1) Traditional Mold - wall thickness
n traditional molds, made of stainless steel AISI 304, we studied the performance difference between plates ranging in thickness between 0.5 mm and 0.8 mm, the most commonly used by mold makers in Brazil and abroad.
The theoretical modeling was based on using pure water inside the mold, only taking into account the total heat to be removed, without simulating the dynamic effects of the exchange and phase change. Experiments were conducted under various conditions using only water inside the molds.
There is a 20% difference in freezing time between the stainless steel plates used. The thickness of 0.5 mm was more rapid and more applicable to molds used in machines of smaller capacity. A thickness of 0.8 mm can only be used in refrigeration systems that are more powerful.
The thickness of 0.5 mm was found to be unsuitable for immersion in baths of calcium chloride and sodium chloride, due to low durability, while the thickness of 0.8 mm can be used with sodium chloride only. Calcium chloride is also inadequate for the 304 steel.
2) Immersion in glycol
We investigated the use of nontoxic propylene glycol instead of alcohol, commonly used as an intermediary fluid to freeze popsicles in small scale equipment.
From previous research (item 1), we concluded that the molds with a plate thickness of 0.5 mm only resist alcohol and should not be used with sodium chloride or calcium. But alcohol has the great disadvantage of being flammable.
The nontoxic propylene glycol, mixed with water in correct proportion, proved quite effective in freezing popsicles without being flammable. Its major disadvantage is cost.
In this study we obtained mainly the theoretical and practical knowledge of the main characteristics that a fluid for this purpose must have. Basically, this is a freeze by shaking the fluid system. The speed of the movement plus its thermal conductivity at each temperature has vital importance for the outcome.
3) Alcohol agitation system - patented
Machines produce ice cream using a traditional centrifugal pump to move the alcohol from the molds. Normally, the direction goes from one side to the other where the templates are; the alcohol is cooled by the evaporator that is in contact with the first mold on one side, and loses temperature as it moves to the opposite side of the tank. This means that the popsicle molds never freeze evenly.
To solve this problem, we investigated new ways of circulating the refrigerant and concluded that the centrifugal pump is ineffective because the flow rate drops considerably with increasing its viscosity. Moreover, by evaporating alcohol during the process, the fluid becomes increasingly dense and the movement becomes almost nonexistent, delaying the freezing time of the popsicles.
The result of this research was to develop a propeller stirrer for the alcohol that moves upwards on all the templates at once. In other words, instead of alcohol moving from one tank to another, it moves from bottom to the surface. The performance gain, even after the evaporation of much of the alcohol, is impressive.
4) Evaporator with spheres - patented
As a complement to previous research, we realized that the amount of alcohol contained in the tank could be reduced, which would further increase the efficiency of the agitation and of the thermal inertia.
Since the evaporator was made from copper piping immersed in the same tank of molds, a considerable quantity of alcohol was used only to cover the evaporator (commonly called serpentine).
We created an evaporator that occupies less than 1 / 3 of the volume that was previously used. To do this, we inserted small aluminum spheres throughout the copper and the results were fantastic.
5) Fiberglass tank - patented
Following the two previous studies, we noticed that the heat loss of the refrigerant was not something to be dismissed. The smaller the amount of the fluid, the greater the effect.
We decided to search for alternative materials instead of the stainless steel normally used in such tanks.
The solution in fiberglass proved to be the most suitable for accommodating the evaporator and the best way to prefabricate the fittings. The biggest problem was finding the appropriate materials to support the alcohol, for which we had the support of BASF and other manufacturers of resins. The first tests were problematic because the interior of the tank "popped", bubbles formed and after only two to three months of use.
The result was to introduce a special 'blanket', a special resin used on the exterior of the tank and a special resin used inside the tank. With all this, the final price of the tank was still less than half that of the stainless steel tank.
Over time, several other machine manufacturers have adopted this same solution (fiberglass), but most of them gave up because they could not get rid of problems with blisters.
5) Fiberglass tank - patented
Following the two previous studies, we noticed that the heat loss of the refrigerant was not something to be dismissed. The smaller the amount of the fluid, the greater the effect.
We decided to search for alternative materials instead of the stainless steel normally used in such tanks.
The solution in fiberglass proved to be the most suitable for accommodating the evaporator and the best way to prefabricate the fittings. The biggest problem was finding the appropriate materials to support the alcohol, for which we had the support of BASF and other manufacturers of resins. The first tests were problematic because the interior of the tank "popped", bubbles formed and after only two to three months of use.
The result was to introduce a special 'blanket', a special resin used on the exterior of the tank and a special resin used inside the tank. With all this, the final price of the tank was still less than half that of the stainless steel tank.
Over time, several other machine manufacturers have adopted this same solution (fiberglass), but most of them gave up because they could not get rid of problems with blisters.
6) Aeration of popsicle - patented
The race for the shortest time to produce a popsicle has always existed between machine manufacturers. On top of researching new solutions refrigerants, new coolers, new ways and systems of agitation, and new refrigeration systems, this race "against time" led us to look at the composition of ice cream, where we realized that the aeration of the milk mixture could substantially reduce its production time.
The conclusion of this research was to develop a propeller to mix the ingredients of the ice cream, which is still marketed by our company, in the simple and low cost product called MIXER 15. Strictly speaking, the mixer 15 is a kind of "blender", but it contains a helix specifically designed to incorporate air into the mix.
7) Control system for rotary popsicle machines.
8) Control system for popsicle tunnel freezers.
