Solar Energy Laboratory

Research > Projects

Design of a stratification manifold for use in a liquid desiccant energy storage tank


The Solar Energy Laboratory is evaluating the use of a liquid desiccant to more than double the energy density of sensible water storage. The increase in energy density is made possible by taking advantage of the chemical binding energy of calcium chloride and water. Calcium chloride is a salt used to prevent ice build up on roads. In this project, we dissolve the salt in water. To maximize the availability of stored energy, it is necessary to minimize mixing of regions of different salt concentration within the tank. We are designing a novel rigid porous stratification manifold to minimize mixing when fluid is added or extracted from the tank. The concept is shown in Fig. 1. The manifold uses a stack of hydraulic resistances within a porous tube to equilibrate the pressure distribution in the manifold and tank and still allow inflow and outflow. Experimental validation of the manifold performance is underway in a prototype tank.


Fig. 1. A schematic of an RPM design. Incoming flow is directed through a diffuser to reduce inlet flow momentum. The duct is drilled with holes to allow fluid flow at any height of the storage. The orifice plates are sized such that the vertical pressure distribution in the manifold equals the pressure distribution at the tank until the desired height of outflow.