Solar powered cooling apparatus

Solar powered cooling apparatus is disclosed in which liquid refrigerant is vaporized in a collector/evaporator by solar radiations concentrated by a reflector, and the pressurized vapors operate an aspirator to reduce the pressure in an evaporator containing the same liquid refrigerant to cool the same. The mixture of vapors leaving the aspirator are condensed in a higher positioned condenser and supplied to a gathering vessel from which the liquid refrigerant is forced back into the collector/evaporator with the assist of pressurized vapors periodically withdrawn from the collector/evaporator.

DESCRIPTION 
1. Technical Field 
The present invention relates to cooling systems powered by solar 
radiation. 
2. Background Art 
Solar radiation is commonly used for heating liquids to moderate 
temperatures for diverse heating purposes. In some instances, more 
sophisticated solar powered systems have been used for the generation of 
electricity, and once electricity is available, it can be used for any 
desired purpose. However, it must be appreciated that solar powered 
systems are usually most practicable where the sun is strongest, and this 
is where cooling, not heating, is commonly the factor of greatest 
interest. Solar refrigeration usually requires that one first employ 
equipment for converting solar energy to electricity, and then this 
electricity can be used to operate equipment, usually including 
compressors, for producing the low temperature fluids needed for cooling. 
It is also possible to use an absorption cooling system, but such 
installations are sizeable and expensive and at least two pumps are 
required together with many controls. This invention has, as its purpose, 
to convert the solar energy directly into the low temperature fluids 
needed for cooling, and without the use of any compressor which 
considerably simplifies the system. The use of only a single fluid in the 
system is particularly contemplated, which further simplifies the needed 
construction. 
DISCLOSURE OF INVENTION 
In accordance with this invention, reflector means are used to concentrate 
the incident solar radiations onto a refrigerant, like Freon 11, contained 
in a collector/evaporator. This generates pressurized vapors which are 
passed through an ejector which functions as an aspirator to reduce the 
pressure in an evaporator containing the same refrigerant in liquid form. 
This reduced pressure causes the refrigerant to evaporate (boil) which 
lowers the temperature of the remaining liquid to provide a low 
temperature coolant for refrigeration purposes. The mixture of vapors 
leaving the ejector are cooled in a condenser to liquify the refrigerant, 
and this liquid refrigerant is divided into two portions to supply both 
the collector/evaporator and the evaporator. 
In preferred practice, a portion of the vapor produced in the 
collector/evaporator is recycled back to provide a pressurized assist to 
force the liquid refrigerant into the collector/evaporator. 
The invention will be more fully understood from the accompanying drawings.

