- Dettagli della rivista
- Pubblicato per la prima volta
- 01 Jan 1992
- Periodo di pubblicazione
- 4 volte all'anno
- Accesso libero
Steady State Flow in the Cigarette and its Influence on Pressure Drop - Die stationäreStrömung in der Cigarette und derenEinfluß auf den Zugwiderstand
Pagine: 93 - 122
A theoretical treatment of steady state fluid mechanics of filtered cigarettes has been developed. By assuming laminar fluid flow, the well knownKozeny-Carman equation has been used to evaluate the flow resistance of the tobacco rod and the linear relationship of cigarette pressure drop to flow rate. Based on this relationship, models with distributed parameters (using impedances per unit length and differential equations) and lumped parameters (using a four terminal network of flow impedances and difference equations) have been established. These were used to calculate spatial flow variables such as pressure drop, volumetric flow rate and degree of ventilation. The effects of changes in coal resistance and reduction in rod length during smoking are demonstrated in a parameter study. A great advantage of mathematical modeling based on physical principles is the wide range of validity which allows a deeper insight into the behaviour of the fluid flow process. This is illustrated using a canonical example. Invariant model parameters such as the characteristic wave impedance and the propagation coefficient have been calculated and are presented as measurable. In order to calculate the dynamic fluid flow pattern of filtered cigarettes smoked on a conventional smoking machine, the model must be extend to include kinetic terms according to the Bernouilli equation. This will be presented in a later paper.
- Accesso libero
Pagine: 123 - 128
The semivolatile fraction of cigarette smoke contains the most important aroma and taste compounds which contribute to the smoker's enjoyment. Obviously, the semivolatile composition is strongly affected by cigarette filters and consequently by the material which is used for filter manufacturing. We have studied the effect of cellulose acetate and polypropylene as filter material on the smoke semivolatiles. Further, the effect of other parameters like pressure drop and the use of additives has been investigated. Smoke condensate was collected on a Cambridge filter pad, the semivolatiles were evaporated using a headspace apparatus and subsequently collected in a cold trap. Semivolatile analyses were performed by high-resolution GC/MS. The cellulose acetate filter, due to its polar structure, selectively retains polar compounds such as phenols and furans while the non-polar polypropylene filter shows a non-selective retention behaviour. The addition to polypropylene filters of a polar compound such as triacetin, which is used as plasticiser in the manufacturing of cellulose acetate filters, does not affect the retention behaviour towards the semivolatiles.
- Accesso libero
Pagine: 129 - 134
Analyses of indices observed in macro-photographs of a variety of cigarette cross-sections have shown that tobacco shreds forming the internal structure of cigarettes are highly arranged in a defined pattern in which their lenghts are predominantly oriented along the cigarette lenghts and their widths - parallel to the cigarette seams. These pattern-arrangements of tobacco shreds have an effect upon the dielectric properties and deformation of cigarettes. The deformation has been found to be bigger when measured perpendicular to seams.