I am a high school student that is really interested in car engines and how they work. I am in the process of writing my school report, and I am thinking of doing it on car coolant. Using newton’s law of cooling, I can create a function for change in temperature with respect to time. If anyone can recommend me with an article that talks about car coolant and how they work according to newton’s law of cooling that will be very helpful.


  • Heat Transfer by Simonson covers all the theory you need.
    – Solar Mike
    Commented Dec 26, 2020 at 15:12
  • I see that this is a book, is there a way that I can access this? Commented Dec 26, 2020 at 15:17
  • Also long story short, I am applying an uncertainty in the change in temperature using a sine graph to show that change in temperature is not stable and therefore we would have different values of temperature at different intervals that will give us the wrong impression about the cooling system and how effectively does in work @Solar Mike Commented Dec 26, 2020 at 15:20
  • Try the power of Google... Seen a pdf version...
    – Solar Mike
    Commented Dec 26, 2020 at 15:24

1 Answer 1


I am glad to see young automotive enthusiasts who are also taking an interest in physics. If you want to simplify the coolant heat transfer it comes down to the following:

  1. We will assume for the sake of simplicity that the engine puts out heat at a constant temperature (which should be roughly proportional to the power output of the engine) We can assume this to be constant. So we have what we call a constant heat flux boundary condition.

  2. The engine block and the coolant exchange heat via a process known as convection (often called newton's law of cooling) q=ha(DT)v , where q is the heat flow in watts, h is the convective heat transfer coefficient, and DT is the temperature difference between the engine block and the coolant.

  3. The coolant can be modeled as a flow which changes temperature via the formula q=mDotcDT_fluid , where mDot is the mass flow rate, c the specific heat of the coolant, and DT_fluid the temperature change of the coolant or it can be modeled as a aggregate mass via q=mcDT_fluid/timeElapsed , where m is the mass of the fluid, and time Elapsed is how much time has passed

  4. the coolant has a transient (changes in time) warm up behavior and a steady state (constant) temperature (which is modulated by the thermostat in the car)

coolant temperature and temperatures in an internal combustion engine in general are very complex studies, but they can be greatly simplified to make for a simple overview of the problem

If you are interested we can exchange emails and I can help you out a bit more. You can even use my paper on heat transfer as a source since the problem is fairly similar to what I am working on in my research. I also have some log files off my subaru which you can use to makes some graphs. You could try to compare newton's law of cooling to the data from the logs.

I am an engineering masters degree student with emphasis in heat transfer and an avid Subaru enthusiast ( I am currently learning engine tuning)

  • 1
    Hello @Sebastian , I saw your answer and looks like what I am looking for. My plan is and let me know if it makes sense, I am assuming that the temperature of the engine is decreasing according to newton’s law of cooling until no further change is observed where equilibrium in temperature has been reached with the car coolant. Commented Jan 2, 2021 at 13:32
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    I don’t know if I make sense. The main plan is to check how effective is a car coolant. Then my plan is to assume that there is influence to the temperature of the engine due to temperature of the environment which keeps changing therefore we have the wrong assumption about a car coolant and how efficient it is. Maybe because I don’t have your email, you can contact my using this email: [email protected] Commented Jan 2, 2021 at 13:37
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    I really appreciate people like you and thanks a lot for your answer and help. Commented Jan 2, 2021 at 13:38

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