Patent Publication Number: US-8978381-B2

Title: Method for cooling air and devices

Description:
FIELD OF THE INVENTION 
     The present invention relates to methods and devices for cooling gas and more specifically cooling a gas for air-conditioning and use of its internal energy. 
     BACKGROUND OF THE INVENTION 
     The known method of cooling air in air-condition system is by compressing a gas like Freon™, which under room temperature and atmospheric pressure is in gaseous state, to a pressure of several bars so it liquefied to become a liquid-gases like this are name “refrigerants”. Since compressing the gas heats it to about 80° Celsius, the liquid is then chilled by flowing through a heat exchange and then flow the liquid through a drying bottle where water are extracted from the liquid gas. Then the liquid is pushed into a porous plug where the pressured liquid gas flow through narrow passage until it exits the passage and arrives at a much wider pipe, where the pressure is about 1 bar. Since under this pressure the material natural phase is gaseous, it evaporates. This evaporation process requires substantial amount of heat, taken from the pipe walls the liquid is flowing inside. Thus the pipe becomes cold and a flow of air, pushed by an electrical fan, heats the pipe and provides more heat to the liquid inside the pipe to evaporate. The heat taken from the airflow makes it colder while it passes through the heat exchanger and entering a space needed to be cooled. 
     The major flaw of the current art air-conditioning is the compressing stage, which is not efficient due to the fact that while the compressor compresses the refrigerant it also heats it and this heat is undesirable and requires more energy and device to get rid off. The compressor requires about 75% of the air-conditioning power consumption. 
     It is therefore desirable to have a more efficient air-conditioning method and systems. 
     SUMMARY OF THE INVENTION 
     According to the present invention, there is provided a method and system to generate cold zone, which absorb heat so it becomes an air condition cooling unit by making a gas flowing into a convergent-divergent nozzle. While the gas advances toward smaller cross section areas it accelerates. The kinetic energy added to the gas is on the expense of the gas own internal energy, thus the gas become colder as it accelerates. This process forms a cold zone in the nozzle throat or in a divergent nozzle in case of supersonic flow. 
     A major aspect of the invention is the use of heat exchanger in the cold zone to make use of this “coldness” to be a cooling unit of an air-condition and air conditioning method. 
     A major aspect of the invention is the incorporation of a fan or compressor that sucks air and flows it into a convergent-divergent nozzle. 
     Another major aspect of this invention is the use of heat exchanger around the nozzle walls and especially the skin at the nozzle throat. 
     Another aspect of the invention is nozzle walls and skin made of high thermal conductive material such as metals and preferably copper, silver or gold. 
     Another aspect of the invention is the installation of an axial turbine within a convergent-divergent nozzle, where the gas speed is high, close to the nozzle throat, so that the turbine extracts energy from the gas flow, to further decrease the flow temperature, when gas leaves the nozzle. 
     Yet another aspect of the invention is the use of power extracted by the turbine in any useful purpose such as generating electrical power or to provide mechanical energy to machines and vehicles so the it becomes vehicle driving engine. 
     Yet another aspect of the invention is to use cold air expelled from a nozzle and turbine to cool spaces. 
     Yet another aspect of the invention is that the nozzle throat is elongated, to form a cylindrical body having enlarged surface area, to increase the rate of heat transfer. 
     Still another aspect of the invention is a nozzle equipped with a turbine coupled with electrical generator that decelerates the airflow and so the cold airflow exits the nozzle is cold enough to air-condition spaces. 
     Yet another aspect of the invention is that the exit flow of the device is further chilled by a heat exchanger that provides heat to another device according to this invention. 
     Still another aspect of the invention is the incorporation of air pushing-flowing device between the nozzle throat and the nozzle exit plane. 
     Yet another aspect of the invention is the incorporation of a digital control system that monitors gas flow parameters such as temperature, pressure and speed at various stations along the nozzle and electrical currents consumed or produced by inlet fan-compressor, turbine generator and secondary fan-compressor and their rotations speed and internal temperatures, and changes the nozzle inlet flow speed in order to achieve desired optimal performance. 
