Abstract: The invention relates to a flat solar collector comprising individual vacuum chambers. The invention is formed by two heads and a series of parallel tubes having high transmittance in the solar spectrum, which is disposed between said heads. The opposite side of the heads is provided with vacuum chambers which closure the connections of the conducting tubes. One of the vacuum chambers is characterized in that it is fitted with a vacuum valve at one end thereof. In addition, conducting tubes are disposed inside the aforementioned tubes having high transmittance in the solar spectrum and said conducting tubes are in turn connected to collector plates, all under vacuum conditions which minimize convection energy losses. When the conducting tubes are configured in series, the collector can raise the temperature of the working fluid to above 200° C. All of the above is performed in a novel, simple and economical manner.

Abstract: A cooling machine, useful for air conditioning, refrigeration, ice production, or the like, based on the ammonia absorption thermodynamic cycle, and operated by a heat source of relatively low temperature, as for example a set of solar heat collectors, wherein the generator of said cooling machine comprises a first vessel through which said ammonia solution is circulated and is subject to separation of ammonia from water in the solution by raising its temperature through heat exchange relationship with a stream of a hot liquid, heated in the set of solar collectors; and a second vessel coaxially disposed surrounding said first vessel, whereby the walls of said first and second vessels define an annular hot water circulation chamber; said first vessel having a plurality of staggered series of heat transfer fins of predetermined dimensions so as to optimize the heat transfer from said hot liquid to the ammonia solution in said generator.