Radiant Heating and Cooling Handbook

Chapter 1: INTRODUCTION TO RADIANT PANELS

1.1 RADIANT PANEL BASICS

A radiant heating panel, normally a flat surface, is defined as a surface from which at least 50 percent of energy transfer is accomplished through radiation. The balance of surface or panel face heat transfer occurs by convection. Radiant heating panels include concealed and visible panels that cover or encompass a large or small fraction of a wall, floor, or ceiling. Panel form ranges from discrete ceiling units to cove, recessed, or surface-mounted wall units, and embedded floor, ceiling, or wall hydronic tubing, or electric cables, wire, and mats.

Research results and physical governing laws prove that the radiative emission from a surface is independent of surface orientation. However, it is well documented that convection heat transfer is a strong function of surface orientation. For example, Nusselt number (Nu) correlation for a heated horizontal plate facing downward versus the same heated horizontal plate facing upward leads to substantially different convective heat transfer coefficients. As long as the surface temperature and other characteristics remain the same, the radiation heat transfer rate is unchanged. However, the varying heat transfer coefficient changes the percentage of the total energy that is represented by the radiant energy emitted from the surface.

For example, a heated plate facing downward with a surface temperature of 370 K exposed to an air temperature of 290 K results in a natural convection Nu of 98, leading to a convective heat flux from the surface of 110 W/m 2. The same plate exposed to...

UNLIMITED FREE ACCESS TO THE WORLD'S BEST IDEAS

close
Already an Engineering360 user? Log in.

This is embarrasing...

An error occurred while processing the form. Please try again in a few minutes.

Customize Your Engineering360 Experience

close
Category: Central Heating Systems
Privacy Policy

This is embarrasing...

An error occurred while processing the form. Please try again in a few minutes.