Air-layer-integrated Ceiling Radiant-cooling Panels for Hot and Humid Climates: System Dynamics, Control and Energy Performance

Description

Cooling through ceiling radiant-cooling panels (CRCPs) provides better thermal comfort and energy efficiency than cooling through air circulation, yet have not gained wider application in hot and humid climates because of their comparatively limited cooing power and vulnerability to condensation. Air-layer-integrated CRCPs (AiCRCPs), however, provide several design improvements: (i) significantly higher cooling power using low radiant cooling temperature (e.g. 5°C); and (ii) reduced condensation risk using an infrared-transparent membrane with an enclosed dry air-layer to separate their air-contact and radiant-cooling surfaces. Besides, low radiant cooling temperature (e.g. 5°C) does not reduce the remarkable thermal comfort from radiant cooling. These characteristics enable AiCRCPs to deliver the merits of radiant cooling to buildings in hot and humid climates. However, there are several critical issues in realizing the full potential of AiCRCPs, which must be thoroughly investigated. The first issue is the dynamics of AiCRCP systems, which may be very different to that of conventional CRCP systems because the former uses a lower radiant-cooling temperature (e.g. 5°C vs 15°C) and a wider temperature range (e.g. 5−20°C vs 15−20°C). The second issue is control of AiCRCP systems. The larger variation of the AICRCP’s radiant-cooling temperature means the dynamic nonlinearity may be more dominant than in conventional CRCP systems, which may necessitate new tailored control methods. The third issue is the energy performance of the AiCRCP system in hot and humid climates. The AiCRCP system provides enough cooling power that its operation can be decoupled from that of its ventilation system, e.g. its dedicated outdoor air system (DOAS); the DOAS only deals with latent heat and the AICRCP system accounts for all sensible load. This leads to the question of whether the energy efficiency of CRCP-DOASs, where the DOASs are needed to deal with both cooling and sensible load, is still maintained by the AiCRCP-DOAS. This project aims to address the above issues, to gain understanding of the dynamics of AiCRCP systems, find suitable control methods and provide insights into the energy performance of AiCRCP-DOASs for different indoor environments in hot and humid climates. Specified research objectives will be achieved through experiments, dynamic modelling and numerical simulations.