A number of factors can affect heat transfer. It’s important to understand what these factors and outcomes are in order to find the right way to address the heat dissipation with the right insulation.
Heat dissipation is an unavoidable but nonetheless negative side effect of a number of processes in a range of industries – from forging steel to powering an electric vehicle.
Factors That affect heat transfer:
The thermal conductivity, thickness and total area of the material impact how effectively it dissipates heat. There’s an equation for calculating the rate of heat transfer across the material, which is as follows:
Rate of heat transfer = k•A•(T1 – T2)/d
K = thermal conductivity value
A = surface area
T1 = temperature inside the object
T2 = temperature outside the object
d = thickness of insulation
Insulating materials, such as mica, have much lower thermal conductivity values. Mica has thermal conductivity of approximately 0.71 – meaning the rate of heat transfer through mica is much lower. Our Elmtherm microporous products have thermal transfer rates much lower at 0.020 W/mK at low temp and 0.036W/mK at higher temperatures.
Thus, through adding an insulative layer with a lower thermal conductivity and therefore a lower rate of heat transfer, you slow down the rate of heat transfer (or loss) overall.
This slowing down of heat transfer can be vital for a number of reasons.
Loss of heat during manufacturing processes – especially those which require incredibly high temperatures – can have a big impact on the energy consumption and therefore the cost of running equipment. Taking an example from a recent project we worked on providing thermal insulation for rotary kiln – in a specific section of the kiln, prior to installing our Elmtherm solution, the rate of heat transfer was on average 182 mJ/H (mega-Joules per hour).
In industrial or even consumer settings, the reduction of the rate of heat transfer can be vital for making the equipment safe to use, often in order to comply with strict industry regulations. In a more specific example, reducing the rate of heat transfer can be especially important in electric vehicles. Electric vehicles (EV) are powered by lithium-ion batteries. These batteries are ideal for powering EVs because of their high energy density, but unfortunately they are at risk of a process called thermal runaway. Thermal runaway occurs when the battery short circuits or malfunctions – causing an increase in temperature within the cell, which quickly spreads to the rest of the pack via heat transfer. This creates an unstoppable chain reaction, incredibly high temperatures throughout the pack, and eventually, fire or explosion. Utilising insulation between the battery cells and in the housing of the pack enables you to slow down the rate of heat dissipation, giving the occupants of the vehicle more time to reach safety.
Reducing Maintenance Costs
Consistent exposure to extremely high temperatures negatively impacts a material’s thermal properties and even structural integrity. Without proper insulation, accelerated heat transfer could mean the system or machinery has to be repaired more often. This leads to increased downtime, loss of productivity and ultimately, higher costs.
Contact Axim Mica for expert advice on your next project!