Another bump for Travelsick on the water tank question.
Erich
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Another bump for Travelsick on the water tank question.
Erich
Nice but doesn't the exhaust heat the water to a nice warm temperature ?
(Good for coffee I guess).
Keep the shovel - it has "character" like all good Defender bits should !
The water temperature is no higher than ambient. The air gap with the air moving through the gap makes for an excellent insulator.Quote:
Originally Posted by VladTepes
We usually keep 2 litres of water in our fridge, which we top up in the morning.
Erich
I've just installed a water tank in exactly the same location and am/was worried about the effect the exhaust might have on the temperature of the water. Just out of curiosity, what had you planned to use as an insulator if the water was being heated up??Quote:
Originally Posted by Bundalene
Heat transfer obeys laws of physics. There are 3 modes of heat transfer:
1. Conduction - will not happen because the dry air between the exhaust and tank is a very good insulator. Adding another insulator will not achieve much unless it is much better than air - unlikely, but don't let me stop you. Insulation combats conduction.
2. Convection - heat is transferred to the air in contact with the exhaust, which becomes less dense and rises to where it contacts the surface of the tank. If the heated air is dispersed by vehicle motion or wind this wont be a problem until you stop, but then the exhaust starts to cool - this is where an insulator against the tank may help as a barrier.
3. Radiation - the dominant mode of heat transfer in this application. Polished stainless steel or aluminium is a very good reflector (note that dullbird's black plastic tank does, but Bundalene's stainless tank doesn't suffer from water being heated.
A reflecting shield close to the tank can reflect a lot of the radiation and the air between the shield and tank surface will serve as insulation - just my 2 cents from someone who has has done the calculations to apply this to industrial applications from time to time and observed the results.
The tank material then has to transfer heat to the water. Stainless steel conducts less heat than plain carbon steel, which conducts less than aluminium.
Heat transfer and insulation problems differ between short and long periods of time. Over a long period (we may often be driving for long periods) the temperature will rise across the thickness of insulation and heat transfer will increase. In this situation it is much better expend your effort/$$ to reflecting the radiant heat away and to disperse (ventilation and air flow) air that is heated by the exhaust, than to add insulation.