Since the Republic of Indonesia ratified the Vienna Convention and the montreal protocol, with the RI Presidential Decree No. 23 of 1992, then Indonesia will follow the program decreased the use of CFCs (Freon 11, 12, 113, 114 and 115) and halon (fire extinguishing material) in accordance with the schedule particular. Originally the use of CFCs will expire in 2000, but with "proposed EEC regulation 1992", end the use of CFCs filed until 1 January 1996, with details of January 1, 1994 85% reduction in the use of CFCs. As it is known that the CHC and halon is a substance that can erode the ozone and the greenhouse effect, for the earth (ozone depletion potential). Freon 12 is much used for motor vehicle air conditioner and refrigerator, while Freon 22 is used in AC buildings and hotels. As a substitute for freon - 12 used HFC - 134a which has similar properties, particularly for motor vehicle air conditioning refrigerant, is a substitute Freon - 22 used klea blend 60. Freon Substitute 12 with HFC - 134a not without problems. The main problem is the problem of packing / compressor seals, flexible pipes and lubricating oils, in addition to other problems. In research on replacing freon 12 with HFC - 134a, apparently there is little difference to work on machines for refrigeration. The cooling effect of HFC - 134a were higher about 23% and power per kg / hr of refrigerant more than 30%, while the coefficient for the work (with the basic lattice bonds), smaller 8%, when compared with the use of refrigerant Freon 12. At high temperatures, pressures on HFC - 134a is slightly higher than Freon - 12
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Oct 8, 2010
About Refrigeration and AC
Air conditioning is the cooling of indoor air for thermal comfort. In a broader sense, the term can refer to any form of cooling, heating, ventilation, or disinfection that modifies the condition of air.[1] An air conditioner (often referred to as AC or air con.) is an appliance, system, or machine designed to stabilise the air temperature and humidity within an area (used for cooling as well as heating depending on the air properties at a given time), typically using a refrigeration cycle but sometimes using evaporation, commonly for comfort cooling in buildings and motor vehicles.For details component anime education please download here
The concept of air conditioning is known to have been applied in Ancient Rome, where aqueduct water was circulated through the walls of certain houses to cool them. Similar techniques in medieval Persia involved the use of cisterns and wind towers to cool buildings during the hot season. Modern air conditioning emerged from advances in chemistry during the 19th century, and the first large-scale electrical air conditioning was invented and used in 1902 by Willis Haviland Carrier.
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The concept of air conditioning is known to have been applied in Ancient Rome, where aqueduct water was circulated through the walls of certain houses to cool them. Similar techniques in medieval Persia involved the use of cisterns and wind towers to cool buildings during the hot season. Modern air conditioning emerged from advances in chemistry during the 19th century, and the first large-scale electrical air conditioning was invented and used in 1902 by Willis Haviland Carrier.
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Oct 2, 2010
News: Differential Low-Pressure Sensors
The LBA Series offers differential low-pressure measurement with ranges of 250 and 500 Pa (1 and 2 inches of water) full scale. The sensors perform fully analog on-chip CMOS signal conditioning to allow for linear and temperature-compensated outputs. The devices are based on thermal flow measurement of gas through a micro-flow channel integrated within the sensor chip.
The very narrow channel decreases the flow through the LBA sensor by several magnitudes compared to other flow-based pressure sensors, claims the manufacturer. The extremely low gas flow ensures high immunity to dust contamination and condensation and allows the use of connecting tubes and input filters without the need to recalibrate or correct the output signal. Because the flow impedance is predefined at the sensor chip level, the sensors provide very small and cost-effective PCB-mountable housings.
www.sensortechnics.com
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The very narrow channel decreases the flow through the LBA sensor by several magnitudes compared to other flow-based pressure sensors, claims the manufacturer. The extremely low gas flow ensures high immunity to dust contamination and condensation and allows the use of connecting tubes and input filters without the need to recalibrate or correct the output signal. Because the flow impedance is predefined at the sensor chip level, the sensors provide very small and cost-effective PCB-mountable housings.
www.sensortechnics.com
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Sep 30, 2010
Hear That? The Fridge Is Chilling
It's hard to decide what's weirder: that Penn State researchers are building a sonic refrigerator using acoustics to keep food cold, or that the U.S. Navy has teamed up with Ben & Jerry's to fund the project.
Both the leftie ice-cream maker and the American military have a vested interest in keeping things cool. Ben & Jerry's wants to keep their Chunky Monkey and Phish Food from melting; the Navy needs to keep seamen's meals fresh and electronics rooms temperate.
But neither group wants to do it while wrecking the atmosphere. The most common chemical refrigerants, chlorofluorocarbons (commonly known as CFCs), are ozone rippers, banned by a 1996 international convention. But their replacements, hydrofluorocarbons and hydrochlorofluorocarbons, or HFCs and HCFCs, are also global-warming villains.
