- When water phase changes to steam, and the 1.5C temp is deducted from steam, in addition all surrounding cells that were hot enough to cause the phase change have their temperatures adjusted (so the phase change reduction happens multiple times).
The following image (from that thread) highlights the issue.
The turbines all give the same wattage if side walls touching the vent are insulation (like the one on the right). However, the more contact surfaces there are, the more heat is lost. The heat loss on the left turbine is 4 times the heat loss on the right turbine (from left to right the heat loss is 4 times, 3 times, 2 times, the right turbine). The left most turbine has 4 cells (3 windows and 1 gas) that are hotter than the incoming water (hence 4 phase transition reductions). The next turbine has 2 windows and 1 gas, hence 3 reductions. The crude one (after the water rises above the crude) has 1 gas and one liquid cell involved in the transition, hence 2 phase transition deductions.
The problem appears all over the place, not just in steam turbine setups. It affects just about any place where we want a boiler plate to perform phase transitions.
Repeat @wachunga's experiment here.