Calculation Method Of Refillable Vape Core Oil Inlet Hole Size

The size of the oil inlet hole of the atomizing core has a significant impact on the effectiveness of the vape

The oil inlet is connected to the e-liquid(or oil) storage tank and the heating coil absorption storage medium.

• If the oil inlet is too large, the e-liquid(or oil) will leak from the gas channel under the action of capillary force and gravity when it is in a static state, causing unnecessary waste.
• If the oil inlet is too small, the heating coil absorption storage medium cannot guarantee timely supply of e-liquid(oil) during atomization, which affects the atomization effect and user experience.

Therefore, a reasonable design of the size of the oil inlet hole is of great significance for the effectiveness of the vape. So, how to control the size of the oil inlet hole through calculation during the design phase to ensure that there is no leakage during static operation and good atomization effect during operation?

Today, from the perspective of an engineer, we will introduce a method for calculating the size of the oil inlet hole of an atomizing core

Establish an equation for the equivalent relationship between physical quantities in static and working states, and obtain the following function:

Static status

M-The mass of the heating coil absorption storage medium, measured in milligrams.
A-Surface area of the metal shell interlayer, unit: mm².
υ-E-liquid carrying capacity per unit area and time, measured in mg/(s·mm²).
ε-The ratio of the area of oil inlet hole to surface area of the metal shell interlayer, 0<e<1.
t-Liquid absorption time, unit: s.

Work status

The overcurrent flow rate of the heating coil absorption storage medium during the working process is equal to the amount of e-liquid replenished in the oil storage tank. According to Darcy’s law, the following equation is established:

Q₁– E-liquid total seepage flow rate, unit: mm³/s.
Q₂– E-liuqid axial seepage flow rate, unit: mm³/s.
K- Permeability of absorption storage medium, unit: mm².
ΔP- The pressure difference between the two ends of absorption storage medium, unit: Pa.
μ- Dynamic viscosity of e-liquid, unit Pa·s.
L- The cross-sectional thickness refers to the thickness of the heating coil absorption storage medium, unit: mm.
ρ- Eliquid density, unit: mg/mm².

For a demonstration case of a certain vape

1. When the liquid absorption time t during standing is not less than a second, it can be considered that the heating coil absorption storage medium is completely immersed
2. The duration of each operation of the vape is b seconds. Then, we can get equation:

According to the above relationship, it can be inferred that:

In this demonstration case,the parameters involved in the absorption storage medium, the parameters involved in the properties of the e-liquid, and the parameters involved in the atomization process are as follows:

By substituting these parameters into the previous formula, we can obtain:

From this, it can be determined that the percentage of the oil inlet area to the outer shell surface area should be between 56.43% and 74.69%.

The refillable vape atomizer core directly contacts the e-liquid in the oil tank, which poses a greater risk of liquid leakage compared to disposable vapes.
How to ensure sufficient oil flow and good taste without liquid leakage has always been the core of designing atomizers.
This calculation method can control the size of the oil inlet hole within a reasonable range during the design stage, and then adjust it on this basis to save time and improve development efficiency.

The above is an introduction to some of the working principles of the vape atomizer. As a professional vape manufacturer. We have professional OEM and customization services. Meet various vape needs.
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