Session: K6-04: HEAT TRANSFER IN ENERGY SYSTEMS - ENERGY STORAGE II

Paper Number: 131082

131082 - Effect of Reactor Configuration on the Performance of a Closed Thermochemical Energy Storage System 

Abstract: 

Compared to sensible and latent heat storage systems, thermochemical energy storage systems (TESS) provide higher energy storage densities, resulting in compact storage systems. In a TESS, thermal energy from an external heat source is stored with the help of an endothermic dissociation reaction between the solid-gas pair of the storage material. Subsequently, the stored thermal energy is retrieved by performing a reversible exothermic reaction between the same solid-gas pair of the storage material. Another advantage of TESS is that the reactants and products of the involved chemical reactions can be stored separately even in ambient conditions with minimum heat loss, thus allowing the option of long-term storage in various heating applications. Based on the operating principle, TESS are classified as ‘open’ and ‘closed’ types. In an open type of TESS, mass and energy interactions take place between the TESS and the surroundings. Whereas in a closed type of TESS, only energy interactions happen between the TESS and the surroundings. The closed type of TESS consists of a reactor in which dissociation-recombination reactions of the storage material are performed, and a separate gas storage tank in which the gaseous reactant/product is stored. Potassium carbonate salt hydrate is considered as the storage material for the present analysis of a closed TESS. The performance of such a closed type of TESS is strongly influenced by the configuration of the reactor selected for the system. In the present study, various aspects of the reactor configuration suitable for the closed type of TESS are discussed with the help of numerical studies. It is observed that the cylindrical type of reactor offers a volumetrically compact design for a given mass of storage material. However, the compact design of a cylindrical reactor is accompanied by challenges such as lesser surface area for water vapour interaction with the salt hydrate, unreacted salt hydrate at the bottom of the cylinder, and smaller diameter tubes for the flow of heat transfer fluid through the salt hydrate domain resulting in higher pressure drop and higher thermal mass of the reactor. A flat type of reactor configuration is another promising configuration for the reactor of the TESS. Such a reactor offers larger surface area for water vapour interaction with the salt hydrate but with a higher volume requirement for the reactor. To overcome these challenges associated with cylindrical and flat reactor configurations, an improved reactor configuration with multiple stacks of smaller flat reactors is proposed. The number and dimensions of the reactor stacks are optimized to yield the optimum reactor performance for a given mass of storage material.

Presenting Author: Akshay Chate Indian Institute of Science (IISc)

Presenting Author Biography: Akshay Chate is a Ph.D. student in the Department of Mechanical Engineering, Indian Institute of Science (IISc), Bangalore, India. He is working with Professor Pradip Dutta in the Heat Transfer Lab of the Mechanical Engineering Department. He obtained his B.Tech. Degree in Mechanical Engineering from Visvesvaraya National Institute of Technology (VNIT), Nagpur, India, in 2015, and M.Tech. Degree in Mechanical Engineering (Thermal Sciences) from IISc, Bangalore, in 2019. His broad research interests include various aspects related to thermal energy storage systems.

Authors:

Akshay Chate Indian Institute of Science (IISc)
Kartik Jain Indian Institute of Science (IISc)
Susmita Dash Indian Institute of Science (IISc)
Pradip Dutta Indian Institute of Science (IISc)