Retroreflective materials and optical imaging.
A retroreflective sheet returns each ray toward its source. If intercepted by a semireflecting plane mirror, the rays form a real image which lies as far behind the mirror as the source is in front. This principle can be used to make imaging systems with large apertures but without the usual aberrations.
Constant-deviation reflection with a microlens array
A novel form of reflector, incorporating an array of microlenses, is described. Incident illumination is reflected through an angle of deviation that is nominally independent of the angle of incidence. The reflector performs a function that is similar to a retroreflector but differs in that the angle of deviation is other than 180 degrees . This dispenses with the need to use a beamsplitter to extract the reflected wavefront, making for more efficient use of the available illumination.
Experimental Study for a Double-Glazed Forced-Flow Solar Collector/Regenerator
Experimental study of a double-glazed forced-convection solar collector/regenerator for absorption solar cooling is presented. The south facing experimental solar collector/regenerator with 10 deg slope is located at Kaohsiung, Taiwan at 120{degree}19minutesE longitude and 22{degree}34minutesN latitude. The size of the collector is 1 m wide and 7 m long with an effective regeneration area of 0.9 m by 6 m. Previous study for single-glazed forced-convection solar collector/regenerator operated at the same location has shown to have a best day-average efficiency of 17%. In order to raise the system performance, a double-glazed collector/regenerator is constructed such that air can be preheated in the upper channel flow. The preheated air is then conducted into the lower channel where it contacts with the film flow of solar heated lithium-chloride solution and regenerates the solution by carrying out the evaporated water vapor. The preheated air has lower relative humidity but the same humidity ratio since it is sensibly heated. Therefore, the regeneration driving potential is increased. The present study shows that the best day-average efficiency can reach 20% which increases the feasibility of the open-cycle absorption solar cooling system. Effects of controlling parameters on the collector/regenerator performance are studied, and heat and mass transfer correlationsmore » are also presented for design purposes.« less