Energy savings and thermal comfort evaluation of a novel personal conditioning device

Personal Conditioning Devices (PCD) create a microenvironment around their users and therefore, better satisfy an individual's thermal comfort than central HVAC systems can. Existing PCDs are categorized into stationary devices and wearable devices. Both types of devices have respective advantages and disadvantages. This paper introduces a novel personal conditioning device called Roving Comforter (RoCo) which is ductless, portable, and capable of providing up to 8 h of conditioned air without rejecting waste heat while in use. The conditioned air, typically 5 K cooler than the ambient air, is produced by a 150 W-mini heat pump system that rejects its condenser heat to an onboard phase change material (PCM) container. The PCM is solidified by the heat pump's reverse cycle after the cooling operation or by a thermo-syphon mode. Cyclic tests conducted in the lab confirmed the concept of RoCo design and its technical specifications. We further conducted EnergyPlus simulation to evaluate the power saving potential of RoCo in centrally air-conditioned buildings in seven US cities. The results show that increasing the central HVAC's temperature setpoint by 2.6 K during the peak hours of the day in the summer season could lead to energy savings between 10% and 70% among the seven cities. Finally, a survey investigation with 14 valid datasets from 40 human subjects demonstrated that RoCo could improve the thermal comfort for the users.