| WO/2015/059320 | STAND-ALONE WIND TURBINE WITH ENERGY ACCUMULATION AND APPLICATIONS |
| JPS61163670 | WIND-FORCE AND SOLAR RAY COMBINED ELECTRIC POWER PLANT |
| WO/2002/020983 | ENERGY CONVERSION METHOD |
| WO2008092449A2 | 2008-08-07 |
| ES2014513A6 | 1990-07-16 | |||
| ES2156707A1 | 2001-07-01 | |||
| DE102008027365A1 | 2009-12-10 | |||
| ES2150352A1 | 2000-11-16 |
| 5- Claims The following elements are to be protected 1- Utilizing wind energy which is clean and renewable for driving the water from air system. 2- Direct drive of the refrigeration compressor by wind turbine through the power divider and speed increaser. This arrangement saves about 40% of the mechanical power of the wind turbine 3- Dividing the mechanical power of the wind turbine between the refrigeration compressor and the electric power generator by a power divider gearbox. The electric generator supplies power to the electric fan and other services. 4- Utilizing of high speed refrigeration compressor with magnetic bearing increases the coefficient of performance up to 10. |
1- Technical Field
Ambient air at different temperatures includes water vapor which is called air humidity. Part of the humidity condensates when the air temperature falls below the dew point. This happens naturally when air rises in the atmosphere and meets cold air at high altitudes and forms clouds, which may rain if adequate conditions are fulfilled. This happens artificially in A/C and refrigeration units when air touches cold surfaces resulting undesirable condensate.
This project aims to make use of that water condensate and get water from air by wind power for drinking and may be, for some extent for irrigation 2- Background Art
Extracting water from air by condensation has found some
applications recently. This has been achieved by utilizing
electrical refrigeration units for cooling the air below the dew point and get drinking water from air. 3- Disclosure of Invention
3.1 What is new?
The new concept of this invention is to use the wind power for direct driving the compressor in the refrigeration unit without converting it to electrical power. This will save a considerable part of wind power that is lost through power conversion. The saving may exceed about 30%.
1. Description of The Invention
The attached process flow diagram Fig. 1 shows the process of power generation and water extraction from air. The power generated from the windmill is utilized for driving a compressor and electric power generator. The majority of wind power shall be used to drive the compressor. The remaining wind power shall be used to drive an electric generator. The electric power is used to drive the condenser cooling fan in the refrigeration unit and some other services of the system (control, lighting, etc.). A variable speed drive is used for the fan to control air flow rate to be suitable for wind speed.
The water condensation unit takes ambient air and passes it through evaporator. The water condensate is collected in the bottom of the evaporator and then to the water condensate tank. The cooled and partially dried air passes through the condenser to cool it. The following is a detailed description of the system. Wind Power
The mechanical power of the wind can be expressed as follows:
Where
P = Windmill Power
A = turbine rotor area m
p = air density, kg/m 3
m = mass flow rate of air, kg/sec
v = velocity of wind, m/sec.
It has been proved by Albert Betz ( 1885 - 1968) that the maximum power that can be extracted from wind = 59.3% of the total power in the wind. In practical applications the max power is 42% of the total power. When the wind power is used to generate electricity, the efficiency falls practically 30%. Using the wind power to directly drive the refrigeration compressor will enhance the efficiency as described above by the ratio 42/30 i.e. about 40 %.
Let us define the power conversion factor as Cp, the wind mill power equation becomes:
P m = ½ CpApv 3 (3)
Where:
P nl is the effective mechanical power that can be generated from wind turbines... P e = ½ C e ApV 3 (4)
Where P e is the effective electrical power that can be generated from wind turbines. ..
C e = 0.30 for electric power generation.
Chart no. 1 - Wind Map in Egypt
Chart no.1 shows the wind map in Egypt where it noticed that the Suez Gulf area has an excellent potential regarding wind speed and wind power generation. The wind speed exceeds 9 m/sec in some areas. The wind power intensity shown on the map is for
conventional wind turbines without funnel. In order to increase the windmill power intensity, i.e. the power for unit area of rotor, a funnel shall be installed in front of the windmill to increase the wind speed at the inlet of the rotor. This concept is already used recently by Green Energy Technologies Co. with its Wind Cube turbines.
