Controlling the thermal power of a wall heating panel with heat pipes by changing the mass flowrate and temperature of supplying water—experimental investigations

Abstract

Renewable energy sources for the purpose of heating buildings cooperate perfectly with so-called low-temperature heating systems. Water loop surface heating systems had been thoroughly tested. In contrast, thermal performance of wall panels with heat pipes have not been fully recognized, yet. The determination of the thermal power as well as the control of panels thermal performance cannot be performed with the methods developed for water loop systems. In this paper, the novel heating panels with heat pipes were tested to analyze the possibility of controlling their performance by changing the mass flowrate of heating water and its temperature. Specific heating power of the investigated panels varies from 16.9 W/m2 to 93.8 W/m2 when supplying a water temperature ranging from 35 °C to 65 °C and mass flowrate from 10 g/s to 47.5 g/s. Investigations revealed that the thermal performance of the panels is more sensitive to the changes of temperature than to the changes of mass flowrate of supplying water, and thus, should be controlled by changing the supply water temperature at low mass flowrates to obtain a low energy usage of pumps (diminished pressure losses) and good quality of controlling.