     Yet another aspect of the invention is the incorporation of a digital control system that change inlet fan-compressor, secondary fan compressor and turbine generator electrical currents. 
     Yet another aspect of the invention is the incorporation of a digital control system that monitors air temperature at the nozzle throat and changes the nozzle inlet flow speed in order to keep the throat temperature at a desired temperature. 
     Still another aspect of the invention is the incorporation of digital control system that monitors noise along the nozzle and changes air inlet flow speed to keep the noise level at a desired level. 
     Still another aspect of the invention is the starting procedure in the turbine-generator is operated for a short while as secondary fan-compressor to help push-flow the flow toward the nozzle exit concurrently with inlet fan-compressor, until the flow in the nozzle throat reach the desired speed and then electrical current is not provided to the turbine-generator thus the turbine generator turns into power generator that uses the airflow power to generate electricity. 
     Still another aspect of the invention is the liquefying water vapors within the airflow entering the nozzle and accumulating this water and use them. 
     Still another aspect of the invention is spraying water droplets into the gas flow in the inlet vicinity so the that the water droplets evaporates and later liquefies at the nozzle throat to lower the pressure and help sucking flow into the nozzle. 
     Still another aspect of the invention is water desalination and salt extracting by spraying salty water in a pipe where the gas flows before entering the nozzle inlet so that salt is separated and accumulated and water are drained and accumulated. 
     Still another aspect of the invention is a control system that changes a convergent-divergent nozzle throat area in order to achieve desired airflow speed at the throat. 
     Still another aspect of the invention is the incorporation of water drain system that prevents water from accumulating within the nozzle or the rotor chamber. 
     Still another aspect of the invention is a convergent nozzle equipped with a powered fan that drives air into the nozzle so that the nozzle converts air internal energy into kinetic energy, which drives a turbine-generator that provides electrical power to the inlet fan-compressor. 
     Still another aspect of the invention is the use of the gas flowing in the nozzle in a close circuit so that the exit gas is flowing back to the nozzle inlet. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention will be further understood and appreciated from the following detailed description taken in conjunction with the drawings in which: 
         FIG. 1  is a side view cross section along one embodiment of the invention. 
         FIG. 2  is a front view of one embodiment of nozzle throat cross section. 
         FIG. 3  is a front view of another embodiment of nozzle throat cross section. 
         FIG. 4  is a side view section of another embodiment of the invention having an axial turbine-generator. 
         FIG. 5  is a side view section of another embodiment of the invention having an axial powered fan in the exit nozzle. 
         FIG. 6  is a schematic drawing shows how device according to the invention integrated with central air-conditioning system. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The invention disclosed here is a method and devices that use gas like air as a refrigerant for air-condition purposes. Due to the physical law of continuity, as the nozzle cross-section decreases the gas must accelerates. Thus the kinetic energy of the gas increases. In an adiabatic flow the kinetic energy comes on the expense of the gas internal energy C p T, where C p  is the gas constant pressure specific heat and T is the absolute temperature. At the nozzle throat, the gas has maximum speed and consequently minimum temperature. It is possible to use air at 50° Celsius and accelerate it to speed of sound at the throat, where its temperature will be: 0.834 (273+50)° C.=269.4° K., i.e., −3.8° C. This low temperature is good for air-condition system even it hottest countries in the world. The cold airflow cools the nozzle skin so we can use it to absorb heat from a heat exchanger and use the cooled flow within the heat exchanger to cool remote spaces or basically anything. The use of this phenomenon to create cold place that absorbs heat as a cooling unit for air-condition is a major aspect of the invention. The use of this phenomenon together with heat exchanger to exploit the cooling unit of air-condition is another major aspect of the invention. 
     Installing a powered fan, compressor or using other source of gas flow within a convergent nozzle forms a method that generates cold zone in the nozzle throat. Thus we could use this method at any desired time to cool virtually anything. Thus, using a controlled gas flow source into a convergent nozzle and use it for generating cooling effect is another aspect of the invention. 
