Abstract:
The development of products which enable passive solar-energy
air-heating to be integrated into the heating strategies of public,
commercial and industrial buildings is described. These buildings
are, in general, only occupied significantly during the day;
consequently the bulk of heating demand coincides with the period of
solar gain. In these circumstances collected solar heat should be
delivered with the minimum of delay.
The design and operation of units which are capable of supplying solar
heated air in this manner is outlined. These are passive, naturalcirculation
air-heating collectors, also known as natural-convection
air-heaters, or thermosyphoning air panels.
Four methods of retrofitting such solar collectors to non-domestic
buildings have been identified, one of which, the overcladding
collector, has not been proposed previously. Problems associated with
the successful installation and operation of these units have also
been considered.
The relative merits of a number of methods of testing passive solarenergy
air-heating collectors have been investigated. A method of
determining instantaneous collector efficiency based on the
measurement of glazing temperature, inlet and outlet air temperature,
ambient temperature and insolation has been developed.
Three novel design proposals have been presented: i) a collector
constructed with the insulation fitted outside, rather than inside, so
that the metal body of the collector may provide more symmetrical
heating of the air flow than the conventional arrangement, ii) an
absorber which consisted of parallel ducts to increase the rate of
heat transfer to the air, heating it symmetrically, (iii) a hinged
air-deflector for conversion from the heating to the ventilation mode.