Referring more particularly to FIG. 1, it is convenient to start the 
consideration at the condenser 10, where cooling water entering the 
condenser at 11 and leaving at 12 is used to liquify the refrigerant which 
exits through line 13 passing through check valve 14 which prevents the 
pressure which intermittantly builds up in the gathering vessel 15 from 
passing through into the condenser 10. 
The refrigerant is desirably Freon 11 since its characteristics are 
particularly well adapted to the system which is described herein, but 
many refrigerants are known and can be selected to replace Freon 11 
depending upon the ambient conditions encountered and the desired 
temperature of refrigeration. 
The refrigerant liquid shown in vessel 15 passes via lines 16 and 17 and 
control valve 18 into a collector/evaporator 19 which is heated by the 
solar radiation concentrated by reflector 20. 
As will be evident, the liquid refrigerant is evaporated and pressurized in 
the collector/evaporator 19, and it is necessary to overcome this pressure 
in order to supply liquid thereto, and this is achieved by recycling a 
part of the vapor which suddenly lowers the pressure in the 
collector/evaporator. The recycled vapor adds its pressure to the head of 
liquid in the gathering vessel 15. Control valve 18 opens only when the 
inlet pressure is about equal to or exceeds the pressure in the 
collector/evaporator 19. This means that the collector/evaporator will 
only be supplied with liquid refrigerant periodically. At other times the 
refrigerant will pass through lines 16 and 21 to move toward the 
evaporator 22. 
Evaporator 22 accepts liquid refrigerant whenever the liquid level within 
it falls below a predetermined level. This is detected by level control 23 
which controls control valve 24. Liquid refrigerant thus moves down past 
check valve 25 through line 21 passing through valve 24 whenever the 
liquid level in the evaporator 22 falls excessively. 
The vapor produced in the collector/evaporator 19 passes through a 
pressure-actuated control valve 25 whenever the sun produces a sufficient 
vapor pressure, and the pressurized gases pass through line 26 to an 
ejector 27 which serves as an aspirator, withdrawing vapor from evaporator 
22 which reduces the pressure therein which causes the liquid in the 
evaporator to boil and lose heat in this way. This provides a reservoir of 
cooled liquid through which the coolant of an external refrigerating 
circuit is passed via cooling coils 28 and exit line 29 which is 
controlled by an optional thermostatically controlled valve 30. The 
details of the refrigerant circuit form no part of this invention and will 
not be discussed. 
The pressure and temperature of the pressurized gases in line 26 are 
reduced by admixture with the vapors withdrawn from evaporator 22, and the 
mixture passes through line 31 to return to the overhead condenser 10. The 
term "overhead" indicates a higher position so that the liquid which 
gathers in vessel 15 will be above the inlet to the collector/evaporator 
so that a head of liquid will provide assistance in overcoming the 
pressure within the collector/evaporator. 
The overall operation of the solar powered refrigeration system can now be 
described. 
BEST MODE FOR CARRYING OUT THE INVENTION 
Liquid refrigerant in a collector/evaporator is boiled by concentrated 
solar radiation to provide pressurized vapor which aspirate refrigerant 
vapor from an evaporator to provide a pool of cool liquid which supplies 
the chill needed to operate a refrigerating device. The mixture of 
pressurized vapor and aspirated vapor is condensed in a higher positioned 
or overhead condenser which drains into a gathering vessel which supplies 
liquid refrigerant to the evaporator whenever it needs it. The liquid 
refrigerant supply to the collector/evaporator is periodic and is 
triggered by tapping off the pressurized gases to add to the head of 
liquid established by the gathering vessel to overcome the pressure which 
remains in the collector/evaporator. 
This periodic supply of pressurized gases is obtained by periodically 
connecting the collector evaporator 19 with the top of the gathering 
vessel 15 via lines 32 and 33 which are interconnected by means of a 
pressure interrupting device 34. 
The interrupting device 34 includes a piston 35 which moves within a 
cylinder 36 which receives pressurized gases through line 32. Piston 35 
normally prevents the pressure in line 32 from reaching line 33, the 
piston being held in its closed position by a compression spring 38. As 
pressure builds in the collector/evaporator right after a recycle, piston 
35 moves toward its open position, movement being slowed by an hydraulic 
brake 39. 
The hydraulic brake 39 is formed by a piston 40 which moves in a cylinder 
41 which interconnects with piston 35, via shaft 42. As pistons 35 and 40 
move toward the open position, the hydraulic fluid in cylinder 41 slowly 
moves to the other side of piston 40 via metering valve 43 which 
determined the speed of the pistons 35 and 40. When piston 35 opens up 
line 33 vapor shoots through into the top of gathering vessel 15 as well 
as starts to actuate control valve 18 and the collector/evaporator 19 gets 
a new liquid supply from vessel 15. The suddenly dropping pressure in 
collector/evaporator 19 as well as in cylinder 36, make pistons 35 and 40 
slow down their motion, come to a stop and the reverse motion starts as 
the low pressure level in cylinder 36 as well as the collector/evaporator. 
The return movement produced by spring 38 after piston 35 is in its open 
position is a rapid one as the hydraulic fluid in cylinder 41 returns 
through the check valve 44. The volume of cylinder 36 is relatively small 
compared with the volume of collector/evaporator 19. So the return 
movement does not get slowed because pressure increase in cycle 36 caused 
by this return movement is virtually negligible. 
The cyclic supply operation is illustrated in the graph of FIG. 2 where the 
solid line indicates the pressure in the collector/evaporator. As can be 
seen this pressure is constant assuming a steady supply of solar energy. 
However, when piston 35 moves to the open position, there is a sudden 
lowering of pressure as the vapor moves rapidly through lines 32 and 33 in 
the absence of back pressure. After refill of the collector/evaporator 19, 
the pressure builds back to normal. In contrast, the dotted line shows the 
pressure in the gathering vessel which is normally low, except just after 
the piston 35 moves into its open position. Thereafter, the pressure 
decreases to its normal level. 
Increased solar radiation shortens the cycle of the system because vapor 
travels faster towards ejector 27. Pressures will be at a slightly higher 
level in the collector/evaporator 19 and in cylinder 39 and interrupter 34 
works faster at a similar rate. Start up happens if radiation becomes such 
that the pressure in the collector/evaporator becomes high enough. 
INDUSTRIAL APPLICABILITY 
The result is a composite apparatus containing no pumps in which a single 
fluid is heated by concentrated solar radiation, and the product is a 
reservoir of cool liquid for refrigeration purposes. This particularly 
enables air conditioning in hot sunny climates to be obtained with a 
relatively simple apparatus which does not require any electrical hook-up, 
and without consuming large amounts of energy other than that supplied by 
the sun.