Let us assume that:
A f = Funnel area
A r = Windmill rotor area
V w = Wind speed at the Funnel inlet
V r = Air speed at the rotor inlet
m = mass flow rate of air
The particular model that shall be used in this invention has the following specifications:
Funnel inlet has a square section 7x7m i.e. A f= 49 m 2
Rotor diameter = 4.25 m hence A r = 14. 19 m 2
A f /A r = 49/14. 19 = 3.454
Chart no. 2 gives the relation between wind speed and the wind power for a wind turbine with a funnel having the following specifications
• Funnel dimensions: square 7X7 m
• Rotor diameter = 4.25 m
Water Condensation Characteristics
Fig. No. l- psychometric chart of air - shows the relative and absolute air humidity at different air temperature
Chart no 3: This figure shows on the psychometric chart of water the condensation process that takes place during water from air extraction.
From the chart we can see that the content of humidity in air increases with increase of temperature and relative humidity. This means that areas in the world where temperature and relative humidity is high, the potential of water condensation from air is also high. For the sake of investigation of the technical feasibility of the process, we can take the following case assuming that:
- Ambient air temperature = 30°
- Relative humidity = 55%
- From the chart the starting dew point is 20° c - This means that we need to cool the air by 10° c to reach a dew point
- To have water condensate we need to extract heat from air vapor mixture = quantity of water condensate x Latent heat of water condensation at the temperature varying from 20° c. to 13o C
- Latent heat of condensation of water vapor varies with temperature as follows:
- Latent heat of water condensation : L h cond , in j per Kg of water condensate = -0.000061 *T3 +0.001 158927T2-2.36418T+2500
Table No.2 shows the latent heat of condensation with air temperature
Power Requirements for Extraction of Water fro
Assuming:
Taking into account that in order to condensate one kg of water from air every hour, we have to extract a quantity of heat =
Latent heat of condensation of water vapor + a quantity of sensitive heat = Quantity of air that gives one kg of water x Specific heat of air at condensation temperature multiplied by temperature difference, i.e
After the condensation process starts, the air must be cooled further to get more condensation. This means that we shall reach a lower dew point. The final dew point shall be proportional to the quantity of water extraction. This is illustrated in Fig No. 1.
The refrigeration power requirements can be expressed as follows:
P
Mechanical power required
Introducing high speed refrigeration compressor (magnetic bearing type with speed up to 18000 RPM), COP can reach an average of value of 8 which is used in the analysis. Keeping in mind also that direct mechanical drive will increase efficiency by 30%, the COP value of 8 seems reasonable
Chart no. 4 (produced from tables' no. 3, 4 and 5) gives the water quantity in liters per hour at different ambient air temperature and relative humidity. It is obvious from the chart that:
- Quantity of water condensate increases with increase of temperature for the same value of relative humidity.
- Quantity of water increases with increase of relative humidity at the same temperature.
- The conclusion is: The performance is best when we have high temperature and high relative humidity.
Chart no. 5 shows the relation between quantities of water extraction and wind turbine power for small capacities.
3.5 Best mode for carrying out the invention
The water from air system can be executed in different size modules according to market demands. Fig no. 5 shows the relation between size of wind turbine and water condensate production for small size units (2 L/hr to 16/L/hr ). The following steps can be followed to realize industrial application of the system:
1- Construction of a small size prototype, say 50 L/day module. This means wind turbine of nominal capacity about 1.3 KW
2- Installation of the prototype in a suitable area where wind and air humidity are convenient and make necessary performance tests
3- According to test results technical and economic feasibility should be assessed.
4- Production program can be established taking into account the techno-economic study results.
The system is suitable for implementation in the following areas:
• Along desert roads
• Isolated and remote districts
• Resorts and beaches
• Crude oil and gas extracting fields 4. Brief description of the drawings
- Fig no. 1 is a Process Flow Diagram
- Figures no, 2, 3 & 4 shows the mechanical arrangement of the system and is described as follows: