Solar Engineering of Thermal Processes, 4th Edition

3.12 Convection Suppression

One of the objectives in designing solar collectors is to reduce the heat loss through the covers. This has led to studies of convection suppression by Hollands (1965), Edwards (1969), Buchberg et al. (1976), Arnold et al. (1977, 1978), Meyer et al. (1978), and others. In these studies the space between two plates, with one plate heated, is filled with a transparent or specularly reflecting honeycomb to suppress the onset of fluid motion. Without fluid motion the heat transfer between the plates is by conduction and radiation. Care must be exercised since improper design can lead to increased rather than decreased convection losses, as was first shown experimentally by Charters and Peterson (1972) and later verified by others.

For slats, as shown in Figure 3.12.1, the results of Meyer et al. (1978) can be expressed as the maximum of two numbers as

3.12.1

where and are given in Figure 3.12.2 and the subscript indicates that the plate spacing is the characteristic ...