Operation optimization of prefabricated light modular radiant heating system:Thermal resistance analysis and numerical study

The utilization of prefabricated light modular radiant heating system has demonstrated significant increases in heat transfer efficiency and energy conservation capabilities.Within prefabricated building construction,this new heating method presents an opportunity for the development of comprehensive facilities.The parameters for evaluating the effectiveness of such a system are the upper surface layer’s heat flux and temperature.In this paper,thermal resistance analysis calculation based on a simplified model for this unique radiant heating system analysis is presented with the heat transfer mechanism’s evaluation.The results obtained from thermal resistance analysis calculation and numerical simulation indicate that the thermal resistance analysis method is highly accurate with temperature discrepancies ranging from 0.44℃ to−0.44℃ and a heat flux discrepancy of less than 7.54%,which can meet the requirements of practical engineering applications,suggesting a foundation for the prefabricated radiant heating system.

Characteristics Analysis of Condensation outside Horizontal Tube Bundles and Novel Condensation Enhancement Method

Condensation is a phase-change heat-transfer phenomenon crucial in many industries involving latent heat release and mass transfer.Shell-and-tube condensers are essential contributors to the condensation process,and their tube bundles serve as a substrate.Here,the thermal-hydraulic characteristics of condensation in a longitudinal-flow shell-and-tube condenser were investigated numerically.The shell-side longitudinal-flow condensation on the horizontal tube bundles was studied considering inlet flow rate,overheating temperature,and non-condensable gases.Related pressure drops and heat transfer coefficients were subdivided into several components to provide further insights.Two-phase interface behavior analyses were conducted to demonstrate the outcomes with respect to the non-condensable gas layer,vapor quality,and non-condensable gas type.Based on the thorough quantitative analyses outlined above,the thermal resistance of the condensation on the horizontal tube bundle was investigated.The thermal resistance outside the tube was found to dominate the condensation process.Finally,hexagon clamping baffles(HCBs)were introduced as a novel solution to impair condensate boundary layers and provide perturbations to intensify condensation heat transfer.The results revealed that the HCBs enhanced the total heat transfer coefficients by 8.1%–40.7%while reducing the critical overheating temperature and the threshold ratio between sensible and latent heat.