     Note: All formulae in this patent application and the data used are taken from the reference book: 
     FOUNDATIONS OF AERODYNAMICS 2 nd  Edition 
     BY: A. M. KUETHE and J. D. SCHETZER 
     Department of Aeronautical Engineering 
     University of Michigan (USA) 
     Publisher: JOHN WILEY &amp; SONS 
     Library of Congress Catalog Card Number: 59-14122) 
     Surprisingly, natural air at 0° C. has huge amount of energy (called “internal” energy) compared to its kinetic energy even at freezing temperature. 
     To realize this statement, one must look at equation of energy for isentropic compressible flow for a unit mass:
 
 C   p   T+V   2 /2=const  (Eq. 24 Ref. Book P140)
 
     In the following discussion, flow parameters are quoted for air for convenient purposes, however, other gases could be used instead of air. 
     Eq. 24 parameters are:
         C p  is the constant pressure specific heat of air—see page 132 in the reference book   T is the absolute temperature of the air   V is the speed of the air       

     C p ×T is the internal energy of the gas (air) while V 2 /2 is the kinetic energy of gas unit mass. For isentropic flow (heat is not added or taken from the air), the energy relation given by Eq. 24 must be satisfied”, i.e., conservation of energy exists. 
     To demonstrate the ratio between kinetic energy and internal energy we calculate these energies for a flow having a speed of 25 meter/second, having a temperature of T=32° F. 
     Using the British Unit System
         C p =6000 FT×LB/Slug ° R   T=460+32=492° R   V=25/0.3048=82.02 FT/SEC   The internal energy is: C p T=6000×492=2,952,000 FT×LB/Slug       

     The kinetic energy is: V 2 /2=(82.02) 2 /2=3,201.6 FT×LB/Slug 
     Therefore the ratio between the air kinetic energy to the air internal energy in this case is: 3,201.6/2,952,000=0.00108, i.e., the kinetic energy is about one thousandth of the air internal energy. 
     Table 2 in page 419 of the reference book presents data of a gas flow in a nozzle as a function of the Mach number. The data of Table 2 shows that when a flow is at Mach=0.7, T/T°=0.9107. That means that the local airflow temperature is about 92% of the same gas at rest, i.e., before its acceleration within the convergent nozzle. If atmospheric air— 130 , see  FIG. 1 , is at 35° C. while it is sucked into a device of  FIG. 1  and assuming the Mach number of the flow  135  in the throat is 0.7, then the air temperature in the throat is: 0.9107(273.16+35)=280.5° K, which is 280.5−273.16=7.5° C. This low temperature of the throat skin  109  can be used to cool a liquid, like water, flowing in pipe  170 ,  174 ,  172 . If the Mach number at the throat reaches 0.8 then, T/T°=0.8865 and the temperature of the flow at the throat is T=0.8865(273+35)=273.0° C., which is: T=0° C. This low temperature is adequate to cool water to be used in air-conditioning systems. 
     The advantage of this method to cool gas, compared to conventional method of cooling gas is reduced amount of energy to cool gas. 
