How to Scale Up with a Recirculating Chiller
A key challenge facing growing labs is the scaling up of existing operations. The entire process must be refactored to maintain quality and consistency as production is escalated.
For temperature control systems, this can be an even greater challenge. Temperature is fickle, and in an interconnected system there are many ways to inadvertently add or remove heat. High heat is also uniquely dangerous, posing risks not only the currently-processed batch, but also to the immediate and long-term health of all components in the system.
To maintain safe and healthy temperatures during scale-up, all aspects of the chiller and other cooling systems should be carefully reviewed. While no article can address every encounterable challenge, below you'll find many tips for the challenge of scaling up up a process with a recirculating chiller.
Rules of thumb
Whatever the size or urgency of your scale-up, there are two universal rules that you should keep in mind:
- Incorporate a safety capacity. Even simple setups are at risk of surprise heat fluctuations and efficiency loss. Generally, you want to incorporate a capacity safety factor of at least 20%. This is valuable insurance against small miscalculations, environmental changes, and aging equipment.
- Follow the manufacturer's advice & specifications. It's easy to equivocate chillers, but these are complex machines that differ from brand to brand and unit to unit. When scaling up, it's not uncommon for labs to upgrade the chiller with a different brand + model, or to operate more than one type of chiller. This can work perfectly, but keep in mind that every chiller is different and may have specifications and requirements to which you're lab isn't accustomed. You're already trusting the manufacturer with the design of the entire unit; you need to trust, too, that they know best how to maintain their own unit.
Tap water doesn't scale
In small scale cooling operations, the use of tap water is common. It's the cheapest available solution, and it does the job just fine. But if you're scaling up to an operation greater than 22 liters (5 gallons) per minute, be mindful of the cons of tap water, and be certain that it's the right solution for your lab (because it usually isn't!).
The 3 problems with tap water
The 3 big issues with tap water are temperature stability, expense, and availability.
Temperature stability is an issue because tap water temps just aren't uniform. Temps can fluctuate from one day to the next, a constantly-changing variable that can introduce uncertainty into production-level processes. Without a chiller between the setup and the tap, the process is at the mercy of an unknown.
Expense is an issue because tap water is hardly as cheap as it might at first seem. Tap water plus sewage treatment can be surprisingly expensive, especially around metropolitan areas. It's not uncommon for facilities to see water costs of $15,000+ a year. This is often much more expensive than a recirculating chiller, especially considering that a chiller's cost is distributed over its operational lifespan.
Lastly, tap water can be an issue during water shortages. Some areas of the United States -- such as California and the Southwest -- suffer from periodic droughts. The subsequent rationing and/or high water cost detrimentally impacts any business reliant on significant volumes of incoming tap water. Reducing this reliance is a way to reduce risk.
You should perform a cost-analysis to determine the true cost of relying on tap water. Large facilities may even contract environmental impact studies. Whatever your methodology, you should know how much tap water will cost your laboratory.
Alternatives to the tap
If tap water is imperfect for your scaled-up process, then the best solution is the recirculating chiller. A dedicated chiller bypasses all the challenges of using tap water in production operations: it's cheaper, more reliable, and protects your lab from droughts or environmental concerns.
There's always a chiller for your application. Chillers are manufactured in a wide array of sizes and capacities, so even the largest facilities can find chillers to suit their processes. High-volume circulators can even control more than one process or line, simplifying process design and reducing costs.
Chillers have other advantages over tap water. For one, they can use other fluids. Glycol- and alcohol-based fluids have lower heat capacities than water, which allows them to be cooled more quickly, improving the process's efficiency.
Additionally, modern chillers equipped with controllers offer exacting temperature control, guaranteeing temperatures within tenths of a degree Celsius.
Maximizing your chiller for scale-up
If you're using a chiller for your scaled-up process, then there are a few steps you can take to maximize its effectiveness.
- Keep tubing length short. The longer the tubing, the more heat is lost. The chiller's position in the floor layout can do much to shorten connection distance.
- Keep connections exact. If the tubing or its joints and connectors are too small, then the chiller's maximum flow will be inhibited. If the connectors are too large, fluid can be lost to leaking.
- Insulate everything. Insulation will protect tubing, connections, and vessels from heat loss.
