For one thing, time is not a factor in heat transfer - at least not in the example you are trying to analyze. What drives the removal of heat is the temperature difference between one area and another (aka Heat Flux). Generally speaking, if you minimize the time the coolant is in contact with something hot, the temperature difference will be greater everywhere heat transfer is occurring and the heat transfer rate will be higher. For example, if you pump coolant through a heat exchanger at 5 gpm and the outlet temperature is 30 degrees higher than the inlet, you have great "Heat Soak" but probably worse heat transfer than if you pump at 20 gpm and have an outlet temperature only 5 degrees higher than the inlet. In this case, we are talking about a water pump operating at a pretty nearly constant rate, and the thermostat is constantly making decisions about whether to send coolant to the radiator or bypass the radiator. So in an absolute sense, an 82 degree stat will removal heat faster from the engine (greater temperature difference) but will not exchange heat as efficiently through the radiator (less temperature difference) as will an 89 degree thermostat. Since the system is not really operating at its limits, the amount of heat being removed is, in a practical sense, exactly the same once the engine reaches equilibrium temperature.

I think you may be intending to say that cooler thermostats are not beneficial to engine operation, which is correct except for the head gasket problem. The head is kept somewhat cooler with an 82 degree stat, which some consider beneficial to the head gasket life, since the expansion and contraction cycle will be slightly less severe. Removing the thermostat is a good way to cause the engine to run too cold and will lead to incomplete combustion and other problems to dire to contemplate on the day after Thanksgiving.

posted by 64.94.19...

• Can I straighten out a misconception here!?!?, bkoeth, Thu, 27 Nov 2003 21:00:35
  • Re: Can I straighten out a misconception here!?!?, Dean, Fri, 28 Nov 2003 08:47:29
    • What Dean says makes more sense., J, Fri, 28 Nov 2003 09:57:24
  • Re: Can I straighten out a misconception here!?!?, jp, Fri, 28 Nov 2003 07:16:29
    • Not really, bkoeth, Sat, 29 Nov 2003 12:38:11
    • Almost - your thermostat keeps you at 98.6 F >, ChipJ, Fri, 28 Nov 2003 07:48:48
  • Someone needs a course in Thermodynamics >, ChipJ, Fri, 28 Nov 2003 05:53:54 <-- Viewing This Message
  • Re: yup, steveC, Thu, 27 Nov 2003 22:23:59
    • Re: oops must qualify one comment, stevecx, Thu, 27 Nov 2003 22:27:57
  • So, does the specific heat of coolant change with temp?, RS , Thu, 27 Nov 2003 21:17:40
    • I'd guess it might have to do with the coolant system, nt moore, Thu, 27 Nov 2003 21:54:47

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