Thermal dynamics - Metals on Engine Components

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Discussion Overview

The discussion revolves around the thermal properties of materials used in car engine components, particularly focusing on specific heat capacities, thermal resistance, and the effectiveness of various materials in resisting heat. Participants explore questions related to the best materials for engine components, the role of insulation, and the concept of thermal diffusivity.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • One participant questions the relationship between specific heat capacities and a material's ability to resist heat, noting that gold wrapping is used in engine compartments despite its low specific heat capacity.
  • Another participant suggests that shiny materials in car engines reflect heat rather than relying on heat capacity, and mentions the use of insulation to keep temperatures lower.
  • There is a discussion about the definitions of heat capacity and thermal resistance, with one participant explaining that insulation has higher thermal resistance.
  • A participant introduces the concept of thermal diffusivity, describing it as a dimensionless quantity that combines density, heat capacity, and thermal conductivity, suggesting that materials with low thermal diffusivity resist heat.
  • Some participants express a desire for further reading and clarification on these topics, indicating a lack of clear answers in existing resources.

Areas of Agreement / Disagreement

Participants have not reached a consensus on the best materials for resisting heat in engine components, and there are multiple competing views regarding the definitions and implications of thermal properties. The discussion remains unresolved with ongoing questions and explorations.

Contextual Notes

Participants express uncertainty about the terminology used to describe heat resistance and the implications of different thermal properties, indicating a need for clearer definitions and understanding of the concepts involved.

ZCHondaCRX91
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I have some car engine related questions, but basically just physics.

-Do different specific heat capacities have anything to do with how certain materials resist heat? I know that on some engine compartments there is gold wrapping because it resists heat best, but it has a low specific heat capacity. I know the higher the heat capacity the more energy is needed to increase the temperature.

-What are the best metals or materials that resist heat? For example in an engine compartment where the underhood temperature fairly warm, what materials for the intake components would resist heat best so the IAT won't increase too much?

-Are there plastics or rubbers that resist heat more than metals?

-Is that the correct way to say it, "resists heat?" If you have two containers filled with water, with the same mass and thickness, but different materials, and are placed in a oven for the same amount of time. Then when you measure the temperature in both containers and in one the water is a lower temperature than the other, would you say that material resists heat better?

I want to learn, but can't find any clear answers for these specific questions. Any help is very much appreciated. Thanks.
 
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250 views, no answers? If you know of something I should read please let me know. Thanks.
 
ZCHondaCRX91 said:
250 views, no answers? If you know of something I should read please let me know. Thanks.

The parts of your car, such as under the hood, have a shiny material to reflect the heat and basically nothing to do with heat capacity. Between the shiny and hood is some insulation to further resist the heat as you say to keep the hood a little bit cooler.

A material has heat capacity and thermal resistance. You could say that insulation has a higher thermal resistance.

A container which has a higher thermal resistance will allow the temperature of the water in your oven example to rise less quickly than the other container, if you would plot temperature of the water versus time. Eventually though after a certain long enough period of time the water in both containers would be the same all other things considered equal.
 
256bits said:
The parts of your car, such as under the hood, have a shiny material to reflect the heat and basically nothing to do with heat capacity. Between the shiny and hood is some insulation to further resist the heat as you say to keep the hood a little bit cooler.

A material has heat capacity and thermal resistance. You could say that insulation has a higher thermal resistance.

A container which has a higher thermal resistance will allow the temperature of the water in your oven example to rise less quickly than the other container, if you would plot temperature of the water versus time. Eventually though after a certain long enough period of time the water in both containers would be the same all other things considered equal.

Thank you, that makes sense.
 
Have you heard of thermal diffusivity?

It's a dimensionless quantity (no units) which combines density, heat capacity, and thermal conductivity. I can't link yet, but the wikipedia page explains more.

A material with a low thermal diffusivity would "resist heat".
 
pa5tabear said:
Have you heard of thermal diffusivity?

It's a dimensionless quantity (no units) which combines density, heat capacity, and thermal conductivity. I can't link yet, but the wikipedia page explains more.

A material with a low thermal diffusivity would "resist heat".

No, didn't know that. Will do some reading on that. Thank you.
 

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