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Pot-in-pot Refrigerator
A pot-in-pot refrigerator, clay pot cooler or zeer ( ar, زير) is an evaporative cooling refrigeration device which does not use electricity. It uses a porous outer clay pot (lined with wet sand) containing an inner pot (which can be glazed to prevent penetration by the liquid) within which the food is placed. The evaporation of the outer liquid draws heat from the inner pot. The device can cool any substance, and requires only a flow of relatively dry air and a source of water. History Many clay pots from around 3000BC were discovered in the Indus Valley civilization and are considered to have been used for cooling as well as storing water. The pots are similar to the present-day ''ghara'' and ''matki'' used in India and Pakistan. There is evidence that evaporative cooling may have been used in North Africa as early as the Old Kingdom of Egypt, circa 2500BC. Frescoes show slaves fanning water jars, which would increase air flow around porous jars to aid evaporation and co ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Humidity
Humidity is the concentration of water vapor present in the air. Water vapor, the gaseous state of water, is generally invisible to the human eye. Humidity indicates the likelihood for precipitation, dew, or fog to be present. Humidity depends on the temperature and pressure of the system of interest. The same amount of water vapor results in higher relative humidity in cool air than warm air. A related parameter is the dew point. The amount of water vapor needed to achieve saturation increases as the temperature increases. As the temperature of a parcel of air decreases it will eventually reach the saturation point without adding or losing water mass. The amount of water vapor contained within a parcel of air can vary significantly. For example, a parcel of air near saturation may contain 28 g of water per cubic metre of air at , but only 8 g of water per cubic metre of air at . Three primary measurements of humidity are widely employed: absolute, relative, and specific. Ab ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Food Preservation
Food preservation includes processes that make food more resistant to microorganism growth and slow the oxidation of fats. This slows down the decomposition and rancidification process. Food preservation may also include processes that inhibit visual deterioration, such as the enzymatic browning reaction in apples after they are cut during food preparation. By preserving food, food waste can be reduced, which is an important way to decrease production costs and increase the efficiency of food systems, improve food security and nutrition and contribute towards environmental sustainability. For instance, it can reduce the environmental impact of food production. Many processes designed to preserve food involve more than one food preservation method. Preserving fruit by turning it into jam, for example, involves boiling (to reduce the fruit's moisture content and to kill bacteria, etc.), sugaring (to prevent their re-growth) and sealing within an airtight jar (to prevent reconta ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Appropriate Technology
Appropriate technology is a movement (and its manifestations) encompassing technological choice and application that is small-scale, affordable by locals, decentralized, labor-intensive, energy-efficient, environmentally sustainable, and locally autonomous. It was originally articulated as intermediate technology by the economist Ernst Friedrich "Fritz" Schumacher in his work ''Small Is Beautiful.'' Both Schumacher and many modern-day proponents of appropriate technology also emphasize the technology as people-centered. Appropriate technology has been used to address issues in a wide range of fields. Well-known examples of appropriate technology applications include: bike- and hand-powered water pumps (and other self-powered equipment), the universal nut sheller, self-contained solar lamps and streetlights, and passive solar building designs. Today appropriate technology is often developed using open source principles, which have led to ''open-source appropriate technology'' ( ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Evaporative Cooler
An evaporative cooler (also known as evaporative air conditioner, swamp cooler, swamp box, desert cooler and wet air cooler) is a device that cools air through the evaporation of water. Evaporative cooling differs from other air conditioning systems, which use vapor-compression or absorption refrigeration cycles. Evaporative cooling exploits the fact that water will absorb a relatively large amount of heat in order to evaporate (that is, it has a large enthalpy of vaporization). The temperature of dry air can be dropped significantly through the phase transition of liquid water to water vapor (evaporation). This can cool air using much less energy than refrigeration. In extremely dry climates, evaporative cooling of air has the added benefit of conditioning the air with more moisture for the comfort of building occupants. The cooling potential for evaporative cooling is dependent on the wet-bulb depression, the difference between dry-bulb temperature and wet-bulb temperature ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Solar-powered Refrigerator
