Thermal performance of hydronic radiator with flow pulsation - Numerical investigation

Improving the heat output of hydronic central heating system in buildings can play a major role in energy saving. Current panel radiators of central heating systems are operating at constant flow strategy with thermostat control device. Such operating mode is not efficient in terms of energy consumption; therefore an alternative operating scenario is required to enhance the heat output of the panel radiator. The main aim of this research is to investigate the effect of pulsed flow input on the energy consumption of panel radiators while maintaining the target panel surface temperature. CFD modelling of two hydronic panel radiators with constant and pulsating flows were developed using the conjugate heat transfer module in COMSOL Multiphysics software. The radiators used were one with single finned surface (type11) and the second is without fins (type10), both with the dimensions of 500 mm long and 300 mm high. The CFD results of the constant flow conditions were compared to published experimental work showing good agreement with maximum deviation of 2.4% in the heat output. To investigate the effects of pulsating flow on the performance of the two panel radiators, a wide range of input pulsating flows with amplitude ranging from 0.027 m/s to 0.051 m/s and frequency ranging from 0.0523 rad/s to 0.209 rad/s while the flow supply temperature remained constant at 75° were simulated. The simulation results showed that using pulsed flow can reduce the energy consumption of panel radiators by up to 20% compared to constant flow operating condition while maintaining the same radiator surface temperature of 50 °C. Such results highlight the potential of using pulsed flow to reduce the energy consumption of central heating systems in buildings without compromising the user comfort.