View Full Version : falling film chillers?

02-18-2014, 05:08 AM
Anyone out there using a "falling film" chiller for glycol? Looking at a Mueller and seems like it will work. Just like to hear any pros or cons. Thanks for any input.

02-18-2014, 12:47 PM
Disclaimer- We manufacture chillers, but don't sell Falling Film Chillers. I am familiar with them and see them utilized in some of the non-brewery markets we serve.

Falling Film Chiller systems have been around for many years, it is a real simple design and they are pretty bullet proof in construction. Essentially water, or glycol water, is pumped through a distributor manifold that cascades the water down the surface of a series of stainless steel cooling plates. As the water cascades down the surface of the cooling plate, the heat is absorbed into the refrigerant, cooling the water.

The downside is these are not very efficient, especially at the lower temperatures of 25 F to 28 F required in breweries. These are very common in the Dairy Industry where they are operated at 35-40 F, and used to chill Milk- but in general it will take more HP on a Falling Film Chiller System to do the same job when compared to a traditional Chiller System designed for the dairy cooling application. The reason it requires more HP to remove the same BTU/HR is due to the passive Heat Exchange versus a more direct Heat Exchange.

In addition to seeing these in the Dairy market for cooling raw milk, I've also seen them used for cooling potable water in bakery applications for their ingredient water. They are also used as brine chillers in cheese plants. I honestly don't recall seeing a Falling Film Chiller used in a brewery, but I'm sure there are some out there.

Hope this is helpful, good luck!

Jim VanderGiessen Jr
Pro Refrigeration Inc.


dick murton
02-18-2014, 11:25 PM
Don't get a falling film chiller

For what it is worth, this type of chiller used to be used extensively for wort cooling, but as already mentioned, due to hygiene problems, i.e. they are not easily cleaned, and very low efficiency, they have almost completely disappeared. The last one I saw in use was used for cooling wort sample from the lauter runoff and wort kettle - hardly hygiene critical as no product was returned to the brewstream. I expect there is someone in the UK or Germany using one simply for aesthetic reasons - certainly not with GMP in mind

Stick to plate and frame chillers for hygiene and thermal efficiency reasons. Plate chillers may cost a little more to buy, but they won't give you the hassle long term.

02-19-2014, 04:46 AM
Does anyone have the ability to calculate the needed length/diameter for a tube in tube HX? assuming stainless for both tubes.

02-19-2014, 06:47 AM
Thanks for your replies. I plan to run glycol and water over the chiller so no wort will be in contact with the unit. The Mueller sales rep. Said they have seen this used for glycol before...maybe not in a brewery. Please educate me. How is glycol falling down stainless plates filled with refrigerant an inefficient heat exchange? I guess there is heat gain from ambient air since the glycol is not in a closed loop? Mueller said they design for 10* F differential between refrigerant and the product which in this case is glycol so it seems like the lower temps can be achieved. Again, thanks for your replies.

dick murton
02-19-2014, 08:31 AM
Ask them what efficiency they get and then compare it to a conventional plate chiller from say Alfa Laval. Then also ask them what guarantees they will put against absolute sterility, and what conditions are required to achieve this.
Ask them about maintenance costs, and frequency.
Ask them how flexible the sytem is for increasing or reducing throughput whilst maintaining efficiency and hygiene.

You are going to gain some heat from the environment. The poor heat exchange is because of the low level of turbulence, due to comparatively low flow rate compared to a conventional plate exchanger, and because you only get heat exchange on one side of the glycol flow (I know this isn't strictly accurate becasue it will mix a little as it falls, but compared to a plate H/Ex where you get mixing AND two sides of both the glycol and the wort being cooled...)

02-20-2014, 06:50 AM
Swag, the first thing I would ask is why are you bent on that design?
The word " cascades " is a give away and a Refrigeration expert above has given you a good, zero cost overview offering his knowledge.
That HX design is less effieient because it is less efficient.
The HX tek used in Brewery chillers is flooded, not cascading and more likely than not has a lot better surface area and is more scientifically designed. Jim may be able to give particulars. Things such as fins, rifled tubing, pressure differentials across the device and so forth.
They are more efficient and are made for this duty. The other ones are not made for Brewery glycol chilling.

02-20-2014, 10:21 AM
I own this 20 hp unit and unloaded into our facility yesterday. I will use it for a while and if it can't handle the duty, i will scrap it and recoup most of my investment. Thanks for the advice.