Design charts for combined chilled ceiling displacement ventilation system and personalized evaporative cooler.

Abstract

This work introduces operational energy-comfort design charts for a chilled ceiling (CC)-displacement ventilation (DV) system aided with personalized evaporative cooler (PEC) for typical office load of 70 W-m². The proposed charts depict the resulting occupant’s overall thermal comfort (OTC) at different operating conditions of DV and CC with and without the PEC. They simplify the sizing procedure of the CC-DV-PEC system by specifying the operational design parameters. In generating the charts, comprehensive numerical simulations were performed using: 1) a multilayer space thermal model of CC-DV and PEC system to determine the temperature of the microenvironment surrounding the human; and 2) a bio-heat and segmental comfort model to determine occupant thermal comfort. The developed design charts are presented in terms of DV supply temperature, CC temperature, PEC airflow rate, ratio of total load over DV airflow rate - defined as displaced air parameter (P), CC cooling load, and OTC. The use of charts is shown through different study cases. It is found that addition of PEC 10 can provide the desired thermal comfort while allowing for DV supply temperatures of as high as 26 °C. In such conditions, combination of CC-DV has cooling capacity of as low as 83percent of the space baseline load that leads to energy savings of up to 17.1percent only on internal space cooling load. In general, the number of operative parameters’ combinations that can provide comfort expands by increase in PEC airflow rate; however, the implication of PEC on expanding the operative comfortable region is higher when the ratio of the CC-DV cooling capacity to the baseline load is lower.