WO2011018680A1

WO2011018680A1 - Solar powered heat exchanger for water tanks

Info

Publication number: WO2011018680A1
Application number: PCT/IB2009/053573
Authority: WO
Inventors: Khalil Khalil Ebrahim Abdulla Alhammadi
Original assignee: Khalil Khalil Ebrahim Abdulla Alhammadi
Priority date: 2009-08-13
Filing date: 2009-08-13
Publication date: 2011-02-17

Abstract

An economical reliable solar powered heat-exchange system is being disclosed, running only on photovoltaic cell solar module, without any other source of power or back-up battery, capable of ventilating and normalizing the water in over-head / roof water tanks for domestic use. The invention overcomes the problems of thermal heated water in over-head / roof tanks during hot and humid weather in many countries, besides removing biological pollutants and VOC gases. Although designed originally for domestic water tanks; yet equally suitable for ventilating the outdoor telecom cabinets, electrical feeder pillars / enclosures directly from the solar, by reconfiguration facilitates in the subject heat exchanger (without any major design change).

Description

SOLAR POWERED HEAT EXCHANGER FOR WATER TANKS

(ABREEJ)

INTRODUCTION & BACKGROUND:

1. Sun is the sole creative, donation of solar energy and the ideal controller of free solar power. The Sun is by far the largest object in the solar system. It contains more than 99.8% of the total mass of the Solar System. The Sun's power (about 386 billion billion megawatts) is produced by nuclear fusion reactions. Each second about 700,000,000 tons of hydrogen is converted to about 695,000,000 tons of helium and 5,000,000 tons of energy in the form of gamma rays. As it travels out toward the surface, the energy is continuously absorbed and re-emitted at lower and lower temperatures so that by the time it reaches the surface, it is primarily visible light. Therefore, for the following invention, the source of power being considered is solar, since it is free and available in full capacity at the time wanted and during specific period of the requirement.

2. In summer season, in hot countries like those mapped in Africa, South America, Middle East ... etc, the temperature around & inside the domestic over-head water tanks (G.I, Fiber, Propylene etc.) is rising very high during hot & humid whether. This subsequently increase the temperature of stored water and the air above water level inside a tank, resulting in high internal temperature, moisture and continuous hot water, that impact the human sense organs of skin, face, eyes... etc. this hot water is unsuitable for drink, hand wash or other usage / purpose, such as direct watering / irrigation. In fact in Gulf Cooperation Council countries (GCC) in peak summer, it is noted that, the water cannot be directly utilized during mid day (1200 HRS to 1500 HRS), specially, if the overhead / roof water tanks are not insolated or shaded. Simply, the temperature of roof top water is almost equal to ambient temp or more if tank is improperly vented i.e. equal to or over 48 degrees C (118.4 degrees F) at peak summer, the same has been experienced at UAE, KSA, Kuwait and Qatar states.

3. In UAE, mainly at Abu Dhabi & RAK emirates, it is found that, in mid day of summer, the temperature goes high / increased and keeps evaporating the water surface inside a roof top water tank, this process result to hot water in the same tank even in the night time at humid area, leads to temperature continue to rise further on the coming day and water remain hot / heated.

4. People in GCC countries are adopting some of the means to overcome this effects like :

a. By replacing the cover of the tank with mosquito's mesh, that's relive a vapor, normalize the pressure & results slight reduction of internal temperature during night only (poor efficiency of the system).

b. By raising / removing the cover of the tank and providing alternative current (AC) fan instead; but that is un-safe as it may results electrical shock due to high humidity, beside entrance of dust, insects and other particles into the tank. The system remains unsafe and water not healthy.

c. Another option is constructing a roof top room for the tank with air conditioning also adopted by few people but it is very expensive and cannot be adopted by everyone.

d. Majority of peoples are using shades on the top of the tank but its efficiency is also low due to high humidity, thermal side transfer, besides spoiling the image of their private residence /premises. e. Some experiment of using refrigerant type cooling system (coil & compressor) is also adopted by few people / companies but this is also not very practical as over cooling of normal water and remains expensive in installation, operation and maintenance thereafter. f. Some people in agricultural areas / farms are utilizing the available underground waters (usually cooled) to replace the hot water from the over-head tank while irrigation by refilling the water tank from underground on daily basis, but this result in wastage of lot of water and electricity for pumping up the water.

g. Even in some countries where by-laws permit, people use to construct RCC (concrete) over-head tanks, that have a better cooling method, but it is heavy built, usually results crakes / leakage in the tank /construction which may impact whole building and dangerous in case of earthquake, therefore, it is not allowed in certain countries.

