The Physics and Chemistry of Shisha Smoking

In this article, we will discuss the physical and chemical processes of smoking a hookah — the influence of the length, diameter, and depth of immersion of the shaft, the influence of the diffuser, the shape of the bowl, and why it is worth blowing out the hookah.

First, let’s take a look at what is included in hookah tobacco and define each component.

Composition of hookah tobacco: tobacco, flavoring, glycerin, inverted syrup. Note that the nicotine and carbohydrate content in the raw tobacco, the quantitative and qualitative composition of polysaccharides, the moisture content of the tobacco, the amount of glycerin, and the amount and composition of flavorings significantly affect the quality of hookah tobacco.

The moisture content of hookah tobacco is one of the significant indicators that allows for the correct interpretation of the content of all components and the assessment of the possibility of storing the finished product.

Next, let’s take a closer look at each component.

Flavorings — substances used to give products or goods specific smells and to create or improve the aroma.

There are 3 types of flavorings: natural, identical to natural, and artificial flavorings.

Glycerin — an organic compound, the simplest representative of three-atom alcohols. Glycerin acts as a binding substance when the mixture evaporates and is a transporter of all volatile components.

Propylene glycol — a colorless viscous liquid with hygroscopic properties, diatomic alcohol (glycol). Some manufacturers, for example, of tea blends, use propylene glycol to keep all the ingredients of the mixture in a mixed state, which improves volatility.

Invert syrup (sugar) — invert sugar is obtained from sucrose by hydrolysis. Invert syrup is used to bind ingredients and average the specific heat of the mixture.

Preservatives — substances that inhibit the vital functions of microorganisms and some other types of living organisms in food products. It increases the shelf life and prevents spoilage of the product.

Now that we have a general understanding of the components of hookah tobacco, let’s look at its physical and chemical processes using the example of airflow through the hookah.

The influence of shaft length on the physics of hookah smoking

As hookah smoke travels through the shaft, several processes occur, including coagulation, condensation/evaporation, deposition on the inside surface of the shaft, and movement in the direction of the produced flow.

Coagulation refers to the combination of small particles with larger particles, which results in a decrease in the number of particles and an increase in their size. In the context of a hookah, as the length of the shaft increases, the number of particles decreases, and their average diameter increases because the smoke remains in the shaft for a longer time. Condensation and evaporation processes also affect particle size.

Hookah vapor is formed by condensation, and the particles are nucleated in the bowl and enter the shaft when you puff. The presence of a temperature gradient along the entire length of the shaft creates an oversaturation in the system, promoting particle growth through condensation. As the smoke passes through the shaft, diffusion can cause particles to deposit on the surface of the shaft, resulting in a decrease in the number of particles with increasing shaft length.

Furthermore, aerosol vapors can condense on cold sections of the shaft, releasing heat and causing volatile substances to remain on the shaft. The concentration of volatile compounds decreases as the length of the shaft increases, resulting in less flavor in the output. The length of the shaft also affects the hydrodynamic resistance or the traction that you feel when you draw. The longer the shaft, the more effort you will need to exert when smoking.

There are three sizes of hookahs: small (22 cm shaft length), medium (36 cm shaft length), and tall (55 cm shaft length). A decrease in shaft length from 55 cm to 22 cm results in a significant increase in the number of aerosol particles and a decrease in the average modal diameter. Interestingly, a 2.5-fold increase in shaft length leads to a 10-fold decrease in particle number, while a 1.6-fold increase in shaft length reduces particle number by only 2 times while maintaining the average modal size. Thus, medium-sized hookahs are the most balanced in terms of the properties of the generated smoke.

The Impact of Shaft Diameter on Hookah Smoking Physics

It is important to keep in mind the following:

1. As the diameter of the shaft increases, so does the diameter of the bubbles, resulting in a quicker coagulation process and allowing the inhaled smoke to be enjoyed more quickly.
2. Increasing the length of the shaft reduces the absorption of gases due to the larger diameter of the bubbles and their reduced number.
3. As the volume of the bubble increases, the number of bubbles produced per puff decreases. The hydrodynamics of bubbles determines the processes of mass transfer, where the bubble contains both aerosol particles and gas components that interact with water resulting in processes like settling of aerosol particles, absorption of volatile components by water, and condensation of water vapor on aerosol particles.

The Influence of Mine Immersion Depth on the Physics of Hookah Smoking

The depth of shaft immersion can significantly affect the smoking experience, including the flavor, aroma, and strength. Hydrodynamic resistance increases as the immersion depth increase, whereas puff resistance is typically caused by hydrostatic pressure from the water in the flask. Additionally, the hose, mouthpiece, personal mouthpiece, and their respective diameters can all contribute to the final resistance.

The Effect of the Diffuser on the Physics of Hookah Smoking

The diffuser, originally invented for noise reduction, has additional advantages. By breaking steam into smaller bubbles, the diffuser increases the area of contact between steam and water, moistening the inhaled steam and facilitating the draft.

The Flask and Its Shape

The shape of the bulb also affects the smoking process. The more space above the liquid, the less effort is required to take a puff, making smoking easier. The shape of the flask directly affects the pressure density, where inhaling the contents of the flask creates an area of reduced pressure. As the vapor is pulled from the shaft, water replenishes the flask.

Hookah Blowing

Blowing the hookah is a necessary process for comfortable smoking. Harmful carbon monoxide accumulates in the free space between the water and the base, resulting in an unpleasant bitterness that should be released every 2–3 puffs.

Conclusion

After reading this article, you now have a comprehensive understanding of how physical and chemical processes affect the process of smoking a hookah. Pay attention to details such as the length, diameter, and depth of the puff to improve your smoking experience.