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Document Type and Number:
WIPO Patent Application WO/2001/079519
Kind Code:
Evaporative cooling from Luffa Egyptiaca. There is huge demand for filters for desert coolers and pads for evaporative cooling for various industrial and agricultural purposes. Extensive studying and testing have shown that Luffa have excellent potential for use as evaporative medium. And since they are a very cheap raw material, it promises to be very competitive compared to other alternatives (aspen, or impregnated paper). Properties: Luffas are very durable material when dealing with water and can withstand water for a very long time. Also when immersed in water and taken out they retain a considerable amount of water for sometime which means they can be of use for evaporative cooling. Moreover when wetted or moistened they become soft and can be pressed, moulded and shaped in many forms. However, Luffas have a drawback compared to other materials used as media. Because they do not absorb water, the water does not spread within them easily. Filter: The Luffas are pressed mechanichally or are power-pressed in moulds in layes ot the required size. They are of course wrapped in nylon mesh as other media. Pads: The pads are formed of an external and internal filter. Sandwitched inbetween are loose cuttins of Luffa to allow the right aire velocity to pass through. The sizes produced are 80.100.150 m m thick pads, which give saturation efficiencies of well over 80 %. Moreover they provide humidities of almost up to 100 % which is needed in a number of usages.

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Application Number:
Publication Date:
October 25, 2001
Filing Date:
April 15, 2000
Export Citation:
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International Classes:
C09K5/00; F24F5/00; F24F6/04; F28D5/00; (IPC1-7): C12P/
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1. where the supply of water proved to be adequate. In the case of luffa, though, the water behaves as shown in the diagram. (Fig 1). Water pumped into the channel flows through the outlets and by gravity through down to the bottom. The spaces between the drops remain dry. They admit hot or warm air into the room negating any coolhng. Also part of the cross section remains dry.
2. 3 production : 3. A. Filters : An. er several trials and testing we reached the conclusion that 4 layers ofluffa offers the best saturation efficiency and good. air velocity. However the luffas on their own with the restricted amount of water as in desert coolers do not satify the requirements of an acceptable saturation efficiency. Therefore an addition of some other material with absorptive characteristics and at the same time matching the durability of a must be sought after. Several experiments were conducted. The best reults so far were achieved by the use of leaves of hythacnathe brake trees. Those leaves are tough enough and will match the durability of the luffa.
3. They are washed in soap and water to remove the impervious layer preventing the leaf from absorbing water and there cut m pieces 2.
4. cm long and placed between the layers. Added are shreds of the same leaves placed horizontally for the full width of the filter to improve water distribution within the filter. The results are given in University of Khartoum Measurement Doc No. 1.
5. 3 B. Pads : 3. B. a Theory : For the required saturation eficiency the air to be cooled must pass through as long a distance as possible within the cooling space l. e pad. But this cooled space must not obstruct theairHowinsideseriouslyiethepadmustbethickenough but allow in the right air velocity. Because of the nature of the luffas pads must be formed of two external and internal filters with loose cuttings of luffa (the strips housing the seeds aner thoroughly removing the seeds and washing them) to give the right velocity of air. (see Fig 2).
6. 3 Bb. Production We have produced pads BO 100, and 150mm thick to provide saturation efficiencies of well above 80%. And up to 95% humidity to satisfy the different specifications. (See university of Khartoum measurement Doc. N. 2.
7. Economics : 4. A. Luffa grows on its own (not planted) in various parts of the countryi. e a wild plant. It costs little to pick up, shell and clean. It is very light to transport, but its bulkiness must increase the cost of transport. However our suppliers menage to tie (the luffa bundles) it on top of other cargo and thereby reducing the cost of transport considerably. Therefor luffa is a very economic material for use in industry.
8. 4 B. Luffa is a very durable material which can last 34 years of continuous use. It only requires maintenance in the form of washing which is very cheap to administer. For factors A&B above, pads and filters manufactured of luffa are considerably cheaper than imported alternatives. In the case case filters, in particular, they cost at least three times importedfilterswhich need to be replaced every year.
9. 4 C. Moreover, the industry had other side benefits. Our purchases of luffa have up to now been confined to one area. in south eastern Sudan. There we have been informed, that collection of the luffas have been carded out by school children and old women. They sell it to our suppliers at a small price. When one sells tens of luffas they may earn a useful amount of pocket money.<BR> <P>5. claim for Protection : We need the protection against the production of cooling media from luffp Egyptiaca. Nobody shall manufacture filters or pads in any way similar to the method described in our report above i. e. The pressing of Luffas (Mechanically or powerd. rivcn) m layers.
LUFFA EGYPTIACA (LEEF)AS MEDIUM FOR EVAPORATIVE COOLING 1.Background : Luffa is fruit of a creeper vegerable belonging to the cucurbilacea family. In its green form the fruit is cooked and eaten in some parts of world-e. g China. If the fruit is left in its"tree"it dries up in about 4-5 months. After being picked up, the shell is broken away and the luffa inside is split, the seeds removed and the luffa is then used extensively with soap for extra cleansing. The seeds contain edible oil and used to be extracted and eaten in places like Japan.

2. Properties: 2. A. When immersed in water and taken out it retains a considerable amount of water by:- a)Surface tension on top of the fibers. b)Surface tension between fibers lying close together Hence when hot or warn air passes through it, the air cools evaporatively.

2 B Luffa is of course very durable compared to most other materials (Aspen, sonwood etc..) used as cooling media.

Water-hard or soft-does not seem to affect it. We have immersed some luffa in a water container for several months without undergoing any deterioration only a slight darkening <BR> <BR> m colour.<BR> <BR> <BR> <BR> <BR> <BR> <BR> <P> 2. C. As we all know that luffa becomes quite soft when wetted or moistened with water, and will remain soft for a few hours. This should facilitate pressing and shaping.

2. D.However, luffa as a colling medium does not avail it self to water distribution either longitudinally horizontally or transferring to any adjacent fibers.

2. D. a. This characteristic is not a serious drawback m die case of coolling pads where the amount of water shed for cooling is not too restricted. The luffa Perform its cooling satisfactorily.

2. D. b But the case is different'in filters for desert coolers.

HersmaU water pumps raising a limited amount of water air used They are designed to be used with absorptive media