       FIG. 1  shows schematically one embodiment of the invention. A pod  100  comprises of convergent nozzle  108  having a throat  109  and optional divergent nozzle  110 . In this embodiment of the invention, the nozzle typical cross-section shape is circular. However any cross section is suitable for this device. A powered fan or compressor,  120  optionally, equipped with electric motor  128  has at least one rotating wing  120 , sucks air  130  into the nozzle  108  and pushes it toward the exit plane  118 . Optional guide walls  140  prevent turbulence within the flow, to keep the airflow isentropic. As the airflow advance into smaller cross-sections along the convergent nozzle, it accelerates and its static temperature decreases—see P. 158 in the reference book. If the flow is not accelerating above Mach=1.00, then the minimum temperature exist at the throat  109 , where, a heat exchanger in the form of pipe  170 ,  174 ,  172  is installed. Note that the pipe  174  is coiled around the throat  109  to increase the area where heat is flowing from the liquid within pipe  174  to the throat skin  109 . The liquid within the pipe  174  is driven by a pump (not shown) could be water or other liquids which do not freeze at temperatures like −20° C. The liquid gives its heat to the throat skin  109 , which preferably made from high thermal conductivity metal, preferably, copper, silver or gold or other alloy. If the airflow further accelerates after passing the throat to Mach&gt;1.00 in the divergent nozzle  110 , then the minimum temperature is at the divergent nozzle and the heat exchanger should be installed to wrap this part. It should be noted that the powered fan could be replaced by any other source of gas flow, that cause gas to flow into the nozzle inlet  110  at temperatures between about 25 to 50 degrees Celsius. The speed of the flow at the inlet should be about a range of Mach=0.03 to 0.1 and the ratio throat area to inlet area should be about 3 to 15 to ensure the flow acceleration of speeds ratio V throat /V inlet  of about 5 to about 15. Since the static pressure at the nozzle is substantially below that of the ambient air, the skin  108 ,  109 ,  110  is preferable made of high strength materials such as metals like aluminum, steal or composites. Frames  103  are added to prevent the nozzle collapse while operating. To increase the area through which heat flows from pipe  174  to the throat area, the nozzle  109  can be extended to any desired length so that additional pipes  174  can be coiled around the nozzle throat. 
     The liquid flows in pipe  174  becomes colder as it leaves as flow  176  toward a remote heat exchanger  608  shown in  FIG. 6 . 
     It should be noted that although the convergent nozzle is preferably made of circular cross section, other cross section might be use. Rectangular cross section has the advantage of enabling dynamic change of the convergent-divergent throat area. This can be done by using two parallel walls while the other two walls, opposite to each other, are moveable. In one arrangement, the inlet cross section area can be increased or decreased while the throat section is constant. In another arrangement, the inlet and exit cross sections are kept constant while the throat area is increased or decreased continuously. To move such wall, one edge is hinged and fixed while the other wall edge is moveable under the force of electrical or hydraulic actuator as can be seen in PCT patent application PCT/IL2005/001208. 
       FIG. 2  shows another embodiment of a throat cross-section shape where the flow passes through area  222  perpendicular to the page. Here the ratio of circumference length divided by the cross section area is greater than of a circular cross section, thus the coiled pipe  204  has more length and contact area with the throat skin  220 . The liquid  210  gives its heat to the skin  220  becomes colder and flows away to cool a remote heat exchanger such as  608  in  FIG. 6 . 
       FIG. 3  shows another embodiment of a throat cross-section where throat area  322  is having multiple ribs  305  that further increases the area through which heat flows from the skin  300  and the ribs  305  to the cold throat flow. These ribs preferably made of highly thermal conductive material such as copper, aluminum, silver, gold or other alloy, built along the nozzle throat area. 
     Heat exchange ribs can be used in any cross section shape. 
       FIG. 4  is another embodiment of the invention. As the flow  132  accelerates downstream to smaller cross-section areas, the flow must accelerate to obey the continuity law. Thus when the local cross section area is half of the inlet cross section area, then the speed is about twice of that in the inlet and the flow kinetic energy in the local station is 4 times of the flow in the inlet. The source for this increased kinetic energy is the gas internal energy according to:
 
 C   p   T+V   2 /2=const  (Eq. 24 Ref. Book P140)
 
     Thus the kinetic energy increases while the thermal energy decreases. If the ratio of a cross section divided inlet  110  cross section is ⅕ that means that the local velocity of the flow is about 5 times greater than the speed of flow  130  entering the inlet  110  and the kinetic energy is 25 times than that of the flow  130 . If some of this kinetic energy is extracted from the flow, then the flow temperature will not rise back as it is in a classic convergent-divergent nozzle (the Laval nozzle). Thus we get colder airflow  136  exiting the nozzle, so it can be used as direct cooled air to air-condition spaces and useful energy as electrical energy to power the fan-compressor  120 . Further, surplus energy can be provided to external consumers or converted into mechanical energy to be used in any form including driving vehicles. 
