Numerical evaluation of indoor thermal comfort and energy saving by operating the heating panel radiator at different flow strategies

• CFD simulation of hydronic panel radiators and heated rooms with constant and pulsed flow conditions.
• Flow pulsation enhances the heat transfer performance of hydronic panel radiators.
• Pulsating the flow of hydronic radiator increases specific heat output of panel radiators that by 25%.
• The work highlights the potential of energy saving using flow pulsation for panel radiator while maintaining the indoor comfort standards of the occupants.

Enhancing the performance of central heating systems in buildings can play a major role in energy savings. Pulsed flow to the radiators can lead to enhancing the specific heat output of radiators. The aim of this work is to investigate the effect of radiator flow pulsation on the indoor spatial temperature and velocity distributions to achieve energy saving without compromising the user thermal comfort defined by ASHRAE standard 55 and EN ISO 7730. CFD modelling of panel radiators at constant and pulsed flows were carried out and the results were validated with published data. Such radiators were then incorporated in a room and CFD modelling of the room was carried out using flow pulsation strategies.The simulation of the radiator at constant flow was validated against published experimental data in terms of heat output showing maximum deviation of 2.44%. Results from CFD simulation of the radiator with pulsed flow using frequency ranging from 0.0083 Hz to 0.033 Hz and amplitude ranges from 0.0168 kg/s to 0.0228 kg/s showed that 25% improvement in the specific heat output can be achieved while maintaining the same radiator target surface temperature of 50 °C. Also using the pulsed flow applied in this work the pump power can be reduced by about 12% compared to the pump operating at constant flow. As for the heated space with the integrated radiator, results of CFD simulation for pulsed flow with frequency of 0.033 Hz and amplitude of 0.0192 kg/s showed that the temperature, velocity and draught rate were maintained within the required comfort levels of 20 ± 1.5 °C; less than 0.15 m/s and less than 15%, respectively.