / material combinations. The project will also provide engineering novelty through the design of heat exchangers capable of transferring energy from the porous solid phase thermochemical material to the liquid water phase. This will need o be achieved with a minimum of working transfer fluid, in order to maintain thermal response, efficiency of transfer and compactness of design. In developing a suitable solution, new experimental methods and apparatus will need to be developed and this will be coupled with simulation techniques which can be used to explore the process envelope more thoroughly.