Step two years ago a bunch of aluminum air conditioning industry generation copper, recently, gas water heater industry sparked controversy on aluminum in place of copper. Recent media reports claimed that the market is part of the water heater quietly "heart", for many years use copper gas water heater tanks, parts manufacturers to reduce the cost to be quietly changed into aluminum. The article claimed that the aluminum properties far inferior to copper, used for water heater core components prone to security risk. This statement raises many concerns of consumers. In response to the market parties ' concerns, the press-ask the experts.
"What we call the aluminum in place of copper, not what people think of pure aluminum, but joined the titanium alloy. "Chongqing University City construction and environmental engineering Professor Ng Fuk told reporters, because adding material, alloy melting point will change to the current use of the water heater and the melting point of aluminium and titanium, 650 ° c to 700 in Celsius, although no copper high melting point, however, also fully meets the requirements of national standards.
There is a saying that the water heater products now, in the heat exchanger at the entrance to high temperature flue gas temperature has reached 1000 degrees Celsius, and copper melting temperature, much higher than the melting point of pure aluminium, aluminium-generation copper is not secure, the national gas appliances product quality supervision and inspection center, Minister Zhang mingwei indicates that inspection, the heat exchanger at the entrance to high temperature flue gas temperatures up to 1000 ° c is only a limit. He said that the national standard for material resistance 500 degree requirements is actually much higher than the actual run-time temperature. Because of the gas water heater is working with water, and therefore their operating temperature of 110 ° c to mostly in 260 degrees Celsius. High temperature flue gas temperature of 1000 degrees Celsius did have reached, however, this was mainly due to product design not reasonable cause stem burn, if this happens, do not say is aluminum, copper, also be shaohua.
Reportedly, at home, gas water heater heat exchanger has been using dip lead-copper materials, gas water heater, easy discharge large amounts of waste containing heavy metals from smoke, according to the EU RoHS directive, European non-leaching, lead and copper heat exchanger. But in China, almost the entire unburnt products and most of the strong type products also are used in the materials, only in the high-end products on the use of oxygen-free copper brazing technology. Due to the water tank and external layers are high concentrations of lead packages, and the melting point of lead only to 327 ° c, if aluminum tanks will being burn, then dip lead and copper products more can't stand the test of high temperature.
As for aluminum in place of the copper heat after materials and heat transfer properties, Zhang mingwei explained that if simply from two materials, aluminium heat conduction performance indeed than copper. However, this problem is by product design and process improvement to solve. He said that the leaching of lead, copper products, finned tube fin and tube, combustion chamber wall and the coil connection is also the lead through leaching. In between there solder and gaps. While the lead and air of conductivity lower than aluminum, therefore, greatly affects its heat transfer rate. Currently aluminum heat exchanger brazing technology due to improved use, finned tubes and pipes in fin has not gap between, allowing the heat transfer area greatly increase the thermal efficiency is increased.
It is understood that the production of aluminum in place of copper as a part of the company's ongoing technological innovation. Back in 1996, some enterprises of China put forward the idea of aluminum in place of copper, and carry out scientific and technological research, in 2007, the first prototype of aluminum in place of copper. Last November, the national gas appliances product quality supervision and inspection center on two paragraphs to aluminium titanium alloy heat exchanger gas water heater products for testing, inspection conclusions: all projects meet the national standards. Also, Chongqing University, from the beginning the month of August 2008, also on behalf of copper products for 96 days (2304 hours) of durable life simulation test, concluded that "the use of aluminum heat exchanger water heater structure is reasonable, in simulated user 8 years of using the cycle, the heat exchange efficiency is a good, safe and reliable running. "China household electrical appliances Association Vice Director Liu fortunate they said that in recent years, taking into account the impact of the global environment, countries on energy saving and environmental protection products increasingly high demands of standards, new technologies, new materials development and application of the implementation of household electrical appliances from the traditional to the Green primary means of upgrading. So the home appliance industry exploration of alternative materials will continue to be, of course, this exploration will be to protect the safety of the product.
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