     Example of energy calculation in convergent-divergent nozzle. 
     Assuming the following data: 
     Inlet area=10 FT 2  (diameter of 1.087 Meter) 
     Inlet flow speed=100 FT/Sec 
     Inlet FAN pressure=20 LB/FT 2    
     Inlet temperature=20° Celsius=528° R 
     Inlet air density=0.002378 Slug/FT 3    
     Throat area=1 FT 2    
     Using the energy equation
 
 C   p   T+V   2 /2=const  (Eq. 24 Ref. Book P140)
 
     The Inlet energy per unit mass flow is: 6000×528+100 2 /2=3,173,000 FT Lb 
     Assuming throat speed to be 1000 FT/Sec
         The throat static temperature is: 3,173,000−1000 2 /2)/6000=445.5° R       

     The mass flow rate in the nozzle is: m=ρ V A=0.002378×100×10=2.378 Slug/Sec 
     The throat kinetic energy per second is: mV 2 /2=2.378×1000 2 /2=1,189,000. Ft Lb/Sec==1,611,001.5 Watt 
     That means the flow kinetic energy per second in the throat is about 1600 Kilo-Watt If a turbine extract 50% of this energy we get an engine with 800 Kilo-Watt power. This high value shows the potential of such engine. 
     To exploit this kinetic energy of the nozzle flow an axial turbine-generator  407 , equipped with rotate-able blades  402 , is installed in the nozzle as shown or alike. The turbine-generator  407  can be installed in the convergent part, before the throat or after the throat, in divergent part of the nozzle  110 , especially if the Mach number in the divergent nozzle is greater than 1.00. The turbine-generator is attached to the nozzle skin by wings  400  having a cambered profile  401 , which directs the flow to optimally hit the turbine blades  403 . Note that the turbine profile  403  redirects the flow to be axial and parallel to the throat axis of symmetry  150 . The number of turbine stages could be more than 1 according to the kinetic energy available and the desired velocity of airflow  118 . The rotating energy of the turbine is converted to electrical power by an electrical generator  407 . This electrical power could be used to drive the electrical motor  128  that drive the inlet fan/compressor  120 . Since the turbine extracts energy from the flow, the temperature of the flow decreases as it exit the turbine thus decreasing the flow temperature at the throat and increasing the cooling ability of the device while generating useful power. Since the exit flow  136  lost some energy in the turbine  307 , it leaves the device at lower temperature and speed comparing to the embodiment in  FIG. 1 . This exit flow may be used as direct cooled air to cool anything needed to be cooled like machines parts, rooms, etc. Further, this exit flow can be further cooled by a heat exchanger (not shown) that uses the cooled liquid  176 . 
     The power generated by the turbine-generator may exceeds the power consumption required by electrical engine  128 , thus this machine could be used to generate electrical power from air/gas internal energy, especially in hot climates. Such a surplus electrical power can be used in any electrical device or even selling it to electrical power company. Farther surplus energy can be used to drive machines or vehicles as disclosed by PCT/IL2005/001208 patent application. This can easily done by mechanically connecting a power shaft to the turbine  407  shaft using a gear box. The power shaft further connected to a vehicle gearbox so power can be given to vehicle wheels or other pushing-pulling devices. Alternatively such driving elements may be powered by electrical motors fed by turbine-generator  407 . It should be noted that the fan-compressor  120  may alternatively powered by a belt driven by external engine or other source power such as wind, steam under pressure and alike. Alternatively, turbine  407  could be mechanically connected to fan-compressor  120  so the two devices rotating simultaneously. Such a connection could use a clutch that can connect or disconnect the two rotating devices. A digital controller that monitors the airflow temperatures along the nozzle could control such a clutch, fan-compressor  120  electrical power and speed. 
     The use of a turbine that extracts power from the flow in the nozzle so that the flow exits the divergent nozzle is colder than the flow entered the nozzle is another aspect of the invention. 
