Simplified model for heat transfer and surface temperature of prefabricated radiant heating and cooling system

•Simplified models for heat transfer and surface temperature were established.•Calculated heat transfer and surface temperature agreed well with experimental data.•Heat transfer and surface temperature linearly changed with mean water temperature.•The pipe space clearly affected the heat transfer and surface temperature.•Heat transfer and surface temperature varied greatly as the transition changed. Prefabricated radiant heating and cooling (RHC) system is a typical form of high efficiency and lightweight radiant terminal, which has been extensively used in the residential and non-residential buildings. Heat transfer and surface temperature are the key parameters for rational design of a prefabricated RHC system. Therefore, in this paper, based on the analysis of the heat transfer mechanism, simplified models and numerical models were established for calculating the heat transfer and surface temperature of the prefabricated floor or ceiling RHC system. Compared with experimental test results, when the supply water temperature increased from 35 °C to 50 °C under heating condition or from 13 °C to 19 °C under cooling condition, the relative errors calculated by the simplified models were between −10.8% and 3.7% and between −3.8% and 5.0% for the heat transfer and surface temperature of the prefabricated floor RHC system, and ranged from 0.8% to 6.9% and from −0.7% to 0.3% for the prefabricated ceiling RHC system. Moreover, the calculated heat transfer and surface temperature of the prefabricated ceiling or floor RHC system using the simplified models were highly consistent with the numerical simulation results. Hence, the calculation accuracy of the proposed simplified models for the heat transfer and surface temperature can meet the requirements of engineering application, which will provide the support for the rational design of a prefabricated floor or ceiling RHC system.