- Choose compatible bath fluid. Make sure you choose the right bath fluid for your chiller and your process's temperature range. Most manufacturers sell fluid compatible with their chillers, but note that different models require different fluid formulations.
- Choose low viscosity fluid. Whatever your operating temperature range, choose a fluid with a low viscosity at that temperature to maximize flow rate.
- Validate & verify. Before you connect all components, separately test each one; this applies to temperature probes, controllers, and so on. You don't want to disconnect and reconnect the entire apparatus to fix what is likely a small problem.
Addressing demanding applications
Some applications are especially challenging. A demanding application is one that requires high volumes of low temperature (-20°C or less). This introduces complexities to any scale-up endeavor.
The primary solution to this problem is a large, modern chiller. Those with internal bath volumes of 10 gallons or greater will serve for most processes. A large reservoir is beneficial because of its inherent resistance to the temperature fluctuations that afflict smaller chillers.
If you choose a large chiller, note that atmospheric exposure must be avoided at extra low temps. Most fluids produce humidity at subzero temperatures, which can form ice crystals in the chiller's reservoir. This both inhibits performance and reduces the fluid's lifespan.
A jumbo chiller aside, the second solution to low temperature applications is to use an advanced temperature control system. While they only store a small volume of liquid (typically less than 6 gallons), it is quickly cooled and rapidly transferred throughout the system by use of a powerful pump. This solution isn't cheap, but it well-serves numerous applications due to its superb temperature range (-91 to 250°C).
The importance of communication
The modern lab is all about connectivity and clarity. Your chiller should function within the framework of a cohesive system.
A modern chiller can be connected to a remote computer or controller through a built-in connector, usually RS232. The connecting software allows for data capture, temperature monitoring, and emergency alarms. These features can make any lab better by eliminating manual labor and isolating the often-sensitive process apparatus from unwanted foot traffic. In some larger facilities, over one dozen chillers are connected and operated from a single computer: a highly efficient solution requiring minimum labor.
Chillers can even be connected to a handheld remote control. Multiple chillers can be connected in this way, allowing a researcher to monitor the process from anywhere in the lab. (Just don't lose the remote!)
What's a chiller worth?
While chillers typically aren't the most expensive component in a process, they aren't cheap. Their relative invisibility means that many labs underspend on the chiller, and are subsequently disappointed with the results. Many are left wondering why their cheap chiller isn't meeting its own supposed specifications.
The biggest common mistake you can make while scaling-up is to wildly underestimate the cost of a halt in production. For many labs and applications, the loss of a workday's processing output can easily cost thousands of dollars. And a severe equipment failure can sometimes take several days to correct: a catastrophic outcome for the lab's bottom line.
Humans aren't very good at assessing risk, and this scenario is no exception. Many labs simply don't protect themselves. They act as though their processing equipment is invulnerable, when in reality failure is inevitable given a long enough timeframe.
Once this is understood, the reticence towards quality equipment evaporates. It's not a needlessly pricey boondoggle; it's insurance against ruin. Care must be taken to procure quality equipment that will keep your process operational for years to come. This includes the recirculating chiller: if it fails, the process collapses, sometimes with the destruction of the batch.
But it's not all about the sticker price. When shopping for a chiller, be sure to look at the manufacturer's maintenance contract and service options. The warranty time period is an obvious indicator of the manufacturer's trust in the product's quality. Regular service can greatly increase the life of a chiller; the long-term savings are considerable.
If your operation is large (or particularly well-funded!), then a spare chiller is a worthwhile emergency mechanism, allowing processing to continue while the primary chiller is repaired or replaced. The perfect scenario is one in which the backup chiller is the same model as the production chiller. This facilitates on-the-fly replacement when an emergency strikes.
Scaling up for good
The chiller is a killer piece of equipment: potentially vital for your application, as it is in thousands of laboratories and facilities. Thankfully, modern chillers are manufactured for the challenge, with the quality and consistency required in every lab.
If you'd like help with finding and buying the perfect chiller, feel free to reach out to us at firstname.lastname@example.org or 1-833-476-9420. We provide recirculating chillers from the best brands in the industry: Julabo, Huber, and Across International. We know our way around the lab, and would be thrilled to support your growing laboratory.