A systematic pinch approach to integrate stratified thermal energy storage in buildings

Abstract In this study, dynamic streams including space heating, domestic hot water, renewable solar thermal energy and waste heat such as gray water are extracted from a typical multi-family building under extreme winter conditions for one day or 24 hours. The maximum heat recovery (MHR) is targeted through an adapted time slice model (TSM) of pinch analysis. Time slices are selected such that all changes in dynamic heat capacity flow rates can be included in the pinch analysis. Moreover, charging and discharging streams of the thermal energy storage (TES) is calculated based on the adapted TSM graphical approach. The integration of a heat pumping system, gray water and solar thermal collectors through mixed direct/indirect heat recovery (i.e. via TES) can reduce hot utility usage in the studied case by as much as 72 percent. An appropriate heat exchanger (HE) and TES network is proposed for the test building to benefit from this underutilized resource. Additionally, the dynamic thermal behavior of the proposed stratified TES is numerically investigated. The results reveals that combined heat loss and thermocline thickness can reduce the heat recovery from TES tank by 10 percent, which is 2 percent of MHR in the test building.