Heat Transfer Technology AG

Heat Transfer Technology BUCO FALLING FILM CHILLER

Falling Film Chiller or so-called baudelot ice water cooler are mainly designed for cooling water down to 0.5°C near freezing point.

Falling Film Chiller

Falling Film Chiller Process reliability to produce constant cooling of ice water near freezing point

specially Ice water (near 0°C) has a very good heat capacity, i.e. by contrast with other cooling agents, relatively small quantities can convey a large amount of heat.

What makes the falling-film chiller so interesting is its relatively simple and relieble operation including a high cooling performance to represent the ideal industrial water chiller. Water flows down the vertical plates. It is an open system that is accessible for cleaning, even during operation. Completly made out of stainless steel.

The flow-specific and thermodynamic parameters of water are favorable, so that high heat transfer rates can be achieved. However, the freezing point of the water itself (zero point) sets crucial physical boundaries for ice water production and cooling with ice water. Above all, temperatures achievable in the water are made to approach the zero point as closely as possible in order to exploit maximum temperature differences for the products to be chilled with ice water and to keep the temperature of the cooled product as low as possible.

What’s a Falling Film Chiller?

How does a Falling Film Chiller work?

The Falling Film Chiller or so-called baudelot ice water cooler consists of a distribution tray for the water at the top, a heat exchange system, a frame and a cover and a bottom collecting tank for water (optional). Water is pumped into the distribution tray and at a controlled rate is distributed homogeneously by a distribution through onto vertical panels in an open system.

The process water flows in a thin film over the outer surface down on the panels and obtains the highest possible outside film coefficient. By highest descent speed, highest U transmission coefficients are reached.

In order to avoid building of ice at the panels, the suction gas pressure at the evaporator suction header has to be regulated. To keep the evaporation temperature not lower than the designed one, e. g. -3°C, as well as the water temperatures and flow. At systems used with e. g. glycole inside, the glycol inlet temperature has to be controlled. 

A high flow velocity ensures highly efficient heat transfer and a kind of a helpful self cleaning effect, which allows the operation with polluted liquids as well. Completely made out of stainless steel, it assures all required sanitary requirements, as the Ice water is always in contact with stainless steel parts AISI 304 or 316L or higher stainless steel grades up to titanium.


Low-specific and thermodynamic parameters from an industrial water chiller of ice water near freezing point

As zero point is approached, the problems in ice water production with the attendant risk of ice formation increase. The known anomaly of water (lowest specific volume at 4°C) results in the water volume expanding when it freezes, and under certain circumstances this can cause destruction of the equipment used. Furthermore, ice formation in ice water systems with their thick layers of ice always involves considerable performance losses because the ice layer acts like insulation and greatly reduces the thermal transmission output.

Consequently ice water production calls for a technique that on the one hand brings the water temperature as close as possible to zero point, but on the other hand is not susceptible to potential ice formation. If control fluctuations of the cooling system lead to ice formation, a layer of ice on the panels will reduce the heat transfer and reduce the cooling power of the baudelot ice water cooler. Building of ice at the panels may occur for some minutes, but there will not follow any mechanical destruction as in Plate Heat Exchangers. Ice will melt automatically after raising of the temperature inside the panels within the next normal operation mode cycle.

Comparison of Falling Film Chillers and Plate Heat Exchangers

If you are an engineer looking for the most efficient and effective process cooling solutions of ice water near freezing point of 0,5°C, then you should consider the advantages of a falling film chiller versus a plate heat exchanger. This type of chiller offers some very distinct benefits when compared to plate heat exchangers and could be just what your application needs. We’ll explore how each type of solution works, discuss the various pros and cons associated with both types of chillers, and provide advice on making the best choice for your project. By examining all of these elements, you’ll gain a better understanding as to why falling-film technology may be preferable over traditional plate heat exchangers in certain projects.

The Falling Film Chiller is a specialized engineering solution, designed with Pillow Plates arranged side-by-side in an efficient frame. As the interior of each plate undergoes evaporation with ammonia or refrigerant, water streams down along the exterior to create thin films for heat exchange - enabling temperatures near freezing point and optimized efficiency far beyond HVAC applications. With precisely spaced plates at 50/150mm apart from one another complemented by 0.5/0.4 mm thick fluid layers transitionally descending downwards – this product ensures successful thermal energy transfer without fail!

The FALLING FILM CHILLER, a widely-employed technological solution for businesses in both the food and beverage industry as well as chemical and pharmaceutical sectors abroad, relies on optimized film layer thickness to achieve better exchange coefficients. A thinner falling film is associated with higher levels of efficiency while increased plate numbers will result in thicker layers that reduce overall performance.

The simplicity of a Falling film chiller with open design to produce water at 0,5°C

  • Fully welded, no spare parts such as seals.
  • Easy access to the open system industrial water chiller and easy to clean even during operation.
  • Falling-Film-Chillers need mainly shut valves on suction and liquid.
  • Suitable chiller for contaminated liquids (for example greywater or red water)
  • Low tendency to fouling.

In direct contrast to the Plate Heat Exchanger:

  • Need seals to be exchanged periodically.
  • For cleaning, the unit must be stopped and dismantled. This costs time and interrupts the production process.
  • Hot gas-defrost and flow control on the water side, costs for the controllers and temperature sensors do not depend on the capacity.
  • Additional cost incurred due to the planning, piping, mounting of valves and electric wiring as well as setting and programming of the controller.
  • Contaminated media in the inner channels of the plates, especially in the pathes, pose a major problem of ice formation and mechanical destruction of the entire apparatus.

To give you an idea of the difference to a Plate Heat Exchanger, here is an excerpt from a manual of a well-known Plate Heat Exchanger manufacturer:

“Despite all mentioned advantages of Plate Heat Exchanger, it has to be told, that the Plate Heat Exchanger ice water plant needs special control features and a careful operation (according to the water temperature near freezing point). It has to be secured, that the water temperature on the waterside of the plates never undergoes 0.5 °C. Suction pressure control is recommended. The suction pressure regulator has to have an accuracy of 0.25 °C (at the ice water probe). A regulation valve is necessary.”

In conclusion,plate-heat-exchangers require temperature control, hot gas-defrost and flow control on the water side. The costs for the controllers and temperature sensors do not depend on the capacity while control valves, pilot valves as well as solenoid valves and shut valves are dependent on capacity. Having said that it should be taken into account that there could be enormous additional cost incurred due to the planning, piping, mounting of valves and electric wiring as well as setting and programming of the controller. Plate-Heat-Exchangers have gaskets between plates likely needing cleaning depending on various water qualities causing massive lose of power if overlooked.

For further guidance, please get in touch with our engineers who are ready to offer personalized advice tailored specifically to your requirements for your next 0,5°C ice water project.