So the two organizations turned to a team lead by Steven Garrett, a Penn State professor of acoustics -- and former drummer -- who has been working for years to build a refrigerator that relies on sound waves, rather than toxins, to take the temperature down.
How is that possible? To oversimplify, blasts of sound from a speaker create pressure. And when this pressure is applied to a gas in an enclosed space -- as it is in Garrett's design -- the gas heats up. The heat is then transferred through a series of woven stainless steel screens, taken into a heat exchanger, and carried out of the system.
"It's a little like a (firefighters') bucket brigade, carrying heat from one to the next to the next," said Matt Poese, a Penn State research associate working with Garrett.
It's also a little like a Black Sabbath concert and the New York City subway at rush hour, all rolled into one. The Penn State fridge cranks up to 173 decibels -- hundreds of thousands of times louder than what actually hurts people's ears.
But from the outside, it's no noisier than your typical icebox. The noise generated by the Penn State fridge can only be reached when the gas is under tremendous amounts of pressure -- 10 atmospheres worth. If the gas escapes, the pressure dissipates and the sound dies down.
Thermoacoustics' roots are almost two centuries old. In 1816, the Reverend Robert Sterling patented an engine that used pressure to heat a gas, which would then drive pistons.
Nearly 170 years later, in the 1980s, Los Alamos National Laboratory physicist Greg Swift began looking into a "Stirling engine" that relied on sound to create the needed pressure.
Around the same time, Garrett decided to apply the same principles to refrigeration. Over almost 20 years, he's slowly increased the efficiency and decreased the size of the cooler. One of his earlier models even flew on the space shuttle in 1992. The Office of Naval Research funded much of this work.
Then, about two years ago, Ben & Jerry's got together with Garrett's team to build a thermoacoustic freezer case, like the kind you see in your local deli. Unilever, corporate parent to Ben & Jerry's, has committed $375,000 to the project. There's a working pre-prototype at Penn State, but a fully functioning model is still several years away.
http://www.wired.com/science/discoveries/news/2003/01/57063#ixzz10sJYkaIg Add to Cart View detail
Both the leftie ice-cream maker and the American military have a vested interest in keeping things cool. Ben & Jerry's wants to keep their Chunky Monkey and Phish Food from melting; the Navy needs to keep seamen's meals fresh and electronics rooms temperate.
But neither group wants to do it while wrecking the atmosphere. The most common chemical refrigerants, chlorofluorocarbons (commonly known as CFCs), are ozone rippers, banned by a 1996 international convention. But their replacements, hydrofluorocarbons and hydrochlorofluorocarbons, or HFCs and HCFCs, are also global-warming villains.
So the two organizations turned to a team lead by Steven Garrett, a Penn State professor of acoustics -- and former drummer -- who has been working for years to build a refrigerator that relies on sound waves, rather than toxins, to take the temperature down.
How is that possible? To oversimplify, blasts of sound from a speaker create pressure. And when this pressure is applied to a gas in an enclosed space -- as it is in Garrett's design -- the gas heats up. The heat is then transferred through a series of woven stainless steel screens, taken into a heat exchanger, and carried out of the system.
"It's a little like a (firefighters') bucket brigade, carrying heat from one to the next to the next," said Matt Poese, a Penn State research associate working with Garrett.
It's also a little like a Black Sabbath concert and the New York City subway at rush hour, all rolled into one. The Penn State fridge cranks up to 173 decibels -- hundreds of thousands of times louder than what actually hurts people's ears.
But from the outside, it's no noisier than your typical icebox. The noise generated by the Penn State fridge can only be reached when the gas is under tremendous amounts of pressure -- 10 atmospheres worth. If the gas escapes, the pressure dissipates and the sound dies down.
Thermoacoustics' roots are almost two centuries old. In 1816, the Reverend Robert Sterling patented an engine that used pressure to heat a gas, which would then drive pistons.
Nearly 170 years later, in the 1980s, Los Alamos National Laboratory physicist Greg Swift began looking into a "Stirling engine" that relied on sound to create the needed pressure.
Around the same time, Garrett decided to apply the same principles to refrigeration. Over almost 20 years, he's slowly increased the efficiency and decreased the size of the cooler. One of his earlier models even flew on the space shuttle in 1992. The Office of Naval Research funded much of this work.
Then, about two years ago, Ben & Jerry's got together with Garrett's team to build a thermoacoustic freezer case, like the kind you see in your local deli. Unilever, corporate parent to Ben & Jerry's, has committed $375,000 to the project. There's a working pre-prototype at Penn State, but a fully functioning model is still several years away.
http://www.wired.com/science/discoveries/news/2003/01/57063#ixzz10sJYkaIg Add to Cart View detail
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