5. In addition to the above problems of heated water, ventilation of water tanks is necessary for a few reasons, including:

i. Air-tight : Storage water tanks designed and built in recent years are more airtight than in the past. The benefit of an airtight of storage water tank is to lower the cost of heating/ cooling the water and to prevent dust and bacteria's. However, pollutants retained in airtight tanks can be hazardous to users and jeopardize health integrity.

ii. Biological Pollutants: Good ventilation is suggested to avoid moisture and excess build-up from biological pollutants such as mold and mildew. Excess pollutants are not only detrimental to health, but can also lead to the deterioration of structure supports of the most type of large capacity water tanks and walls

iii. Volatile Organic Compounds (VOCs): Most of water tanks are fire resistant and can withstand great temperatures, however, VOCs are gases released from tank materials, pipes , relevant accessories and other household items as a result of aging, decomposition or curing. A good ventilation system will prevent prolonged exposure to VOCs and keep the air in your domestic tanks fresh and well circulated.

PROBLEM SOLVED BY THE INVENTION:

As described in the following paragraphs, the above problem is completely solved by a simple solar-powered heat exchanger that is reliable. It is cheap in comparison with the application being currently adopted (detailed in item #3 above) which are costing in CAPEX such as civil works, air-conditioning and OPEX (Operation & Maintenance) thereafter. Beside functions in such a manner to keep the water and its trapped air cool; thus resulting in normal temperature of the water, throughout the day and night and its continues hygienic use without investing big and keeping the operational expenses almost nil.

COMPONENT DETAILS:

As described in the drawings, this new design of simple, flexible and intelligent solar ventilation system consists of the following items/parts:-

1. Solar photovoltaic cell of 20 to 25 Watt capacity maximum & size of 550x440x25mm +/- 10%.

2. Two of 12 Volt DC Fans of 175 to 190 CFM and diameter of 150 to 175mm each.

3. Plenums frame of Aluminum of 505x400x50mm +/- 10%, or two plenums / frames of aluminum of 400x250x50mm dimension each (Ultra PVC to replace aluminum is optional). 4. Divider or vertical support sheet (500x300x2mm) of stainless steel (Aluminum alloy is optional). For other applications, the height is subject to the available space.

5. Horizontal bars (2nos.) of spring / stainless steel (300x60x3mm) +/- 5%.

6. Insect Mesh, flexible , antibacterial, dust resistant to surround the system (1900x200x1 mm)

Exact dimensions are subject to the size of over head water tank; however, all above dimensions are designed to match and fulfill the standard opening diameters (400 to 600mm) of domestic water tanks.

Detailed description / specification of each part / item are given hereunder:

1. Solar panel, solar module or photovoltaic array:

i. This 20 watt (12 to 17 Volts) green energy device is selected to convert sunlight directly into electricity by the photovoltaic effect. It is green energy related to the application of solar cells in producing electricity, hence specifically & solely selected to be applied for this invention. According to the solar cell technology, both mono-crystalline and polycrystalline options of solar arrays are available. However, mono-crystalline is preferred / recommended as it's made from very pure silicon; has a single and continuous crystal lattice structure with practically zero defects or impurities. In this application, it is considered more reliable than other types of silicon cells, highly efficient, though results in slightly higher costs than other silicon technologies. The solar panel is mounted at the top of the system, covering/ shading the plenum, framed DC fans, terminals and electro junction box. .

ii. Since the maximum energy of power (electricity) is required in mid day of peak summer, where sunlight is perpendicular, producing maximum visible light and higher temperature resulting the fans to run on full capacities; the system is designed to be fixed horizontally instead of standard 35 to 45 degrees angle recommended for alignment of solar array. This horizontal arrangement provides very easy installation, more strength and support against wind, prevent a crystalline surface of solar from sandstorm and maintain the life of solar array. The same will also replace the cover of the water tank (de-rating factors have been considered in the size & capacity of solar panel accordingly).

iii. The solar panel is also designed to be portable and could be relocated above any constructed room/ shade of the existing water tanks.

