So how do you prevent fuel of an unknown (colder then indicated fuel temp) temperature (and possible gelforming already taking place) from clogging pump inlets/filter screens and oil/fuel intercoolers aka the British Airways that flamed out on the ILS?
Has the 744 suffered from the same problem? I know the heat exchanger was modified to help prevent this problem on the 777.
My (non-expert) take on this:
The diameter of the transfer pipe probably reduces the flow of cold fuel from the reserves. There will be mixing as the fuel enters the tank.
The O/J pumps will initially be the pumps providing the engine supply. The inlets for these are around the 3~4 tonne level, not in the bottom of the tank. Assuming the coldest fuel from the reserves sinks to the bottom, the fuel being used probably won't be the coldest of the cold.
I've heard of pilots turning on the wing anti-ice in the belief it will heat up the fuel in the tanks. I can't see how it would make any noticeable difference. The anti-ice ducts only run in the very forward part of the wing leading edge which is several feet away from the tank. No heated air is vented into the cavity where the leading edge flaps are stowed. Only way heat can get to the tanks is through heat conduction through the skin. With cold winds blasting across the surfaces of the wing, I think this effect will be negligible. You already have some very large heat-generating pneumatic ducts in the leading edges that are heated all the time.