Water generation from air utilizing solar energy and adsorption refrigeration unit

Abstract

The invention is a water generator device from air utilizing solar thermal energy and adsorption principle. The system is based on an adsorption refrigeration unit with Ether as a refrigerant and activated carbon as adsorbed. The required heat is generated from evacuated tube solar system and the heat sink is the atmosphere. The adsorption unit is an air-cooled refrigeration unit that can operate at relatively low hot water temperature (60-70° C.) and relatively high atmospheric temperature (30-40° C.). The water condensed from air is than driven through a simple water purification unit to assure its quality as drinking water. The very small electricity needed to operate the hot water and cold water pumps along with the filtration unit and the controller of the adsorption unit is generated from a small Photo Voltaic (PV) unit for stand alone systems.

1 . A system for water generation from air comprising;
 an adsorption unit, performing a heat operated refrigeration cycle, for water generation by cooling air to condense the humidity in the air and to accumulate that in a container;   a solar collector with evacuated tubes (E.S.C.) providing the hot water for the adsorption unit;   a radiator (R), as a heat sink of the system, to dissipate heat to the atmosphere; and providing cold water for the adsorption unit;   a water filtration unit processing the condensed water from the adsorption unit to eliminate any bacteria which might contain, also filtering and mineralizing the water;   a hot water circulation pump (PH) for said solar collectors (E.S.C.); a cold water circulation pump (PC) for said radiator (R);   a controller unit of the system;   a source of electricity to operate the system;   said system is characterized in that the adsorption unit, utilizing ether as refrigerant, comprises;
 two generators (G 1 , G 2 ), filled with activated carbon as adsorbent, and connected to each other by refrigerant flow line where an on-off valve (S 2 ) is located, said generators (G 1 , G 2 ) having hot water outlets connected to said circulation pump (PH), cold water outlets connected to said circulation pump (PC), hot and cold water inlets from two three-way valves, and refrigerant inlets and outlets; 
 a condenser (C) unit firstly connected to a junction coming from two refrigerant flow lines of non-return valves (N 1 , N 2 ) which are on outlets of the generators (G 1 , G 2 ); secondly connected to an on-off valve (S 1 ) whose flow line extends to an expansion valve (E.V); 
 an evaporator (E) unit firstly connected to the expansion valve (E.V); secondly connected to a junction coming from two refrigerant flow lines of non-return valves (N 3 , N 4 ) which are on the other outlets of the generators (G 1 , G 2 ); 
 a fan unit for cold air blowing from the evaporator (E) to the condenser (C); 
 two three-way valves ( 3 W 1 ,  3 W 2 ) that allow either hot water or cold water to enter the generators (G 1 , G 2 ); first one ( 3 W 1 ) is connected to the first generator (G 1 ), the second one ( 3 W 2 ) is connected to the second generator (G 2 ); also both ( 3 W 1 ,  3 W 2 ) are either connected to cold water line coming from the radiator (R) or hot water line coming from the solar collector with evacuated tubes (ESC); 
 a coil, between the condenser (C) and the evaporator (E), connected to cold water line coming from the radiator (R); and connected to said three-way valves ( 3 W 1 ,  3 W 2 ) 
   in that the adsorption unit generates the water from the humidity in the air accumulated on the cooled outer surface of the evaporator (E), by means of the refrigeration cycle in adsorption unit.   
     
     
         2 . A method according to  claim 1 , wherein refrigeration cycle has a start-up operation in a condition that both generators (G 1 , G 2 ) are at atmospheric temperature and of equal vacuum level and said start-up operation comprises the following steps where
 i. on-off valves (S 1 , S 2 ) are closed, second three-way valve ( 3 W 2 ) allows hot water, first three-way valve ( 3 W 1 ) allows cold water to flow in, if cold water pump (PC) is operated (or preventing hot water from flowing in); hot water circulation pump (PH) is turned on, cold water circulation pump (PC) is turned off, desorption occurs in the second generator (G 2 ) releasing the gas from the activated carbon and increases the pressure in the condenser due to gas build up and heat;   ii. on-off valves (S 1 , S 2 ) are closed, second three-way valve ( 3 W 2 ) allows cold water, first three-way valve ( 3 W 1 ) allows hot water, hot water circulation pump (PH) and cold water circulation pump (PC) are turned on, the generator (G 2 ) is cooled and depressurized getting ready to receive refrigerant and first generator (G 1 ) is heated and getting ready for adsorption.   
     
