Develop and Investigate Decoupled Radiant Cooling Mechanism

Project: Research

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Indoor cooling is an essential technology for human thermal comfort and is a significant end-use of energy. It generally constitutes up to 60% of the total energy use of buildings in hot and humid climates. Currently, air-cooling is still the dominant mechanism for delivering cooling to building occupants, but radiant cooling has the merits of high thermal comfort, low energy use, quiet operation, and space saving. Two important issues affect the application of radiant cooling in hot and humid climates: a limited radiant cooling capacity and potential condensation on the air-contact surface of radiant cooling panels. These issues are coupled because the air-contact surface also serves as the radiant surface. The radiant surface requires a low temperature to increase the cooling capacity. However, when a low radiant temperature is used in a hot and humid climate, the dew-point temperature of conditioned spaces can easily exceed the radiant surface temperature, which leads to condensation on the surface, and thus limits the cooling capacity of radiant cooling. The current achievable maximum cooling capacity, as reported in many studies, is generally less than 100 W/m2, which cannot fulfil the typical cooling demand of around 150 W/m2in hot and humid climates. This poses a challenge to the successful commercialisation of radiant cooling in such climates.  To solve the above problems, we propose to develop a new radiant cooling mechanism in this research. We plan to physically separate the radiant surface from the air-contact surface in order to weaken the link between the temperature control of the radiant surface and the air-contact surface. Thus, the radiant surface temperature can be adjusted low enough to enhance the cooling capacity without sacrificing reliable condensation prevention. We refer to this new mechanism as decoupled radiant cooling. We will develop a structure design for the radiant cooling unit by selecting a suitable IR-pass window, ensuring that the unit has high infrared-transparency (ideally 100% transparent for IR radiation) and high conductive resistance (ideally infinite). Through experiments and computer simulations, we will systematically analyse the heat transfer process of the decoupled radiant cooling, and build a heat transfer model to estimate the cooling capacity and thermal environment required for thermal comfort. The ultimate objective of this research is to develop a decoupled radiant cooling prototype that is suitable for applications in hot and humid climates. 


Project number9042774
Grant typeGRF
Effective start/end date1/01/207/12/23