Most of the Better Phase change materials are non metallic in nature and do not posses good thermal conductivity.However a better conducting material can results in better release and absorption of heat.so what is the constraint that limits the thermal conductivity of a phase change material?
Dear Vikash
in solar system phase change materials are used for storing heat energy. cause that it should have high specific heat and low thermal conductivity. if it has high thermal conductivity like metals so how could it store heat?
It need only hight specific heat, the thermal conductivity issue can be resolved by using thermally insulated storage devices.
Now my question is Can it be done?
Dear Vikash, regarding the original title question, thermal conductivity is a physical property of a material, while phase-change is a chemical-physical phenomenon depending on many variable (primarily pressure, volume, temperature). So the two concepts are not depending each other. For a possible relation conductivity vs phase-change (temperature or pressure), you could try comparing the numerical values at triple-point of a material, because this point is well defined in (e.g.) Pressure-Temperature plane.
Gianluca
Dear Vikash
Usually the metals have low latent heat while they have high thermal conductivit. This because they have free electrons and they need low energy to destroy bond-valence then they will be changed to molten. This is the physics.
Therefore, if you need to use a phase change material (pcm) which has low thermal conductivity, you should add a metal fins inside the pcm or add some nano material. If you add fins to the system , you should simulate the system by some software like ANSYS fluent or comsol . While , if you add some nano material, you should test the new thermal conductivity.
Regards
Hasan
Dear Vikash, there are some possible substances you can use, but let us go to the basics. As we have learned by Hasan: 1) metals have a good thermal conductivity due to the free electron. 2) Water and similar substance have a good thermal conductivity due to the agility of the hydrogen bridges. 3) As Gianluca wrote the melting enthalpy is a chemical-physical phenomenon depending on ! structure !. and structure is sometimes depending on other variables.
So what do we need: A material which has free electrons OR mobil bonds AND chemical (better physicochemical) bonds between the molecules (not the atoms!). Such physicochemical bonds can be hydrogen bridges, sulfur bridges, strong van-der-Waals forces and so on.
I think you know the solution: Not waxes and not metals.
Best Regards
Steffen.
This is based on the structure of the material. Generally, the materials with a high latent heat have low thermal conductivity.
- Badges
- Science topic
- Similar topics
- Engineering
- Modeling