     
         3 . A method according to  claim 2 , wherein, after said start-up, refrigeration cycle has a continuous and repeated operation with the following steps;
 i. in the first step; the first valve (S 1 ) is open and second valve (S 2 ) is closed; the hot water pump (PH) and cold water pump (PC) are turned on, the first three-way valve ( 3 W 1 ) allows hot water to flow to generator (G 1 ) (initially filled with refrigerant) while second three-way valve ( 3 W 2 ) allows cold water to flow to the other generator (G 2 ) that is initially empty (or at low level) of refrigerant; since first generator (G 1 ) is pressurized due to heat then the refrigerator will be desorbed from the activated carbon and flows through the first non return valve (N 1 ); the third non-return valve (N 3 ) prevents refrigerant from flowing in the other direction and second non-return valve (N 2 ) prevents the refrigerant from going to second generator (G 2 ) which is at vacuum, then the refrigerant goes to the condenser (C) where the refrigerant condenses due to the low temperature of air flowing from the evaporator (E); then the refrigerant flows through the expansion valve (E.V.) evaporates in evaporator (E) at low temperature depends on the level of condensation needed; finally the refrigerant will then be adsorbed in second generator (G 2 );   ii. in the second step, the first on-off valve (S 1 ) is closed, the second one (S 2 ) is open, the pumps (PH, PC) are turned off to allow flowing of residual gases from first generator (G 1 ) to second generator (G 2 ) through the second valve (S 2 ); and this step takes time until the pressure in both generators (G 1 , G 2 ) equalizes;   iii. in the third step, both on-off valves (S 1 , S 2 ) are closed; the pumps (PH, PC) are turned on; first three-way valve ( 3 W 1 ) allows cold water and second three-way valve ( 3 W 2 ) allows hot water; and this step takes time until the pressure in first generator (G 1 ) comes to vacuum level, and pressure in second generator (G 2 ) rises above atmospheric pressure;   iv. in the fourth step; first on-off valve (S 1 ) is open, second on-off valve (S 2 ) is closed, the pumps (PH, PC) are turned on, first three-way valve ( 3 W 1 ) allows cold water and second three-way valve ( 3 W 2 ) allows hot water; in this step the refrigerant flows from the second generator (G 2 ) through the second non-return valve (N 2 ) to the condenser (C), through the first one-off valve (S 1 ) to the expansion valve (E.V) to the evaporator (E), through the third non-return valve (N 3 ) to the first generator (G 1 );   v. in the fifth step, second step is repeated;   vi. in the sixth step, both on-off valves (S 1 , S 2 ) are closed; the pumps (PH, PC) are turned on; first three-way valve ( 3 W 1 ) allows hot water and second three-way valve ( 3 W 2 ) allows cold water;   
     
     
         4 . A system according to  claim 2 ; wherein the said generator comprises a group of coaxial tubes filled with activated carbon and immersed in water reservoir allowing the carbon to heat and cool. 
     
     
         5 . A system according to  claim 4 ; wherein the said generator comprises the activated carbon ( 10 ) which is filled between an inner tube ( 11 ) and an inner perforated tube ( 12 ) which is around the inner tube ( 11 ); an outer perforated tube ( 13 ) is around the other perforated tube ( 12 ); an outer tube ( 14 ) which is used to cover the said tubes ( 11 ,  12 ,  13 ); another activated carbon ( 10 ) layer between the outer tube ( 14 ) and outer perforated tube ( 13 ); an accumulation chamber (A.C.), for the refrigerant, at the inlet and outlet of the generator. 
     
     
         6 . A system according to  claim 5 ; wherein the refrigerant gas ( 30 ) is passed through the gap between two perforated tubes ( 12 ,  13 ); water ( 20 ) flows through the inner tube ( 11 ) and around the outer tube ( 14 ) in the generator. 
     
     
         7 . A system according to  claim 1 ; wherein the source of electricity comprises at least a photo voltaic unit.