     The use of a turbine that extracts power from the flow in the nozzle where the nozzle is heated by heat exchanger to energize the flow in the nozzle is another aspect of the invention. 
     Further, the turbine-generator can be used to help start the machine by providing it with electrical current so the electrical generator is now electrical motor that rotates and drive the turbine that sucks air-flow/gas from the inlet. After the flow in this embodiment of the invention stabilizes and the static pressure along the nozzle is gradually decreases from the inlet toward the nozzle throat, the electrical current to the turbine-generator should be gradually decreased, while the electrical current supplied to the electrical motor  128  to increase the rotational speed of the fan/compressor  120  so as to increase the pressure after the fan-compressor to over come the turbine-generator  407  resistance to the flow in the nozzle. The electrical current devices that change the electrical current are not shown however such devices are commercially available. The use of axial turbine-generator to start and stabilize the flow in the convergent-divergent nozzle is another aspect of the invention. 
       FIG. 5  shows another embodiment of the invention, where additional fan  500  is installed in the divergent nozzle to help push the airflow out of the device. Support wings  520  help stop the airflow circulation due to the turbine effect. 
     Please note that here the exit area is about the same size of the inlet area  110  to allow the flow to decelerate and increase its pressure to about one bar so it can be flown in regular air-condition tunnels. 
       FIG. 6  shows schematically a layout of central air-conditioning system using either embodiments of the invention. A unit  600  is either of the embodiments shown in  FIG. 1 ,  4  or  5 . Air  130  is sucked into a convergent divergent nozzle. At the nozzle throat, a heat exchanger  604  gives heat to the cold airflow in the throat. A hydraulic pump  607  pushes liquid, for example water, through pipe  606 , so the liquid become cold as it flows in the heat exchanger  604 . From there the cold liquid flows through pipe  606  to heat exchanger  608 , to chill the air  38  passes through  608 . Airflow  138 , now chilled, is pushed into tunnel  624  that carries the cold airflow  138 ,  630  to spaces required to be cooled. Outlet  640  allows cold airflow to flow into spaces/rooms to be cooled. Inlet  642  allows air from cooled spaces to be sucked into the tunnel to bring the airflow back to device  600 . The airflow enters the tunnel at inlet  642  and flows toward electric powered fan  640 , which sucks air from tunnel  620  and pushes it toward the heat exchanger  608 . Optional turbine-generator  610  extracts energy from air  130 , converts it into electrical power by an electrical generator and provides it to power the electric fan-compressor  640 . In case turbine-generator  610  doesn&#39;t generates enough electrical power, external electrical power is needed to power the inlet fan-compressor  640 . 
     Two other alternatives to this central-air conditioning system are possible: 
     First alternative, the above system may comprise device  600  without heat exchangers  604 ,  608  to be installed in tunnel  650 . This arrangement must include the turbine  610 , which extracts energy from the flow, so that the airflow in the nozzle throat is chilled so that the flow  136 , now within the tunnel  650  is cold enough to be used as cold air ready to flow in air-condition channel  624  to cool spaces. In this arrangement fan-compressor  640  could be eliminated as the inlet fan-compressor of unit  600  serve to drive the airflow through tunnels  650 ,  624 . 
     Second alternative is to combine the first alternative with the cooling system of  FIG. 6 , i.e., device  600  and heat exchangers  604  and  608  so that heat exchanger  608  further cools the exit flow of a convergent-divergent device installed in tunnel  650 . 
     To use this system for heating purposes an electrical heater is added to the hydraulic pump  607  so the heater heats the water in pipes  606 ,  605  that flows to the exchanger  608  to heat the airflow  138 . When the air-conditioner heats the flow  130  is stopped. 
     The embodiments of this invention can be used for water generation from humid air and salted sea-water as well as extracting salt from sea water. Spraying sea water into the gas flow before the inlet, either in into the gas flow that is about to enter the nozzle or in a special pipe, will evaporate the water while salt powder will be accumulated in an expanding pipe where the flow slows, thus this salt can be accumulated and use. The flow with its water vapors arrives at the nozzle throat and chilled causing the water vapors to liquefy thus water can be accumulated and used while the liquefying process lower the pressure in throat thus sucking more gas into the inlet nozzle. 