2. DC Motor Fan :

i. Two numbers of DC fans (drawing no. 1 ) of approx. 12 watt each (~12VoIt, 1 Amp) are connected in parallel to a solar module, each fan generate around 175 to 190 CFM air flow from/to the area inside a water tank, this moisture is trapped between hot water surface and the cover of the tank being replaced by the subject ventilating system.

ii. In order to create maximum air flow/circulation and relive of trapped hot & humid air, each fan is connected to rotate in opposite direction of other. In case of one fan failure, the system efficiency still remains around 50%. The DC fan selected for such application is permanently lubricated ball bearing design made of aluminum to insure proper stability, reliability & smooth operation; these 2 fans are placed inside the frame by 2 hinged sheets (wings), one in each sheet and closer to the divider sheet & hinges. Each fan is installed in reverse directions to other, fan #1 is connected to run in clockwise rotation, while fan #2 connected to rotate in anticlockwise, so if fan #1 throw the fresh air inside the water tank, fan #2 should throw the hot air/ moisture outside the tank and vise versa.

iii. The simplest way to calculate the size of required fan is: a. Calculate the cubic feet of tank (length x width x height) b. Divide by 60 (the number of minutes in an hour)

c. Multiply the result by 8 (the number of recommended air changes per hour)

d. Multiply the result by 3 (24/8 operating period per day) iv. However in addition to step # iii (d) above, other factors have been considered for this invention such as internal hot air, ambient temperature, moisture, moisture and variable speed of relevant fans; these need to increase the size of the fan to compensate for all above / additional factors by minimum 50% CFM.

3. Plenum Frame:

i. A frame of two fan box-type objects made of Aluminum alloy is to be mounted on top of the water tank by 4 legs / stays located in the frame corners. This frame equally divided into two plenums to accommodate the dc fans (one plenum per fan). These plenums are located/ fixed below a solar panel screwed with solar panel frame. The complete set designed to function as plenum for the inlet and outlet air generated by relevant DC fans. Fans installed on a moveable door type sheet (wing). 2^nd fan installed, in reverse direction of 1^st as stated above and in electrical circuit (drawing no.6).

ii. This plenum frame shall be covered by aluminum sheet of same dimensions to replace/ relocate the solar panel in case of shaded area in order to provide/maintain the direct sunlight on a solar array.

4. Divider:

Stainless steel or Aluminum alloy sheet is provided and designed to slide between the two fan boxes / plenums, to segregate the fans, plenum, wings, and the internal air in two portions, one for inlet/positive (+) and the other for outlet/ negative(-) air flow , the same sheet will be partially inserted into water in order to transfer some cooling effect gained during ventilation to the water surface, beside additional support and balancing of the subject ventilation system, this divider sheet will be suspended/ hanged vide a rectangular tube of aluminum ( 400x60x22 mm) placed in the middle of the system frame below the solar array. The rectangular aluminum tube fixed in the middle of the system is also considered the main holder of wings / hinged sheets of ventilating fans , beside the base of above divider.

5. Stain steel flexible bars/ spring :-

Two numbers of thick sprig / mechanism bars of stainless steel shall be horizontally inserted into the above vertical sheet (divider) while installation . These bars should cross the divider sheet below system frame and wings vide opening slots provided at both edges / sides, either top, middle or lower slots subject to the size of tank access /opening. Both bars should be in line, stand horizontal by adjusting the center/mid of each bar in relevant side slot. Mechanism strength of both bars shall be functioned simultaneously and upon moving of fan sheets/wings to a certain angle inside the water tank, and then returned back automatically by reaction / back force of these bars to block the access/ opening of a tank (drawing no.4).

6. System pedestals / legs:

Once the fans system fitted inside the opening space of water tank and a solar panel mounted on top, blocking the access, the ventilation system should be raised 150mm up immediately, by using the existing pedestal (4 legs) located in each corner to be moved to vertical positions as per drawing no. 4 & 5. Height of the system shall be adjusted by these legs. Accordingly, the both wings of DC fans will be in required position /shape and angle of 45 degree to facilitate adequate air flow from / to the tank.

