5th Thermal and Fluids Engineering Conference (TFEC) April 5–8, 2020 New Orleans, LA, USA TFEC-2020-32463 *Corresponding Author: jon.longtin@stonybrook.edu SMART THERMAL SEPARATOR: ADVANCED HOT-WATER ENERGY STORAGE USING AN ACTIVELY CONTROLLED INSULATING DISK Jay M. Gite, Tom Butcher 1 , Rebecca Trojanowski 1 , Jon P. Longtin 2 1 Brookhaven National Laboratory, Upton, NY 11793, USA 2 Stony Brook University, Stony Brook, NY 11790, USA ABSTRACT Thermal energy storage (TES) will play a vital role in the transition to renewable and non-traditional residential heating. The thermal output of biomass/wood, solar (thermal and PV), and geothermal heating systems, for example, can differ dramatically from a home’s hourly heat demand, and thus benefit significantly from thermal storage. Traditional hot-water systems require either two separate tanks, which doubles the storage footprint and cost, or a single thermo-cline tank in which hot water resides in the upper region and cold water below. This design however has several short comings which limit the extent of its use. This study introduces the smart thermal separator (STS). The idea is to incorporate a movable, insulated, rigid disk (STS) inside a water storage tank to physically separate the hot- and cold-water regions. The vertical location of the disk between the hot- and cold- water regions is actively maintained using temperature sensors, a gyroscope, a pressure transducer and adjustable buoyancy control. The technical scope of the project includes a combined numerical and experimental development of a working prototype. A 190-liter or 50-gallon prototype is modeled and tested to assess the heat transfer and fluid flow in the system. This paper also demonstrates sizing of the STS for integration with a Biomass/Woodstove Powered Absorption Heat Pump System. KEY WORDS: Thermal Energy, Renewable, Thermal Storage, Smart Thermal Separator, Stratification Efficiency, Absorption Heat Pump 1. INTRODUCTION There is a consensus towards adoption of Renewable Energy as a way forward towards Sustainable Development. Thermal Energy Storage (TES) is both environmentally as well as economically vital. It is especially important in bridging the gap between availability of energy and its demand. Efficient thermal storage allows offsetting heat pump, electric heat, and A/C run times to reduce peak load, thus helping to achieve the goal of reducing peak loads. Ground-source heat pumps, specifically, would benefit from thermal storage as this technology has the potential to solve some of the challenges associated with the complexity of ground piping loop and degradation of ground temperature (reduction in system COP) that current ground- source heat pumps face that are restricting the widespread use of this renewable energy source. Absorption Heat Pump Systems which use heat as the driving energy source will benefit greatly if coupled with efficient thermal storage unit as it will extend the spectrum of its adoption even when there are discrepancies in heat energy supply and demand. TES can also allow the use of Solar Energy, or Wood/Biomass Stoves as primary sources of energy to drive an Absorption Heat Pump Unit making it a Renewable Energy System. Even traditional gas- and oil-fired appliances benefit nominally from thermal storage, by allowing for optimal cycling times and minimizing short-cycling. Currently, however, thermal storage remains only sporadically used, due to the large size and space requirements of traditional tanks, restrictions on tank water withdrawal rates, which often result in oversizing, and high tank costs, due to the internal baffling requirement. 707