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K.Satish5 • Sep 13, 2015

Heat produced in IC engines

Hi fellow CEians!

It may be an already answered question or thought of by someone else, but I have to blurt it here goes!

We all pretty much know how IC engines work and that they produce heat as any combustion reaction would do. Also, there has been a lot of research done and advances have happened in technology used in cars to make optimal use of this heat that is produced. I am not going into details of those efficiency here, but I do have a question here - or some of you may find it some food for thought.

After we have driven our cars typically from home to work or back home from work, we just switch off the engine, get out of the car and head straight to where we want to go. We forget that the engine that has been running all along is all heated up (unless you are driving when you can walk), and that heat is just getting dissipated into the atmosphere without getting utilized for something - yes for something that can be useful. For e.g., heating my oven, heating my house in winters, heating the water for bath instead of using electric geysers, basically using it for anything that needs heating. What I am basically thinking of is some kind of "container" that I can use to take all that heat into, and just use it wherever I need.
Well, it may sound crazy (that's why we are here! ;-)), but have a mechanism or means to "pour" all that heat from the engine into my "container" and then use it to wherever I need it. I am an engineer myself and I do know the basics of heat transfer - so "pouring" of that heat is not going to be possible, however I am using these terms just so that my idea is clearly conveyed. 😀

Would appreciate your thoughts and criticism on this idea.

Thank you!
Let us try an order of magnitude calculation.
1. Storing heat. This can be stored as sensible heat, latent heat of change of state, electrical energy and chemical energy.
2. Considering use in a motor vehicle the best will be as latent heat of fusion.
3. Most vehicles operate at about 20% realized efficiency. Even granting it at 30% one gets about 7000 KCals of waste heat/litre of fuel burnt.
4.Paraffin wax (cmpounded to an M.P. of 80 degC) has a latent heat of about 50 KCal/kg.
5. About 140 kg of this wax in an insulated container with a proper heat exchanger to take up heat from the radiator water will be needed/litre of fuel burnt.
6. A quick change design of the container will be needed to remove this container from the car at the user end and connection to the domestic water heating system has to be worked out. The built in heat exchanger can be now used in reverse.
7. Assuming a cold water temperature of about 30 degC, one can get about 200 litres of water at about 55 degC/litre of fuel burnt.

Is it worth the cost and effort?
K.Satish5 • Sep 14, 2015
Ramani sir, thank you for sharing your thoughts.

It is indeed thought provoking to know that it seems not worth the cost for the benefits this idea can offer. I am going to think on these lines more and post my thoughts.

Again, sincere thanks for sharing.


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