7. Insect Mesh / Screen:

Fiberglass or Polyester insect/mosquito net to be vertically rolled around the system as per drawing no. 5 to the international standard, specifications in term of heat, humidity, corrosion resistive and ventilation characteristics. This netting is washable, keeping shape and strong in tensile force.

ADVANTAGES AND PROSPECTIVES OF ABREEJ:

^■ The only free of charge electricity will be utilized to operate this invention by using a solar powered module of photovoltaic cell.

^■ The solar energy will be utilized when it is available and it will be available when it is needed during sunlight time. It is not required in night time nor in winter or spring seasons to normalize the water, hence neither grid nor back-up battery power is required.

Intermittent ventilation is used in the day time i.e. when sun is rising and during night natural ventilation is provided through the mesh from all directions. Both type of ventilations help killing the pollutants, bacteria and dust particles besides throwing out the trapped hot air above the water in the tank.

All operational parts of this invention (Solar cells & DC fans) are provided with natural rest / switch off of approximate 12 to 16 hours daily.

No operation cost/ fees involved, abundant solar energy is the source of power designed to run this system.

No routine maintenance involved.

Easy assembly, installation, testing and commissioning procedures, which can be carried out vide instruction manuals.

Less weight (< 5 Kg):- can be hand-carried.

Portable— can be packed and transported anywhere with ease.

Flexible— solar panel can be shifted away from system, if water tank is shaded. Similarly, the wings can be tilted at a wide range of angles to fit in any size of tank or other openings. Further, wings/ fan supported sheets are designed to support different size of fans depending upon the air flow requirement.

Reliable — - components selected are of such standard that except cleaning, preventive & corrective maintenance are foreseen; at least 5-7 years.

Environment friendly — green energy, fresh air, normal temperature, natural water, almost silent, green, no smoke and no pollution.

Long Life -— Expected much more life time before break as the system activates mainly 8 hrs /day and less hours/ speed in winter.

Green Energy— the alternate energy source i.e. Green Energy (solar power) is being utilized. The impact is small for one unit but may rise to millions of watts when considered for one or multiple countries. Huge energy savings is expected, on application of the product. TEST TRIAL OF THE SYSTEM:

The physical testing of the subject product sample has been carried out successfully in Abu Dhabi (UAE) in end June, July and Aug. 2009. The system has been installed at Khalifa city "A" Villa No. 105 Opposite Khalifa Super Market Abu Dhabi, since 29^th June 2009 and result found very successful during peak summer of July, 2009.

The water in the subject over-head tanks was extremely hot during last summer (2008) that is harmful for human sense organs such as eyes, teeth, gums, skin... etc. and can not be used without further indoor storage. After deployment of a trial sample system, results found very positive. The temperature of the water remained within normal acceptable limit and can be used easily. A few pictures of the product after installation have been taken and pasted below for quick review. ISA / any other authority are fully welcomed to visit the premises and check themselves the sample installed system. Comprehensive report is also provided in a CD, which includes videos of running system at different times during days of July & Aug. 2009.

What is ABREEJ:

ABREEJ is an Arabic word, a common name of a kettle, the device found in all homes. In the past of GCC countries, the kettle used to be one of a traditional portable devices at home and during traveling, there were bronze / iron metal vessels used for water, it is almost similar to a modern kettle in shape, with a decorated spout, however, all kettles were probably used for daily practices of watering such as washing, cleaning, filtering, drinking rather than for boiling water by directly heated over a fire or wood stove.

On the other hand, the word ABREEJ would be abbreviation of Abu Dhabi Green Energy, beside it consist five letters ( A, El Fi E & J), which have been found in the name of all Emirates of UAE, for minimum 2 letters in the word UAE and each Emirate as follows: ABU DHABI, DUBAI, SHARJAH, RAK ( Ras Al Khaimah), AJMAN, UMM AL QWEEN and FUJAIRAH

Hence it's proud, glad and glory to go for ABREEJ as a brand name of this invention.

Claims

1. The invention is capable of normalizing water temperature in overhead tanks, making it suitable for all type of usages.

2. The invention is capable of ventilating over-head tanks making it free from biological pollutants and VOC gases.

3. The invention can also be used to ventilate and normalize the internal temperature in many outdoor applications like telecom cabinets, electrical feeder pillars / enclosures, by reducing a height of the divider of the subject heat exchanger only (minor reconfiguration).

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