     The embodiments according to this invention are preferably equipped with digital controller that controls the airflow speeds by increasing or decreasing electrical current provided to the various electrical motors that drive the airflow in the system. At least one temperature sensor is installed tunnel  624  to monitor the airflow temperature so digital, controller could change the fan-compressor  600  speed and the pump  607  in order to achieve desired temperature at the entrance of tunnel  624 . Optionally, additional temperature sensors can be installed in various stations of the airflow  630  and in the throat of device  600  to prevent water freezing. Optionally anti-freezing additives could be added to the water in pipes  605 ,  606 . 
     The digital control system that monitors and controls the embodiments of the invention preferably monitors temperatures in various locations by installing temperature sensors that transmit their readings to the digital controller. Such temperature sensors preferably installed in the inlet  110  ( FIG. 1 ), throat  109  and in the divergent nozzle  110  before and after the axial turbine  407  ( FIG. 4 ) and before the second fan  500  ( FIG. 5 ) and at the exit plane  118 . The digital controller or CPU optionally has access to gas temperature data, similar to that of table 2 from the reference book, stored in a computer memory device. The data as T/T° (static temperature divided by stagnation temperature) could be used by a special software, to calculate the Mach number at the throat, to keep the device running at maximum efficiency by avoiding the flow speed to reach Mach=1.00. This can be done by changing the inlet fan/compressor  120  rotation speed to increase or decrease the inlet flow speed so that the desired Mach number is achieved at the nozzle throat. 
     Alternatively, pressure sensors may be installed to measure the pressure ratios P/P° of the gas in the nozzle to monitor and control the gas speed to achieve optimum performance of the device. Also, temperature and pressure sensors can be both use to increase the device reliability. 
     Optional pressure sensors could be installed in the throat so that the electrical power provided to the fan-compressor motor  128  is increased if more cooling power is required or more produced energy in the turbine is required. Such control system can be monitored from distance by a computer using wire or wireless communication network and by the Internet. 
     Since low temperature in the throat  109  will liquefy airflow humidity to become water. This water may be collected at the exit  118  or other station along the nozzle. Since the airflow  130  mass rate is about 1 KG per second for small system and up to 1000 KG or more in big system, the amount of water accumulated could be significant to justify building a drainage system to collect this water and use them. 
     To increase the amount of energy produced by the turbine-generator  407  ( FIG. 4 ), the liquid  176  can be preheated by ambient air, sun power, fire or any other heat source to energize the airflow in the throat so its speed can be increased although the axial turbine  407  extracts energy from this flow. 
     It should be noted that the elements, which incorporate in the various embodiments of the invention are only examples of wide variety of different designs, which have the same purposes. For example there are many types of machines to push air other than electrical fan-compressors depicted in  FIGS. 1 ,  4  and  5 . Another example is the heat exchanger  174  comprises of coiled pipes around the nozzle coldest part. Heat exchangers exist in many shapes and those depicted in  FIGS. 1 ,  2  and  3  are only an example. Also, mechanical connection between the powered fan  120  in  FIG. 4 , and the turbine generator  407  could be made by installing these elements on a common shaft, thus the generator  407  is used to start the system, acting as an electric motor, which gets electrical power from an external power source and rotating the fan compressor  120 . When the air  132  arrives the turbine it rotates the turbine blades  403  to such rotating speed that turns the motor  407  into electric generator  407 . Such arrangement has the advantage of using one electric motor/generator instead of two electric machines  128  and  407 . Consequently, electric motor  128  could be used for this purpose instead of electric generator/motor  407 . The amount of energy generated by the turbine could be significantly more than required to operate the entire air conditioning system described in  FIG. 6  thus, surplus electricity could be used elsewhere or sold to electric power company. 
     It will be appreciated that the invention is not limited to what has been described hereinabove merely by way of example. Rather, the invention is limited solely by the claims, which follow.