and so for todays lesson we are covering:
Thermal conductivity
Thermal conductivity (k, also denoted as λ or κ) is a measure of a material's ability to conduct heat. Heat transfer across materials of high thermal conductivity occurs at a higher rate than across materials of low thermal conductivity. In the International System of Units (SI), thermal conductivity is measured in watts per meter Kelvin (W/(m•K)). In the Imperial System of Measurement (British Imperial, or Imperial units), thermal conductivity is measured in Btu/(hr•ft⋅F).[12]
Copper has a thermal conductivity of 231 Btu/(hr-ft-F). This is higher than all other metals except silver, a precious metal. Copper has a 60% better thermal conductivity rating than aluminium and a 3,000% better rating than stainless steel.[13]
Thermal conductivity of some common metals [14]
Metal Thermal conductivity (Btu/(hr-ft-F)
Silver 247.87
Copper 231
Gold 183
Aluminium 136
Yellow brass 69.33
Cast iron 46.33
Stainless steel 8.1
source:
Copper in heat exchangers - Wikipedia, the free encyclopedia
now, lets understand a little bit out heat tranfer shall we.
the metals ability to carry heat means its able to dissipate it at a faster rate. if you heat a small section of copper, the copper will then transfer that heat evenly across its surface area. more surface area allows for greater heat loss, greater heat loss means its able to absorb and dissipate more heat. in the case of our radiator, thats EXACTLY what you want to happen. cool air blows over the evenly heated copper and allows it to cool faster, thus the coolant carrying all that heat energy allows the heat to be transfered and dissipated at a faster rate.
all good quality CPU and GPU coolers for PC's are made of copper. alloy being their cheap cousin. the more solid the copper (generally speaking) the better the cooling
all good quality heater cores were copper, but due to rising copper costs, most manufacturers have gone to the cheaper cousin, alloy
all good frying pans have a copper base
and so on, and so on, and so on.
the ONLY reason you would buy an ally rad over a copper one is cos' you want it to look good. problem with it is the ally wont be polished forever and eventually itll tarnish, so itll look **** and work ****.
whats that you say? "but ari, copper radiators are painted, if the ally tarnishes, i can just paint it"
well no, thats a failure too, because ally rads are that bad, that if you paint them, they effectively become useless as youve now taken away their surface area, which was the ONE thing that let them work.
having said ALL that, "copper" radiators are not actually copper, they are a mix of copper, brass and some mild steel. a good brand copper rad will contain LOADS of copper, but the cheapies will contain less, OEM spec rads have HEAPS of copper in them, thats why they are so expensive.
they are expensive, becuase they are worth it.
hope youve enjoyed your lesson for the day
