Experimental study on heating performance of air-conditioned bed system under unsteady operating conditions in sleep mode

As global energy consumption rises, improving air conditioning energy efficiency has become a major research focus. Conventional personalized comfort systems (PCS) have limited functions and operating modes and generally evaluate human thermal comfort based on skin temperature. To address these limitations, this study proposes an energy-efficient Air-Conditioned Bed (ACB) system with cooling, heating and multiple operating modes, adopting interface temperature as a novel evaluation index instead of skin temperature. A 12-hour heating experiment was carried out under unsteady supply water temperatures. Experimental results show that conduction-radiation heating consumes 2.4 kW·h of electricity with an average heat dissipation of 84.7 W, whereas convective heating consumes 7.5 kW·h of electricity and delivers an average heat dissipation of 1128.8 W. Furthermore, all measured parameters, including supply and return water temperatures, capillary tube surface temperature, duct outlet air temperature, and power consumption, exhibited periodic fluctuations. The conduction-radiation mode generated six full cycles, each lasting approximately 110 minutes, while the convection mode produced seven full cycles of about 100 minutes each. For both modes, subjects felt cold and uncomfortable during the initial 15-20 min, followed by neutral thermal sensation, mild warm comfort, and ultimately strong warm comfort. Obvious dryness discomfort occurs in the later stage of convective heating. The methods and findings of this study provide valuable references for future application of the proposed technology.