Abstract
The Underfloor Plenum Building Structure Thermal Storage (UP-BSTS) HVAC system is a system which mainly utilizes a concrete floor slab and the modular cement floor panels built above its slab, which acts as a thermal storage device. Cold air is supplied to the underfloor space composed of the slab and panels as a plenum chamber to store heat, and then returns from the outlets in the space to an AHU at night in the summer. Cold air also flows through the openings on the floor panels from the chamber into a room and circulates through the room and ceiling chamber to the AHU during the normal daytime cooling operation mode.
This paper reports the results of experiments to ascertain how key factors for the design and operation of the UP-BSTS HVAC system affect quantitatively the heat charge/discharge performances of its system. The results can be obtained as follows:
1) The average heat removed from the slab with panels is 382kJ/m2 (floor area) for 5 heat charging operation hours and 446 kJ/m2 for 7.5 hours respectively.
2) It is more important to increase the heat charged during the nighttime by varying the supply air temperature and supply air volume rather than by changing the heat charging operation hours.
3) The decrease in the heat removed during the nighttime leads to a decrease in the heat discharged during the daytime, which could cause the inexpedient heat charge during hours of HVAC operation.