A solar-powered refrigerator is a refrigerator which runs on energy directly provided by sun, and may include photovoltaic or solar thermal energy. Solar-powered refrigerators are able to keep perishable goods such as meat and dairy cool in hot climates and are used to keep much-needed vaccines at their appropriate temperature to avoid spoilage. Solar-powered refrigerators are typically used in off-the-grid locations where utility-provided AC power is not available. History In 1878, at the Universal Exhibition in Paris, Augustin Mouchot displayed Mouchot's engine and won a gold medal in Class 54 for his works, most notably the production of ice using concentrated solar heat. "In developed countries, plug-safely, but in developing countries, where electricity supplies can be unreliable, alternative refrigeration technologies are required". Solar fridges were introduced in the developing world to cut down on the use of kerosene or gas-powered absorption refrigerated coolers wh ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Botijo
A botijo, also called ''búcaro'', is a traditional porous clay container designed to contain water. The botijo is a typical element of Spanish culture and may vary in shape, color and material. The botijo has the property that once filled, it cools the water that it contains, acting as an evaporative cooler. The botijo has a wide belly and one or more mouths where it is filled and one or more outputs called ''pitón'' or ''pitorro'' to drink from. The ''búcaro de Indias'' is a special type, made of fragrant clay from Mexico, that was prized in Europe.https://www.metmuseum.org/art/collection/search/662163 Operation The operating principle of the botijo is as follows: the stored water is filtered through the pores of the clay and in contact with the outside dry environment (characteristic of Mediterranean climate), it evaporates, producing a cooling (2.219 kilojoules per gram of evaporated water). The key for cooling it, is by the evaporation of bleed water, as the water ev ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nigerian Naira
The naira (currency sign, sign: ₦; ISO 4217, code: NGN) is the currency of Nigeria. One naira is divided into 100 ''kobo''. The Central Bank of Nigeria (CBN) is the sole issuer of legal tender money throughout the Federal Republic of Nigeria. It controls the volume of money supplied in the economy in order to ensure monetary and price stability. The Currency Operations Department of the CBN is in charge of currency management, through the designs, procurement, distribution and supply, processing, reissue and disposal or disintegration of bank notes and coins. History The naira was introduced on 1 January 1973, replacing the Nigerian pound at a rate of £1 = ₦2 naira. The coins of the new currency were the first coins issued by an independent Nigeria, as all circulating coins of the Nigerian pound were all struck by the Colonial Nigeria, colonial government of the Federation of Nigeria in 1959, with the name of Elizabeth II, Queen Elizabeth II on the obverse. This also made ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Wet-bulb Temperature
The wet-bulb temperature (WBT) is the temperature read by a thermometer covered in water-soaked (water at ambient temperature) cloth (a wet-bulb thermometer) over which air is passed. At 100% relative humidity, the wet-bulb temperature is equal to the air temperature (dry-bulb temperature); at lower humidity the wet-bulb temperature is lower than dry-bulb temperature because of evaporative cooling. The wet-bulb temperature is defined as the temperature of a parcel of air cooled to saturation (100% relative humidity) by the evaporation of water into it, with the latent heat supplied by the parcel. A wet-bulb thermometer indicates a temperature close to the true (thermodynamic) wet-bulb temperature. The wet-bulb temperature is the lowest temperature that can be reached under current ambient conditions by the evaporation of water only. Even heat-adapted people cannot carry out normal outdoor activities past a wet-bulb temperature of , equivalent to a heat index of . The theoretic ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Seawater
Seawater, or salt water, is water from a sea or ocean. On average, seawater in the world's oceans has a salinity of about 3.5% (35 g/L, 35 ppt, 600 mM). This means that every kilogram (roughly one liter by volume) of seawater has approximately of dissolved salts (predominantly sodium () and chloride () ions). The average density at the surface is 1.025 kg/L. Seawater is denser than both fresh water and pure water (density 1.0 kg/L at ) because the dissolved salts increase the mass by a larger proportion than the volume. The freezing point of seawater decreases as salt concentration increases. At typical salinity, it freezes at about . The coldest seawater still in the liquid state ever recorded was found in 2010, in a stream under an Antarctic glacier: the measured temperature was . Seawater pH is typically limited to a range between 7.5 and 8.4. However, there is no universally accepted reference pH-scale for seawater and the difference between measurement ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Permeation
In physics and engineering, permeation (also called imbuing) is the penetration of a permeate (a fluid such as a liquid, gas, or vapor) through a solid. It is directly related to the concentration gradient of the permeate, a material's intrinsic permeability, and the materials' mass diffusivity. Permeation is modeled by equations such as Fick's laws of diffusion, and can be measured using tools such as a minipermeameter. Description The process of permeation involves the diffusion of molecules, called the permeant, through a membrane or interface. Permeation works through diffusion; the permeant will move from high concentration to low concentration across the interface. A material can be semipermeable, with the presence of a semipermeable membrane. Only molecules or ions with certain properties will be able to diffuse across such a membrane. This is a very important mechanism in biology where fluids inside a blood vessel need to be regulated and controlled. Permeation can occ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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